Step 1 – Connect to your server using SSH. If you are using Windows you can use the program Putty or if you are using iOS simply use the terminal.
Step 2 – Now find the below line in the sshd_config file:
This line indicates which port you are using for SSH.
Step 3 – Remove the # symbol to uncomment the line. This can be done by hitting the X key whilst the cursor is over the # symbol. Edit the number “22” to your desired port value, the valid range for the port is 0 to 65535. Press ESC and type :wq, this exits you out from edit mode.
W stands for write and Q for quit. In this example i have chosen to use port 57343.
Step 4 – Now we need to update the firewall rules. Enter the command below.
iptables –I INPUT 1 –p tcp –-dport 57343 –j ACCEPT
Step 5 – Save the new settings using the command below
Step 6 – We need to test whether our new SSH port working or not. But before that disable the firewall temporarily.
service iptables stop service ip6tables stop
Step 7 – Type the following command to reload SSHD service:
service sshd reload
Step 8 – You can verify the new port settings using the command below.
netstat -tulpn | grep sshd
Step 9 – If we see that the new port is working fine, we will start firewall using the commands:
service iptables start service ip6tables start
Step 10 – Without closing this session, try and connect using your new port. If you are successful then please enter the below command to drop port 22 from the SSH access list.
iptables –A INPUT –j DROP –p tcp –dport 22