How to change the SSH port number on a Linux server

Question

How to change the SSH port number on a Linux server?

Answer

1. Connect to the server via SSH.

2. Open the SSH configuration file /etc/ssh/sshd_config in any text editor. In this example we are using the vi editor:

   # vi /etc/ssh/sshd_config

3. Modify the file according to your needs using one of these steps:

   Warning: Be careful when modifying the file. The incorrect SSH configuration may lead to server inaccessibility via SSH.

   • Set up one custom SSH port

     Remove the hash "#" in the line #Port 22 and specify your custom SSH port, which will be used instead of standard SSH port 22.
     Example:

     CONFIG_TEXT: Port 2222

   • Set up several SSH ports

     Remove the hash "#" in the line #Port 22 and additionally add your custom SSH port on the next line. In this case, SSH connections will be available on both ports.
     Example:

     CONFIG_TEXT: Port 22
     Port 2222

4. Save the changes and close the file.

5. Restart the sshd service to apply the changes:

   # service sshd restart

   Note: The new port must be opened in server firewall. Visit this KB article to find out how.

   Note: If port is changed on a SELinux system, it is needed to tell SELinux about this change:
   # semanage port -a -t ssh_port_t -p tcp #PORTNUMBER