ban.sh

#!/bin/bash

CHAIN=SELFCONTROL
IPTABLES=/sbin/iptables
IP_PATTERN='/^[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}$/p'

usage() {
        echo "Usage: $0 <IP address or hostname>"
        exit 1
}

ban() {
        local retval=0
        e=$($IPTABLES -I $CHAIN -s $1 -j REJECT)
        if [ "X$e" != "X" ]; then
                retval=1
        fi
        e=$($IPTABLES -I $CHAIN -d $1 -j REJECT)
        if [ "X$e" != "X" ]; then
                retval=1
        fi
        return $retval
}

is_ip() {
        [[ "X$(echo $1 | sed -n $IP_PATTERN)" != "X" ]] && return 0 || return 1
}

chain_exists() {
        $IPTABLES -n -L $CHAIN > /dev/null 2>&1
}

create_chain() {
        $IPTABLES -N $CHAIN
        $IPTABLES -I OUTPUT -j $CHAIN
        $IPTABLES -I $CHAIN -j RETURN
}

[[ $# -eq 0 ]] && usage

chain_exists || create_chain

for arg in $@; do
        echo -n "Banning: $arg ... "
        if ( is_ip $arg ); then
                ban "$arg"
        else
                echo
                for ip in $(dig $arg +short); do
                        if ( is_ip $ip ); then
                                echo -n  "    -> $ip "
                                if ( ban $ip ); then
                                        echo "OK"
                                else
                                        echo "Fail"
                                fi
                        fi
                done
        fi
        echo "done."
done
service iptables save