What Is CIFS (Common Internet File System)?

Last Updated: 2021-11-18
Resumo: This article will give a full introduction to the CIFS – Common Internet File System. Keep reading to get more information about CIFS.


CIFS, short for Common Internet File System, is a cross-platform, transport-independent protocol that defines a standard for using millions of computers at a time to access the remote file. It offers a mechanism for client systems to utilize files and printing services provided over the server system’s network.

That is, by using CIFS, users with different computers and platforms can share files without installing new software.

CIFS runs through TCP/IP but uses the SMB (Server Message Block) protocol, which Microsoft Windows found to access files and printers. As a result, CIFS allows all applications, but not just web browsers, to open and share files over the Internet.

With CIFS, changes made to files are saved on both the server and client-side simultaneously.


Flexible connections: A single client can use CIFS to connect to multiple servers and even establish various connections to a single server when necessary.

euntelligent transmission: Though the CIFS protocol is typically based on connection-oriented protocols, it can also use connectionless protocols.

Notifications for file and directory change: The CIFS protocol includes a mechanism where clients will be notified when changes are made to shared resources.

Resource access: The CIFS protocol doesn’t limit the types of resources to which clients can connect. CIFS clients can connect to named pipes, print queues, shared files, and other resources simultaneously.

Support for distributed file systems: The Windows Server operating system supports to use a DFS (Distributed File System), which creates a global namespace able to contain resources on multiple servers. The CIFS protocol offers full support for DFS functionality.

Teoria do Trabalho

As the CIFS client needs to communicate with the CIFS server, it almost always starts at the application level.

  1. The first step in accessing shared resources is finding a NetBIOS session between the client and the server.
  2. After that, the client and server will negotiate to determine which dialect will be used.
  3. After the client and server agree on the dialect, the client uses a unique identifier (UID) to transfer authentication credentials, typically user names and passwords, to the server.
  4. The Active Directory usually settles authentication on modern systems. But authentication is not a direct feature of the CIFS protocol.
  5. Then, the server returns the assigned UID to the client when authentication is successful.
  6. Finally, the server will check to ensure that the share name is valid and that the client has the required permissions. When these checks succeed, clients are granted access to the share and can begin requesting access to the shared resources.


SMB is widely applied in accessing files and folders on windows networks. And the CIFS protocol is the source of the current SMB protocol for file sharing in Windows systems. Though the CIFS protocol is typically related to Microsoft, there is an open-source version of the protocol.

The CIFS/SMB protocol is sometimes used to connect a container with shared resources.


  • SMB, standing for Server Message Block, is a network file sharing protocol invented by IBM and has been in existence since the mid-eighties. And implemented in Microsoft Windows, it is famous as Microsoft SMB Protocol. While CIFS is a dialect of SMB
  • SMB and CIFS are both available on multiple versions of Unix, VMS, and other operating systems.
  • SMB allows computers to read and write files over the local network. CIFS and SMB are often used interchangeably, but Microsoft introduced the CIFS protocol as an updated version of SMB in earlier Windows operating systems.
  • SMB 2.0 was introduced into the Windows operating system in 2006 and provided better performance than SMB 1.0 by reducing commands and sub-commands from more than 100 to 19.
  • SMB 3.0 was introduced in Windows 8 and Windows Server 2012, and it initiated SMB Direct, SMB multichannel, and SMB transport failover.
  • SMB’ s CIFS implementation is now rarely used. Most modern storage systems use SMB 2 or SMB 3 instead of CIFS.
  • CIFS has a negative connotation among the pedants. SMB 2 and SMB 3 are large-scale upgrades to the CIFS dialect, a term that is not appreciated by storage architects who are close to and valued by file-sharing protocols.


The above introduces the definition, features, work theory and usage of CIFS. It also outlines the differences between CIFS and SMB. I hope this article will help you better understand CIFS.



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