#!/bin/bash
#Copyright 2003 William Stearns <wstearns@pobox.com>

if [ -z "$4" ] || [ -n "$5" ]; then	#Usage
	echo $0: scan all or part of a class C for rogue routers. >&2
	echo Usage: >&2
	echo $0 Subnet startIP EndIP MonitorIP >&2
	echo Example: >&2
	echo $0 17.18.19 1 254 99.99.99.99 >&2
	echo MonitorIP should have the following running to collect output:
	echo tcpdump -qtnX \'icmp[0]=8\' >&2
	exit 1
fi

Subnet=$1
StartIP=$2
EndIP=$3
Monitor=$4

for IP in `seq $StartIP $EndIP` ; do
	echo Probing $IP
	sudo route add -host $Monitor gw $Subnet.$IP
	case $IP in
	[0-9])
		ping -c 3 -w 4 -p 000$IP $Monitor >/dev/null 2>/dev/null
		;;
	[0-9][0-9])
		ping -c 3 -w 4 -p 00$IP $Monitor >/dev/null 2>/dev/null
		;;
	*)
		ping -c 3 -w 4 -p 0$IP $Monitor >/dev/null 2>/dev/null
		;;
	esac
	sudo route del -host $Monitor gw $Subnet.$IP
	sleep 5
done