SSH port

Default SSH port 22

SSH was created as a solution to replace both file transfer protocol FTP (port 21) and remote access protocol telnet (port 23), so port 22 was a particularly fitting choice.

Changing SSH port on the server

You can make SSH server run on any available port by changing the Port directive in the /etc/ssh/sshd_config file.

Usually Port is the very first option defined in the file, and it’s commented out if default value is used:

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

just update this section by uncommenting Port and changing 22 to the port number you need, like 212 in this example:

Port 212
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

For privileged port (port number less than 1024), you would have to start sshd as root.

For non-privileged port (port number above 1024), you can start sshd as a regular user on your server.

Best practice: change default SSH port

If you are running SSH server on publicly available IP addrrsses, it’s best to minimize your chances of having SSH access compromsied:

• change the default port for SSH (to limit chances of SSH being discovered by external scans)
• switch to key only authentication (prevents password brute force attacks)
• use firewall to allow SSH access from known IP networks only (if possible)

See Also

• SSH command
• SSH port forwarding
• Advanced Unix Commands
• Important SSH server configuration options
• How To: Generate SSH key
• Check SSH port with telnet
• How To: Change SSH key passphrase
• SSH reference