Celebrating 10 years in web hosting [email protected]

How To UNIX / Linux Open TCP / UDP Ports

Opening TCP/UDP ports in UNIX/Linux involves configuring the system firewall and ensuring that the services bound to the ports are properly set up. Here’s a step-by-step guide:

1. Check Current Firewall Status

Before making changes, determine the current firewall status to avoid conflicts.

sudo ufw status # For systems using UFW (Ubuntu/Debian)
sudo firewall-cmd --state # For systems using firewalld (CentOS/RedHat/Fedora)
sudo iptables -L # For iptables users
If you want then buy a good, reliable, secure web hosting service  from here: click here

2. Open Ports Using UFW (Uncomplicated Firewall)

If your system uses UFW, you can open ports as follows:

Open a TCP Port:

sudo ufw allow <port_number>/tcp

Open a UDP Port:

sudo ufw allow <port_number>/udp

Open a Range of Ports:

sudo ufw allow <start_port>:<end_port>/tcp
sudo ufw allow <start_port>:<end_port>/udp

Reload UFW:

sudo ufw reload
If you want then buy a good, reliable, secure web hosting service  from here: click here

3. Open Ports Using firewalld

For systems using firewalld, use the following commands:

Open a TCP Port:

sudo firewall-cmd --zone=public --add-port=<port_number>/tcp --permanent

Open a UDP Port:

sudo firewall-cmd --zone=public --add-port=<port_number>/udp --permanent

Reload firewalld to Apply Changes:

sudo firewall-cmd --reload

Check Open Ports:

sudo firewall-cmd --list-ports
If you want then buy a good, reliable, secure web hosting service  from here: click here

4. Open Ports Using iptables

If your system uses iptables, you can open ports as follows:

Open a TCP Port:

sudo iptables -A INPUT -p tcp --dport <port_number> -j ACCEPT

Open a UDP Port:

sudo iptables -A INPUT -p udp --dport <port_number> -j ACCEPT

Save iptables Rules:

=>On Debian-based systems:

sudo sh -c "iptables-save > /etc/iptables/rules.v4"

=>On RedHat-based systems:

sudo sh -c "iptables-save > /etc/sysconfig/iptables"

Reload iptables:

sudo systemctl restart iptables
If you want then buy a good, reliable, secure web hosting service  from here: click here

5. Bind a Service to the Port

Opening a port alone doesn’t start a service. Make sure the service you want is bound to the open port.

Verify Listening Ports:

sudo netstat -tuln | grep <port_number>

Ensure Service is Running: Check if the service is configured to start and bound to the desired port.

If you want then buy a good, reliable, secure web hosting service  from here: click here

6. Test the Open Port

Use tools like telnet, nc (netcat), or curl to test if the port is accessible.

Test TCP Port:

telnet <server_ip> <port_number>

Test UDP Port:

nc -u <server_ip> <port_number>

By following these steps, you can open TCP/UDP ports on your UNIX/Linux system securely and effectively.

Recent Posts

If you want then buy a good, reliable, secure web hosting service  from here: click here

In Conclusion,  If you enjoyed reading this article and have more questions please reach out to our support team via live chat or email and we would be glad to help you. In Other Words, we provide server hosting for all types of need and we can even get your server up and running with the service of your choice.