Using the SMB/CIFS Protocol on Non-Microsoft Clients: Samba

SMB/CIFS is a protocol that is highly entrenched in the Microsoft world of operating systems and networking products. It makes sense, then, that there would be a way in which these workstations and servers could be integrated into a Unix/Linux environment without a lot of difficulty. The answer to this problem is called Samba, which is a set of products that provide for SMB conversations between SMB servers, such as Microsoft Windows operating systems, and those that do not use it natively,such as many different variants of Unix or Linux systems. In addition, Samba has been ported to several other popular operating systems, including OpenVMS.

Samba was originally developed by Andrew Tridgell and is now maintained by him and other developers (the "Samba Team") on the Internet.

From this Web site you can choose a mirror Web site for your country, and then you can view the documentation for Samba and download the most recent version. The software is freely distributed under the GNU public license.

You can configure Samba servers on your Unix boxes to enable high-performance machines to beused as file servers on the Windows network. You can still manage the servers using Unix file administration procedures, and yet to the client computers, the shares appear no different than those offered by other Windows-based file servers.

Troubleshooting a Samba server can be made easier by starting the Samba server software using the - d parameter to specify a debug level (from 1 to 100), which will cause more output messages, depending on the level you specify.

You can also use a LAN analyzer to view the sequence of exchange of SMB messages between server and client. Available as a download from the Samba home page is an extension to the tcpdump utility, called tcpdump-smb. You can use this to capture smb packets and decode the header information.

The Common Internet File System (CIFS)

CIFS is intended to be a replacement, or an upgrade, of the SMB protocol. Design considerations include making it platform-independent. While SMB resides in the NetBIOS legacy environment, CIFS runs on top of TCP. Other improvements over SMB include the following:

• Unicode filenames are used. Because the Internet is global, it's helpful to be able to encode char acters that support multiple languages.
• Service is automatically restored after a network disruption.
• CIFS is not proprietary to Microsoft. It is an Open Group standard (X/Open CAE Specification C209). It has also been proposed as an Internet standard to the Internet Engineering Task Force (IETF). This is an improvement over the earlier SMB protocol.
• DNS is used to translate between computer hostnames and IP addresses.
• Both share-level authentication and user-level authentication are supported. With user-level authentication, the user must be authenticated (using a username/password valid on the server) before access is granted.
• CIFS has been optimized to make communications across a slow link—such as a dial-up modem—possible.
• CIFS is basically an enhanced version of SMB and still uses server message block messaging. Better security and the use of DNS are necessary additions if the protocol is to be used on the Internet.