How to on basic iptables commands on linux?

amurleopard

A iptables chain is a set of packet filtering rules. The default chains are in uppercase INPUT, OUTPUT, and FORWARD, these cannot be deleted.

To create use defined ipchains, best practice to use lowercase to differentiate from the default chains.

Create a new iptables chain

$ sudo iptables -N myapp

Delete the iptables chain

$ sudo iptables -X myapp

List iptables rules

$ sudo iptables -L

More verbose output, show packets, bytes

$ sudo iptables -L -v

List just the INPUT iptables chain

$ sudo iptables -L INPUT

Find ip address in the iptables rules

$ sudo iptables -L -n | grep <you ip>

List iptables rules by number, for the INPUT chain, exclude INPUT for all rules

$ sudo iptables -L INPUT --line