Change the port for SSH connections

The SSH daemon listens on port 22 by default. Follow these steps to change it.

1. Log in to the server

   Log in via SSH.

2. Open the SSH configuration file

   sudo nano /etc/ssh/sshd_config
   
3. Update the Port line

   Find the Port line and replace the value 22 with the new port number. If the line begins with #, remove the # to uncomment it first.

   

   
4. Save and close the file

   Press Ctrl+O, then Enter to confirm the filename, and Ctrl+X to exit nano.

5. Restart the SSH service

   On Ubuntu and Debian:

   sudo systemctl restart ssh
   

   On CentOS, AlmaLinux, and Rocky Linux:

   sudo systemctl restart sshd
   

   On FreeBSD:

   sudo service sshd restart
   
6. Allow traffic on the new port

   On Ubuntu and Debian (ufw):

   sudo ufw allow 2233/tcp
   

   On CentOS, AlmaLinux, and Rocky Linux (firewalld):

   sudo firewall-cmd --permanent --add-port=2233/tcp && sudo firewall-cmd --reload
   

   Replace 2233 with the chosen port number.

7. Verify the port is reachable

   From a local machine (not from the server), run:

   telnet <server_ip> 2233
   

   Replace <server_ip> with the server IP address and 2233 with the chosen port. A successful response includes the SSH banner line starting with SSH-2.0.

   
8. Test the SSH connection

   Keep the current SSH session open. Open a separate terminal window and connect using the new port:

   ssh -p 2233 username@<server_ip>
   

   Replace username with the server username (typically root) and <server_ip> with the server IP address. If the connection fails, revert the Port value in /etc/ssh/sshd_config back to 22 and restart the SSH service again.