How to Change the SSH Port in Linux

If you’re looking to enhance your server’s security, one of the simplest yet effective methods is to change the default SSH port from 22 to a custom port. This can help reduce the number of automated attacks your server faces. In this guide, we’ll walk you through the steps to change the SSH port on a Linux server.

Step 1: Connect to Your Server

Before making any changes, connect to your server via SSH using the default port (22):

ssh username@your_server_ip

Step 2: Backup the SSH Configuration File

It’s always a good practice to back up configuration files before making changes. You can do this by running:

sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

This command creates a backup of the sshd_config file, which is crucial for SSH settings.

Step 3: Edit the SSH Configuration File

Now, open the SSH configuration file in your favorite text editor. Here, we’ll use nano:

sudo nano /etc/ssh/sshd_config

Now, open the SSH configuration file in your favorite text editor. Here, we’ll use nano:

sudo nano /etc/ssh/sshd_config

Look for the line that specifies the port. It usually looks like this:

#Port 22

Uncomment this line (remove the #) and change 22 to your desired port number, for example 2222:

Port 2222

Make sure to choose a port number between 1024 and 65535, as ports below 1024 are reserved for system use.

Step 4: Adjust the Firewall

After changing the SSH port, you need to allow the new port through your firewall. If you’re using UFW, you can do this with the following commands:

sudo ufw allow 2222/tcp
sudo ufw delete allow 22/tcp

For firewalld, use:

sudo firewall-cmd --zone=public --add-port=2222/tcp --permanent
sudo firewall-cmd --zone=public --remove-port=22/tcp --permanent
sudo firewall-cmd --reload

Step 5: Restart the SSH Service

For the changes to take effect, restart the SSH service:

sudo systemctl restart sshd

Step 6: Test the New SSH Port

Before logging out of your current session, it’s wise to test the new port to ensure everything is functioning correctly. Open a new terminal window and try to connect using the new port:

ssh -p 2222 username@your_server_ip

If everything is set up correctly, you should be able to log in without issues.

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