Prevent Linux firewalls interfering with Samba commands in a home network that uses broadcast NetBIOS name resolution

Or “How come devices in a home network can browse SMB shares but Linux Samba commands and Windows nbtstat commands do not work properly?”

Introduction

In a previous post I explained how it is possible to browse SMB shares when using broadcast NetBIOS name resolution in a home network consisting of machines running Linux, Windows and other operating systems. Browsing SMB/Samba shares will work as expected, but Samba commands such as ‘smbtree‘, ‘smbclient‘ and ‘nmblookup‘ will not work properly if the Linux machines use a firewall that has not been configured for broadcast NetBIOS name resolution. This post is to explain how to do that.

If broadcast NetBIOS name resolution is being used and none of the Linux machines has a firewall enabled, or if their firewalls have been correctly configured, the output of e.g. the ‘smbtree‘ command on one of those machines would look something like the example below.

anne@akhanaten:~$ smbtree
Enter anne's password: 
HOME
        \\AKHANATEN                     Samba 4.3.11-Ubuntu
                \\AKHANATEN\IPC$                IPC Service (Samba 4.3.11-Ubuntu)
                \\AKHANATEN\guest               guest account
                \\AKHANATEN\matthew             matthew share
                \\AKHANATEN\marilla             marilla share
                \\AKHANATEN\anne                anne share
        \\TUTANKHAMUN                   Samba 4.5.10
                \\TUTANKHAMUN\Samsung_Xpress_C460FW     Samsung Xpress C460FW
                \\TUTANKHAMUN\Canon_MP560_Printer       Canon PIXMA MP560
                \\TUTANKHAMUN\Canon_MP510_Printer       Canon PIXMA MP510
                \\TUTANKHAMUN\Virtual_PDF_Printer       Virtual PDF Printer
                \\TUTANKHAMUN\IPC$              IPC Service (Samba 4.2.11)
                \\TUTANKHAMUN\Public
                \\TUTANKHAMUN\anne-share
                \\TUTANKHAMUN\print$
                \\TUTANKHAMUN\netlogon          Network Logon Service
        \\BTHUB5                        BT Home Hub 5.0A File Server
                \\BTHUB5\IPC$                   IPC Service (BT Home Hub 5.0A File Server)
        \\THUTMOSEIII                   Windows 10 computer

If Linux firewalls have not been correctly configured, the output would be missing some information about other machines in the network. For example, compare the output above with the output below from the same network, this time with the Linux firewalls configured using typical rules for Samba specified in Web articles, blog posts and forums.

anne@akhanaten:~$ smbtree
Enter anne's password: 
HOME
        \\AKHANATEN                     Samba 4.3.11-Ubuntu
                \\AKHANATEN\IPC$                IPC Service (Samba 4.3.11-Ubuntu)
                \\AKHANATEN\guest               guest account
                \\AKHANATEN\matthew             matthew share
                \\AKHANATEN\marilla             marilla share
                \\AKHANATEN\anne                anne share
        \\TUTANKHAMUN                   Samba 4.5.10
        \\BTHUB5                        BT Home Hub 5.0A File Server
        \\THUTMOSEIII                   Windows 10 computer

To avoid this problem you need to add a further Linux firewall rule to the set of rules usually used for Samba. Below I first list the usual firewall rules for Samba, then I give the additional rule necessary if using broadcast NetBIOS name resolution. In each case I give the applicable rules for a pure IPTABLES firewall and for UFW (Uncomplicated Firewall). The rules listed here assume the IP address range of the home network is 192.168.1.0/24, so change the range to suit the specific network.

Firewall rules typically specified for machines using Samba

IPTABLES

The rules listed below assume the machine uses interface eth0, so change the interface to suit the specific machine.

# NetBIOS Name Service (name resolution)
iptables -A INPUT -i eth0 -p udp --dport 137 -s 192.168.1.0/24 -j ACCEPT

# NetBIOS Datagram Service (BROWSER service)
iptables -A INPUT -i eth0 -p udp --dport 138 -s 192.168.1.0/24 -j ACCEPT

# NetBIOS Session Service (data transfer legacy SMB/NetBIOS/TCP)
iptables -A INPUT -i eth0 -p tcp --dport 139 -s 192.168.1.0/24 -j ACCEPT

# Microsoft Directory Service (data transfer SMB/TCP)
iptables -A INPUT -i eth0 -p tcp --dport 445 -s 192.168.1.0/24 -j ACCEPT

UFW

In some Linux distributions the ufw application allows a single command to add Samba support, such as:

user $ sudo ufw allow Samba

or

user $ sudo ufw allow CIFS

These ‘application profiles’ are specified in files in the directory /etc/ufw/applications.d/, so you could add application profiles or modify existing ones if you wish. In one of my installations the file /etc/ufw/applications.d/ufw-fileserver includes the following application profile for Samba, for example:

[CIFS]
title=SMB/CIFS server
description=SMB/CIFS server
ports=137,138/udp|139,445/tcp

If such an application profile does not exist in your installation, typical Samba rules can be added in UFW using the following two commands:

user $ sudo ufw allow from 192.168.1.0/24 to any port 137,138 proto udp
user $ sudo ufw allow from 192.168.1.0/24 to any port 139,445 proto tcp

The correct addition of the rules can be checked using the following command:

user $ sudo ufw status verbose
Password:
Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), disabled (routed)
New profiles: skip

To                         Action      From
--                         ------      ----
137,138/udp (CIFS)         ALLOW IN    192.168.1.0/24
139,445/tcp (CIFS)         ALLOW IN    192.168.1.0/24

The extra rule required when using broadcast NetBIOS name resolution

The reason why an extra rule is required when using broadcast NetBIOS name resolution is because UFW (which is based on IPTABLES) is ‘stateful’, as is a purely IPTABLES firewall (unless explicitly configured not to be stateful). The firewall does not consider packets it receives in response to its broadcast to be ESTABLISHED or RELATED, and therefore drops those packets. So, despite the IPTABLES and UFW rules listed above including a rule to accept incoming UDP packets on Port 137, any UDP packets received on Port 137 that do not constitute a one-to-one, two-way communication flow are dropped by the firewall. The extra rule below overrules this and makes the firewall accept packets coming from other devices’ Port 137 in response to broadcast NetBIOS Name Service packets. To do this, the extra rule uses a CT (Connection Tracking) helper named ‘netbios-ns‘ (obviously meaning ‘NetBIOS Name Service’). In order to use this rule the kernel must have been configured to use the IPTABLES ‘raw‘ table and to use CT (see the section ‘Kernel configuration’ further on).

IPTABLES

# All NetBIOS clients must have the netbios-ns helper enabled for broadcast name resolution to work
iptables -t raw -A OUTPUT -p udp -m udp --dport 137 -j CT --helper netbios-ns

By the way, in addition to flushing the usual tables, flush the ‘raw‘ table too when you restart the firewall:

iptables -t raw -F OUTPUT

UFW

Add the following lines to the end of the file /etc/ufw/before.rules

# The following is needed to enable Samba commands to
# work properly for broadcast NetBIOS name resolution
#
# raw table rules
*raw
:OUTPUT ACCEPT [0:0]
-F OUTPUT
-A OUTPUT -p udp -m udp --dport 137 -j CT --helper netbios-ns
COMMIT

Note that the output of the command ‘ufw status verbose‘ will not include the above rule. This is not a bug.

Kernel configuration

If you are using a binary-based distribution such as Ubuntu Linux, the kernel will probably have been configured to include the needed modules (CONFIG_IP_NF_RAW=m, CONFIG_IP6_NF_RAW=m and CONFIG_NETFILTER_XT_TARGET_CT=m), and the installation configured to load the modules automatically. However, if you are using a source-based distribution such as Gentoo Linux make sure the kernel configuration includes these three options before you build the kernel, and also add the module names ‘iptable_raw‘ and ‘xt_CT‘ to the module list in the file /etc/conf.d/modules as shown in the example below, so that the modules are loaded at boot:

modules="r8169 nvidia agpgart fuse bnep rfcomm hidp uvcvideo cifs mmc_block rtsx_pci snd-seq-midi vboxdrv vboxnetadp vboxnetflt iptable_raw xt_CT"

You can use the following two commands to check if the two modules are loaded:

user $ sudo lsmod | grep iptable_raw
user $ sudo lsmod | grep xt_CT

How to check the additional rule is active

You can use the command below whether you are using pure IPTABLES or UFW.

user $ sudo iptables -nvL -t raw
Password: 
Chain PREROUTING (policy ACCEPT 2613 packets, 1115K bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 2773 packets, 475K bytes)
 pkts bytes target     prot opt in     out     source               destination         
   16  1248 CT         udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:137 CT helper netbios-ns

The packet and byte counts will increase whenever you use a Samba command.

Bibliography

  1. The netfilter.org "iptables" project
  2. Iptables Tutorial
  3. Introduction to IPTables
  4. Gentoo Wiki : iptables
  5. Arch Linux Wiki : Samba : "Browsing" network fails with "Failed to retrieve share list from server"
  6. Ubuntu : Manpage : ufw-framework
  7. Gentoo Wiki : UFW

A correct method of configuring Samba for browsing SMB shares in a home network

SMB
SMB (Server Message Block) is the underlying protocol that Microsoft Windows computers use to connect to resources, such as file shares and printers, and to transfer information when the connections are established. Samba is the Linux implementation of SMB that allows file and printer information to be transferred between Windows and Linux computers. An early variant of the SMB protocol is known as ‘CIFS’ (Common Internet File System). CIFS is actually obsolete, so the correct term to use these days is ‘SMB’ (see the blog post Why You Should Never Again Utter The Word, "CIFS"), although ‘CIFS’ is still used sometimes when referring to SMB.

Terminology
You are likely to come across several terms when reading about Samba, such as NetBIOS, Active Directory (AD), Lightweight Directory Access Protocol (LDAP), Kerberos, Windows Internet Name Service (WINS) and Winbind, to name but a few. Most are used in larger corporate or enterprise networks but you can ignore most of them – only broadcast NetBIOS name resolution or WINS are necessary to configure Samba in small home networks. For example, my home network uses broadcast NetBIOS name resolution and sometimes has up to 15 devices connected (Linux, Windows 7/10, macOS, Android and iOS), all of which can browse file shares using SMB/Samba.

Note: You should not use Broadcast NetBIOS Name Resolution and WINS at the same time.

To explain the terminology – Active Directory is a central database of user accounts and passwords used primarily in Windows networks to authenticate users, and LDAP is the protocol that clients and servers use to access the Active Directory database. Kerberos is a separate encrypted authentication mechanism used for client-server applications, such as computers that access a specific file or web server, or SQL database. WINS is a mechanism for storing Windows computer name to IP address mappings on a central server – the WINS Server. Computers in a LAN interrogate the WINS server to obtain the IP addresses of other computers. It’s a bit like DNS except that the WINS Server stores Windows computer names rather than URLs or domain names. Winbind is a Unix/Linux mechanism that allows Windows NT accounts to look like a Unix service to Unix/Linux machines.

NetBIOS
How is NetBIOS relevant to Samba? Samba uses NetBIOS in three different ways:

  1. NetBIOS over UDP Port 137 to advertise Windows computer names for name to IP address resolution;

  2. NetBIOS over UDP Port 138 to advertise services that the computer offers and to elect a ‘Master Browser’ (explained below);

  3. SMB over NetBIOS over TCP/IP Port 139 to connect to file shares or printers. Once connected, the computers may negotiate using SMB direct over TCP/IP Port 445 to improve efficiency of the connection.

NetBIOS over UDP (Port 137) is a connectionless broadcast protocol that Windows machines use to advertise over the LAN their names and corresponding IP addresses. Other computers receive the broadcasts and cache the names and IP addresses in a name to IP address mapping table.

NetBIOS over UDP (Port 138) is a connectionless broadcast protocol that Windows machines use to advertise their eligibility to become the Master Browser or Backup Browser for a Windows Workgroup in the LAN. An automatic election process elects only one machine in a Workgroup to become the Master Browser for that workgroup, and elects one or more ‘Backup Browsers’ in the Workgroup. The Master Browser and Backup Browser(s) collate a list of all the computers in the Workgroup and the services that they offer. It is more efficient for a single computer to assume the master role and to collate the information than it is for the information to remain distributed. When you click on ‘Network’ in File Explorer’s ‘Network Neighbourhood’ window, your computer interrogates the Master Browser(s) to obtain a list of the Windows Workgroups in the LAN, the members of the Workgroup(s) and the file and printer services that each Workgroup member offers. If the Master Browser fails or is disconnected, a re-election takes place and a new Master Browser is elected from the list of Backup Browsers in that Workgroup. The same process occurs if you are using a Linux file manager (Dolphin in KDE, Nautilus in GNOME, etc.) with Samba. You can configure the ‘priority’ of the Samba server in each machine in the Workgroup so that it is either more likely or less likely to be elected the Master Browser for the Workgroup. You could even configure Samba on a Linux machine so that it will never be a Master Browser. (It is also possible to configure a Windows machine so that it will never be a Master Browser.)

     Renamed ‘Entire Network’ in some versions of Windows.
     Renamed ‘My Network Places’ or simply ‘Network’ in some versions of Windows.

SMB over NetBIOS over TCP/IP (Port 139) is a connection orientated protocol that Windows computers use to connect to file shares and printers, to retrieve directory listings and to transfer files. Having obtained a list of computers and file shares from the Master Browser, if you click on a particular file share to connect to it, your computer looks up the name of the target computer in the local name table, obtains the target computer’s IP address and initiates a SMB over NetBIOS over TCP/IP connection to it. The target computer then issues a username and password prompt for you to complete the connection. If authentication is successful, the SMB protocol is used to transfer a directory listing of the contents of the share. If you drag and drop a file from the share to your local machine, or vice-versa, SMB is used to transfer the file. Behind the scenes, during the initial connection set-up, your computer and the target carry out a negotiation. If both machines support SMB direct over TCP/IP, the directory listing and subsequent file transfer are transported using SMB over TCP/IP Port 445. This is much more efficient because it eliminates completely the NetBIOS overhead.

When you install and configure Samba on a Linux computer, the ‘smbd‘ and ‘nmbd‘ daemons enable all of the functionality above. In a small network you do not need to enable or use AD, LDAP, Kerberos, WINS, Winbind or anything else for that matter. Samba and its built-in NetBIOS mechanisms will allow you to participate in a Windows Workgroup environment to share and use folders, files and printers.

Workgroups
The majority of Windows computers running in home networks are configured, by default, in a single Workgroup. A Workgroup is a simple way for computers in small networks to advertise and share resources, such as folders and printers, with other members of the same group. You can configure multiple Workgroups in the same LAN but each computer can belong to only one Workgroup. The theory is that different computers can share different resources within their group.

Please Note: A Windows Workgroup is not the same thing as a Windows HomeGroup. The latter concept was introduced in Windows 7 and is an ‘evolution’ of the Workgroup concept, in which you share folders and files but specify a pre-determined group password. All computers wishing to join the HomeGroup specify the same password to connect to the resources in that group. Samba does not participate in Windows HomeGroups because the latter is a Windows-only feature.

Configuring Samba
Firstly, install Samba on the Linux computer. Use Samba 4 and avoid Samba 3, which is obsolete. I have several laptops and a Network Addressable Storage (NAS) server, all running Linux with various releases of Samba 4. I also have a desktop computer running Windows 10 for family use. In addition, family and friends connect various laptops running Windows 7 and Windows 10 to my home network, as well as tablets and smartphones (see How to Access Shared Windows Folders on Android, iPad, and iPhone). This NAS runs 24/7 so I could have configured Samba to always make it the Master Browser but this is not necessary as the remaining computers in the network will elect a new Master Browser should the NAS fail.

Below is a summary of the steps to configure Samba in a Windows Workgroup:

  1. Configure the same Workgroup name on all of the Windows computers (for example, How to Change Workgroup in Windows 10). The default Windows 10 Workgroup is called ‘WORKGROUP‘. In the example further down I used the Windows GUI to change the Workgroup name to ‘GREENGABLES‘. There is plenty of information on the Internet about how to configure Windows file sharing so I won’t repeat any of it here (for example, How to Enable Network Discovery and Configure Sharing Options in Windows 10 and How to set up file sharing on Windows 10 (Share files using File Explorer)).

  2. Configure Samba on the Linux machines by editing the file ‘/etc/samba/smb.conf‘ on each. The contents of the file ‘smb.conf‘ are shown below for a Linux NAS and two Linux laptops. The NetBIOS name of the NAS is ‘akhanaten‘ and the laptops are ‘tutankhamun‘ and ‘smenkhkare‘. You can use either of the smb.conf files of the two laptops as a template for the smb.conf file of any Linux computer in your own home network. You can ignore the smb.conf file of the NAS if you simply want to be able to browse SMB/Samba shares on other computers in your home network.

  3. Use the command ‘pdbedit‘ on each Linux machine to define and configure the Samba users on that machine. The command ‘smbpasswd‘ is an alternative to ‘pdbedit‘ but I recommend you use the latter, as ‘smbpasswd‘ is deprecated. Each Samba user must exist as a Linux user because it is the Linux users who own the shares and are used for authentication.

  4. The NAS has Linux users ‘anne‘, ‘marilla‘, ‘matthew‘ and ‘guest‘, whereas each of the laptops has a Linux user ‘anne‘. The user name does not have to be the same on different computers.

  5. The purpose of each variable in ‘smb.conf‘ is explained on the applicable Samba manual page (enter the command ‘man smb.conf‘ in a terminal window) and the Samba documentation page for smb.conf on the Web.

Furthermore, make sure the Winbind daemon is not running. If Winbind is installed, make sure the service is not running and is disabled.

smb.conf of NAS running Ubuntu Server Edition:

[global]
# SMB uses ports 139 & 445, as explained in this blog post
smb ports = 139 445
netbios name = akhanaten
workgroup = greengables

# Use either NetBIOS broadcast for name resolution or entries in the /etc/hosts file
name resolve order = bcast host

# Don't care if the workgroup name is upper or lower case
case sensitive = no

# User authentication is used to access the shares
security = user
map to guest = bad user
guest account = guest

# Don't allow the use of root for network shares
invalid users = root

# Domain master only applies to LANs that are inter-connected across a WAN
domain master = no

# This machine is eligible to be a Master Browser and its priority is 4
# (the higher the os level, the more preferred to be Master Browser)
# (the maximum allowable value for os level is 255)
preferred master = yes
os level = 4
dns proxy = no

# Always advertise the shares automatically
auto services = global

# Interfaces on which to listen for NetBIOS broadcasts and to allow SMB connections
# Include "lo" because it is the internal interface
# em1 is the name of the Ethernet interface, found using the ifconfig command
interfaces = lo em1
bind interfaces only = yes
log file = /var/log/samba/log.%m
max log size = 1000
syslog = 0

panic action = /usr/share/samba/panic-action %d
server role = standalone server
passdb backend = tdbsam
obey pam restrictions = yes

# Don't synchronise the Linux and Samba user passwords - they can be different
unix password sync = no
passwd program = /usr/bin/passwd %u
passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
pam password change = yes

# This Samba configuration does not advertise any printers
load printers = no

# File to map long usernames to shorter Unix usernames, if necessary
username map = /etc/samba/smbusers

# Allow guest user access if specified in the shares
guest ok = yes

# First user share is called "anne" - only user "anne" specified below can connect to the share
[anne]
comment = "anne share"
path = /nas/shares/anne
writeable = yes
valid users = anne

# Second user share is called "marilla" - only user "marilla" specified below can connect to the share
[marilla]
comment = "marilla share"
path = /nas/shares/marilla
writeable = yes
valid users = marilla

# Third user share is called "matthew" - only user "matthew" specified below can connect to the share
[matthew]
comment = "matthew share"
path = /nas/shares/matthew
writeable = yes
valid users = matthew

# Fourth user share is called "guest" - any user can connect to the share
[guest]
comment = "guest account"
path = /nas/shares/guest
writeable = yes
guest ok = yes
valid users = guest anne marilla matthew

smb.conf of laptop #1 running Gentoo Linux:

[global]
;no need to specify 'smb ports' as ports 139 & 445 used by default
workgroup = GREENGABLES
netbios name = tutankhamun
case sensitive = no
browseable = yes

;If this machine becomes a Master Browser, the following parameter allows it to hold the browse list
browse list = yes

printcap name = cups
printing = cups

log file = /var/log/samba/log.%m
max log size = 50

security = user
map to guest = bad user

encrypt passwords = yes
passdb backend = tdbsam

domain master = no
local master = yes
preferred master = yes
; os level = 6 on the other laptop, so I have made it 5 on this laptop.
os level = 5
name resolve order = bcast
wins support = no
dns proxy = no

;Listen for NetBIOS on Ethernet and Wireless interfaces
;Names of the interfaces found using ifconfig command
interfaces = enp4s0f1 wlp3s0

[netlogon]
comment = Network Logon Service
path = /var/lib/samba/netlogon
guest ok = yes

[printers]
comment = All Printers
path = /var/spool/samba
guest ok = yes
printable = yes
create mask = 0700

[print$]
path = /var/lib/samba/printers
write list = @adm root
guest ok = yes

[anne-share]
path = /home/anne/anne-share/
guest ok = yes
;read only = no
writeable = yes
browseable = yes
valid users = anne

[Public]
path = /home/anne/Public/
guest ok = yes
;read only = no
writeable = yes
browseable = yes

smb.conf of laptop #2 running Gentoo Linux:

[global]
;no need to specify 'smb ports' as ports 139 & 445 used by default
workgroup = GREENGABLES
netbios name = smenkhkare
case sensitive = no
browseable = yes

;If this machine becomes a Master Browser, the following parameter allows it to hold the browse list
browse list = yes

printcap name = cups
printing = cups

log file = /var/log/samba/log.%m
max log size = 50

security = user
map to guest = bad user

encrypt passwords = yes
passdb backend = tdbsam

domain master = no
local master = yes
preferred master = yes
; os level = 5 on the other laptop so I have made it 6 on this laptop
os level = 6
name resolve order = bcast
wins support = no
dns proxy = no

;Listen for NetBIOS on Ethernet and Wireless interfaces
;Names of the interfaces found using ifconfig command
interfaces = eth0 wlan0

[netlogon]
comment = Network Logon Service
path = /var/lib/samba/netlogon
guest ok = yes

[printers]
comment = All Printers
path = /var/spool/samba
guest ok = yes
printable = yes
create mask = 0700

[print$]
path = /var/lib/samba/printers
write list = @adm root
guest ok = yes

[anne-share]
path = /home/anne/share-share/
guest ok = yes
;read only = no
writeable = yes
browseable = yes
valid users = anne

[Public]
path = /home/anne/Public/
guest ok = yes
;read only = no
writeable = yes
browseable = yes

Samba Commands
The following are Samba commands you can use on any of the Linux computers to find information on the Samba shares.

The ‘smbtree‘ command lists the computers currently using SMB in the local network:

user $ smbtree
GREENGABLES
        \\AKHANATEN                     Samba 4.3.11-Ubuntu
                \\AKHANATEN\IPC$                IPC Service (Samba 4.3.11-Ubuntu)
                \\AKHANATEN\guest               guest account
                \\AKHANATEN\matthew             matthew share
                \\AKHANATEN\marilla             marilla share
                \\AKHANATEN\anne                anne share
        \\SMENKHKARE                    Samba 4.2.14
                \\SMENKHKARE\Samsung_CLX-8385ND Samsung CLX-8385ND
                \\SMENKHKARE\Canon_MP510_Printer        Canon MP510 Printer
                \\SMENKHKARE\Virtual_PDF_Printer        Virtual PDF Printer
                \\SMENKHKARE\Canon_MP560_WiFi   Canon MP560 WiFi
                \\SMENKHKARE\IPC$               IPC Service (Samba 4.2.14)
                \\SMENKHKARE\Public         
                \\SMENKHKARE\anne-share     
                \\SMENKHKARE\print$         
                \\SMENKHKARE\netlogon           Network Logon Service
        \\TUTANKHAMUN                   Samba 4.2.11
                \\TUTANKHAMUN\Samsung_Xpress_C460FW     Samsung Xpress C460FW
                \\TUTANKHAMUN\Canon_MP560_Printer       Canon PIXMA MP560
                \\TUTANKHAMUN\Canon_MP510_Printer       Canon PIXMA MP510
                \\TUTANKHAMUN\Virtual_PDF_Printer       Virtual PDF Printer
                \\TUTANKHAMUN\IPC$              IPC Service (Samba 4.2.11)
                \\TUTANKHAMUN\Public
                \\TUTANKHAMUN\anne-share
                \\TUTANKHAMUN\print$
                \\TUTANKHAMUN\netlogon          Network Logon Service
HOME
        \\BTHUB5                        BT Home Hub 5.0A File Server
                \\BTHUB5\IPC$                   IPC Service (BT Home Hub 5.0A File Server)

BTHUB5‘ is a BT Home Hub 5 (a network router and broadband modem). Notice that it is configured by default to be in a Windows Workgroup named ‘HOME‘. The BT Home Hub 5 has a USB port to which an external USB HDD could be attached, so I assume computers in the home network could have been configured to use the HOME Workgroup instead of GREENGABLES and hence access that USB HDD, i.e. use it as a NAS. However, no HDD is attached to the BT Home Hub 5, so just ignore the BTHUB5 device and the HOME Workgroup.

The ‘nmblookup‘ command is used to see which services each computer offers. The strings ‘..__MSBROWSE__.‘ and ‘<1d>‘ in the output indicate that the computer is currently the Master Browser (see the Microsoft TechNet article NetBIOS Over TCP/IP for details):

user $ nmblookup akhanaten
192.168.1.70 akhanaten<00>

user $ nmblookup -A 192.168.1.70
Looking up status of 192.168.1.70
        AKHANATEN       <00> -         B <ACTIVE>
        AKHANATEN       <03> -         B <ACTIVE>
        AKHANATEN       <20> -         B <ACTIVE>
        GREENGABLES     <00> - <GROUP> B <ACTIVE>
        GREENGABLES     <1e> - <GROUP> B <ACTIVE>

        MAC Address = 00-00-00-00-00-00

user $ nmblookup tutankhamun
192.168.1.79 tutankhamun<00>

user $ nmblookup -A 192.168.1.79
Looking up status of 192.168.1.79
        TUTANKHAMUN     <00> -         B <ACTIVE>
        TUTANKHAMUN     <03> -         B <ACTIVE>
        TUTANKHAMUN     <20> -         B <ACTIVE>
        GREENGABLES     <00> - <GROUP> B <ACTIVE>
        GREENGABLES     <1e> - <GROUP> B <ACTIVE>

        MAC Address = 00-00-00-00-00-00

user $ nmblookup smenkhkare
192.168.1.90 smenkhkare<00>

user $ nmblookup -A 192.168.1.90
Looking up status of 192.168.1.90
        SMENKHKARE      <00> -         B <ACTIVE>
        SMENKHKARE      <03> -         B <ACTIVE>
        SMENKHKARE      <20> -         B <ACTIVE>
        ..__MSBROWSE__. <01> - <GROUP> B <ACTIVE> 
        GREENGABLES     <00> - <GROUP> B <ACTIVE>
        GREENGABLES     <1d> -         B <ACTIVE>
        GREENGABLES     <1e> - <GROUP> B <ACTIVE>

        MAC Address = 00-00-00-00-00-00

..__MSBROWSE__.‘ and ‘<1d>‘ in the above output indicates that the laptop named smenkhkare is currently the Master Browser of the Workgroup named GREENGABLES. See the Microsoft TechNet article NetBIOS Over TCP/IP to interpret the output.

Now let’s look at what happens when thutmoseiii, the Windows 10 desktop connected to this home network, is powered up:

user $ smbtree
GREENGABLES
        \\AKHANATEN                     Samba 4.3.11-Ubuntu
                \\AKHANATEN\IPC$                IPC Service (Samba 4.3.11-Ubuntu)
                \\AKHANATEN\guest               guest account
                \\AKHANATEN\matthew             matthew share
                \\AKHANATEN\marilla             marilla share
                \\AKHANATEN\anne                anne share
        \\SMENKHKARE                    Samba 4.2.14
                \\SMENKHKARE\Samsung_CLX-8385ND Samsung CLX-8385ND
                \\SMENKHKARE\Canon_MP510_Printer        Canon MP510 Printer
                \\SMENKHKARE\Virtual_PDF_Printer        Virtual PDF Printer
                \\SMENKHKARE\Canon_MP560_WiFi   Canon MP560 WiFi
                \\SMENKHKARE\IPC$               IPC Service (Samba 4.2.14)
                \\SMENKHKARE\Public
                \\SMENKHKARE\anne-share
                \\SMENKHKARE\print$
                \\SMENKHKARE\netlogon           Network Logon Service
        \\TUTANKHAMUN                   Samba 4.2.11
                \\TUTANKHAMUN\Samsung_Xpress_C460FW     Samsung Xpress C460FW
                \\TUTANKHAMUN\Canon_MP560_Printer       Canon PIXMA MP560
                \\TUTANKHAMUN\Canon_MP510_Printer       Canon PIXMA MP510
                \\TUTANKHAMUN\Virtual_PDF_Printer       Virtual PDF Printer
                \\TUTANKHAMUN\IPC$              IPC Service (Samba 4.2.11)
                \\TUTANKHAMUN\Public
                \\TUTANKHAMUN\anne-share
                \\TUTANKHAMUN\print$
                \\TUTANKHAMUN\netlogon          Network Logon Service
        \\THUTMOSEIII                   Lounge Computer
HOME
        \\BTHUB5                        BT Home Hub 5.0A File Server
                \\BTHUB5\IPC$                   IPC Service (BT Home Hub 5.0A File Server)

user $ nmblookup thutmoseiii
192.168.1.74 thutmoseiii<00>
192.168.56.1 thutmoseiii<00>

user $ nmblookup -A 192.168.1.74
Looking up status of 192.168.1.74
        THUTMOSEIII     <20> -         B <ACTIVE> 
        THUTMOSEIII     <00> -         B <ACTIVE> 
        GREENGABLES     <00> - <GROUP> B <ACTIVE> 
        GREENGABLES     <1e> - <GROUP> B <ACTIVE> 

        MAC Address = AA-BB-CC-DD-EE-FF (anonymised by me)

So Linux computer smenkhkare remained the Master Browser. This is because the Windows 10 computer has its Registry subkey HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Browser\Parameters\MaintainServerList set to ‘Auto‘, and also there is no subkey \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Browser\Parameters\IsDomainMaster so implicitly its value is False (i.e. the computer is not a Preferred Master Browser). See Microsoft TechNet article Specifying Browser Computers for details.

By the way, notice that two IP addresses are listed for thutmoseiii. This is because thutmoseiii is connected to two network adapters: 192.168.1.74 is the IP address of thutmoseiii in the home network, and 192.168.56.1 is the IP address of the virtual network interface for the virtual computers in VirtualBox installed on thutmoseiii.

If the Samba service on smenkhkare is now stopped from the command line, Windows 10 computer thutmoseiii is elected Master Browser after more than a minute has elapsed:

user $ nmblookup -A 192.168.1.74
Looking up status of 192.168.1.74
        THUTMOSEIII     <20> -         B <ACTIVE> 
        THUTMOSEIII     <00> -         B <ACTIVE> 
        GREENGABLES     <00> - <GROUP> B <ACTIVE> 
        GREENGABLES     <1e> - <GROUP> B <ACTIVE> 
        GREENGABLES     <1d> -         B <ACTIVE> 
        ..__MSBROWSE__. <01> - <GROUP> B <ACTIVE>

        MAC Address = AA-BB-CC-DD-EE-FF (anonymised by me)

If the Samba service on smenkhkare is then restarted from the command line and the Windows 10 computer is allowed to go to sleep, the laptop named smenkhkare becomes the Master Brower again as expected.

NetBIOS Commands in Windows
Now let’s look at some NetBIOS equivalent commands on the Windows 10 computer (Windows computer name: thutmoseiii).

First let’s see which remote computers thutmoseiii detects:

C:\WINDOWS\system32>nbtstat -c

VirtualBox Host-Only Network 2:
Node IpAddress: [192.168.56.1] Scope Id: []

    No names in cache

Ethernet:
Node IpAddress: [192.168.1.74] Scope Id: []

                  NetBIOS Remote Cache Name Table

        Name              Type       Host Address    Life [sec]
    ------------------------------------------------------------
    AKHANATEN      <20>  UNIQUE          192.168.1.70        381
    TUTANKHAMUN    <20>  UNIQUE          192.168.1.79        407
    SMENKHKARE     <20>  UNIQUE          192.168.1.90        416

WiFi:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

Local Area Connection* 11:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

Four adapters are listed in the above output: ‘VirtualBox Host-Only Network 2‘, ‘Ethernet‘, ‘WiFi‘ and ‘Local Area Connection* 11‘. Let’s look at why they are listed:

  • The first adapter listed exists because VirtualBox is installed on thutmoseiii and has a virtual network adapter to enable virtual computers to be networked together (see What Is A Oracle VM VirtualBox Host-Only Network Adapter? if you don’t know what is a VirtualBox Host-Only Network Adapter).

  • The second adapter listed is the computer’s Ethernet adapter. thutmoseiii is connected to the home network via this interface, and the above output shows that thutmoseiii has correctly detected the three other computers connected to the home network.

  • The third adapter listed is the computer’s wireless adapter. thutmoseiii also has a Wi-Fi interface, currently disabled in Windows, hence no active wireless connection is listed.

  • The fourth adapter is a ‘Microsoft Wi-Fi Direct Virtual Adapter’ according to the output of the ipconfig/all command. As the Wi-Fi interface is currently disabled in Windows, no active connection is listed here either.

Now let’s see what thutmoseiii reports about itself:

C:\WINDOWS\system32>nbtstat -n

VirtualBox Host-Only Network 2:
Node IpAddress: [192.168.56.1] Scope Id: []

                NetBIOS Local Name Table

       Name               Type         Status
    ---------------------------------------------
    THUTMOSEIII    <20>  UNIQUE      Registered
    THUTMOSEIII    <00>  UNIQUE      Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1E>  GROUP       Registered
    GREENGABLES    <1D>  UNIQUE      Registered
    ☺☻__MSBROWSE__☻<01>  GROUP       Registered

Ethernet:
Node IpAddress: [192.168.1.74] Scope Id: []

                NetBIOS Local Name Table

       Name               Type         Status
    ---------------------------------------------
    THUTMOSEIII    <20>  UNIQUE      Registered
    THUTMOSEIII    <00>  UNIQUE      Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1E>  GROUP       Registered

WiFi:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

Local Area Connection* 11:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

The above is correct: thutmoseiii is the Master Browser in the Windows Workgroup of VirtualBox Host-Only Network 2, but not a Master Browser in the GREENGABLES Workgroup to which thutmoseiii is connected by Ethernet cable. As the Wi-Fi interface in thutmoseiii is currently disabled, no active wireless connection is listed.

Now let’s take a look at what thutmoseiii reports about akhanaten:

C:\WINDOWS\system32>nbtstat -a akhanaten

VirtualBox Host-Only Network 2:
Node IpAddress: [192.168.56.1] Scope Id: []

    Host not found.

Ethernet:
Node IpAddress: [192.168.1.74] Scope Id: []

           NetBIOS Remote Machine Name Table

       Name               Type         Status
    ---------------------------------------------
    AKHANATEN      <00>  UNIQUE      Registered
    AKHANATEN      <03>  UNIQUE      Registered
    AKHANATEN      <20>  UNIQUE      Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1E>  GROUP       Registered

    MAC Address = 00-00-00-00-00-00


WiFi:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

Local Area Connection* 11:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

The above is also correct, as akhanaten is indeed not a Master Browser.

Now let’s have a look at what thutmoseiii reports about tutankhamun:

C:\WINDOWS\system32>nbtstat -a tutankhamun

VirtualBox Host-Only Network 2:
Node IpAddress: [192.168.56.1] Scope Id: []

    Host not found.

Ethernet:
Node IpAddress: [192.168.1.74] Scope Id: []

           NetBIOS Remote Machine Name Table

       Name               Type         Status
    ---------------------------------------------
    TUTANKHAMUN    <00>  UNIQUE      Registered
    TUTANKHAMUN    <03>  UNIQUE      Registered
    TUTANKHAMUN    <20>  UNIQUE      Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1E>  GROUP       Registered

    MAC Address = 00-00-00-00-00-00


WiFi:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

Local Area Connection* 11:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

The above is also correct, as tutankhamun is indeed not a Master Browser.

Now let’s have a look at what thutmoseiii reports about smenkhkare:

C:\WINDOWS\system32>nbtstat -a smenkhkare

VirtualBox Host-Only Network 2:
Node IpAddress: [192.168.56.1] Scope Id: []

    Host not found.

Ethernet:
Node IpAddress: [192.168.1.74] Scope Id: []

           NetBIOS Remote Machine Name Table

       Name               Type         Status
    ---------------------------------------------
    SMENKHKARE     <00>  UNIQUE      Registered
    SMENKHKARE     <03>  UNIQUE      Registered
    SMENKHKARE     <20>  UNIQUE      Registered
    ☺☻__MSBROWSE__☻<01>  GROUP       Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1D>  UNIQUE      Registered
    GREENGABLES    <1E>  GROUP       Registered

    MAC Address = 00-00-00-00-00-00


WiFi:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

Local Area Connection* 11:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

The above is also correct, as smenkhkare is indeed the Master Browser (notice the ‘☺☻__MSBROWSE__☻‘ and ‘<1D>‘).

Q.E.D.
So there you have it; Browser Elections take place and the Master Browser is any one of the Linux or Windows computers in the home network, thus enabling SMB browsing to take place. No WINS, no LDAP, no AD, no Kerberos. All SMB communication is carried out using NetBIOS over TCP/IP and Broadcast NetBIOS Name Resolution, as shown by the output of the command ‘nbtstat -r‘ on thutmoseiii:

C:\WINDOWS\system32>nbtstat -r

    NetBIOS Names Resolution and Registration Statistics
    ----------------------------------------------------

    Resolved By Broadcast     = 65
    Resolved By Name Server   = 0

    Registered By Broadcast   = 233
    Registered By Name Server = 0

    NetBIOS Names Resolved By Broadcast
---------------------------------------------
           BTHUB5         <00>
           呂啈㕂†††††䱃噅坏㌲匰⁓†
           TUTANKHAMUN    <00>
           AKHANATEN      <00>
           SMENKHKARE     <00>

I assume the line of Chinese and other characters is because of some deficiency in NBTSTAT.EXE, CMD.EXE or Windows 10 generally — despite having entered ‘CHCP 65001‘ and chosen a Unicode TrueType font in CMD.EXE — but the important point is that the statistics listed by the ‘nbtstat -r‘ command clearly show that only broadcasts are used for NetBIOS Name resolution, as promised. NetBIOS name resolution works fine in the home network and all the sharing-enabled computers in the home network can browse SMB shares on other sharing-enabled computers, whether they are running Windows, Linux, macOS, Android or iOS. I reiterate that this is for a typical home network.

Command to find Master Browsers
In Linux you can use the ‘nmblookup‘ command as follows to find out which machine in the home network is currently the Master Browser in each Workgroup:

user $ nmblookup -M -- -
192.168.1.254 __MSBROWSE__
192.168.1.90 __MSBROWSE__
192.168.56.1 __MSBROWSE__

You can see above that there are currently three Master Browsers in this home network. Let’s check the details for these three Master Browsers:

user $ nmblookup -A 192.168.1.254
Looking up status of 192.168.1.254
        BTHUB5          <00> -         B <ACTIVE>
        BTHUB5          <03> -         B <ACTIVE>
        BTHUB5          <20> -         B <ACTIVE>
        ..__MSBROWSE__. <01> - <GROUP> B <ACTIVE>
        HOME            <1d> -         B <ACTIVE>
        HOME            <1e> - <GROUP> B <ACTIVE>
        HOME            <00> - <GROUP> B <ACTIVE>

        MAC Address = 00-00-00-00-00-00

You can see above that the machine BTHUB5 (which is actually the home network’s router) is the Master Browser in the Workgroup named HOME (see earlier).

user $ nmblookup -A 192.168.1.90
Looking up status of 192.168.1.90
        SMENKHKARE      <00> -         B <ACTIVE>
        SMENKHKARE      <03> -         B <ACTIVE>
        SMENKHKARE      <20> -         B <ACTIVE>
        ..__MSBROWSE__. <01> - <GROUP> B <ACTIVE>
        GREENGABLES     <00> - <GROUP> B <ACTIVE>
        GREENGABLES     <1d> -         B <ACTIVE>
        GREENGABLES     <1e> - <GROUP> B <ACTIVE>

        MAC Address = 00-00-00-00-00-00

You can see above that computer SMENKHKARE is currently the Master Browser in the Workgroup named GREENGABLES.

user $ nmblookup -A 192.168.56.1
Looking up status of 192.168.56.1
No reply from 192.168.56.1

You can see above that the network node 192.168.56.1 is inactive, which is not surprising considering that it is a node on a VirtualBox virtual subnet on the Windows 10 computer thutmoseiii (see earlier) and VirtualBox is not running at the moment on that computer.

On a Windows machine it is not quite so easy to find out which machines are currently Master Browsers. However, on the face of it the third-party utility lanscan.exe can do it (see How to Determine the Master Browser in a Windows Workgroup):

C:\WINDOWS\system32>lanscan

LANscanner v1.67 - ScottiesTech.Info

Scanning LAN...

Scanning workgroup: HOME...

Scanning workgroup: GREENGABLES...

BTHUB5            192.168.1.254    11-11-11-11-11-11  HOME         MASTER
THUTMOSEIII       192.168.56.1     22-22-22-22-22-22  GREENGABLES  MASTER
SMENKHKARE        192.168.1.90     aa-bb-cc-dd-ee-ff  GREENGABLES  MASTER
TUTANKHAMUN       192.168.1.79     33-33-33-33-33-33  GREENGABLES
AKHANATEN         192.168.1.70     55-55-55-55-55-55  GREENGABLES

Press any key to exit...

(MAC addresses anonymised by me.)

Notice above that lanscan.exe listed the VirtualBox virtual subnet node 192.168.56.1 in Windows 10 computer thutmoseiii (see earlier) but omitted to list the node 192.168.1.74 (also thutmoseiii) in the real network. Now, in this particular case thutmoseiii on 192.168.1.74 is not a Master Browser. Nevertheless, as lanscan.exe is supposed to list all nodes, its failure to list the node 192.168.1.74 is a shortcoming.

And what happens if thutmoseiii on node 192.168.1.74 becomes a Master Browser? In that case lanscan.exe still omits the node from the list and, in addition, wrongly shows tutankhamun as a Master Browser:

C:\WINDOWS\system32>nbtstat -n

VirtualBox Host-Only Network 2:
Node IpAddress: [192.168.56.1] Scope Id: []

                NetBIOS Local Name Table

       Name               Type         Status
    ---------------------------------------------
    THUTMOSEIII    <20>  UNIQUE      Registered
    THUTMOSEIII    <00>  UNIQUE      Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1E>  GROUP       Registered
    GREENGABLES    <1D>  UNIQUE      Registered
    ☺☻__MSBROWSE__☻<01>  GROUP       Registered

Ethernet:
Node IpAddress: [192.168.1.74] Scope Id: []

                NetBIOS Local Name Table

       Name               Type         Status
    ---------------------------------------------
    THUTMOSEIII    <20>  UNIQUE      Registered
    THUTMOSEIII    <00>  UNIQUE      Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1E>  GROUP       Registered
    GREENGABLES    <1D>  UNIQUE      Registered
    ☺☻__MSBROWSE__☻<01>  GROUP       Registered

WiFi:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

Local Area Connection* 11:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

C:\WINDOWS\system32>nbtstat -A 192.168.1.79

VirtualBox Host-Only Network 2:
Node IpAddress: [192.168.56.1] Scope Id: []

    Host not found.

Ethernet:
Node IpAddress: [192.168.1.74] Scope Id: []

           NetBIOS Remote Machine Name Table

       Name               Type         Status
    ---------------------------------------------
    TUTANKHAMUN    <00>  UNIQUE      Registered
    TUTANKHAMUN    <03>  UNIQUE      Registered
    TUTANKHAMUN    <20>  UNIQUE      Registered
    GREENGABLES    <00>  GROUP       Registered
    GREENGABLES    <1E>  GROUP       Registered

    MAC Address = 00-00-00-00-00-00


WiFi:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

Local Area Connection* 11:
Node IpAddress: [0.0.0.0] Scope Id: []

    Host not found.

C:\WINDOWS\system32>lanscan

LANscanner v1.67 - ScottiesTech.Info

Scanning LAN...

Scanning workgroup: HOME...

Scanning workgroup: GREENGABLES...

BTHUB5            192.168.1.254    11-11-11-11-11-11  HOME         MASTER
THUTMOSEIII       192.168.56.1     22-22-22-22-22-22  GREENGABLES  MASTER
TUTANKHAMUN       192.168.1.79     33-33-33-33-33-33  GREENGABLES  MASTER
SMENKHKARE        192.168.1.90     aa-bb-cc-dd-ee-ff  GREENGABLES
AKHANATEN         192.168.1.70     55-55-55-55-55-55  GREENGABLES

Press any key to exit...

(MAC addresses anonymised by me.)

Linux appears to have the edge on Windows in this respect, as the Samba command ‘nmblookup -M -- -‘ detects all the Master Browsers correctly in the above situation:

user $ nmblookup -M -- -
192.168.1.254 __MSBROWSE__
192.168.1.74 __MSBROWSE__
192.168.56.1 __MSBROWSE__

So it appears that, from a Windows computer, the only sure way to find all Master Browsers is to use the command ‘nbtstat -a <computer name>‘ to check each remote machine in the home network, plus the command ‘nbtstat -n‘ to check the Windows computer you are using.

Footnote
The ebuild of the current Gentoo Stable Branch package net-fs/samba-4.2.11 (and probably the ebuild of the Testing Branch package net-fs/samba-4.2.14 as well) is not entirely correct, as it pulls in unnecessary dependencies (see Gentoo Bug Report No. 579088 – net-fs/samba-4.x has many hard dependencies, make some optional). For example, Kerberos is not required at all if you are not using LDAP, AD, etc. and are just using NETBIOS Name Resolution by Broadcast in a Windows Workgroup (like most home users). However, the Gentoo samba ebuild forces the user to install Kerberos (either the MIT implementation app-crypt/mit-krb5 or the Heimdal implementation app-crypt/heimdal) even if you specify that Samba should be built without support for LDAP, AD, etc. This does not cause any harm, but it is unnecessary.

user $ eix -I samba
[I] net-fs/samba
     Available versions:  3.6.25^t 4.2.11 ~4.2.14 [M]~4.3.11 [M]~4.4.5 [M]~4.4.6 [M]~4.5.0 {acl addc addns ads (+)aio avahi caps (+)client cluster cups debug dmapi doc examples fam gnutls iprint ldap ldb +netapi pam quota +readline selinux +server +smbclient smbsharemodes swat syslog +system-mitkrb5 systemd test (+)winbind zeroconf ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32" PYTHON_TARGETS="python2_7"}
     Installed versions:  4.2.11(19:40:03 16/09/16)(avahi client cups fam gnutls pam -acl -addc -addns -ads -aio -cluster -dmapi -iprint -ldap -quota -selinux -syslog -system-mitkrb5 -systemd -test -winbind ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="64 -32 -x32" PYTHON_TARGETS="python2_7")
     Homepage:            http://www.samba.org/
     Description:         Samba Suite Version 4

If you are a Gentoo Linux user, you can merge the package net-fs/samba with the same USE flags shown above (obviously change “-systemd” to “systemd” if you use systemd instead of OpenRC), and use the laptops’ smb.conf files shown in this post as templates, and you will be able to share files and printers using Samba and NetBIOS name resolution. Don’t forget to use pdbedit to define the Samba users, and don’t forget to stop and disable winbindd if it is already installed.

Further reading

ADDENDUM (October 30, 2016): You probably already use the Public folder in Windows. If not, you can find a brief explanation in the article Simple Questions: What is the Public Folder & How to Use it?. There are a number of default sub-folders in C:\Users\Public\ on a Windows machine. There are some differences depending on the version of Windows, but in Windows 10 (Anniversary Update) these sub-folders are named:

C:\Public\Libraries
C:\Public\Public Account Pictures
C:\Public\Public Desktop
C:\Public\Public Documents
C:\Public\Public Downloads
C:\Public\Public Music
C:\Public\Public Pictures
C:\Public\Public Videos

These predefined sub-folders are not ordinary folders, and I have noticed a surmountable minor limitation when accessing them from a Linux machine using Samba, as explained below.

If I enable Public Folder Sharing on a Windows machine (‘Turn on sharing so that anyone with network access can read and write files in the Public folders’) and configure the security permissions of the Public folder for Everyone, from another Windows machine in the Workgroup I can copy files to the first machine’s Public folder and default sub-folders. From a Linux machine in the Workgroup I can copy files to the Public folder on Windows machines in the Workgroup but I cannot copy files to the default sub-folders (the Dolphin file manager displays the error message ‘Access denied. Could not write to .‘). However, this is not a big deal because I can copy files into the Public folder itself and into manually created sub-folders in the Public folder.

KDE Connect on a hotel Wi-Fi network

I am a fan of KDE Connect (see my 2014 post about an earlier version), but had previously been unable to use it with a hotel network. However today I managed to do that, and here is how I did it …

I first connected my laptop and my Samsung Galaxy Note 4 to the hotel’s Wi-Fi network, then used the ifconfig command in Linux on my laptop to find the IP address of my laptop on the hotel’s network. Note that the IP address one sees if one uses a Web site such as WhatIsMyIPAddress will be the laptop’s outward-facing IP address, not the IP address of the laptop on the hotel network. For example, the ifconfig command has just shown me that my current DHCP-allocated IP address is 10.154.245.40 on this hotel’s network for this session whereas the Web site WhatIsMyIPAddress is showing my IP address as 78.100.57.102.

By the way, I can also use the excellent Android utility Fing on my Galaxy Note 4 to find the IP address of my laptop on the hotel’s network. It is quite interesting to use Fing to see what other devices (their hostname and IP address) are currently connected to the hotel’s network.

Anyway, then I launched KDE Connect on the Galaxy Note 4, tapped and ‘Add devices by IP’, and entered the laptop’s IP address (10.154.245.40 in this specific case). I was able to pair with KDE Connect running on my laptop and send files from my phone to the laptop, and vice versa.

NetworkManager: Failed to activate – The name org.freedesktop.NetworkManager was not provided by any .service files

Because I need to connect quickly and easily to numerous wired and wireless networks (DHCP or static IP addressing), I use NetworkManager in my Gentoo Linux amd64 installation running OpenRC and KDE 4. My Clevo W230SS laptop has an Intel Dual Band Wireless-AC 7260 Plus Bluetooth adapter card, and my installation uses the iwlwifi module:

# lspci -knn | grep Net -A2
03:00.0 Network controller [0280]: Intel Corporation Wireless 7260 [8086:08b1] (rev bb)
        Subsystem: Intel Corporation Dual Band Wireless-AC 7260 [8086:4070]
        Kernel driver in use: iwlwifi
# lsmod | grep iwl
iwlmvm                143919  0
iwlwifi                75747  1 iwlmvm

As I am using NetworkManager instead of netifrc, in accordance with the instructions in the Gentoo Wiki article on NetworkManager I do not have any net.* services enabled (not even net.lo):

# rc-update show -v
       NetworkManager |      default                 
                acpid |                              
            alsasound |                              
         avahi-daemon |                              
       avahi-dnsconfd |                              
               binfmt | boot                         
            bluetooth |      default                 
             bootmisc | boot                         
         busybox-ntpd |                              
     busybox-watchdog |                              
                clamd |                              
          consolefont |                              
           consolekit |      default                 
               cronie |      default                 
         cups-browsed |      default                 
                cupsd |      default                 
                 dbus |      default                 
                devfs |                       sysinit
               dhcpcd |                              
                dhcpd |                              
             dhcrelay |                              
            dhcrelay6 |                              
                dmesg |                       sysinit
              dropbox |                              
           fancontrol |                              
                 fsck | boot                         
                 fuse |                              
           git-daemon |                              
                  gpm |                              
              hddtemp |                              
             hostname | boot                         
              hwclock | boot                         
            ip6tables |                              
             iptables |                              
              keymaps | boot                         
            killprocs |              shutdown        
    kmod-static-nodes |                       sysinit
           lm_sensors |                              
                local |      default                 
           localmount | boot                         
             loopback | boot                         
      mit-krb5kadmind |                              
          mit-krb5kdc |                              
       mit-krb5kpropd |                              
              modules | boot                         
             mount-ro |              shutdown        
                 mtab | boot                         
                mysql |                              
                  nas |                              
         net.enp4s0f1 |                              
               net.lo |                              
             netmount |      default                 
           ntp-client |                              
                 ntpd |                              
           nullmailer |                              
              numlock |                              
  nvidia-persistenced |                              
           nvidia-smi |                              
              osclock |                              
              pciparm |                              
               procfs | boot                         
              pwcheck |                              
            pydoc-2.7 |                              
            pydoc-3.4 |                              
               rfcomm |                              
                 root | boot                         
               rsyncd |                              
            s6-svscan |                              
                samba |      default                 
                saned |                              
            saslauthd |                              
            savecache |              shutdown        
                 sntp |                              
                 sshd |      default                 
             svnserve |                              
                 swap | boot                         
            swapfiles | boot                         
              swclock |                              
               sysctl | boot                         
                sysfs |                       sysinit
            syslog-ng |      default                 
        teamviewerd10 |                              
         termencoding | boot                         
             timidity |                              
         tmpfiles.dev |                       sysinit
       tmpfiles.setup | boot                         
               twistd |                              
                 udev |                       sysinit
                  ufw | boot                         
              urandom | boot                         
       wpa_supplicant |                              
                  xdm |      default                 
            xdm-setup |

I have left the netmount service enabled in case I want to use network-attached file shares at home or in one of the various office locations where I work.

Networking works fine on my laptop with the many wired and wireless networks I have used except for one particular public wireless network (it is in an airport, has multiple Access Points, and its Access Points only support 802.11a/b/g, which may or may not be relevant) for which the following message would usually appear in a pop-up window when I tried to connect to the network from the KDE network management GUI after start-up:

Failed to activate
The name org.freedesktop.NetworkManager was not provided by any .service files

Error message displayed by KDE when trying to connect to one specific network

Error message displayed by KDE when trying to connect to one specific network


This occurred with both networkmanager-1.0.2-r1 and networkmanager-1.0.6, the two Stable Branch releases of NetworkManager currently available in Gentoo Linux.

The wireless network is not the only network at that particular location, and the ‘Failed to activate’ message occurred whichever network (wireless or wired) I tried to access at that location. When this problem occurred, it transpired that the NetworkManager service was not running (it had crashed):

$ nmcli d
Error: NetworkManager is not running.
$ rc-status
Runlevel: default
 dbus                   [  started  ]
 NetworkManager         [  crashed  ]
 netmount               [  started  ]
 syslog-ng              [  started  ]
 cupsd                  [  started  ]
 samba                  [  crashed  ]
 consolekit             [  started  ]
 cronie                 [  started  ]
 bluetooth              [  started  ]
 xdm                    [  started  ]
 cups-browsed           [  started  ]
 sshd                   [  started  ]
 local                  [  started  ]
Dynamic Runlevel: hotplugged
Dynamic Runlevel: needed
 xdm-setup              [  started  ]
 avahi-daemon           [  started  ]
Dynamic Runlevel: manual

(I am not bothered that Samba crashes in that particular location. It crashes even if a connection is established, because the public wireless network does not provide network file systems. Samba works fine when I connect the laptop to an office network or to my home network.)

Even if the ‘Failed to activate’ message occurred, sometimes (but not always) the laptop could still connect to networks after I restarted the NetworkManager service (albeit sometimes it was necessary to restart it more than once):

# /etc/init.d/NetworkManager restart

When it is possible to connect to networks, the NetworkManager service is of course running:

$ nmcli d
DEVICE    TYPE      STATE        CONNECTION           
sit0      sit       connected    sit0                 
wlp3s0    wifi      connected    Free_Airport_Internet
enp4s0f1  ethernet  unavailable  --                   
lo        loopback  unmanaged    --        
$ rc-status
Runlevel: default
 dbus                   [  started  ]
 NetworkManager         [  started  ]
 netmount               [  started  ]
 syslog-ng              [  started  ]
 cupsd                  [  started  ]
 samba                  [  crashed  ]
 consolekit             [  started  ]
 cronie                 [  started  ]
 bluetooth              [  started  ]
 xdm                    [  started  ]
 cups-browsed           [  started  ]
 sshd                   [  started  ]
 local                  [  started  ]
Dynamic Runlevel: hotplugged
Dynamic Runlevel: needed
 xdm-setup              [  started  ]
 avahi-daemon           [  started  ]
Dynamic Runlevel: manual

I searched the Web for the error message and, based on a recommendation on the Web page ‘nm-applet gives errors‘ claiming the problem is due to the iwlwifi driver when used with an Intel 7260 controller, I created a file /etc/modprobe.d/iwlwifi.conf containing the following line, and rebooted:

options iwlwifi power_save=0

However, the error message still occurred. So I changed the iwlwifi module options line to the following, as also recommended on that page, and rebooted:

options iwlwifi 11n_disable=1 power_save=0

However, the error message still occurred.

The default value for OpenRC’s rc_depend_strict variable is YES if rc_depend_strict is not declared in the file /etc/rc.conf, but I do not think that is the cause of the problem:

# Do we allow any started service in the runlevel to satisfy the dependency
# or do we want all of them regardless of state? For example, if net.eth0
# and net.eth1 are in the default runlevel then with rc_depend_strict="NO"
# both will be started, but services that depend on 'net' will work if either
# one comes up. With rc_depend_strict="YES" we would require them both to
# come up.
#rc_depend_strict="YES"

As already mentioned, sometimes just restarting the NetworkManager service once or more did enable the laptop to connect to the network. This made me wonder whether the problem had something to do either with the timing of the launch of the NetworkManager service or with the timing of the service establishing a connection. As netmount is the only other network-related service enabled at start-up, I checked the netmount service’s configuration file /etc/conf.d/netmount to see what it contained (it’s the same in both the latest stable openrc-0.17 and the latest testing openrc-0.18.2):

# You will need to set the dependencies in the netmount script to match
# the network configuration tools you are using. This should be done in
# this file by following the examples below, and not by changing the
# service script itself.
#
# Each of these examples is meant to be used separately. So, for
# example, do not set rc_need to something like "net.eth0 dhcpcd".
#
# If you are using newnet and configuring your interfaces with static
# addresses with the network script, you  should use this setting.
#
#rc_need="network"
#
# If you are using oldnet, you must list the specific net.* services you
# need.
#
# This example assumes all of your netmounts can be reached on
# eth0.
#
#rc_need="net.eth0"
#
# This example assumes some of your netmounts are on eth1 and some
# are on eth2.
#
#rc_need="net.eth1 net.eth2"
#
# If you are using a dynamic network management tool like
# networkmanager, dhcpcd in standalone mode, wicd, badvpn-ncd, etc, to
# manage the network interfaces with the routes to your netmounts, you
# should list that tool.
#
#rc_need="networkmanager"
#rc_need="dhcpcd"
#rc_need="wicd"
#
# The default setting is designed to be backward compatible with our
# current setup, but you are highly discouraged from using this. In
# other words, please change it to be more suited to your system.
#
rc_need="net"

As I am using NetworkManager rather than netifrc, I followed the instructions in the file’s comments and changed the file’s contents from:

rc_need="net"

to:

rc_need="networkmanager"

After making the above change, the console messages at boot-up included a new message:

* ERROR: netmount needs service(s) networkmanager

That message made sense: rc_need had been set to "networkmanager" and, obviously, netmount can only do its job if NetworkManager is running (AND a network connection has been established). However, notice that the name of the NetworkManager service initscript is /etc/init.d/NetworkManager, not /etc/init.d/networkmanager. In other words, the instructions in /etc/conf.d/netmount are wrong: the name of the service is actually ‘NetworkManager‘, not ‘networkmanager‘. So I changed /etc/conf.d/netmount to contain rc_need="NetworkManager" instead of rc_need="networkmanager" and, unsurprisingly, the above-mentioned error message no longer occurs. I have filed Gentoo Bugzilla Bug Report No. 564846 requesting that the comment in the configuration file be changed.

Nevertheless, the ‘Failed to activate’ message still occurred when I tried to connect to any network at that location by using the DE’s network management GUI, and therefore I still needed to restart the NetworkManager service manually in order to be able to connect to any network there. Although I am not yet sure of the root cause and solution, I have found a work-around which avoids me having to manually restart the NetworkManager service, as explained below.

Although OpenRC correctly launches the NetworkManager service, that service remains inactive until it actually establishes a network connection. This is not a bug, it is the way OpenRC and NetworkManager work (see the explanation in the Gentoo Forums thread NetworkManager has started, but is inactive). This is why the following console message appears during boot-up:

* WARNING: NetworkManager has already started, but is inactive

If you did not configure NetworkManager to connect automatically to a network, after logging-in to the DE you will need to use the DE’s network management GUI (plasma-nm in the case if KDE, nm-applet in the case of e.g. Xfce) to tell NetworkManager to connect to the desired network. However, I found that waiting that long before trying to connect is too late to avoid the ‘Failed to activate’ problem, i.e. NetworkManager crashes after a while. I do not know why this happens, but it usually happens only when I am at the location covered by one specific wireless network (which is why I wonder if the problem is a result of that network only supporting 802.11a/b/g). By configuring NetworkManager to connect automatically to the wireless network which seemed to trigger the problem, the NetworkManager service tries to connect earlier. It is possible to configure NetworkManager to do this either by using the DE network GUI and ticking ‘Automatically connect to this network when it is available’ for the relevant network connection, or by directly editing the relevant connection’s file in the directory /etc/NetworkManager/system-connections/.

Of the various wired and wireless connections I had configured on the laptop, I had named the problematic wireless network’s connection ‘Free_Airport_Internet’. So I edited the file /etc/NetworkManager/system-connections/Free_Airport_Internet and deleted the line ‘autoconnect=false‘ in the [connections] section of the file (the default value of the autoconnect variable is TRUE – see man nm-settings). I could instead have done this by using the DE’s network manager GUI and ticking ‘Automatically connect to this network when it is available’ for that network connection. Now, when the laptop boots, NetworkManager tries to connect to that network and the ‘Failed to activate’ problem is avoided. This works with or without the iwlwifi driver options I mentioned above, so, despite the claim on the Web page I referenced above, the root cause of the problem does not appear to be the iwlwifi driver. What I don’t understand is why the problem only seems to occur with one particular network (a public wireless network which happens to only support 802.11a/b/g), i.e. even if none of the NetworkManager connection files in my installation have been configured to try to establish a connection automatically, with all the other wireless networks I have used in other locations (I believe those all support at least 802.11a/b/g/n) I have been able to establish a connection manually by using the DE’s network management GUI.

The bottom line

If your installation uses NetworkManager and you experience the ‘Failed to activate’ message when trying to connect to networks from the DE’s network management GUI, check if the NetworkManager service is running. You can check by using the command ‘nmcli d‘ in a console. If it is not running, try to restart the NetworkManager service from the command line. If the connection is not already configured to start automatically, configure it to start automatically in order to try to make NetworkManager become active at an early stage.

POSTSCRIPT (November 6, 2015)

The two links below are to old bug reports regarding earlier versions of NetworkManager having trouble using wireless networks with multiple Access Points. I wonder if the problem I saw with NetworkManager crashing when not configured to connect automatically to the specific network I mentioned above is somehow related to those problems:

background scanning causes drivers to disassociate – WiFi roaming causes NetworkManager to lose routing

network-manager roams to (none) ((none)) – background scanning

Roaming to BSSID “(none)” certainly happens with this particular network too, as shown by the messages in the laptop’s system log from yesterday when I was using the laptop with that network (the laptop was stationary the whole time):

# cat /var/log/messages | grep "Nov  5 11" | grep NetworkManager | grep \(none\)
Nov  5 11:01:22 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID 04:C5:A4:C3:F9:EE (Free_Airport_Internet) to (none) ((none))
Nov  5 11:01:22 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID (none) ((none)) to B8:BE:BF:69:89:6E (Free_Airport_Internet)
Nov  5 11:13:23 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID B8:BE:BF:69:89:6E (Free_Airport_Internet) to (none) ((none))
Nov  5 11:13:23 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID (none) ((none)) to 04:C5:A4:C3:F9:EE (Free_Airport_Internet)
Nov  5 11:15:23 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID 04:C5:A4:C3:F9:EE (Free_Airport_Internet) to (none) ((none))
Nov  5 11:15:23 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID (none) ((none)) to B8:BE:BF:69:89:6E (Free_Airport_Internet)
Nov  5 11:19:22 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID B8:BE:BF:69:89:6E (Free_Airport_Internet) to (none) ((none))
Nov  5 11:19:23 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID (none) ((none)) to B8:BE:BF:69:89:6E (Free_Airport_Internet)
Nov  5 11:49:50 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID B8:BE:BF:69:89:6E (Free_Airport_Internet) to (none) ((none))
Nov  5 11:49:50 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID (none) ((none)) to 68:BC:0C:A1:3C:DE (Free_Airport_Internet)
Nov  5 11:51:51 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID 68:BC:0C:A1:3C:DE (Free_Airport_Internet) to (none) ((none))
Nov  5 11:51:51 clevow230ss NetworkManager[2459]:   (wlp3s0): roamed from BSSID (none) ((none)) to B8:BE:BF:69:89:6E (Free_Airport_Internet)

Today I’m using a hotel network in my hotel room, and that does not roam to BSSID “(none)”, but I don’t know if my room is within range of more than one Access Point:

# cat /var/log/messages | grep "Nov  6" | grep NetworkManager | grep \(none\)
#

Anyway, with the work-around described in this post I have not had any further trouble accessing the particular network, but it would be interesting to know the root cause.

‘Waiting for 192.168.1.254…’ (Why I could not access a home hub’s management page)

I had not been able to access the Manager of the BT Home Hub 3 on my home network to view and configure the hub’s settings. All the network’s users could access the Internet, and I could ping the hub, but trying to access the BT Home Hub Manager from a Web browser resulted in the message ‘Waiting for 192.168.1.254…’. The same thing happened whatever the PC, OS, browser and method of connection (wired or wireless). Sometimes, after about ten minutes or so, an incomplete Manager page would appear, but usually the browser would just display ‘Waiting for 192.168.1.254…’ forever.

I should point out that my Ethernet wired connections use Powerline adapters (HomePlug) connected to the mains wiring of my semi-detached house.

Actually, I did find a temporary work-around to enable me to access the Home Hub Manager. If I switched off then on the power supply to the Home Hub I could access the Manager for a short period (the time varied, but typically was less than half an hour). Then I would be back in the same position of seeing ‘Waiting for 192.168.1.254…’ in a browser window if I tried later to access the Manager. Although I do not need to access the Home Hub Manager often, it was still a nuisance to have to cycle the power to the hub every time I needed to access the Manager.

Searching the Web, it seems this is quite a common problem and can occur irrespective of the manufacturer of the hub (or router) and its IP address. In some cases users have fixed the problem by upgrading the hub’s firmware or by performing a ‘factory reset’ of the hub, but some users never found a solution.

In my case, the BT Home Hub 3 has the latest available version of firmware installed. Not only did I check that via the Web, I also checked the firmware version of another BT Home Hub 3 in the house of someone I know who lives in another town. The curious thing was that he has no trouble accessing the BT Home Hub Manager (also IP address 192.168.1.254).

So I decided to perform a ‘factory reset’ of the Home Hub, but that made no difference.

Then, after many hours searching the Web, I found a thread about a similar problem with a different model of hub: Can’t access BT HomeHub 4? But I’m online ok?. A post by user troublegum in that thread made me sit up:

I still reckon it’s the homeplugs. Regardless of whether your PC is connected to it or not, If one of them is connected to your neighbour’s as well as your router, then it’s going to put 2 DHCP servers on your network.

Disconnect the homeplug from the router, renew your DHCP lease if necessary and try again.

Even before finding that thread I had wondered if the problem was somehow linked to my use of Powerline (HomePlug) adapters.

It seems that, if one PC on a home network is connected to the Home Hub via a Powerline adapter AND a neighbour also happens to be using Powerline adapters AND his single-phase mains house wiring is somehow linked to yours (which is unusual, as adjacent houses are normally connected to a different mains phase), there is the possibility that none of your PCs will be able to access the Home Hub Manager (even if they are connected directly to the Home Hub by Ethernet cable or Wi-Fi rather than via a Powerline adapter).

I have been using Powerline (HomePlug) adapters successfully for about nine years. In late December 2012 I changed from HomePlug 1.0 adapters (14 Mbps) to HomePlug AV adapters (200 Mbps). HomePlug 1.0 adapters and HomePlug AV adapters can operate concurrently over the same mains wiring but can only communicate with adapters of the same standard. The problem of not being able to access the Home Hub Manager started two or three years ago, so I assume that either my neighbour began using Powerline adapters at that time or, coincidentally, I changed to the same standard and manufacturer of Powerline adapter he uses.

Powerline adapters each have a non-volatile encryption key, intended to enable separate Powerline networks to co-exist on the same mains wiring by using a different encryption key for each network.

Since the end of December 2012 I have been using NETGEAR XAVB1301 200 Mbps Powerline adapters but had not bothered to change the encryption key in them (they all come configured with the factory default encryption key ‘HomePlugAV’). If my neighbour happens to be using Powerline adapters with the same default encryption key, and a hub with the same IP address as mine, we would both have two DHCP servers on the same network.

So I changed the encryption key on each of the four Powerline adapters I use:

  • Ethernet connection from the BT Home Hub to a mains socket in the Lounge.
  • Ethernet connection from a PC to a mains socket in the Lounge.
  • Ethernet connection from a laptop to a mains socket in my upstairs office.
  • Ethernet connection from a laptop to a mains socket in a bedroom.

It is supposed to be easy to set the encryption key in the model of Powerline adapter I use. You have to press a button on one adapter for 2 seconds, then a button on the next adapter for 2 seconds, and so on. You have to do them all within 2 minutes. The adapters only generate an encryption key once, so if you want to repeat the process you first have to press a recessed Factory Reset button on all the adapters.

However, despite following to the letter the instructions in the NETGEAR manual, I could not get all four adapters to connect to the network. So I downloaded the NETGEAR Powerline Universal Utility, installed it on the PC running Windows 10 in my lounge, connected the Ethernet port of that PC to one of the Powerline adapters and plugged it into a mains wall socket, plugged the other three Powerline adapters into a multi-socket mains adapter and plugged that into a mains wall socket in the lounge, launched the Powerline Universal Utility and I allocated all four adapters the same encryption key. Each adapter has its own MAC address, serial number and ‘Device Password’ (PWD) printed on it, and the NETGEAR utility program required me to enter the relevant PWD for each MAC address. Then I entered an encryption key (any string of characters of my choice) and clicked a button to set the adapters to use that encryption key. As that encryption key is different to the default key used by my neighbour, the two networks can now coexist without interfering with each other.

NETGEAR Powerline Utility showing my four Powerline adapters

NETGEAR Powerline Utility showing my four Powerline adapters.

The use of the NETGEAR Powerline utility program is explained in NETGEAR’s ‘How To’ How to set the Encryption Key for the Powerline adapter network using the Powerline utility.

Problem finally solved! I can now access the Home Hub Manager without any trouble. And, as a bonus, Internet access seems a little quicker.

The problem of scanning using USB multi-function printers in Linux (continued)

My previous post discussed the inability of the Linux installation on my main laptop to use the scanner of my Canon PIXMA MP560 MFP (multi-function peripheral) when they are connected via USB. Linux sees the MP560 as a single USB device with multiple interfaces: Interface 0 (scanner), Interface 1 (printer) and Interface 2 (USB mass storage). The basic problem seems to be that the usb-storage driver — whether built into the kernel or as an external module — claims the USB device and blocks access by userspace’s libusb, which is what the SANE backend (‘pixma‘, in the case of the MP560) uses to access the USB device. However, scanning works fine when using a network connection instead of the USB connection.

Attempts such as unbinding the usb-storage driver from the USB device — either manually or using a UDEV rule — in order to try and allow libusb/SANE to access the scanner, did not solve the problem. Although I can scan by connecting to the MP560 via my home network, the inability of the OS to scan via the USB interface piqued my interest, so I continued my investigations and below I discuss my latest findings.

Disabling kernel auto-binding

I learned from the interesting blog post Controlling USB device access on Linux how to stop the kernel automatically binding a driver to a USB device in the first place, as distinct from unbinding a driver after the kernel has bound it to a device. I thought this approach could be used to stop the usb-storage driver from binding to the MP560 and thus allow libusb/SANE to access Interface 0. The method using sysfs to stop the kernel binding the driver is to disable kernel USB auto-probing before launching a scanner application, by using the following command:

# echo 0 > /sys/bus/usb/drivers_autoprobe

This did indeed stop the kernel from automatically binding USB drivers to USB devices, but unfortunately libusb/SANE would still not access the MP560 scanner via USB. When drivers_autoprobe contains zero, applications such as XSane can use the network-connected MP560 as before, but still hang if the USB-connected MP560 is selected.

Unloading the usb-storage module

According to various blog and forum posts, some people have been able to use MFP scanners via USB after manually unloading the usb-storage module. I decided to try this. As I had built the kernel with the usb-storage driver internally rather than an external module, I first had to rebuild the kernel with CONFIG_USB_STORAGE=m instead of CONFIG_USB_STORAGE=y. Then I unloaded manually the usb_storage module using the command ‘rmmod usb_storage‘ and launched a scanner application, but the application still hung.

Disabling the usb-storage driver using a ‘quirk’

Then I had a thought: Perhaps there is a kernel ‘quirk’ to disable the usb-storage driver from binding to a specific USB device. Indeed there is (see Kernel Parameters or /usr/src/linux-<version>/Documentation/kernel-parameters.txt).

If the usb-storage driver is built into the kernel (CONFIG_USB_STORAGE=y), I would need to add the following kernel boot parameter to the kernel boot line:

usb-storage.quirks=04a9:173e:i

’04a9′ is the Vendor ID and ‘173e’ is the Product ID of the MP560. The ‘i‘ stands for ‘ignore’.

If the usb-storage driver is built as a kernel module (CONFIG_USB_STORAGE=m), I would need to create a file with a name such as /etc/modprobe.d/usb-storage.conf containing the following line:

options usb-storage quirks=04a9:173e:i

So I set up the quirk. Upon rebooting my laptop, the dmesg command reported the following:

usb 1-1.2.2: new high-speed USB device number 8 using ehci-pci
usb 1-1.2.2: New USB device found, idVendor=04a9, idProduct=173e
usb 1-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.2.2: Product: MP560 series
usb 1-1.2.2: Manufacturer: Canon
usb 1-1.2.2: SerialNumber: 1653C4
usb-storage 1-1.2.2:1.2: USB Mass Storage device detected
usb-storage 1-1.2.2:1.2: device ignored

Notice the final line. The quirk does indeed cause the usb-storage driver to ignore the MP560.

The lsusb command still shows the device, which is a good sign:

# lsusb
Bus 002 Device 005: ID 0bc2:3300 Seagate RSS LLC
Bus 002 Device 004: ID 0411:01d9 BUFFALO INC. (formerly MelCo., Inc.)
Bus 002 Device 003: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub
Bus 002 Device 002: ID 8087:8000 Intel Corp.
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 006: ID 5986:055c Acer, Inc
Bus 001 Device 004: ID 8087:07dc Intel Corp.
Bus 001 Device 007: ID 0603:00f2 Novatek Microelectronics Corp. Keyboard (Labtec Ultra Flat Keyboard)
Bus 001 Device 008: ID 04a9:173e Canon, Inc. MP560
Bus 001 Device 005: ID 045e:00d1 Microsoft Corp. Optical Mouse with Tilt Wheel
Bus 001 Device 003: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub
Bus 001 Device 002: ID 8087:8008 Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

# lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
        |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 4, If 0, Class=Mass Storage, Driver=usb-storage, 480M
            |__ Port 3: Dev 5, If 0, Class=Mass Storage, Driver=usb-storage, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M
        |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 2: Dev 8, If 0, Class=Vendor Specific Class, Driver=usbfs, 480M
            |__ Port 2: Dev 8, If 1, Class=Printer, Driver=, 480M
            |__ Port 2: Dev 8, If 2, Class=Mass Storage, Driver=, 480M
            |__ Port 4: Dev 7, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 4: Dev 7, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 4, If 0, Class=Wireless, Driver=btusb, 12M
        |__ Port 3: Dev 4, If 1, Class=Wireless, Driver=btusb, 12M
        |__ Port 4: Dev 6, If 0, Class=Video, Driver=uvcvideo, 480M
        |__ Port 4: Dev 6, If 1, Class=Video, Driver=uvcvideo, 480M

The output of the lsusb -v -d 04a9:173e command applicable to the MP560 is as follows:

Bus 001 Device 008: ID 04a9:173e Canon, Inc. MP560
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x04a9 Canon, Inc.
  idProduct          0x173e MP560
  bcdDevice            0.04
  iManufacturer           1 Canon
  iProduct                2 MP560 series
  iSerial                 3 1653C4
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           85
    bNumInterfaces          3
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xc0
      Self Powered
    MaxPower                2mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           3
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0 
      bInterfaceProtocol    255 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x07  EP 7 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x88  EP 8 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x89  EP 9 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              11
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         7 Printer
      bInterfaceSubClass      1 Printer
      bInterfaceProtocol      2 Bidirectional
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         8 Mass Storage
      bInterfaceSubClass      6 SCSI
      bInterfaceProtocol     80 Bulk-Only
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x05  EP 5 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  bNumConfigurations      1
can't get debug descriptor: Resource temporarily unavailable
Device Status:     0x0001
  Self Powered

The USB device created at boot was as follows:

# ls -la /dev/bus/usb/001/008
crw-rw-r--+ 1 root lp 189, 7 Jul 24 11:01 /dev/bus/usb/001/008

Whether run by the root user or under my user account, the SANE tools detected the MP560 scanner network and USB connections:

$ scanimage -L
device `pixma:MP560_192.168.1.78' is a CANON Canon PIXMA MP560 multi-function peripheral
device `pixma:04A9173E' is a CANON Canon PIXMA MP560 multi-function peripheral

$ sane-find-scanner

  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.

  # No SCSI scanners found. If you expected something different, make sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x04a9 [Canon], product=0x173e [MP560 series]) at libusb:001:008
  # Your USB scanner was (probably) detected. It may or may not be supported by
  # SANE. Try scanimage -L and read the backend's manpage.

  # Not checking for parallel port scanners.

  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

But scanner applications still hung! This time the message displayed by the dmesg command was:

usb 1-1.2.2: usbfs: interface 0 claimed by usbfs while 'scanimage' sets config #1

I unplugged the USB cable and plugged it in again. The output of the dmesg command was:

usb 1-1.2.2: USB disconnect, device number 8
usb 1-1.2.2: new high-speed USB device number 9 using ehci-pci
usb 1-1.2.2: New USB device found, idVendor=04a9, idProduct=173e
usb 1-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.2.2: Product: MP560 series
usb 1-1.2.2: Manufacturer: Canon
usb 1-1.2.2: SerialNumber: 1653C4
usb-storage 1-1.2.2:1.2: USB Mass Storage device detected
usb-storage 1-1.2.2:1.2: device ignored

I then launched XSane several times and each time I was able to select either the MP560 via my home network (pixma:MP560_192.168.1.78) or via the USB cable (pixma:04A9173E_1653C4) and scan successfully.

By the way, it is possible to scan via the command line instead of using a GUI scanner application. For example, tjhe following command will scan an A4 page via the MP560’s USB connection (see man scanimage for details of the options):

$ scanimage -d pixma:04A9173E_1653C4 -l 0 -t 0 -x 215 -y 297 --resolution 150 --mode Color | convert - scanned-page.png

So the problem is solved, right? Wrong! For whatever reason, scanning via the USB interface is not guaranteed to work every time I boot the laptop. Sometimes scanner applications (and the scanimage command) hang if I select the USB interface; at other times they don’t hang and scanning works fine. If scanning using the USB device is not working, if I unplug and re-insert the USB cable a few times it becomes possible to scan using the USB interface. And once scanning via the USB interface does work, from then onwards it works consistently during that session.

I had been using Version 1.0.24-r5 of the sane-backends package in Gentoo Linux, which is the latest stable version according to the Gentoo package manager. To check if that particular version of the SANE pixma backend might be the cause of the problem I installed the latest version available in the Gentoo package manager (currently 1.0.5_pre20150625). However it made no discernable difference.

To sum up, in my case the most successful approach so far has been to use a kernel ‘quirk’ to force the usb-storage driver to ignore the device and not bind to it. However, this approach does not result in libusb/SANE being able to access the scanner during every boot session, but, if access is successful, it remains successful during the current session. Even if access via the USB interface does not work initially, sometimes I can get it to work by unplugging and re-inserting the USB cable.

UPDATE (July 30, 2015): I have now managed to get scanning to work with almost 100% reliability when connected to the MP560 via USB — see my latest post for details.

The problem of scanning using USB multi-function printers in Linux

Whilst searching the Web I have found many other people experiencing this problem, which I believe happens as a consequence of the way Linux is designed. Basically, if you have a multi-function peripheral that you connect to your computer via USB, the chances are that either scanning or printing will not work. The Web is littered with blog posts, forum threads, mailing list posts and bug reports regarding this phenomenon. There are numerous suggested fixes, usually entailing the addition or modification of udev rules. Sometimes the suggested fixes work; often they don’t. Linux can be a major hassle where peripherals are concerned.

I have a Canon Pixma MP560 MFP (multi-function printer/peripheral), which is a printer, scanner and copier. It also has memory card slots and a USB pen drive socket, to be able to store images directly from the scanner without the need to connect a computer. The MP560 provides two alternative means of connection to a computer: USB and Wi-Fi. I normally connect it via USB to my Clevo W230SS laptop running Gentoo Linux (amd64), but I can also connect it to the laptop via my home Wi-Fi network. Either connection method allows me to print, but I can scan only via the wireless connection.

The dmesg command displays the following messages after I plug a USB cable from the MP560 into my laptop:

usb 1-1.2.2: new high-speed USB device number 8 using ehci-pci
usb 1-1.2.2: New USB device found, idVendor=04a9, idProduct=173e
usb 1-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.2.2: Product: MP560 series
usb 1-1.2.2: Manufacturer: Canon
usb 1-1.2.2: SerialNumber: 1653C4
usb-storage 1-1.2.2:1.2: USB Mass Storage device detected
scsi host6: usb-storage 1-1.2.2:1.2
scsi 6:0:0:0: Direct-Access     Canon    MP560 series     0104 PQ: 0 ANSI: 2
sd 6:0:0:0: Attached scsi generic sg1 type 0
sd 6:0:0:0: [sdb] Attached SCSI removable disk

Notice that the device also has some internal storage.

The lsusb command shows the device:

$ lsusb
Bus 002 Device 002: ID 8087:8000 Intel Corp.
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 006: ID 5986:055c Acer, Inc
Bus 001 Device 004: ID 8087:07dc Intel Corp.
Bus 001 Device 007: ID 0603:00f2 Novatek Microelectronics Corp. Keyboard (Labtec Ultra Flat Keyboard)
Bus 001 Device 009: ID 04a9:173e Canon, Inc. MP560
Bus 001 Device 005: ID 045e:00d1 Microsoft Corp. Optical Mouse with Tilt Wheel
Bus 001 Device 003: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub
Bus 001 Device 002: ID 8087:8008 Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

My Linux user account is in the lp and scanner groups:

$ groups
disk lp wheel floppy uucp cron audio cdrom video games cdrw usb users plugdev crontab wireshark vboxusers scanner fitzcarraldo

The device is in the lp group and I can print without any trouble:

$ ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 root lp 189, 8 Jun 19 02:55 /dev/bus/usb/001/009

The usblp driver, a common cause of problems with USB printers, does not exist because I purposely did not set CONFIG_USB_PRINTER when I built the kernel, specifically to avoid such problems:

$ grep CONFIG_USB_PRINTER /usr/src/linux/.config
# CONFIG_USB_PRINTER is not set

so, obviously, the usblp driver is neither built into the kernel nor compiled as a module:

$ lsmod | grep usb
btusb                  22292  0
bluetooth             281605  27 bnep,hidp,btusb,rfcomm

I have the latest stable versions of the udev-related packages installed (as you can see below, I use eudev instead of udev):

$ eix -I udev
[I] dev-python/pyudev
     Available versions:  0.16.1-r1 {pygobject pyqt4 pyside test PYTHON_TARGETS="python2_7 python3_3 python3_4"}
     Installed versions:  0.16.1-r1(03:32:17 18/04/15)(pyqt4 -pygobject -pyside -test PYTHON_TARGETS="python2_7 python3_3 -python3_4")
     Homepage:            http://pyudev.readthedocs.org https://github.com/pyudev/pyudev
     Description:         Python binding to libudev

[I] sys-fs/eudev
     Available versions:  *1.3 *1.5.3-r1 1.9-r2 1.10-r2 ~2.1.1 ~3.0 3.1.2 ~3.1.2-r10 **9999 {doc gudev (+)hwdb introspection (+)keymap (+)kmod +modutils +openrc +rule-generator selinux static-libs test ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32"}
     Installed versions:  3.1.2(19:44:12 16/07/15)(gudev hwdb introspection kmod -doc -selinux -static-libs -test ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="32 64 -x32")
     Homepage:            https://github.com/gentoo/eudev
     Description:         Linux dynamic and persistent device naming support (aka userspace devfs)

[I] sys-fs/udev-init-scripts
     Available versions:  27^t [M]~29^t ~30^t **9999^t
     Installed versions:  27^t(05:29:06 09/04/15)
     Homepage:            http://www.gentoo.org
     Description:         udev startup scripts for openrc

[I] virtual/libgudev
     Available versions:  215-r1(0/0) 215-r2(0/0) 215-r3(0/0) ~230(0/0) {introspection static-libs systemd ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32"}
     Installed versions:  215-r3(10:18:16 11/06/15)(introspection -static-libs -systemd ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="64 -32 -x32")
     Description:         Virtual for libgudev providers

[I] virtual/libudev
     Available versions:  215-r1(0/1) {static-libs systemd ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32"}
     Installed versions:  215-r1(17:51:42 18/04/15)(-static-libs -systemd ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="32 64 -x32")
     Description:         Virtual for libudev providers

[I] virtual/udev
     Available versions:  215 ~217 {systemd}
     Installed versions:  215(05:28:55 09/04/15)(-systemd)
     Description:         Virtual to select between different udev daemon providers

Found 6 matches.

I have the latest stable SANE-related packages installed:

$ eix -I sane
[I] dev-perl/Sane
     Available versions:  (~)0.50.0-r1 {test}
     Installed versions:  0.50.0-r1(17:39:10 23/06/15)(-test)
     Homepage:            http://search.cpan.org/dist/Sane/
     Description:         The Sane module allows you to access SANE-compatible scanners in a Perl

[I] kde-apps/ksaneplugin
     Available versions:  (4) 4.14.3(4/4.14)
       {aqua debug}
     Installed versions:  4.14.3(4)(14:13:01 17/04/15)(-aqua -debug)
     Homepage:            http://www.kde.org/
     Description:         SANE Plugin for KDE

[I] kde-apps/libksane
     Available versions:  (4) 4.14.3(4/4.14)
       {aqua debug}
     Installed versions:  4.14.3(4)(13:55:44 17/04/15)(-aqua -debug)
     Homepage:            http://www.kde.org/
     Description:         SANE Library interface for KDE

[I] media-gfx/sane-backends
     Available versions:  1.0.24-r5 ~1.0.25_pre20150628 {avahi doc gphoto2 ipv6 snmp systemd threads usb v4l xinetd ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32" SANE_BACKENDS="+abaton +agfafocus +apple +artec +artec_eplus48u +as6e +avision +bh +canon +canon630u +canon_dr -canon_pp +cardscan +coolscan +coolscan2 +coolscan3 +dc210 +dc240 +dc25 +dell1600n_net +dmc +epjitsu +epson +epson2 +fujitsu +genesys +gt68xx +hp +hp3500 +hp3900 +hp4200 +hp5400 +hp5590 +hpljm1005 -hpsj5s +hs2p +ibm +kodak +kodakaio +kvs1025 +kvs20xx kvs40xx +leo +lexmark +ma1509 +magicolor +matsushita +microtek +microtek2 +mustek -mustek_pp +mustek_usb mustek_usb2 +nec +net +niash +p5 +pie +pixma +plustek +plustek_pp -pnm +qcam +ricoh +rts8891 +s9036 +sceptre +sharp +sm3600 +sm3840 +snapscan +sp15c +st400 +stv680 +tamarack +teco1 +teco2 +teco3 +test +u12 +umax +umax1220u +umax_pp +xerox_mfp"}
     Installed versions:  1.0.24-r5(17:55:11 18/04/15)(avahi gphoto2 ipv6 usb v4l -doc -snmp -systemd -threads -xinetd ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="32 64 -x32" SANE_BACKENDS="abaton agfafocus apple artec artec_eplus48u as6e avision bh canon canon630u canon_dr cardscan coolscan coolscan2 coolscan3 dc210 dc240 dc25 dell1600n_net dmc epjitsu epson epson2 fujitsu genesys gt68xx hp hp3500 hp3900 hp4200 hp5400 hp5590 hpljm1005 hs2p ibm kodak kodakaio kvs1025 kvs20xx leo lexmark ma1509 magicolor matsushita microtek microtek2 mustek mustek_usb nec net niash p5 pie pixma plustek plustek_pp qcam ricoh rts8891 s9036 sceptre sharp sm3600 sm3840 snapscan sp15c st400 stv680 tamarack teco1 teco2 teco3 test u12 umax umax1220u umax_pp xerox_mfp -canon_pp -hpsj5s -kvs40xx -mustek_pp -mustek_usb2 -pnm")
     Homepage:            http://www.sane-project.org/
     Description:         Scanner Access Now Easy - Backends

[I] media-gfx/sane-frontends
     Available versions:  1.0.14 {gimp}
     Installed versions:  1.0.14(19:47:50 18/06/15)(gimp)
     Homepage:            http://www.sane-project.org
     Description:         Scanner Access Now Easy

[I] media-gfx/xsane
     Available versions:  0.999-r1 {gimp jpeg lcms nls ocr png tiff}
     Installed versions:  0.999-r1(12:03:12 19/04/15)(gimp jpeg lcms nls png tiff -ocr)
     Homepage:            http://www.xsane.org/
     Description:         graphical scanning frontend

Found 6 matches.

The following SANE backends were installed when I installed SANE:

$ ls -F1 /etc/sane.d/ | columns -c 3 -w 20
abaton.conf         agfafocus.conf      apple.conf
artec.conf          artec_eplus48u.conf avision.conf
bh.conf             canon.conf          canon630u.conf
canon_dr.conf       cardscan.conf       coolscan.conf
coolscan2.conf      coolscan3.conf      dc210.conf
dc240.conf          dc25.conf           dell1600n_net.conf
dll.conf            dll.d/              dmc.conf
epjitsu.conf        epson.conf          epson2.conf
fujitsu.conf        genesys.conf        gphoto2.conf
gt68xx.conf         hp.conf             hp3900.conf
hp4200.conf         hp5400.conf         hs2p.conf
ibm.conf            kodak.conf          kodakaio.conf
leo.conf            lexmark.conf        ma1509.conf
magicolor.conf      matsushita.conf     microtek.conf
microtek2.conf      mustek.conf         mustek_usb.conf
nec.conf            net.conf            p5.conf
pie.conf            pixma.conf          plustek.conf
plustek_pp.conf     qcam.conf           ricoh.conf
rts8891.conf        s9036.conf          saned.conf
sceptre.conf        sharp.conf          sm3840.conf
smfp.conf           snapscan.conf       sp15c.conf
st400.conf          stv680.conf         tamarack.conf
teco1.conf          teco2.conf          teco3.conf
test.conf           u12.conf            umax.conf
umax1220u.conf      umax_pp.conf        v4l.conf
xerox_mfp.conf

I checked all the SANE backend configuration files, and none of them mention the MP560 (I was not expecting them to mention it, as, according to man sane-pixma, the pixma backend detects Canon PIXMA USB devices automatically):

$ grep -rnwi /etc/sane.d/ -e "173e"
$

The SANE file dll.conf does list the pixma backend configuration file which is only for declaring networked Canon PIXMA devices, as the pixma backend detects Canon USB devices automatically):

$ grep pixma /etc/sane.d/dll.conf
pixma

$ cat /etc/sane.d/pixma.conf
# pixma.conf configuration for the sane pixma backend
#
# define URI's of scanners (one per line)
# This is only used for network scanners.
# normally scanners will be detected by sending a broadcast
# if this does not work under your OS, or if the scanners
# are on a different subnet, configure your scanners URI here
#
# method must be bjnp
# port number can normally be left out, port 8612 is used as default
# Example:
# bjnp://myscanner.my.domain:8612
# bjnp://printer-1.pheasant.org
#

I don’t think it is even used these days, but the file /etc/hotplug/usb/libsane.usermap already includes the device:

# Canon PIXMA MP560
libusbscanner 0x0003 0x04a9 0x173e 0x0000 0x0000 0x00 0x00 0x00 0x00 0x00 0x00 0x00000000

The file /lib64/udev/rules.d/41-libsane.rules already includes the device:

# Canon PIXMA MP560
ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

However, scanning from Linux via USB is a troubled affair. Very occasionally the scanner application (XSane, Simple Scan, gscan2pdf, or whatever) will launch and the scanner works, but usually the scanner application just hangs and the dmesg command shows one or more error messages such as the following:

usb 1-1.2.2: usbfs: interface 2 claimed by usb-storage while 'xsane' sets config #1

usb 1-1.2.2: usbfs: interface 2 claimed by usb-storage while 'gscan2pdf' sets config #1

I have USB mass storage support enabled in the kernel so that my laptop can access external USB mass storage devices:

$ grep CONFIG_USB_STORAGE= /usr/src/linux/.config
CONFIG_USB_STORAGE=y

As the three interfaces (printer, scanner and internal storage) are all accessed as a single USB device (/dev/bus/usb/001/009, or whatever), there appears to be a conflict between the kernel claiming the MFP’s internal mass storage and SANE trying to access the scanner. I do not want to disable the kernel’s USB mass storage support (not even by rebuilding the kernel with CONFIG_USB_STORAGE=m and temporarily unloading manually the usb-storage module, as some people suggest), as I would not be able to access my external USB mass storage devices.

The scanimage and sane-find-scanner utilities detect the scanner correctly via USB:

$ scanimage -L
device `v4l:/dev/video0' is a Noname BisonCam, NB Pro virtual device
device `pixma:04A9173E_1653C4' is a CANON Canon PIXMA MP560 multi-function peripheral

(The BisonCam is the Webcam built into my laptop.)

$ sane-find-scanner

  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.

  # No SCSI scanners found. If you expected something different, make sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x04a9 [Canon], product=0x173e [MP560 series]) at libusb:001:009
  # Your USB scanner was (probably) detected. It may or may not be supported by
  # SANE. Try scanimage -L and read the backend's manpage.

  # Not checking for parallel port scanners.

  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

  # You may want to run this program as root to find all devices. Once you
  # found the scanner devices, be sure to adjust access permissions as
  # necessary.

The scanimage test commands do not indicate any problem:

$ scanimage -d test -T
scanimage: scanning image of size 157x196 pixels at 8 bits/pixel
scanimage: acquiring gray frame, 8 bits/sample
scanimage: reading one scanline, 157 bytes...   PASS
scanimage: reading one byte...          PASS
scanimage: stepped read, 2 bytes...     PASS
scanimage: stepped read, 4 bytes...     PASS
scanimage: stepped read, 8 bytes...     PASS
scanimage: stepped read, 16 bytes...    PASS
scanimage: stepped read, 32 bytes...    PASS
scanimage: stepped read, 64 bytes...    PASS
scanimage: stepped read, 128 bytes...   PASS
scanimage: stepped read, 256 bytes...   PASS
scanimage: stepped read, 255 bytes...   PASS
scanimage: stepped read, 127 bytes...   PASS
scanimage: stepped read, 63 bytes...    PASS
scanimage: stepped read, 31 bytes...    PASS
scanimage: stepped read, 15 bytes...    PASS
scanimage: stepped read, 7 bytes...     PASS
scanimage: stepped read, 3 bytes...     PASS

$ scanimage -d pixma -T
scanimage: scanning image of size 638x877 pixels at 24 bits/pixel
scanimage: acquiring RGB frame, 8 bits/sample
scanimage: reading one scanline, 1914 bytes...  PASS
scanimage: reading one byte...          PASS
scanimage: stepped read, 2 bytes...     PASS
scanimage: stepped read, 4 bytes...     PASS
scanimage: stepped read, 8 bytes...     PASS
scanimage: stepped read, 16 bytes...    PASS
scanimage: stepped read, 32 bytes...    PASS
scanimage: stepped read, 64 bytes...    PASS
scanimage: stepped read, 128 bytes...   PASS
scanimage: stepped read, 256 bytes...   PASS
scanimage: stepped read, 512 bytes...   PASS
scanimage: stepped read, 1024 bytes...  PASS
scanimage: stepped read, 2048 bytes...  PASS
scanimage: stepped read, 2047 bytes...  PASS
scanimage: stepped read, 1023 bytes...  PASS
scanimage: stepped read, 511 bytes...   PASS
scanimage: stepped read, 255 bytes...   PASS
scanimage: stepped read, 127 bytes...   PASS
scanimage: stepped read, 63 bytes...    PASS
scanimage: stepped read, 31 bytes...    PASS
scanimage: stepped read, 15 bytes...    PASS
scanimage: stepped read, 7 bytes...     PASS
scanimage: stepped read, 3 bytes...     PASS

As mentioned earlier, the udev/eudev rules file appears to contain a valid rule for the scanner:

# Canon PIXMA MP560
ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

Notice the rule assigns the device’s group to be ‘scanner‘, not ‘lp‘, although changing the group assignment to ‘lp‘ in the rule makes no discernable difference to the scanning problem in my case. As the device’s group is actually ‘lp‘, I assume another rule overrides this rule, but I have no idea which rule it is and in which rules file it occurs.

Occasionally I am lucky and scanning does work, but, more often than not, scanner applications cannot access the scanner and just hang.

A work-around if the peripheral also has a network interface

I configured my home network router always to use the IP address 192.168.1.78 for the MP560 and I added the following line to the file /etc/sane.d/pixma.conf in order to be able to scan via Wi-Fi instead of USB (I have the package cups-bjnp installed for printing purposes, but I am not sure if that package is also needed by SANE in this case):

bjnp://192.168.1.78

With the above line added to /etc/sane.d/pixma.conf the scanimage utility detects the scanner correctly via both the Wi-Fi connection and the USB interface:

$ scanimage -L
device `v4l:/dev/video0' is a Noname BisonCam, NB Pro virtual device
device `pixma:MP560_192.168.1.78' is a CANON Canon PIXMA MP560 multi-function peripheral
device `pixma:04A9173E_1653C4' is a CANON Canon PIXMA MP560 multi-function peripheral

So, as I usually cannot get scanning to work via USB, I can scan via Wi-Fi instead. It’s a work-around, not a solution, but at least by doing that I can scan reliably as well as print. Of course you can’t use such a work-around if you have a model of MFP that only provides a USB connection.

Failed experiments

Experiment 1

I also tried unbinding the usb-storage driver from the usb device:

# ls /sys/bus/usb/drivers
btusb hub usb usb-storage usbfs usbhid uvcvideo
# ls /sys/bus/usb/drivers/btusb/
1-1.3:1.0 1-1.3:1.1 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/hub
1-0:1.0 1-1.2:1.0 1-1:1.0 2-0:1.0 2-1:1.0 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/usb
1-1 1-1.2 1-1.2.1 1-1.2.2 1-1.2.4 1-1.3 1-1.4 2-1 bind uevent unbind usb1 usb2
# ls /sys/bus/usb/drivers/usb-storage/
1-1.2.2:1.2 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/usbfs
bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/usbhid
1-1.2.1:1.0 1-1.2.4:1.0 1-1.2.4:1.1 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/uvcvideo
1-1.4:1.0 1-1.4:1.1 bind module new_id remove_id uevent unbind
# tree /sys/bus/usb/drivers/usb-storage/
/sys/bus/usb/drivers/usb-storage/
├── 1-1.2.2:1.2 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/1-1.2.2/1-1.2.2:1.2
├── bind
├── module -> ../../../../module/usb_storage
├── new_id
├── remove_id
├── uevent
└── unbind

2 directories, 5 files
# echo -n "1-1.2.2:1.2" > /sys/bus/usb/drivers/usb-storage/unbind
# tree /sys/bus/usb/drivers/usb-storage/
/sys/bus/usb/drivers/usb-storage/
├── bind
├── module -> ../../../../module/usb_storage
├── new_id
├── remove_id
├── uevent
└── unbind

1 directory, 5 files
# tree /sys/bus/usb/devices/1-1.2.2:1.2
/sys/bus/usb/devices/1-1.2.2:1.2
├── bAlternateSetting
├── bInterfaceClass
├── bInterfaceNumber
├── bInterfaceProtocol
├── bInterfaceSubClass
├── bNumEndpoints
├── ep_05
│   ├── bEndpointAddress
│   ├── bInterval
│   ├── bLength
│   ├── bmAttributes
│   ├── direction
│   ├── interval
│   ├── power
│   ├── type
│   ├── uevent
│   └── wMaxPacketSize
├── ep_84
│   ├── bEndpointAddress
│   ├── bInterval
│   ├── bLength
│   ├── bmAttributes
│   ├── direction
│   ├── interval
│   ├── power
│   ├── type
│   ├── uevent
│   └── wMaxPacketSize
├── modalias
├── power
├── subsystem -> ../../../../../../../../bus/usb
├── supports_autosuspend
└── uevent

6 directories, 27 files

After unbinding the usb-storage driver from the USB device, no more messages such as ‘usbfs: interface 2 claimed by usb-storage while 'xsane' sets config #1‘ are added to /var/log/messages when I launch a scanner application and select the USB device, but the scanner application still hangs (e.g. the XSane windows do not appear until I switch off the MP560 or unplug the USB cable). This happens irrespective of whether the USB device permissions are:

# ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 root lp 189, 8 Jul 20 20:35 /dev/bus/usb/001/009

or:

# ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 fitzcarraldo lp 189, 8 Jul 20 20:35 /dev/bus/usb/001/009

or:

# ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 fitzcarraldo scanner 189, 8 Jul 20 20:51 /dev/bus/usb/001/009

To reiterate, neither unbinding the usb-storage driver from the USB device first nor changing the owner and group of the USB device solves the problem. So possibly the problem is not caused by udev or by a USB driver, but by the SANE software.

Experiment 2

I found a thread in the SANE developers’ mailing list about the same problem with a different model of MFP: Help needed diagnosing strange failure to scan with Samsung SCX-4500W. The same user posted the same query in the Arch Linux forums: [SOLVED] Samsung SCX4500W MFP can’t get scanner to work. Like my Canon PIXMA MP560, that MFP has more than one interface in a single USB device. Notice in the Arch Linux thread that the user never found a solution and finally adopted the same work-around I use, namely to scan via a network interface rather than via the USB interface.

Theodore Kilgore gives a good explanation in that SANE developers’ mailing list thread of why the problem occurs in Linux, and Thorsten Müller’s post suggests a udev rule that sets the permissions for the MFP so that SANE, CUPS and logged-in users can all access the USB device. All I had to do was replace references to Samsung (such as the vendor ID and product ID) with those for my Canon PIXMA MP560. I left everything else in my installation exactly the way it was (for example I did not touch /lib64/udev/rules.d/41-libsane.rules and /lib64/udev/rules.d/70-printers.rules). The only thing I did was to add a udev rules file /etc/udev/rules.d/99-canon-mp560.rules with the following contents:

# ACL settings for Canon PIXMA MP560 printer MFP
ATTR{idVendor}=="04a9", ATTR{idProduct}=="173e", GOTO="canon"
GOTO="canon_end"

LABEL="canon"
RUN+="/bin/setfacl -m g:scanner:rw -m g:lp:rw $env{DEVNAME}"
TEST=="/var/run/ConsoleKit/database", \
        RUN+="udev-acl --action=$env{ACTION} --device=$env{DEVNAME}"

LABEL="canon_end"

Both /bin/setfacl and /var/run/ConsoleKit/database exist in my installation, and, as shown earlier, my user account is a member of both the lp and scanner groups. After adding the above file, I rebooted and it appears the rule works as intended:

# getfacl /dev/bus/usb/001/009
getfacl: Removing leading '/' from absolute path names
# file: dev/bus/usb/001/009
# owner: root
# group: lp
user::rw-
user:fitzcarraldo:rw-
group::rw-
group:lp:rw-
group:scanner:rw-
mask::rw-
other::r--

However, although I was still able to print I still could not scan. Mind you, the line beginning ‘TEST==‘ in the file /etc/udev/rules.d/99-canon-mp560.rules is also in the file /lib64/udev/rules.d/70-udev-acl.rules, but I’m no expert in udev rules, which are frankly beyond the ability of most users.

Experiment 3

I found a blog post about the same problem but with a Canon MP210 MFP: Canon multifunction printer: getting the printer drivers and scanner to work in debian/ubuntu/mint. This post suggested creating a udev rule file /etc/udev/rules.d/40-scanner-permissions.rules containing the following:

# usb scanner
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", MODE:="0666"
SUBSYSTEM=="usb_device",MODE:="0666"

but, although the rule appears to work as intended, it is still not possible to scan in my case. I then changed the file name to /etc/udev/rules.d/95-scanner-permissions.rules, but that made no difference in my case.

Experiment 4

I also tried changing MODE="0664" to MODE="0666" in the following line in the file /lib64/udev/rules.d/50-udev-default.rules but that made no difference either:

SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", MODE="0664"

Experiment 5

I am able to change the group of the USB device to ‘scanner‘ instead of ‘lp‘ by adding a rules file /lib64/udev/rules.d/99-canon.rules (apparently 41-libsane.rules does not work as intended because it is overruled by a higher-numbered file, but I have no idea which one, as 41-libsane.rules is the only one explicitly mentioning the MP560) containing the following:

ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

But scanning still does not work, whether or not I unbind the usb-storage driver from the USB device first and whether or not I change the owner and group of the USB device to root:lp, root:scanner, fitzcarraldo:lp or fitzcarraldo:scanner.

Conclusion

Although my installation can print via USB, scanning via USB does not work, whether or not the usb-storage driver is bound to the USB device and whoever is the owner and group of the USB device. So it could be that the problem is not caused by udev or by the kernel (a USB driver), but by the SANE software itself. However, I think it is more likely to be some sort of contention between kernel and userspace, despite unbinding the usb-storage driver from the device. Although I’m not excluding the possibility of a bug in SANE, irrespective of that it seems to me that the way GNU/Linux handles multiple interfaces of a single USB device is flawed. The udev design results in a morass of confusing and potentially conflicting rules in umpteen files in different directories, and the apparently uncoordinated independent demands on the same USB interface by the kernel and userspace are another potential source of problems. There is no standardisation in the udev rules files and their contents between the different Linux distributions, making investigation and solution of such problems even more complicated. Having to resort to work-arounds such as scanning via a network interface or scanning to a USB pen drive or memory card is a poor way of circumventing the problem, and is of no help anyway if a multi-function peripheral does not have a network interface, pen drive socket or memory card slot.

UPDATE (July 24, 2015): I have tried some other approaches, and had more success using a ‘quirk’ for the usb-storage driver — see my next post for details.

Addendum: How to stop scanning applications detecting a Webcam

By the way, to stop XSane and other scanning applications detecting my Webcam via the Video for Linux SANE backend, I commented out all the device lines in the file /etc/sane.d/v4l.conf like so:

$ cat
# In order to use the v4linux backend you have to give the device
# You can enable multiple lines if
# you really have multible v4l devices.
#
#/dev/bttv0
#/dev/video0
#/dev/video1
#/dev/video2
#/dev/video3

Using a Samsung Xpress C460FW with Gentoo Linux and Android KitKat for printing and scanning

INTRODUCTION

A work colleague has just received a Samsung Xpress C460FW MFP (laser printer, scanner, copier and fax machine) for small print jobs. It is possible to connect to it via USB, Direct USB, wired network, wireless network, Wi-Fi Direct and NFC; that’s impressive for a MFP that can be purchased for GBP 270 in the UK.

I wanted to use the C460FW to print and scan from my laptop running Gentoo Linux, and also to print and scan from my Samsung Galaxy Note 4 running Android KiKat. It turned out that I was able to do all of those, and it was not difficult to set up.

A technician from the IT Support department had already entered a static IP address, subnet mask and default gateway IP address via the C460FW’s control panel to connect it to the office’s wired network. So my options to connect to this particular C460FW are: the wired network for Linux; Wi-Fi Direct for Linux and Android; NFC for Android.

I had never used Wi-Fi Direct before, but it turned out to be easy in Gentoo Linux on my laptop, and also easy in Android KitKat on my Samsung Galaxy Note 4. I had never used NFC before either, and that also turned out to be easy on my Samsung Galaxy Note 4.

Samsung has a series of videos on YouTube explaining how to use Wi-Fi Direct and NFC for printing, scanning and faxing with the C460FW from a Samsung smartphone; here are links to a few of them:

Samsung Smart Printing – 01 NFC Connect

Samsung Smart Printing – 02 Wi Fi Direct

Samsung Smart Printing – 03 Wi Fi

Samsung Smart Printing – 04 NFC Print

Samsung Smart Printing – 05 NFC Scan

Samsung Smart Printing – 06 NFC Fax

Samsung Smart Printing – 11 Samsung Mobile Print App(Printer Status)

PRINTING

Linux

Wired connection

I had installed the package net-print/samsung-unified-linux-driver Version 1.02 from a Portage local overlay back in March 2013 when I needed to print to a different model of Samsung MFP, so I thought I would see if that driver would work with the C460FW. I opened the CUPS Printer Manager in a browser window (http://localhost:631/) to configure my Gentoo installation to print to the device via the wired network. ‘Samsung C460 Series‘ was in the list of discovered network printers in the CUPS Printer Manager, and the driver ‘Samsung C460 Series PS‘ was displayed at the top of the list of models, so it was a piece of cake to set up the printer via CUPS, and I was able to print a test page in no time at all. My colleague uses a laptop running Windows 7, and he had to install the Windows driver from a Samsung CD that came with the C460FW.

Wireless connection

As the IT Support technician had configured the C460FW to print via the office wired network rather than the office wireless network, I decided to configure my laptop to print via Wi-Fi Direct, just to learn about Wi-Fi Direct, really. On the C460FW’s control panel I selected Network > Wireless > Wi-Fi Direct and enabled Wi-Fi Direct. Scrolling through the Wi-Fi Direct entries in the LCD I saw the following information:

Device Name: C460 Series
Network Key: <an 8-digit code>
IP address: 192.168.003.001

Two new networks were listed under ‘Available connections’ in plasma-nm (the KDE GUI front-end to NetworkManager) on my laptop: ‘DIRECT-HeC460 Series‘ and ‘DIRECT-SqC460 Series‘, both using WPA2-PSK encryption. I used the control panel of the C460FW to print a network configuration report in order to check which of the two SSIDs I should select, and it is ‘DIRECT-HeC460 Series‘ (I found out later that an adjacent room also has a C460FW and its Wi-Fi Direct SSID is ‘DIRECT-SqC460 Series‘). So I selected ‘DIRECT-HeC460 Series‘ and plasma-nm prompted me to enter a network password. I entered the 8-digit key I had found from the C460FW’s LCD panel (it’s also listed in the printed network configuration report), and NetworkManager connected to the printer.

In exactly the same way as I do when setting up any printer in Linux, I launched Firefox, opened the CUPS Printer Manager page, clicked on ‘Administration’ > ‘Add Printer’ and entered the user name ‘root’ and the password in the pop-up window. Again the ‘Add Printer’ page had ‘Samsung C460 Series‘ in the list of discovered network printers, so I just selected it and clicked on ‘Continue’. As I had already set up the printer in CUPS for the wired network connection and given it the name ‘Samsung_C460FW_office‘, I entered the name ‘Samsung_C460FW_office_WiFi_Direct‘ to distinguish it from the wired network entry, entered a Description and Location, and clicked on ‘Continue’. The next page had ‘Samsung C460 Series PS‘ first in the driver list so I selected that, clicked on ‘Add Printer’ and that was it. I was able to print a test page from the CUPS Printer Manager, and the printer is now included the list of printers in Linux applications’ print dialogues.

When I want to print using Wi-Fi Direct the only thing I need to remember to do first is select ‘DIRECT-HeC460 Series‘ in the network GUI on the KDE Panel, so that the connection is active when I click ‘Print’ in whichever application I want to print from.

Given the ease of printing via the wired network and Wi-Fi Direct, I have no doubts that printing would also work had the C460FW been configured for the office wireless network instead of the wired network.

Duplex printing

The only downside to the Samsung Xpress C460FW is that it only supports manual duplex printing. If you specify duplex printing when printing from Windows, Samsung’s Windows driver prints all the odd-numbered pages in reverse order and displays a message in Windows telling you what to do next (turn over the pile of paper and put it back in the paper tray!), but in Linux it’s not difficult to work out what you have to do: you simply have to print all the odd-numbered sides first, turn over the paper, then print all the even-numbered sides. The print dialogue in Linux applications gives you the option to print only odd-numbered pages or only even-numbered pages, so there is no problem. The print dialogue in some Linux applications allows you to print pages in reverse order as well but, if not, you have to reverse the order yourself before printing the even-numbered pages (i.e. put Page 1 face down at the top of the pile then Page 3 face down under it, and so on). It’s not a big deal unless the document has a large number of pages.

Android

As you would expect with devices from the same manufacturer, setting up my Samsung Galaxy Note 4 to print with the Samsung Xpress C460FW via WPS (Wi-Fi Protected Setup) was easy. When I selected ‘Print’ on the Galaxy Note 4, it gave me the option to print via wireless network or Wi-Fi Direct. I chose the latter and, as I had already enabled Wi-Fi Direct on the C460FW’s control panel, the printer name was displayed in the list of available devices. I selected it, a blue LED began flashing on the C460FW’s control panel and the LCD prompted me to press the WPS button (on the left of the control panel). As soon as I pressed that, the C460FW printed the document sent by my Galaxy Note 4. From then onwards, I just needed to select ‘Print’ on the Galaxy Note 4, select the printer from the list of available devices, and the document is printed. When I want to print using Wi-Fi Direct the only thing I need to remember to do first on the Galaxy Note 4 is select ‘DIRECT-HeC460 Series‘ as the Wi-Fi network.

NFC

I then decided to try to print using NFC. I placed the Galaxy Note 4, without Wi-Fi enabled and with the Home Screen displayed (not the Lock Screen), on the NFC label on top of the C460FW; Android launched Play Store and prompted me to install Samsung Mobile Print, which I did. Now when I place the Galaxy Note 4 on the NFC label, the Galaxy Note 4 automatically enables Wi-Fi, connects to the C460FW directly and displays the Mobile Print app showing the options Print, Scan and Fax, and a page of icons labelled: Gallery, Camera, Google Drive, E-mail, Web page, Document, Facebook, DropBox, Evernote, OneDrive and Box, as well as a Settings icon to configure the printer (paper size etc.). I am able to select a document, photograph, Web page, etc. on the Galaxy Note 4 and print it. It is also possible to launch the Mobile Print app first and then place the Galaxy Note 4 on the C460FW.

NFC is not entirely trouble-free, though. Sometimes the Galaxy Note 4 displays a ‘Device not found‘ message but I can still print. Sometimes the Galaxy Note 4 displays the message ‘Connecting printer. There was some error while connecting to this device. Check your printer and try again. If NFC Pin was changed then please enter new NFC Pin.‘ and the two devices will not connect. Powering off then on the C460FW solves that. Sometimes the Galaxy Note 4 connects to another wireless network instead of to the C460FW via Wi-Fi Direct and the Samsung Galaxy Note 4 then has to disconnect automatically from the other network. Sometimes the C460FW prompts me to press its WPS button and the Galaxy Note 4 then connects via Wi-Fi Direct but the Mobile Print app then displays the error message ‘Device not found. To troubleshoot please check – C460 Series is powered on. – Wi-Fi direct is enabled on C460 Series. – C460 Series and Mobile are connected to the same network.‘. Again, powering off then on the C460FW solves that. Despite these hiccups, printing via NFC is still handy.

SCANNING

Linux

I found out how to get the C460FW scanner working by consulting the third-party Web site The Samsung Unified Linux Driver Repository which someone created to provide .deb packages for the Samsung driver as well as tips on how to get Samsung printers and scanners working in Linux. It turned out to be relatively straightforward to scan, both via the office wired network and via Wi-Fi Direct. I edited the file /etc/sane.d/xerox_mfp.conf and replaced the following:

#Samsung C460 Series
usb 0x04e8 0x3468

with the following in order to use the C460FW to scan via the office wired network:

#Samsung C460 Series
#usb 0x04e8 0x3468
#Wired network static address of this C460FW:
tcp 10.90.21.125

or with the following in order to use the C460FW to scan via Wi-Fi Direct:

#Samsung C460 Series
#usb 0x04e8 0x3468
#Wi-Fi Direct address of this C460FW:
tcp 192.168.3.1

I found the IP addresses from the network configuration report I printed earlier.

I was able to use the two Linux scanning applications I normally use, XSane and gscan2pdf, to scan via the wired network and via Wi-Fi Direct. The resulting scans were very good. Given the ease of scanning via the wired network and Wi-Fi Direct, I have no doubts that scanning would work via a wireless network had the C460FW been configured for the office wireless network instead of the wired network.

Android

To use NFC to scan a document I place the Galaxy Note 4, without Wi-Fi enabled and with the Home Screen displayed (not the Lock Screen), on the NFC label on top of the C460FW. The Galaxy Note 4 enables Wi-Fi, connects automatically to the C460FW directly and launches the Mobile Print app showing the options Print, Scan and Fax. It is also possible to launch the Mobile Print app first and then place the Galaxy Note 4 on the C460FW. In other words, the procedure is exactly the same as when wanting to print via NFC. If I select Scan, the Galaxy Note 4 displays buttons for previewing and scanning. Amongst other things, the app’s Settings menu allows you to select whether you want to save the scanned image as a JPEG, PNG or PDF file. The hiccups mentioned above when printing via NFC also apply to scanning. Nevertheless, scanning from the C460FW to the Samsung Galaxy Note 4 via NFC is still handy.

CONCLUSION

As I am mainly interested in printing text documents I have only tried to print a few colour photographs on plain copier paper, and they look good. Text in documents looks crisp. Despite the lack of automatic duplex printing the C460FW is an excellent peripheral, especially for the price, although I don’t pay for the consumables so I have no idea of the operating costs. The ease with which I got it printing and scanning in Gentoo Linux (laptop) and Android KitKat (Samsung Galaxy Note 4) means that I would definitely consider purchasing this model for home use.

NetworkManager creates a new connection ‘eth0’ that does not work

Several months ago a new entry ‘eth0’ began appearing under ‘Available connections‘ in the KDE plasma-nm widget (the KDE GUI front-end to NetworkManager) in my Gentoo Linux installation. However, there was already an automatically-created entry ‘Wired connection 1’ for the wired interface. In the plasma-nm GUI I could see that both entries were for the same interface (eth0) and MAC address. My laptop could access the Internet via the connection ‘Wired connection 1’ as usual, but not via the new connection ‘eth0’. And if I deleted ‘eth0’ in the plasma-nm GUI, ‘Wired connection 1’ could not access the Internet until I recreated ‘eth0’ manually.

Apart from the fact that two entries for the same interface is unnecessary, it was annoying because sometimes ‘eth0’ automatically became the active connection instead of ‘Wired connection 1’, despite the fact that only ‘Wired connection 1’ had ‘Automatically connect to this network when it is available’ ticked in the plasma-nm GUI. When this happened, the network icon on the Panel showed an active connection but in fact the laptop could not connect to the Internet. However, the connection did work as expected on the occasions when ‘Wired connection 1’ automatically became the active connection or if I switched manually to ‘Wired connection 1’ via the plasma-nm GUI.

Even more strangely, if I happened to be using WiFi when no Ethernet cable was connected, very occasionally the network icon on the Panel would change from a wireless icon to a wired icon and connection to the Internet would be lost. I would then have to re-select the wireless network in order to reconnect to the Internet.

As my laptop has only one Ethernet port, and as there was previously no ‘eth0’ entry under ‘Available connections‘, initially I thought that the new entry occurred because I had recently installed a new version of udev. I have the parameter net.ifnames=0 in the kernel boot line to stop udev/eudev using the so-called Predictable Network Interface Names, and I have the following udev/eudev rules files relating to networking:

# ls -la /etc/udev/rules.d/*net*
lrwxrwxrwx 1 root root    9 Nov 30 15:25 80-net-setup-link.rules -> /dev/null
# ls -la /lib64/udev/rules.d/*net*
-rw-r--r-- 1 root root  452 Nov  7 09:57 /lib64/udev/rules.d/75-net-description.rules
-rw-r--r-- 1 root root 1734 Jan 28 18:29 /lib64/udev/rules.d/77-mm-huawei-net-port-types.rules
-rw-r--r-- 1 root root  491 Nov  7 09:57 /lib64/udev/rules.d/80-net-name-slot.rules
-rw-r--r-- 1 root root  280 Jan 24 00:41 /lib64/udev/rules.d/90-network.rules

Perhaps udev (well, eudev, as I switched to using eudev after the problem started) did have something to do with the new entry, but I began to suspect that NetworkManager was the culprit. I think the problem first occurred after installing NetworkManager 0.9.10.0 last October, but it remained after I installed NetworkManager 1.0.0, until today when I made the various changes described further on.

I had merged NetworkManager 1.0.0 and preceding versions since 0.9.8.8 with USE flags -dhclient and dhcpcd, i.e. NetworkManager in my installation uses the DHCP client dhcpcd instead of dhclient. (I used to merge NetworkManager to use dhclient but found it did not work with 0.9.8.8 and later versions of NetworkManager.)

The relevant network services running in my installation are as follows, and nothing looks incorrect to me:

# rc-update show | grep -i net
       NetworkManager |      default
                local |      default nonetwork
               net.lo | boot
             netmount |      default
# rc-status | grep -i net
NetworkManager                                                    [ started ]
netmount                                                          [ started ]
# rc-update show | grep dh
# rc-status | grep dh
# rc-update -v show | grep supplicant
wpa_supplicant |
# rc-status | grep supplicant
#

NetworkManager itself launches the DHCP client, so the installation should not be configured to launch a DHCP client. Indeed the output above shows that no DHCP client service is configured to run independently of NetworkManager, and I also double-checked that multiple instances of a DHCP client are not running (they’re not):

# ps -C NetworkManager
  PID TTY          TIME CMD
 6481 ?        00:00:22 NetworkManager
# ps -C dhcpcd
  PID TTY          TIME CMD
10378 ?        00:00:00 dhcpcd
# ps -C dhclient
  PID TTY          TIME CMD
#

As far as WiFi is concerned, NetworkManager itself launches wpa_supplicant, so the installation should not be configured to launch wpa_supplicant. Indeed the output from rc-update and rc-status above shows that no wpa_supplicant service is configured to run independently of NetworkManager, and I also double-checked that multiple instances of wpa_supplicant are not running (they’re not):

# ps -C wpa_supplicant
  PID TTY          TIME CMD
 6491 ?        00:00:00 wpa_supplicant
#

So, as far as I could tell, there was nothing wrong with the non-NetworkManager side of my installation.

I thought the problem might be due to the settings in the file /etc/NetworkManager/NetworkManager.conf, which contained the following:

[main]
plugins=keyfile
dhcp=dhcpcd

[ifnet]
managed=true
auto_refresh=false

[keyfile]
hostname=meshedgedx

I studied the manual pages for NetworkManager.conf:

# man NetworkManager.conf

If I understand correctly, the ifnet plug-in is Gentoo-specific (see References 3, 4 and 5 further on). The entries under [ifnet] in my NetworkManager.conf file were redundant in any case because the ifnet plug-in was not included in the plugins list under [main], so I deleted the entire [ifnet] section. There is no mention of the ifnet plug-in on the NetworkManager.conf manual page or in the Gentoo Linux Wiki article on NetworkManager, and a cursory look in the Gentoo ebuild for NetworkManager 1.0.0 clearly indicates the ifnet plug-in is broken. See, for example, the following comment in the ebuild:

# ifnet plugin always disabled until someone volunteers to actively
# maintain and fix it

and the following warning messages in the ebuild if the user has included ifnet in plugin=<plugin list> in NetworkManager.conf:

ewarn "Ifnet plugin is now disabled because of it being unattended"
ewarn "and unmaintained for a long time, leading to some unfixed bugs"
ewarn "and new problems appearing. We will now use upstream 'keyfile'"
ewarn "plugin."
ewarn "Because of this, you will likely need to reconfigure some of"
ewarn "your networks. To do this you can rely on Gnome control center,"
ewarn "nm-connection-editor or nmtui tools for example once updated"
ewarn "NetworkManager version is installed."
ewarn "You seem to use 'ifnet' plugin in ${EROOT}etc/NetworkManager/NetworkManager.conf"
ewarn "Since it won't be used, you will need to stop setting ifnet plugin there."

I modified NetworkManager.conf to contain the following:

[main]
plugins=keyfile
dhcp=dhcpcd
no-auto-default=eth0

[keyfile]
hostname=meshedgedx

Note that the ifnet plug-in was not specified in the plugins list in the [main] section of my previous NetworkManager.conf so it was not the cause of my problem, but I hoped that adding no-auto-default=eth0 to NetworkManager.conf would solve the problem. I deleted the ‘Wired connection 1’ entry from the plasma-nm GUI, ticked ‘Automatically connect to this network when it is available’ for the ‘eth0’ entry and made sure that option was not ticked for any of the other entries under ‘Available connections‘, then rebooted. There was no longer an entry ‘Wired connection 1’ in the plasma-nm widget GUI, just an entry for ‘eth0’, and the installation connected automatically to the wired network and I could access the Internet, but did not reconnect to the wired network if I removed and reinserted the Ethernet cable when also connected to a wireless network. So I was not home and dry yet.

I have read on various Web sites that NetworkManager prefers wired connections over wireless connections. I assume this is because NetworkManager sets a higher metric for the wired connection.

I am on a work trip at the moment and cannot use a dynamic wired connection, only a static wired connection, but I can see that NetworkManager 1.0.0 does set a higher-priority metric for wired connections:

# # Now with both dynamic wireless and static wired:
# ip route show
default via 10.90.21.1 dev eth0  proto static  metric 100
default via 10.96.0.1 dev wlan0  proto static  metric 600
10.90.21.0/24 dev eth0  proto kernel  scope link  src 10.90.21.112  metric 100
10.96.0.0/16 dev wlan0  proto kernel  scope link  src 10.96.87.86
10.96.0.0/16 dev wlan0  proto kernel  scope link  src 10.96.87.86  metric 303
127.0.0.0/8 dev lo  scope host
127.0.0.0/8 via 127.0.0.1 dev lo
192.0.2.1 via 10.96.0.1 dev wlan0  proto dhcp  metric 600
#

10.90.21.1 is the IP address of the gateway for the wired connection, and 10.90.21.112 is the IP address of my laptop’s wired interface. The smaller the metric value, the higher the routing priority. Notice that the metric for the eth0 interface is 100 whereas the metric for the wlan0 interface is 600, so it does appear that NetworkManager favours a wired connection over a wireless connection when both are active.

After doing all the above, I came across Debian bug report no. 755202: network-manager: keeps creating and using new connection “eth0” that does not work which appears to be exactly what I was experiencing. Various people posted solutions that worked in their particular circumstances, so I am none the wiser. Gentoo user Keivan Moradi posted message no. 79 on that bug report, about a warning message he found in the NetworkManager log file regarding a file /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0, and he then deleted the latter file. I found the same message in /var/log/messages:

# grep networkmanager /var/log/messages
Feb  9 04:10:05 localhost NetworkManager[10355]: <warn>      error in connection /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0: invalid connection: connection.type: property is missing
Feb 11 15:53:05 localhost NetworkManager[13143]: <warn>      error in connection /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0: invalid connection: connection.type: property is missing

The file /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0 also existed in my installation, so I also deleted it. It was a zero-length file and I do not know if it had anything to do with my problem:

# ls -la /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0
-rw------- 1 root root 0 Jan 20 00:09 /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0
# rm /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0
#

Anyway, the file /etc/NetworkManager/system-connections/.keep_net-misc_networkmanager-0 has not reappeared since I deleted it.

Keivan Moradi had ‘id=Wired‘ under [connection] in the file /etc/NetworkManager/system-connections/eth0, and he decided to change the name of the file from ‘eth0‘ to ‘Wired‘. However, in my case the file name and the id in the file /etc/NetworkManager/system-connections/eth0 are both ‘eth0‘:

# cat /etc/NetworkManager/system-connections/eth0
[ethernet]
mac-address=70:5A:B6:3E:C1:8A
mac-address-blacklist=

[connection]
id=eth0
uuid=cb3d5786-f947-44b8-92f7-8471fc94c568
type=ethernet
permissions=
secondaries=

[ipv6]
method=ignore
dns-search=

[ipv4]
method=auto
dns-search=

I had already deleted and recreated the connection ‘eth0’ in the plasma-nm GUI by the time I checked the contents of the directory /etc/NetworkManager/system-connections/ so I do not know if the original file name and id were the same. I had also already deleted the connection ‘Wired connection 1’ in the plasma-nm GUI by the time I checked the contents of the directory; presumably files for connections ‘Wired connection 1’ and ‘eth0’ both existed in /etc/NetworkManager/system-connections/ before then. I do not know why the zero-length file .keep_net-misc_networkmanager-0 was created, but no further files have appeared in the directory since I deleted the connection ‘Wired connection 1’ and the file .keep_net-misc_networkmanager-0.

Keivan Moradi was also previously using a buggy r8169 kernel module (Realtek Ethernet hardware) and switched to using the r8168 module, but I am using a Qualcomm Atheros AR8131 Gigabit Ethernet card and an Intel Corporation Ultimate N WiFi Link 5300 card, so that part of his problem cannot be a factor in my case.

Anyway, as I wrote earlier, I no longer have two connection entries for the wired interface, and NetworkManager no longer creates automatically a second connection entry for the wired interface. And now if I am already connected to a wireless network, NetworkManager connects/reconnects automatically to a wired network with the ‘Automatically connect’ option ticked. So it looks like my problem is completely solved, although I reserve judgement until I have been able to use the laptop in my home network (which has the same router for both wired and wireless connections, whereas the wired network and wireless network are separate networks in the office in which I am now working).

Conclusion

If you had the patience to read all the above, I am impressed! If you also understood it, I am doubly impressed!

To cut a long story short, if you are experiencing a similar problem to mine, I recommend you do the following:

  1. Check that your network driver is reliable. You can search the Web to see if other users have experienced problems with the same driver you are using.

  2. Make sure the contents of NetworkManager.conf are correct. Read the NetworkManager.conf man page and the GNOME Wiki page on NetworkManager settings to find out what options are available.

  3. Delete all the files (i.e. including hidden files) in the directory /etc/NetworkManager/system-connections/ and recreate your connections via either the NetworkManager GUI (e.g. plasma-nm in KDE or nm-applet in GNOME) or NetworkManager TUI (nmtui).

References

  1. man NetworkManager.conf
  2. Gentoo Linux Wiki – NetworkManager
  3. GNOME Wiki – NetworkManager SystemSettings – Configuration Plugins
  4. Gentoo NetworkManager Plugin
  5. Another Gentoo Dev – Ifnet updates for NetworkManager 0.9

UPDATE (March 10, 2015): Well, I was right to reserve judgement until I was able to use my laptop with my home network. I am now back at home and an Ethernet cable is plugged into my laptop’s RJ45 socket. Even with the changes I made, when I boot the laptop NetworkManager sometimes (but not always) has two connections named ‘eth0’, one of them the ‘Active connection’ (but not able to connect to the Internet) and the other an ‘Available connection’. In this situation the wired network icon on the Panel has a yellow question mark superimposed. If I delete the ‘eth0’ active connection and use the other ‘eth0’, the latter works as expected and I have no trouble connecting to the Internet. In Debian bug report no. 755202 (see the link further up) user Frederik Himpe added a comment on March 4, 2015 that he is also still experiencing this problem and “It looks like there is a race somewhere, causing the network interface to be brought up before Network Manager is started, and this prevents correct configuration by NM”. So the problem is still unresolved. Hmm … I wonder if udev does have something to do with it after all.

UPDATE (March 12, 2015): The problem persists. I disabled use of IPv6 in /etc/avahi/avahi-daemon.conf to see if the Avahi daemon has something to do with the problem, but that made no difference. Later I also disabled use of IPv4 in /etc/avahi/avahi-daemon.conf, but that made no difference either. So it looks like the Avahi daemon is not the culprit. Checking via the plasma-nm GUI I notice that the ‘rogue’ eth0 Active connection has IPv4 disabled and IPv6 Link-Local enabled. So why is NetworkManager creating a second eth0 connection just for IPv6 Link-Local? And why on Earth is NetworkManager creating any additional connection at all when NetworkManager.conf contains no-auto-default=eth0? Surely this must be a bug in NetworkManager 1.0.0?

UPDATE (March 17, 2015): I have been investigating the problem further: see my latest blog post for details.

KDE Connect – Link your Android device to your KDE desktop

KDE Connect app icon on my Samsung Galaxy Note II

KDE Connect app icon on my Samsung Galaxy Note II

KDE Connect is a nice tool that links your Android phone or tablet seamlessly via WiFi to KDE on your PC (the latter can be connected via WiFi or cable to the network). It allows your KDE desktop to receive notifications, files and media player commands from your Android device. The available KDE Connect plug-ins are:

Battery report
Periodically report battery status

Clipboard sync
Share the clipboard content

Multimedia remote controls
Control audio/video from your phone
(pause; first track; previous track; next track; last track; change volume)

Notification sync
Access your notification from other devices

Ping
Send and receive pings

Telephony notifier
Send notifications from SMS and calls

You will need to install the Android KDE Connect application on your Android device, and the Linux KDE Connect application on your PC.

Install the KDE Connect app on your Android device from the Google Play Store. You will then see the KDE Connect icon on the apps screen of your Android device.

For Gentoo users an ebuild for KDE Connect is available in the Gentoo KDE team’s testing overlay, so here are the instructions on how to install KDE Connect on your PC from there.

Firstly, mask the KDE overlay so that none of the packages in it interferes with the KDE software you installed from the main Portage tree:

# echo "*/*::kde" >> /etc/portage/package.mask

Then unmask the KDE Connect package in the KDE overlay:

# echo "kde-misc/kdeconnect" >> /etc/portage/package.unmask

N.B. If /etc/portage/package.mask is a directory rather than a file (either is possible) in your installation, and if /etc/portage/package.unmask is a directory rather than a file (either is possible) in your installation, use the following commands instead of the above two commands:

# echo "*/*::kde" > /etc/portage/package.mask/kde_overlay
# echo "kde-misc/kdeconnect" > /etc/portage/package.unmask/kdeconnect

Now add the KDE overlay and merge the package:

# layman -a kde
# emerge kdeconnect

If a firewall is running on your PC, you will need to configure it to allow tcp and udp traffic via a specific range of ports (1714 to 1764). I have UFW running on my main laptop, so in my case I used the following commands:

# ufw allow proto tcp to any port 1714:1764
# ufw allow proto udp to any port 1714:1764

The rules should look like this:

# ufw status verbose | grep 1714
1714:1764/tcp ALLOW IN Anywhere
1714:1764/udp ALLOW IN Anywhere
1714:1764/tcp ALLOW IN Anywhere (v6)
1714:1764/udp ALLOW IN Anywhere (v6)

If you have the KConfig Module kcm_ufw installed on your PC then you can instead use System Settings > Firewall to add the UFW rules via the KDE GUI.

By the way, to check which KConfig modules are installed on your PC you can use the following command under your user account:

$ kcmshell4 --list

Using KDE Connect is not difficult, so I will leave you to play with it. Obviously make sure WiFi is enabled on your Android device, and that it and your PC are connected to the same network. Tap on the KDE Connect icon on your Android device to launch the app, and you should see your PC’s name listed under CONNECTED DEVICES. Tap on the PC name and you should see the following screen:

KDE Connect screen

KDE Connect screen

If you tap on ‘Send ping’, the KDE Notification widget on the KDE System Tray should pop up a notification.

You can see what KDE Connect plug-ins are available, and select/deselect them:

KDE Connect plugins

KDE Connect plugins

KDE Connect also enables you to use your Android device as a remote control for media players running on your PC. When you launch a media player in KDE its name will appear in a list of selectable players in KDE Connect, and the name of the track currently playing will also be displayed:

KDE Connect - Remote control

KDE Connect - Remote control

When you select a file on your Android device and tap the Share icon, KDE Connect will be one of the options displayed on the ‘Share via’ menu. This is a handy way to send files from your Android device to your PC. The KDE Notification widget on your PC will notify you when the file has been transferred to ~/Desktop/ on your PC:

KDE on your PC notifies you when a file has been sent via KDE Connect

KDE on your PC notifies you a file has been sent via KDE Connect

You should also get notifications on your KDE desktop when someone phones or sends you an SMS.

Kudos and many thanks to the people responsible for KDE Connect. KDE is already a superb desktop environment, and with the addition of KDE Connect it is better still.