How to Open a Port in UFW

Uncomplicated Firewall (UFW) is a user-friendly command-line interface for managing iptables, designed to simplify firewall configuration on Linux systems. It is the default firewall management tool in Ubuntu-based distributions starting from version 8.04, including Linux Mint. UncomplicatedFirewall (UFW) helps users easily control network traffic by allowing or restricting access to specific ports.

Knowing how to open a port in UFW is essential when setting up services like Apache, Webmin, or other server applications that require external access. While UFW is primarily used through the command line, desktop users who prefer a graphical interface can use GUFW, a GUI frontend for UFW.

This guide will walk you through the process of opening a port in UFW, ensuring that your system remains secure while allowing necessary connections.

Open a Port in UFW

There are multiple ways to open a port in UFW. Below, we cover how to open ports using the port number, service name, and custom IP/port combination.

1. Log into SSH as root.
2. Check if the application port is defined as a service (e.g. OpenVPN, PostgreSQL, IRC):
   

   cat /etc/services | grep service-name

   Or
   

   cat /etc/services | grep port

   To navigate the full list, use Page Up, Page Down, and arrow keys after using the less command:

   less /etc/services 

3. If the service is listed, you can open the port using the service name (TCP/UDP protocol optional):
   

   sudo ufw allow servicename 

   
   

   sudo ufw allow servicename/tcp

4. If there is no service listed for the port, you can open the port by specifying the port and protocol (TCP/UDP):
   

   sudo ufw allow 10000

   
   

   sudo ufw allow 1352/udp

5. If you need to allow all connections from a specific system or network IP address:

   sudo ufw allow from 1.2.3.4

6. To allow all connections from a particular subnet of IP:
   

   sudo ufw allow from 1.2.3.0/24

7. To allow connections on a specific port from an IP address:
   

   sudo ufw allow from 1.2.3.4 to any port 22

8. After you open a port in UFW, ensure UFW is enabled:
   

   sudo ufw enable

Close a Port in UFW

After you uninstall software, you should close any ports you no longer need to open on your system. You can accomplish this using the service name or port number.

• To close a port in UFW using the service name:
  

  sudo ufw deny pop3

• To close a port in UFW using the port number:
  

  sudo ufw deny 995

Check Open Ports in UFW

After making changes to any firewall, you should verify your changes to ensure they’re correct and active.

1. To check whether UFW is running:
   

   sudo ufw status 

2. To check whether UFW is running with additional information, such as logging and profile status:
   

   sudo ufw status verbose

3. To find the rule number for UFW rules:

   sudo ufw status numbered

4. Then you can remove the rule:

   sudo ufw delete 1

Need to install and enable Uncomplicated Firewall (UFW) on your server? Get started with our UFW Basics guide.

Ready to dive deeper into web server security? Check out our guide on hardening your managed VPS or dedicated server.