SMB: You must open these ports

In this practical tip, we will show you which ports you have to release for SMB. In order to be able to use the full range of functions of SMB, an additional setting may be necessary.

SMB: You must open these ports

SMB now only needs one port to work properly. However, you can also activate further ports if you do not only want to work with IP addresses as identification in your network.

• The most important port is TCP 445. All communication from SMB runs over this by default, so it should be activated.
• If you want to use NetBios / Name resolution, you should enable ports 137, 138 UDP and 137, 139 TCP. But be aware of the security risks that can arise as a result.

SMB port: what is it actually?

• The SMB port is used for communication between services and processes on different computers within a network. Since Windows 2000, the same port of type TCP has always been used for the SMB port, port 445.
• Microsoft developed SMB itself and has always optimized it over the years. In the meantime, there is version 3.0 of SMB, which, among other things, has upgraded end-to-end encryption.
• Since there are numerous areas of application for communication between computers within a network, there are many different protocols and programs that are based on SMB. These do not usually come from Microsoft itself. Samba, NQ and Likewise are known in particular.