SMB/CIFS Utilities

The Common Internet File System (CIFS) offers the possibility to map network drives on Windows workstations; the corresponding network protocol was formerly called Server Message Block (SMB). UNIX/Linux operating systems usually come with some utilities which help to make use of CIFS on these platforms, too:

The smbclient program is a command line tool e.g. for

• listing network shares and network printers offered by windows servers,
• listing directory contents,
• or file transfer.

In the following, lmuelle8 will be used as an example for a valid GWDG user account name, and winfs-uni.top.gwdg.de will serve as an example for a Windows CIFS/SMB server. Since Windows servers are typically part of the Active Directory, a domain has also to be specified. GWDG is usually correct; employees of the Max-Planck-Institute (MPI) for Biophysical Chemistry have to use MBPC, employees of the MPI fuer Experimentelle Medizin MPEM.

smbclient -L winfs-uni.top.gwdg.de -W GWDG -U lmuelle8
Password:

Although the password could be given directly on the command line, this should be avoided for security reasons; it is better to be prompted for the password. The output of the command has been omitted because it is very long.

smbclient //winfs-uni.top.gwdg.de/lmuelle8$ -W GWDG -U lmuelle8
Password: 
Domain=[GWDG] OS=[Windows Server 2008 R2 Enterprise 7601 Service Pack 1] Server=[Windows Server 2008 R2 Enterprise 6.1]
smb: \> dir
  .                                  DR        0  Mon May 23 11:52:52 2011
  ..                                 DR        0  Mon May 23 11:52:52 2011
  $RECYCLE.BIN                      DHS        0  Tue May  3 08:51:59 2011
  Eigene Bilder                     DAR        0  Wed Jun 30 05:24:50 2010
  Eigene Musik                      DAR        0  Wed Jun 30 05:24:50 2010
  IO.SYS                           AHSR        0  Thu Feb  8 11:15:26 2001
  MSDOS.SYS                        AHSR        0  Thu Feb  8 11:15:26 2001
  My Music                           DR        0  Tue May  3 08:51:59 2011
  My Pictures                        DR        0  Tue May  3 08:51:59 2011
  My Videos                          DR        0  Tue May  3 08:51:59 2011
  WINDOWS                             D        0  Tue May  3 08:51:49 2011
  _AdminsOnly                       DAH        0  Wed Jun 30 05:24:46 2010
  _GWDGsys                           DA        0  Wed Jun 30 05:24:48 2010

		65535 blocks of size 33554432. 18580 blocks available
smb: \> quit

These directory entries didn't change for years, but that's life …

Please notice the trailing $ symbol within the name of the network share //winfs-uni.top.gwdg.de/lmuelle8$. It has to be appended because all shares on Windows/CIFS servers exporting user data are hidden and thus require a $ on access.

smbclient //winfs-uni.top.gwdg.de/lmuelle8$ -W GWDG -U lmuelle8
Password: 
Domain=[GWDG] OS=[Windows Server 2008 R2 Enterprise 7601 Service Pack 1] Server=[Windows Server 2008 R2 Enterprise 6.1]
smb: \> put example.doc
putting file example.doc as \example.doc (2142.8 kb/s) (average 2142.9 kb/s)
smb: \> cd "My Music"
smb: \My Music\> get laughter.mp3
getting file \My Music\laughter.mp3 of size 3953876 as laughter.mp3 (16223.6 kb/s) (average 16223.6 kb/s)
smb: \My Music\> quit

As demonstrated, put sends files to the remote host, while get fetches them.

Help is available via manual page (man smblient) or the online help command which can be typed at the smb: prompt.

On FreeBSD or Linux systems, e.g., it is possible to mount a Windows network share into the local directory tree. Here, it is important to realize that it is inevitable to establish a user mapping while mounting the share. Thus on the one hand the user credentials on the remote Windows server as well as a local user name have to be specified. On the FreeBSD/Linux client, all files seem to belong to the specified local user, whereas in reality they belong to the user whose credentials were used when accessing the share. Both user names may be equal but they do not have to be.

Example user, server and share names are as described above within the context of smbclient.

Please look at the manual pages on your system for further help if the examples below won't help.

mount_smbfs -U lmuelle8 -I winfs-uni.top.gwdg.de -W GWDG -u 1001 -g 20 //lmuelle8@winfs-uni/lmuelle8$ /import/lmuelle8
Password:

The password could be given in the command line, but should not for security reasons. Meaning of the arguments is:

• -U lmuelle8 – user account name to authenticate with
• -I winfs-uni.top.gwdg.de – host name or ip address of server
• -W GWDG – active directory domain
• -u 1001 – local user number
• -g 20 – local group number
• //lmuelle8@winfs-uni/lmuelle8$ – //name of remote user@netbios server name/network share name
• /import/lmuelle8 – local directory to mount on

mount.cifs -o domain=GWDG,user=lmuelle8,uid=1001,gid=100 //winfs-uni.top.gwdg.de/lmuelle8$ /import/lmuelle8
Password:

The password could be given in the command line, but should not for security reasons. Meaning of the arguments is:

• -o domain=GWDG,user=lmuelle8,uid=1001,gid=100 – active directory domain, user account name to authenticate with, local user number, local group number
• //winfs-uni.top.gwdg.de/lmuelle8$ – //host name or ip address of server/network share name
• /import/lmuelle8 – local directory to mount on

The mount.cifs command mentioned before works properly if you want to mount the share at once. For a persistent mounting the effort specifying the userid, domain, share URI and mountpoint and always entering the password may be not really comfortable. So you may want to mount the CIFS shares as you do with NFS by adding a line to the /etc/fstab.

# cat /etc/fstab  | grep cifs
//winfs-uni.top.gwdg.de/lmuelle8$  /import/lmuelle8 cifs domain=GWDG,user=lmuelle8,uid=1001,gid=100,file_mode=0664 0 0

This skips out the mount command with all the options, but still requires to enter the password. If it's ok to store the password in your linux system, you can use a credential file instead of giving username, domain and password. Such a file looks like this (taking the example from above):

# cat /etc/smbpasswd
domain=GWDG
username=lmuelle8
password=<User's Password in plain text>

The line in the fstab file then looks like this:

# cat /etc/fstab  | grep cifs
//winfs-uni.top.gwdg.de/lmuelle8$  /import/lmuelle8 cifs credentials=/etc/smbpasswd,uid=1001,gid=100,file_mode=0640 0 0

if you want to mount different shares you can use the same credential file for each, if you need different credentials for different shares just setup different credential files, e.g.

# cat /etc/fstab  | grep cifs
//winfs-uni.top.gwdg.de/lmuelle8$   /import/lmuelle8  cifs credentials=/home/lmuelle8/.smb-lmuelle8,uid=1001,gid=100,file_mode=0640 0 0
//wfs-test.top.gwdg.de/workgroup$   /import/workgroup cifs credentials=/etc/smbworkgroup,uid=1001,gid=1000,file_mode=0664 0 0

chmod 600 <path to credentials file>