• SSH Port Forwarding Dating back to the days where encryption wasn’t available for all protocols, SSH features the ability to forward traffic sent to a local port on an SSH client. The traffic is forwarded through the encrypted SSH session to the SSH server or even beyond.
• Otherwise, changing the default port may cause these applications and services to stop working. To change the SSH port: Log on to the server as an administrator. Open the SSH configuration file sshdconfig with the text editor vi: vi /etc/ssh/sshdconfig. Search for the entry Port 22. Replace port 22 with a port between 1024 and 65536.

SSH server by default listens to port 22 and you don't have to manually specify the port number on your SSH client if you're connecting to the default port. You'll have to manually specify the port number when you're connecting to non-standard SSH ports using the -p option or by adding the port information in your SSH client's configuration file.

By default, port 22 is used to establish an SSH connection. This port is automatically configured during the installation of your operating system.

To reduce the number of brute force attacks, you can configure another port for SSH access.

Please Note

Before changing the port, make sure that the applications and services installed on the server can be configured without a default port. Otherwise, changing the default port may cause these applications and services to stop working.

To change the SSH port:

• Log on to the server as an administrator.

• Open the SSH configuration file sshd_config with the text editor vi:
  vi /etc/ssh/sshd_config

• Search for the entry Port 22.

• Replace port 22 with a port between 1024 and 65536.

Please Note

Make sure that the selected port is not used for other services. You can do this by using the following port list provided by the Internet Assigned Numbers Authority (IANA):

Alternatively, you can view the list of ports in the /etc/services file.

• Save the file.

• Restart the service.
  Ubuntu
  service ssh restart
  CentOS 7
  systemctl restart sshd
  To establish an SSH connection after this change, enter the following command:
  ssh root@IP_address_of_the_server -p NewPort

If you are aware of the SSH basics, you already know that SSH uses port 22 by default.

When you connect to a server via SSH, most of the time you don't provide any port information. And in such cases, your connection goes to the port 22 of the SSH server.

Ssh Port Change

You can change the default port from 22 a port number of your choice using the following steps:

• Open the /etc/ssh/sshd_config file for editing.
• Locate the line that has Port 22 (if it is commented out with #, remove the # as well).
• Change the line to Port 2522 (or any number of your choice between 1024 and 65535).
• Make sure that the new port is allowed by the firewalls (if you have any).
• Restart ssh daemon with sudo systemctl restart sshd.
• From now onwards, you'll have to specify the port to make the ssh connection ssh user@ip_address_of_server -p 2522.

Let me show you the steps in details and also tell you why you may consider changing the

Why change the default SSH port?

One of the most elementary tricks for securing SSH server is to change the default SSH port number 22.

Why? Because a number of bot scripts try the brute force attacks on the default port 22. Most of these scripts don't always scan for open ports, and they target the default ports for various known services like SSH.

Changing the default SSH port reduces number of such attacks. There are other ways to improve the security of your SSH server. If interested, please follow these actionable tips for improving SSH server security.

Now that you know why you would change the default SSH port, let's see how to do it.

Allow traffic on the new port by changing the firewall settings

If you have a firewall set or custom ipconfig or ifconfig or if you are using selinux, you must allow the new ssh port before making the changes. Otherwise you may lock yourself out without an SSH access.

Now this part depends upon what kind of firewall or routing you are using.

If you are using UFW, you can use the following command to allow port 2522:

If you are using iptables, you should use this command:

On Fedora, CentOS, Red Hat, the firewall is managed by firewalld and you can use this command:

On CentOS and Red Hat, you may also have to change the SELinux rules:

Now that you have put the correct firewall settings, let's move on to changing the SSH port.

Changing the default SSH port

Usually, the ssh configuration file is located at /etc/ssh/sshd_config. You'll have to use a terminal-based editor like Vim or Nano or Emacs to edit the file.

Markdown in jupyter notebook. Distributions like Ubuntu have Nano installed by default so you can use it for opening the file in edit mode like this:

As you can see, you'll have to be a sudo user or root to edit the ssh configuration.

Scroll down a bit and you'll see a line with Port 22. If it starts with #, it means the line is commented out. The commented out lines gives you the default settings.

So if you see # Port 22, it means that default port is 22.

Change this line with a port number of your choice. In Linux, port number 0-1023 are usually reserved for various services. It will be good to avoid using anything between 0 and 1023 to avoid conflicts.

You can use any other port number between 1024 and 65535. I am using 2522 in the example. Make sure to remove the # before the Port line.

Ssh Service Port Number

Save your changes and exit the editor. If you are using Nano, use Ctrl+X to save and exit.

The next step is to restart the ssh service. Most modern system use systemd services so you can use the following command:

Now if you want to access the SSH server, you'll have to specify the port number:

Was it helpful?

I hope you find this tutorial helpful in changing the SSH port. Now that you have changed the port, you'll have to use it all the time you want to connect to the server via SSH and that could be annoying.

This is why I recommend using SSH config file to save the settings for easy and quick access.

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