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Server Message Block (SMB)

The Server Message Block (SMB) protocol was originally designed at IBM and later incorporated as the de facto networking file/print sharing system for Microsoft Windows.

In 1996, the latest version of the SMB protocol was renamed to Common Internet File System (CIFS), as many new features were added.

The Samba Project started as a reverse-engineered implementation of the SMB protocol for Solaris servers. To learn more about this, visit Samba's website.

Samba is built to be an SMB/CIFS server which will run on any UNIX-like system.

Samba​

Features​

Samba features include the following:

  • Samba can create file or printer shares.
  • Samba version 3.x can act as a WindowsNT domain controller.
  • Samba version 4.x can act as an Active Directory domain controller.
  • Samba version 4.x is available on most distributions.

Configuration​

The default location for the Samba configuration file is /etc/samba/smb.conf, which uses an INI-file-like syntax, with section headers enclosed in square brackets.

[global]
    workgroup = MYGROUP
    server string = Samba Server Version %v
    log file = /var/log/samba/log.%m
    max log size = 50
    cups options = raw

Each individual share then goes into its own section:

[mainshare]
    path = /srv/exports/
    read only = yes
    comment = Main exports share

User Accounts​

Due to the difference in system password hashing mechanisms, Samba cannot verify some user passwords without additional help.

The smbpasswd command allows you to manage your passwords in both the Samba password file and in directory services.

To create a new password entry for Samba, do:

smbpasswd -a geoff

To change the password for geoff, do:

smbpasswd geoff

In the event that the UNIX username does not match the Samba username, the /etc/samba/smbusers file allows for the translation.

UNIXNAME = SMBNAME SMBNAME2

testparm​

testparm is the syntax checker for smb.conf.

Once you have created your smb.conf file, test the syntax with the testparm command:

testparm

Load smb configuration files from /etc/samba/smb.conf
rlimit_max: increasing rlimit_max (1024) to minimum Windows limit
(16384)
Processing section "[mainshare]"
Loaded services file OK.
Server role: ROLE_STANDALONE
Press enter to see a dump of your service definitions

When you press Enter, you will get a parsed copy of the configuration file.

Clients​

There are several ways to interface with a Samba server:

Query the shares on a server:

smbclient -L 172.16.104.131 -U student


Enter SAMBA\student's password:
Domain=[UBUNTU] OS=[Windows 6.1] Server=[Samba 4.5.8-Ubuntu]
      Sharename     Type          Comment
      -------       ----          ---------
      cifs-share    Disk          Example share for testing home-export-cifs
      IPC$          IPC           IPC Service (ubuntu server (Samba, Ubuntu))

Domain=[UBUNTU] OS=[Windows 6.1] Server=[Samba 4.5.8-Ubuntu]
      Server                 Comment
      ---------              -------
      Workgroup              Master
      -------                -------
      LFLAB                  UBUNTU

Using the FTP-like interface:

smbclient //SERVER/mainshare
smb: \> get /foo

Mount the SMB/CIFS share into your name space:

mount -t cifs -o username,password //SERVER/share/ /mnt/point/

To avoid putting usernames and passwords into a world-readable file (/etc/fstab), the CIFS mount command takes the credentials=filename option.

mount -t cifs -o credentials=filename //SERVER/share/ /mnt/point/

The credentials file has the following syntax:

username=value
password=value
domain=value