CIFS (Common Internet File System) is a protocol that became popular around 2000. This post introduces more information about it. You can know the features and usage of CIFS. Besides, you can know how does it work and the differences between it and SMB.

Definition of CIFS

What is CIFS? CIFS is the abbreviation of the Common Internet File System. It is a network file system protocol, which is used to provide shared access to files and printers between computers on the network.

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Features of CIFS

Then, let’s see the features of CIFS.

  1. Flexible connection – a single client can be connected to multiple servers with CIFS, and even multiple connections to a single server can be established when necessary.
  2. Resource access – the CIFS protocol does not limit the types of resources that clients can connect to. CIFS clients can simultaneously connect to shared files, named pipes, print queues, and other resources.
  3. Intelligent transmission – although the CIFS protocol is usually used on top of connection-oriented protocols, it can also use connectionless protocols.
  4. Support distributed file system – the Windows Server operating system supports the use of the Distributed File System (DFS), which creates a global namespace that can contain resources on multiple servers. The CIFS protocol fully supports the DFS function.
  5. File and directory change notification – the CIFS protocol includes a mechanism that allows clients to be notified when changes are made to shared resources.

Usage of CIFS

The CIFS protocol is the origin of the current SMB protocol, which is used for file sharing in Windows systems. SMB is widely used to access files and folders on the Windows network. Although the CIFS protocol may be most often associated with Microsoft, there is an open-source version of the protocol.

The CIFS/SMB protocol is sometimes also used to provide containers with connections to shared resources.

How Does CIFS Work

How does CIFS work? The following is an instruction. When a CIFS client needs to communicate with a CIFS server, the operation is almost always started at the application level.

Step 1: The first step to access shared resources is to establish a NetBIOS session between the client and the server.

Step 2: After using the NetBIOS session, the client and server perform a negotiation process. During the negotiation process, the client and server will determine which dialect will be used.

Step 3: After the client and the server reach an agreement on the dialect, the client transmits the authentication credentials (usually a user name and password) to the server, with a unique identifier (UID).

Step 4: On modern systems, the authentication process is usually handled by Active Directory. However, authentication is not a direct function of the CIFS protocol.

Step 5: If the authentication is successful, the server returns the assigned UID to the client.

Step 6: The server checks to ensure that the share name is valid and the client has the required permissions. If these checks are successful, the client will be granted access to the share and can then start requesting access to resources in the share (such as files and folders).


The SMB application layer network protocol has appeared since the 1980s. SMB was developed by IBM to allow computers to read and write files through a local area network. Although CIFS and SMB are often used interchangeably, Microsoft introduced the CIFS protocol as an updated version of SMB in the early Windows operating system.

SMB 2.0 was introduced in the Windows operating system in 2006, and by reducing the number of commands and subcommands from more than 100 to 19, it provides better performance than SMB 1.0. SMB 3.0 was introduced in Windows 8 and Windows Server 2012, and SMB Direct, SMB multi-channel, and SMB transmission failover were started.

Samba is a free software implementation of the CIFS/SMB network protocol and supports Microsoft Windows Server domain, Active Directory, and Microsoft Windows NT domain. Using Samba, Unix-like OS can interoperate with Windows and provide file and print services for Windows clients.

Final Words

What is CIFS? You may have found the answer in the post. Moreover, the features, usages, and working theory parts help you obtain a further understanding of CIFS.

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