The full form of CIFS is Common Internet File System.

CIFS (Common Internet File System) is a protocol that gained popularity around the year 2000, as vendors worked to establish an Internet Protocol-based file-sharing protocol.

At its peak, CIFS was supported by operating systems (OSes) such as Windows, Linux and Unix. CIFS used the client-server programming model in which a client program makes a request of a server program — usually in another computer — to access a file or pass a message to a program that runs in the server computer. The server takes the requested action and returns a response.

CIFS is now considered obsolete, because most modern data storage systems use the more robust Server Message Block (SMB) 2.0 and 3.0 file-sharing protocols, which were major upgrades to CIFS.

CIFS/SMB and the Network File System (NFS) are the two major protocols used in network-attached storage (NAS) systems.

Common Internet File System (CIFS) is a file-sharing protocol that provides an open and cross-platform mechanism for requesting network server files and services. CIFS is based on the enhanced version of Microsoft’s Server Message Block (SMB) protocol for Internet and intranet file sharing.

CIFS is an open, cross-platform technology that is based on the native file-sharing protocols of Microsoft Windows platforms. It is supported by other platforms such as UNIX. CIFS is viewed as a possible replacement for both the File Transfer Protocol (FTP) and the Network File System (NFS) file system protocols. CIFS supports encrypted passwords and Unicode filenames; it can be used to mount a remote file system as a directory or drive on the local machine. CIFS also includes features not supported by NFS, including write-ahead and native support for locks.

CIFS and the IETF

Microsoft’s Distributed file system (Dfs) is covered as part of the CIFS specification. CIFS has been submitted to the Internet Engineering Task Force (IETF) by Microsoft. CIFS client and server software is available for the Windows NT operating system platform.