Script to delete an iptables rule inserted by knockd based on an IP address

delete_knockd_iptables_rule

#!/bin/bash

# This script is called by knockd and configured in the knockd.conf : https://gist.github.com/gene1wood/7489372

if [ -z "$1" ]; then
  echo "usage : $0 IPADDRESS"
  exit 1
fi

num="`iptables --list INPUT -n --line-numbers | awk '$13 == "knockd" {print $0}' | awk -v IP=$1 '$5 == IP {print $1}' | head -1`"

if [ -n "$num" ]; then
  iptables -D INPUT $num

else
  echo "Couldn't find IP $1"
  exit 1
fi