UncomplicatedFirewall (UFW) is a command-line frontend iptables manager, similar to Firewalld and ConfigServer Security & Firewall (CSF). It’s beneficial to understand basic UFW commands since it’s pre-installed with many Ubuntu-based operating systems (OSs) including Linux Mint.
Those configuring UFW for a desktop system who prefer not to use the CLI can use the GUFW GUI application.
Below we cover:
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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 combinations.
- Log into SSH
- Check if the application port is defined as a service (e.g. OpenVPN, PostgreSQL, IRC):
cat /etc/services | grep service-nameOr
cat /etc/services | grep portTo navigate the full list, use Page Up, Page Down, and arrow keys after using the
- 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
- If there is no service listed for the port, you can open the port by specifying the port and protocol (TCP or UDP):
sudo ufw allow 10000
sudo ufw allow 1352/udp
- If you need to allow all connections from a specific system or network IP address:
sudo ufw allow from 184.108.40.206
- To allow all connections from a specific IP subnet:
sudo ufw allow from 220.127.116.11/24
- To Allow connections on a specific port from an IP address:
sudo ufw allow from 18.104.22.168 to any port 22
- After you open a port in UFW, ensure UFW is enabled:
sudo ufw enable
Close a Port in UFW
Once you uninstall software that was using a now unneeded port, you should close any ports you no longer need open on your system. You can accomplish this using the service name or port number.
- To close a port in UFW with it’s service name:
sudo ufw deny pop3
- To close a port in UFW with it’s 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.
- To check whether UFW is running:
sudo ufw status
- To check whether UFW is running with additional information such as logging and profile status:
sudo ufw status verbose
- To find the rule number for UFW rules:
sudo ufw status numbered
- Then you can remove the rule:
sudo ufw delete 1
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