#! /bin/sh

BADIP="$1"
BADMAC="$2"
REALIP="$3"
REALMAC="$4"
PATH="${PATH}:/usr/sbin:/sbin:/usr/local/sbin"

if [ $# -ne 4 ]; then
	echo "Usage: $0 <ip_of_spoofer> <spoofers_macaddr> <ip_being_spoofed> <legitimate_macaddr>" >&2
	exit 1
fi

iptables -I INPUT -m mac --mac-source "${BADMAC}" -j DROP
iptables -I INPUT -s "${BADIP}" -j DROP
arp -d "${REALIP}"
arp -s "${REALIP}" "${REALMAC}"
logger -t arpmon "ARP spoofer ${BADIP} (${BADMAC}) is impersonating ${REALIP} (${REALMAC}), now being blocked."
