Samba

From ArchWiki

Samba is a re-implementation of the SMB/CIFS networking protocol, it facilitates file and printer sharing among Linux and Windows systems as an alternative to NFS. Samba is easily configured and operation is very straight-forward.

Installation

Installing only the client program is sufficient for systems that are not meant to share files, only access them:

# pacman -S smbclient

In order to make shares available to clients, install the Samba server package:

# pacman -S samba

A daemon is installed with the server and it must be started for Samba to begin working. Samba typically uses FAM to monitor the file-system for changes, yet Gamin has almost completely replaced FAM as of recent, mainly because the former is poorly maintained and generally an inferior, unpopular choice.

To install Gamin:

# pacman -S gamin

Configuration

The /etc/samba/smb.conf file must be created before starting the daemons. Once that is setup, users may opt for using an advanced configuration interface like SWAT.

smb.conf

As root, copy the default Samba configuration file to /etc/samba/smb.conf:

# cp /etc/samba/smb.conf.default /etc/samba/smb.conf

Open smb.conf and edit it to suit your needs. The default file creates a share for each user's home directory. It also creates a share for printers.

Starting and automating the daemons

If using FAM, start the fam daemon before samba. Gamin does not need a daemon since it automatically starts when needed.

Without rebooting, FAM and Samba can be started with the commands:

# /etc/rc.d/fam start
# /etc/rc.d/samba start

Add fam and samba to the DAEMONS line in rc.conf to automatically start the daemons at boot.

SWAT: Samba web administration tool

SWAT is a facility that is part of the Samba suite. The main executable is called swat and is invoked by the internetworking super daemon, inetd.

There are many and varied opinions regarding the usefulness of SWAT. No matter how hard one tries to produce the perfect configuration tool, it remains an object of personal taste. SWAT is a tool that allows Web-based configuration of Samba. It has a wizard that may help to get Samba configured quickly, it has context-sensitive help on each smb.conf parameter, it provides for monitoring of current state of connection information, and it allows network-wide MS Windows network password management.[1]

To use SWAT, first install xinetd:

# pacman -S xinetd

Edit /etc/xinetd.d/swat using your favorite text editor. To enable SWAT, change the disable = yes line to disable = no.

Additionally, edit /etc/hosts.allow if remote administration is needed.

The web interface can be accessed on port 901 by default,

http://localhost:901/

Adding users

To log into a Samba share you'll need to add a user:

# smbpasswd -a <user>

The user must already have a account on the server. If the user does not exist you will receive the error:

Failed to modify password entry for user "<user>"

You can add a new user to the Linux host with adduser. This article does not cover adding users to Windows systems.

Accessing Samba shares

KDE and Gnome have the ability to browse Samba shares. You therefore do not need any additional packages if using either of these DEs. If however you plan to use the share solely from a shell, you will need an additional package.

Accessing a Samba share from Gnome or KDE

From a Nautilus/Dolphin/Konqueror window, hit Ctrl+L or go to the "Go" menu and select "Location..." -- both actions will allow you to type in the "Go to:" blank. Enter:

smb://servername/share

For a GUI in the KDE System Settings you have to install the kdenetwork-filesharing package from [extra].

Accessing a Samba share from the shell

Shares may be accessed by using an automatic mounter or by using a manual method.

Automatic share mounting

There are several alternatives for easy share browsing.

smbnetfs

1. Install smbnetfs:

# pacman -S smbnetfs

2. Add the following line to /etc/fuse.conf:

user_allow_other

3. Load the fuse kernel module:

# modprobe fuse

4. Start the smbnetfs daemon:

# /etc/rc.d/smbnetfs start

All shares in the network are now automatically mounted under /mnt/smbnet.

Add the following to /etc/rc.conf to access the shares at boot:

MODULES=(... fuse ...)
DAEMONS=(... smbnetfs ...)

fusesmb

1. Install the fusesmb package from the AUR using yaourt or other AUR Helpers:

$ yaourt -S fusesmb

2. Create a mount point:

# mkdir /mnt/fusesmb

3. Load fuse module:

# modprobe fuse

4. Mount the shares:

# fusesmb -o allow_other /mnt/fusesmb

For mounting shares at boot, add the command above to /etc/rc.local and add fuse module to /etc/rc.conf:

MODULES=(... fuse ...)

Autofs

See Autofs for information on the kernel-based automounter for Linux.

Manual share mounting

1. Use smbclient to browse shares from the shell. To list any public shares on a server:

$ smbclient -L <hostname> -U%

2. Create the mount point for the share:

# mkdir /mnt/MOUNTPOINT

3. Mount the share using mount.cifs. Keep in mind that not all options may be needed nor desirable, such as password:

# mount -t cifs //SERVER/SHARENAME MOUNTPOINT -o user=USERNAME,password=PASSWORD,workgroup=WORKGROUP,ip=SERVERIP

SERVER

The Windows system's name

SHARENAME

The shared directory

MOUNTPOINT

The local directory where the share will be mounted to

-o [options]

Specifies options for mount.cifs

user

Username used to mount the share

password

The shared directory's password

workgroup

Used to specify the workgroup

ip

The IP address of the server -- if the system is unable to find the Windows computer by name (DNS, WINS, hosts entry, etc.)

4. To unmount the share, use:

# umount /mnt/MOUNTPOINT

Adding the share to fstab

Add the following to /etc/fstab for easy mounting:

//SERVER/SHARENAME /mnt/MOUNTPOINT cifs noauto,noatime,username=USER,password=PASSWORD,workgroup=WORKGROUP 0 0

The noauto option disables mounting it automatically at boot and noatime increases performance by skipping inode access times.

After adding the previous line, the syntax to mount files becomes simpler:

# mount /mnt/MOUNTPOINT

If adding a Samba share to fstab, the netfs daemon should also be added to rc.conf, somewhere after the network daemon. The netfs daemon will mount network partitions at boot and, more importantly, unmount network partitions at shutdown. Even if using the noauto option in fstab, the netfs daemon should be used. Without it any network share that is mounted when shutting down will cause the network daemon to wait for the connection to time out, considerably extending poweroff time.

Allowing users to mount

Before enabling access to the mount commands, fstab needs to be modified. Add the users options to the entry in /etc/fstab:

//SERVER/SHARENAME /path/to/SHAREMOUNT cifs users,noauto,noatime,username=USER,password=PASSWORD,workgroup=WORKGROUP 0 0

This will allow users to mount it aslong as the mount point resides in a directory controllable by the user; i.e. the user's home. For users to be allowed to mount and unmount the Samba shares with mount points that they do not own, use #smbnetfs, or grant privileges using sudo.

Tips and tricks

Share files for your LAN without user and password

Edit /etc/samba/smb.conf and change the following line:

security = user

to

security = share

If you want to restrict the shares data to a specific interface replace:

;   interfaces = 192.168.12.2/24 192.168.13.2/24

with:

interfaces = lo eth0
bind interfaces only = true

(changing eth0 to the local network you want share with.)

If you want to edit the account that access the shares, edit the following line:

;   guest account = nobody

The last step is to create share directory (for write access make writable = yes):

[Public Share]
path = /path/to/public/share
available = yes
browsable = yes
public = yes
writable = no

Sample configuration file

The configuration that worked for one user:

[global]
workgroup = WORKGROUP
server string = Samba Server
netbios name = PC_NAME
security = share
; the line below is important! If you have permission issues make sure the user here is the same as the user of the 
; folder you want to share
guest account = mark
username map = /etc/samba/smbusers
name resolve order = hosts wins bcast
wins support = no

[public]
comment = Public Share
path = /path/to/public/share
available = yes
browsable = yes
public = yes
writable = no

Discovering network shares

If nothing is known about other systems on the local network, and automated tools such as #smbnetfs are not available, the following methods allow one to manually probe for Samba shares.

1. First, install nmap and smbclient using pacman:

# pacman -S nmap smbclient

2. nmap checks which ports are open:

# nmap -sT 192.168.1.*

In this case, a scan on the 192.168.1.* IP address range has been performed, resulting in:

Starting nmap 3.78 ( http://www.insecure.org/nmap/ ) at 2005-02-15 11:45 PHT
Interesting ports on 192.168.1.1:
(The 1661 ports scanned but not shown below are in state: closed)
PORT     STATE SERVICE
139/tcp  open  netbios-ssn
5000/tcp open  UPnP

Interesting ports on 192.168.1.5:
(The 1662 ports scanned but not shown below are in state: closed)
PORT     STATE SERVICE
6000/tcp open  X11

Nmap run completed -- 256 IP addresses (2 hosts up) scanned in 7.255 seconds

The first result is another system; the second happens to be the client from where this scan was performed.

3. Now that systems with port 139 open are revealed, use nmblookup to check for NetBIOS names:

Looking up status of 192.168.1.1
        PUTER           <00> -         B <ACTIVE>
        HOMENET         <00> - <GROUP> B <ACTIVE>
        PUTER           <03> -         B <ACTIVE>
        PUTER           <20> -         B <ACTIVE>
        HOMENET         <1e> - <GROUP> B <ACTIVE>
        USERNAME        <03> -         B <ACTIVE>
        HOMENET         <1d> -         B <ACTIVE>
        MSBROWSE        <01> - <GROUP> B <ACTIVE>

Regardless of the output, look for <20>, which shows the host with open services.

4. Use smbclient to list which services are shared on PUTER. If prompted for a password, pressing enter should still display the list:

Sharename       Type      Comment
---------       ----      -------
MY_MUSIC        Disk
SHAREDDOCS      Disk
PRINTER$        Disk
PRINTER         Printer
IPC$            IPC       Remote Inter Process Communication

Server               Comment
---------            -------
PUTER

Workgroup            Master
---------            -------
HOMENET               PUTER

This shows which folders are shared and can be mounted locally. See: #Accessing Samba shares

Troubleshooting

Trouble accessing a password-protected share from Windows

If you are having trouble accessing a password protected share from Windows, try adding this to /etc/samba/smb.conf:[2]

Note that you have to add this to your local smb.conf, not to the server's smb.conf

[global]
# lanman fix
client lanman auth = yes
client ntlmv2 auth = no

Getting a dialog box up takes a long time

I had a problem that it took ~30 seconds to get a password dialog box up when trying to connect from both Windows XP/Windows 7. Analyzing the error.log on the server I saw:

[2009/11/11 06:20:12,  0] printing/print_cups.c:cups_connect(103)
Unable to connect to CUPS server localhost:631 - Interrupted system call

I don't have any printer connected to this server, so I added this to the global section:

load printers = no
printing = bsd
disable spoolss = yes
printcap name = /dev/null

Not sure if all of them are necessary, but at least it works now.

Changes in Samba version 3.4.0

Major enhancements in Samba 3.4.0 include:

The default passdb backend has been changed to 'tdbsam'! That breaks existing setups using the 'smbpasswd' backend without explicit declaration!

If you would like to stick to the 'smbpasswd' backend try changing this in /etc/samba/smb.conf:

passdb backend = smbpasswd

or convert your smbpasswd entries using:

sudo pdbedit -i smbpasswd -e tdbsam

Error: Value too large for defined data type

With some applications you could get this error whith every attempt to open a file mounted in smbfs/cifs:

 Value too large for defined data type

The solution[3] is to add this options to your smbfs/cifs mount options (in /etc/fstab for example):

 ,nounix,noserverino

It works on Arch Linux up-to-date (2009-12-02)

Resources

• Samba's official site
• Samba: An Introduction