[Openswan Users] Problems with NAT'd Windows clients

Paul Wouters paul at xelerance.com
Thu Oct 15 12:47:53 EDT 2009


On Thu, 15 Oct 2009, Marc Fisher wrote:

> I've been trying to get NAT-T working for nat'd windows XP and Vista clients for several days now. It works fine without NAT, but when
> the client is nat'd it fails after the tunnel is established.
> I tried both PSK and X.509, several openswan versions (I've been told on irc that NAT-T is broken for 2.6.x version) , even strongswan,
> it's always the same result (after getting through all the other errors):
> After the tunnel is established the server initiates the l2tp conn instead of the client, while the client keeps sending UDP-encapsulated
> packets and ICMP port 1701 unreachable messages to the server. This goes on until both ends timeout.

Replace your openswan 2.4.x _updown script with the one from openswan 2.6.x.
I've attached a copy for you. This will be in /usr/local/lib/ipsec/_updown

Paul
-------------- next part --------------
#! /bin/sh
# iproute2 version, default updown script
#
# Copyright (C) 2003-2004 Nigel Metheringham
# Copyright (C) 2002-2007 Michael Richardson <mcr at xelerance.com>
# Copyright (C) 2007-2008 Paul Wouters <paul at xelerance.com>
# Copyright (C) 2003-2008 Tuomo Soini <tis at foobar.fi>
# 
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
# 
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
# for more details.
#

# CAUTION:  Installing a new version of Openswan will install a new
# copy of this script, wiping out any custom changes you make.  If
# you need changes, make a copy of this under another name, and customize
# that, and use the (left/right)updown parameters in ipsec.conf to make
# Openswan use yours instead of this default one.

LC_ALL=C
export LC_ALL

# Things that this script gets (from ipsec_pluto(8) man page)
#
#
#	PLUTO_VERSION
#		indicates  what	 version of this interface is being
#		used.  This document describes version	1.1.   This
#		is upwardly compatible with version 1.0.
#
#	PLUTO_VERB
#		specifies the name of the operation to be performed
#		(prepare-host, prepare-client, up-host, up-client,
#		down-host, or down-client).  If the address family
#		for security gateway to security gateway
#		communications is IPv6, then a suffix of -v6 is added
#		to the verb.
#
#	PLUTO_CONNECTION
#		is the name of the  connection	for  which  we	are
#		routing.
#
#	PLUTO_CONN_POLICY
#		the policy of the connection, as in:
#		RSASIG+ENCRYPT+TUNNEL+PFS+DONTREKEY+OPPORTUNISTIC
#		+failureDROP+lKOD+rKOD	
#
#	PLUTO_NEXT_HOP
#		is the next hop to which packets bound for the peer
#		must be sent.
#
#	PLUTO_INTERFACE
#		is the name of the ipsec interface to be used.
#
#	PLUTO_ME
#		is the IP address of our host.
#
#	PLUTO_MY_CLIENT
#		is the IP address / count of our client subnet.	 If
#		the  client  is	 just  the  host,  this will be the
#		host's own IP address / max (where max	is  32	for
#		IPv4 and 128 for IPv6).
#
#	PLUTO_MY_CLIENT_NET
#		is the IP address of our client net.  If the client
#		is just the host, this will be the  host's  own	 IP
#		address.
#
#	PLUTO_MY_CLIENT_MASK
#		is  the	 mask for our client net.  If the client is
#		just the host, this will be 255.255.255.255.
#
#	PLUTO_MY_SOURCEIP
#		if non-empty, then the source address for the route will be
#		set to this IP address.
#
#	PLUTO_MY_PROTOCOL
#		is the protocol	 for this  connection.	Useful	for
#		firewalling.
#
#	PLUTO_MY_PORT
#		is the port. Useful for firewalling.
#
#	PLUTO_PEER
#		is the IP address of our peer.
#
#	PLUTO_PEER_CLIENT
#		is the IP address / count of the peer's client subnet.
#		If the client is just the peer, this will be
#		the peer's own IP address / max (where	max  is	 32
#		for IPv4 and 128 for IPv6).
#
#	PLUTO_PEER_CLIENT_NET
#		is the IP address of the peer's client net.  If the
#		client is just the peer, this will  be	the  peer's
#		own IP address.
#
#	PLUTO_PEER_CLIENT_MASK
#		is  the	 mask  for  the	 peer's client net.  If the
#		client	 is   just   the   peer,   this	  will	 be
#		255.255.255.255.
#
#	PLUTO_PEER_PROTOCOL
#		is  the	 protocol  set	for  remote  end  with port
#		selector.
#
#	PLUTO_PEER_PORT
#		is the peer's port. Useful for firewalling.
#
#	PLUTO_CONNECTION_TYPE
#
#	PLUTO_PROTO_STACK
#		is the local IPsec kernel stack used, eg KLIPS, NETKEY,
#		NOSTACK
if [ -f /etc/sysconfig/pluto_updown ]
then
    . /etc/sysconfig/pluto_updown
fi

# Ignore parameter custom
if [ " $1" = " custom" ]; then
    shift
fi

while [ $# -gt 0 ]; do
    case $1 in
	--route)
	    case $2 in
		[Yy]*)
		    ROUTE=yes
		    ;;
		*)
		    ROUTE=
		    ;;
	    esac
	    shift; shift
	    ;;
	--iproute)
	    IPRARGS="$2"
	    shift; shift
	    ;;
	*)
	    echo "$0: Unknown argument \"$1\"" >&2
	    exit 1
	    ;;
    esac
done
	    
# utility functions for route manipulation
# Meddling with this stuff should not be necessary and requires great care.
uproute() {
    doroute replace
    ip route flush cache
}


downroute() {
    doroute del
    ip route flush cache
}


addsource() {
    st=0
    # check if given sourceip is local and add as alias if not
    if ! ip -o route get ${PLUTO_MY_SOURCEIP%/*} | grep -q ^local; then
	it="ip addr add ${PLUTO_MY_SOURCEIP%/*}/32 dev ${PLUTO_INTERFACE%:*}"
	oops="`eval $it 2>&1`"
	st=$?
	if [ " $oops" = " " -a " $st" != " 0" ]; then
	    oops="silent error, exit status $st"
	fi
	case "$oops" in
	    'RTNETLINK answers: File exists'*)
		# should not happen, but ... ignore if the
		# address was already assigned on interface
		oops=""
		st=0
		;;
	esac
	if [ " $oops" != " " -o " $st" != " 0" ]; then
	    echo "$0: addsource \`$it' failed ($oops)" >&2
	fi
    fi
    return $st
}


doroute() {
    if [ -z "$PLUTO_MY_SOURCEIP" ] && [ -n "$DEFAULTSOURCE" ]
    then
	PLUTO_MY_SOURCEIP="${DEFAULTSOURCE%/*}"
    fi

    st=0
    # skip routing if it's not enabled or necessary
    if [ " $PLUTO_MY_SOURCEIP" = " " -a " $ROUTE" != " yes" ]; then
	return 0
    fi
    parms="$PLUTO_PEER_CLIENT"
    parms2=$IPRARGS
    # use nexthop if (right/left)nexthop is set and nexthop is not %direct
    if [ -n "$PLUTO_NEXT_HOP" -a "$PLUTO_NEXT_HOP" != "$PLUTO_PEER" ]; then
	parms2="via $PLUTO_NEXT_HOP"
    fi

    # old: route via pluto_interface
    # parms2="$parms2 dev ${PLUTO_INTERFACE%:*} $IPROUTEARGS"
    # new: route via proper interface according to routing table
    PLUTO_PEER_INTERFACE=`ip -o route get $PLUTO_PEER | sed "s/^.*dev \([^ ]*\) .*/\1/"`
    if [ -z "$PLUTO_PEER_INTERFACE" ]; then
	PLUTO_PEER_INTERFACE=$PLUTO_INTERFACE
    fi
    parms2="$parms2 dev ${PLUTO_PEER_INTERFACE%:*} $IPROUTEARGS"

    # make sure whe have sourceip locally in this machine
    if [ "$1" = "replace" -a -n "$PLUTO_MY_SOURCEIP" ]; then
	addsource
	# use sourceip as route default source
	parms2="$parms2 src ${PLUTO_MY_SOURCEIP%/*}"
    fi

    case "$PLUTO_PEER_CLIENT" in
	"0.0.0.0/0")
	    # opportunistic encryption work around
	    # need to provide route that eclipses default, without 
	    # replacing it.
	    it="ip route $1 0.0.0.0/1 $parms2 && ip route $1 128.0.0.0/1 $parms2"
	    ;;
	*)
	    it="ip route $1 $parms $parms2"
	    ;;
    esac
    oops="`eval $it 2>&1`"
    st=$?
    if [ " $oops" = " " -a " $st" != " 0" ]; then
	oops="silent error, exit status $st"
    fi
    if [ " $oops" != " " -o " $st" != " 0" ]; then
	echo "$0: doroute \`$it' failed ($oops)" >&2
    fi
    return $st
}
 

# the big choice
case "$PLUTO_VERB" in
    prepare-host|prepare-client)
	# Delete possibly-existing route (preliminary to adding a route)
	# Not used for NETKEY
	;;
    route-host|route-client)
	# connection to me or my client subnet being routed
	uproute
	;;
    unroute-host|unroute-client)
	# connection to me or my client subnet being unrouted
	downroute
	;;
    up-host)
	# connection to me coming up
	# If you are doing a custom version, firewall commands go here.
	;;
    down-host)
	# connection to me going down
	# If you are doing a custom version, firewall commands go here.
	;;
    up-client)
	# connection to my client subnet coming up
	# If you are doing a custom version, firewall commands go here.
	;;
    down-client)
	# connection to my client subnet going down
	# If you are doing a custom version, firewall commands go here.
	;;
    #
    # IPv6
    #
    prepare-host-v6|prepare-client-v6)
	# prepare client for connection
	;;
    route-host-v6|route-client-v6)
	# connection to me or my client subnet being routed
	;;
    unroute-host-v6|unroute-client-v6)
	# connection to me or my client subnet being unrouted
	;;
    up-host-v6)
	# connection to me coming up
	# If you are doing a custom version, firewall commands go here.
	;;
    down-host-v6)
	# connection to me going down
	# If you are doing a custom version, firewall commands go here.
	;;
    up-client-v6)
	# connection to my client subnet coming up
	# If you are doing a custom version, firewall commands go here.
	;;
    down-client-v6)
	# connection to my client subnet going down
	# If you are doing a custom version, firewall commands go here.
	;;
    *)	echo "$0: unknown verb \`$PLUTO_VERB' or parameter \`$1'" >&2
	exit 1
	;;
esac


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