How to open TCP port in Kali Linux?

Opening a TCP port on Kali Linux is useful for hosting services, setting up development tools, or testing penetration tools that require incoming connections.

Step 1: Check if the firewall is enabled

Kali Linux does not always have iptables or ufw enabled by default:

sudo iptables -L

If this returns a list of rules, the firewall is active. Otherwise, it’s empty or minimal.

Step 2: Open a TCP port with iptables

To allow incoming TCP traffic on, for example, port 8080:

sudo iptables -A INPUT -p tcp --dport 8080 -j ACCEPT

You can replace 8080 with the port you want to open.

Step 3: Save your iptables rules

By default, iptables rules are not persistent. To save them:

sudo apt install iptables-persistent
sudo netfilter-persistent save

These commands install and save the firewall rules across reboots.

Step 4: Verify the open port

To check if the port is open and listening:

sudo netstat -tuln | grep 8080

Or, use:

sudo ss -tuln | grep 8080

You should see the port listed if a service is listening on it.

Opening TCP ports in Kali Linux can be done via iptables or ufw. Always make sure to only open necessary ports for security reasons.