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

Me='catchmapper'
MyVersion='0.4.0'
DefaultActions='DROP'

[ -r /etc/modwall/modwall.conf ] &&			. /etc/modwall/modwall.conf
[ -r /etc/modwall/$Me.conf ] &&				. /etc/modwall/$Me.conf
[ -r ${MWLibDir:-'/usr/lib/modwall/'}/modwalllib ] &&	. ${MWLibDir:-'/usr/lib/modwall/'}/modwalllib
if [ -z "$MWLibVer" ]; then
	echo 'It looks like modwalllib was not loaded, why?  Exiting' >&2
	exit 1
fi

for OneTask in $Tasks ; do
	case "$OneTask" in
	link)
		$IptablesBin -N $Me >/dev/null 2>&1
		$IptablesBin $AppIn INPUT -i \! lo -m psd					-j $Me
		$IptablesBin $AppIn FORWARD -m psd						-j $Me
		$IptablesBin $AppIn OUTPUT -o \! lo -m psd					-j $Me
		;;
	unlink)
		$IptablesBin -D INPUT -i \! lo -m psd						-j $Me
		$IptablesBin -D FORWARD -m psd							-j $Me
		$IptablesBin -D OUTPUT -o \! lo -m psd						-j $Me
		$IptablesBin -X $Me >/dev/null 2>&1
		;;
	create)
		echo "Starting $Me" >&2
		FlushOrNewChain $Me
		#I would _like_ to tag the recipients of rst's as mappers too, but I can't tell between an
		#IP getting a reset because they're mapping tcp ports, and an IP getting a reset because
		#the server to which they were connected was shut down.  Instead, we'll depend on the psd
		#(port scan detector) module:
		#FIXME - customize psd params later? :
		#--psd-weight-threshold 21 --psd-delay-threshold 300 --psd-lo-ports-weight 3 --psd-hi-ports-weight 1
		#FIXME - add --state?
		#psd and recent order is really picky; -m recent (+opts except --set), -m psd (+opts), --set
		#Screw it.  Add -m psd to the IOF calls.
		LogAs='mapper-portscan'	$Ipt -A $Me -m recent --name mapper --set  	$Tail
		;;
	destroy)
		echo "Stopping $Me" >&2
		DestroyChain $Me
		;;
	renamechain)
		TempChain="$Me-$RANDOM"
		echo "Replacing existing rules in $Me with new rules" >&2
		$IptablesBin -E $Me $TempChain
		;;
	replacelinks)
		if [ -z "$TempChain" ]; then
			echo "No temporary chain to relink in $Me replacelinks, replace operation incomplete." >&2
		elif ! $IptablesBin -L $Me -n >/dev/null 2>&1 ; then
			echo "No $Me chain in $Me, replace operation incomplete." >&2
		elif ! $IptablesBin -L $TempChain -n >/dev/null 2>&1 ; then
			echo "No $TempChain chain in $Me, replace operation incomplete." >&2
		elif [ "`$IptablesBin -L INPUT -n --line-numbers | grep $TempChain | wc -l`" -ne 1 ]; then
			echo "Too few/many references to $TempChain in INPUT in $Me replacelinks, replace operation incomplete." >&2
		elif [ "`$IptablesBin -L FORWARD -n --line-numbers | grep $TempChain | wc -l`" -ne 1 ]; then
			echo "Too few/many references to $TempChain in FORWARD in $Me replacelinks, replace operation incomplete." >&2
		elif [ "`$IptablesBin -L OUTPUT -n --line-numbers | grep $TempChain | wc -l`" -ne 1 ]; then
			echo "Too few/many references to $TempChain in OUTPUT in $Me replacelinks, replace operation incomplete." >&2
		else
			$IptablesBin -R INPUT `$IptablesBin -L INPUT -n --line-numbers | grep $TempChain | awk '{print $1}'` -i \! lo -m psd	-j $Me
			$IptablesBin -R FORWARD `$IptablesBin -L FORWARD -n --line-numbers | grep $TempChain | awk '{print $1}'` -m psd		-j $Me
			$IptablesBin -R OUTPUT `$IptablesBin -L OUTPUT -n --line-numbers | grep $TempChain | awk '{print $1}'` -o \! lo -m psd	-j $Me
			DestroyChain $TempChain
			unset TempChain
		fi
		;;
	status)
		if $IptablesBin -L $Me -n >/dev/null 2>&1 ; then
			echo "$Me created" >&2
		else
			echo "$Me destroyed" >&2
		fi
		;;
	version)
		echo "$Me $MyVersion, modwalllib $MWLibVer" >&2
		;;
	help)
		DefaultHelp
		cat <<EOTEXT >&2
	The $Me module identifies people trying to map our network.  It
uses the psd (port scan detector) module to identify - you guessed it - 
port scans.  When found, the source address of the scan is remembered in
the mapper table for punishment by the punishmapper module.
	Because of the potential for a spoofed source address in a probe
packet, this is a potentially dangerous module.
EOTEXT
		;;
	*)
		echo "Unknown action $Action in $Me, no action taken." >&2
		;;
	esac
done