Server Message Block

What Does Server Message Block Mean?

Server Message Block (SMB) is an application-layer network protocol that facilitates network communication while providing shared access to client files, printers and serial ports.


SMB is prevalent in Microsoft Windows operating systems released prior to the Active Directory protocol, where it was known as Microsoft Windows Network.

SMB is also known as the Common Internet File System (CIFS).

Techopedia Explains Server Message Block

SMB was engineered to run via the following application programming interfaces (API) for the network basic input/output system (NetBIOS) and the NetBIOS extended user interface (NetBEUI):

  • NetBIOS frame
  • NetBIOS over Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX)
  • NetBIOS over Transmission Control Protocol/Internet Protocol (TCP/IP)

SMB features include:

  • Uses Windows platform servers and workstations
  • Includes Samba protocol daemons on Unix and Unix-like platforms
  • Facilitates NetBIOS transport via Windows legacy versions
  • Uses Network Neighborhood (NetHood) protocols that function as NetBIOS transport services
  • Authenticates multiprocess communication channels via Distributed Computing Environment/Remote Procedure Call (DCE/RPC) services

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Margaret Rouse

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.