80) then I will be using the following: sudo iptables -A INPUT -p tcp -dport 80 -j ACCEPT Deny traffic from port -dport is used to specify the destination portįor example, if I want to allow the HTTP (uses port no.

INPUT is used to make rules for incoming traffic.-A will add the rule to the end of the chain.To allow traffic from the specific port, you will have to use the following command syntax: sudo iptables -A INPUT -p -dport -j ACCEPT You can apply the rule at the top of the chain using the -I flag and if you want to add your rule at the bottom, you will use the -A flag. While learning more about iptables, you will come across a term named chains.Ĭhains are nothing but a firewall rule in sequence and your firewall will behave accordingly. Now, let's have a look at how you can add rules to fine-tune your network. So let's start with how you can list the existing rules: sudo iptables -LĪnd if you notice carefully, by default, it is configured to accept traffic. Remember, the iptables is not a service, so you can't start, stop or disable it unless you remove it from your system.

Iptables tutorial