Block an IP address on your linux server

drop.bash

#! /bin/bash

function valid_ip()
{
    local ip=$1
    local stat=1

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
        stat=$?
    fi
    return $stat
}

if ! [ -x "$(command -v iptables)" ]
then
        echo -e -n "You need to have \E[33miptables\E[0m installed"
        echo ""
        exit
fi

if [ "$1" == "" ]
then
        echo -e -n "\E[36mUsage:\E[33m ./`basename $0` [-r] IP \E[0m"
        echo ""
        exit
fi

if [ "$1" == "-r" ]
then
        if [ "$2" == "" ]
        then
                echo -e -n "\E[36mUsage:\E[33m ./`basename $0` [-r] IP \E[0m"
                echo ""
                exit
        fi

        if valid_ip $2
        then
                echo -e -n "Removing IP \E[33m$2\E[0m"
                echo ""
                iptables -D INPUT -s $2 -j DROP
                service iptables save
        else
                echo -e -n "Invalid IP \E[32m$2\E[0m"
        fi
        echo ""
        exit
fi

if valid_ip $1
then
        echo -e -n "Adding IP \E[33m$1\E[0m"
        echo ""
        iptables -A INPUT -s $1 -j DROP
        service iptables save
else
        echo -e -n "Invalid IP \E[32m$1\E[0m"
fi
echo ""