Server Message Block

aliases:

• SMB

A data transfer protocol that is responsible for client-server communications for sharing files, printers, and other network resources.

SMB operates on Layers 5-7 on the OSI model and transports over TCP/IP on ports 137, 138, 139, and 445. SMB should not be exposed to the Internet, and it should only be used in the local network.

Windows

On a Windows network, the File/print Sharing Service is provided using SMB. SMB enables a host to share one if it's directories or its printers for other connected hosts to use.

Linux

Linux devices can also access SMB-based network appliances using the Samba software suite.

Legacy Networks

SMB ran as a part of a deprecated network services protocol called NetBIOS on 139/tcp. All the NetBIOS ports, if in use, should be protected with a perimeter firewall.

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