JackTheStripper - blockip command

#!/bin/bash

if [ "$USER" == "root" ]; then
    if [ "$1" != "" ]; then
        rule="-I INPUT -s $1 -j DROP"
        sed s/COMMIT//g /etc/iptables.firewall.rules > /tmp/blockip.tmp
        echo $rule >> /tmp/blockip.tmp
        echo "COMMIT" >> /tmp/blockip.tmp
        mv /tmp/blockip.tmp /etc/iptables.firewall.rules
        iptables-restore < /etc/iptables.firewall.rules
        echo "Rule added."
    else
        echo "No IP found."
    fi
else
    echo "Permiso denegado."
fi