Change the SSH Port in the Linux Ubuntu operating system

This article demonstrates how to change the default SSH Port on a server using the Linux® Ubuntu® operating system.

Edit the SSH daemon configuration file

Perform the following steps to edit the configuration file:

1. Run the following command to open the sshd_config file:

   root@server-02:~# vi /etc/ssh/sshd_config

2. Use the arrow keys to scroll through the file until you locate the following text:

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

3. Move the cursor to the line below the #Port 22 line and press the i key to enter Insert Mode.

4. Press Enter to insert a new line and enter Port <Specified Port Number>. Port 2021 is the new SSH port in the following example:

   #Port 22
   Port 2021
   #AddressFamily any
   #ListenAddress 0.0.0.0
   #ListenAddress ::

5. Press the Esc key to exit Insert Mode and enter :wq to save your changes and close the file.

Restart SSH daemon

To restart the SSH daemon and complete the bind to the newly specified port, run the following command:

root@server-02:~# systemctl restart ssh

Verify the bind to the new port

Run the following commmand to verify the bind:

root@server-02:~# ss -tlpn| grep ssh
LISTEN    0         128                0.0.0.0:2021             0.0.0.0:*        users:(("sshd",pid=4227,fd=3))
LISTEN    0         128                   [::]:2021                [::]:*        users:(("sshd",pid=4227,fd=4))
root@server-02:~# netstat -tlpn| grep ssh
tcp        0      0 0.0.0.0:2021            0.0.0.0:*               LISTEN      4227/sshd: /usr/sbi
tcp6       0      0 :::2021                 :::*                    LISTEN      4227/sshd: /usr/sbi

Update the firewall

Update the firewall to ensure that the system allows incoming connections to the newly specified port. Enter
the following command with your new port:

root@server-02:~# ufw allow 2021/tcp
Rules updated
Rules updated (v6)

Verify the change by logging in

Attempt to log into the server with Secure Shell (SSH). You should see the following response:

ssh: connect to host 104.239.174.157 port 22: Connection refused

Now, SSH by using the -p <Port Number> option. This should work:

ssh [email protected] -p 2021
[email protected]'s password: