Tutorial on modifying the ssh port in Linux system.

To modify the SSH port on a Linux system, you can follow the steps below:

1. Log in to the Linux system as the root user or a user with sudo permissions.

2. Open the SSH configuration file. On most Linux distributions, the SSH configuration file is located at
   /etc/ssh/sshd_config.

   Use a text editor (such as vi or nano) to open the configuration file, for example:

   sudo vi /etc/ssh/sshd_config

3. Look for the
   #Port line in the configuration file.
   # represents a comment line, so to modify the port, you need to uncomment the line and change the port number. You can choose any unused port number as the new SSH port. For example, change the port number to 2222:

   Port 2222

4. Save the file and close the editor.

5. Reload the SSH service to apply changes. You can restart the SSH service using the following command:

   sudo service ssh restart

   Alternatively, if you are using Systemd as your init system, you can use the following command:

   sudo systemctl restart sshd

6. After modifying the port, you need to update the firewall rules to allow the new SSH port to pass through the firewall. The exact steps depend on the firewall tool and configuration you use. The following are example commands for using iptables, assuming you are using the default iptables configuration:

   sudo iptables -A INPUT -p tcp --dport 2222 -j ACCEPT
   sudo iptables -A OUTPUT -p tcp --sport 2222 -j ACCEPT
   sudo service iptables save

   If you are using ufw (Uncomplicated Firewall), you can execute the following command:

   sudo ufw allow 2222/tcp

7. Make sure your network device (such as a router or firewall) is configured to allow connections to your Linux system through the new SSH port.

Now, you have successfully modified the SSH port. Remember that when connecting to a Linux system using a new port, you need to specify the new port number in your SSH client. For example:

ssh username@your_server_ip -p 2222

Please note that modifying the SSH port is a security measure that can reduce the risk of malicious scans and attacks. However, make sure that the new port you choose is not used by other services and only exposes it for necessary connections.

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