#! /bin/sh
# NAT updown script
#
# Copyright (C) 2010 Andreas Steffen <andreas.steffen@strongswan.org>
#
# 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.

# 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 communica-
#              tions 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_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_REQID
#              is the requid of the ESP policy
#
#       PLUTO_ME
#              is the IP address of our host.
#
#       PLUTO_MY_ID
#              is the ID 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 IP protocol that will be transported.
#
#       PLUTO_MY_PORT
#              is  the  UDP/TCP  port  to  which  the IPsec SA  is
#              restricted on our side.
#
#       PLUTO_PEER
#              is the IP address of our peer.
#
#       PLUTO_PEER_ID
#              is the ID of our peer.
#
#       PLUTO_PEER_CA
#              is the CA which issued the cert of our peer.
#
#       PLUTO_PEER_CLIENT
#              is the IP address / count of the peer's client sub-
#              net.   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 IP protocol that will be transported.
#
#       PLUTO_PEER_PORT
#              is  the  UDP/TCP  port  to  which  the IPsec SA  is
#              restricted on the peer side.
#

# define a minimum PATH environment in case it is not set
PATH="/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin"
export PATH

# resolve octal escape sequences
PLUTO_MY_ID=`printf "$PLUTO_MY_ID"`
PLUTO_PEER_ID=`printf "$PLUTO_PEER_ID"`

case "$PLUTO_VERB:$1" in
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.
	iptables -A FORWARD -i eth1 -o $PLUTO_INTERFACE -s PH_IP_ALICE \
	    -d $PLUTO_PEER_CLIENT -j ACCEPT
        iptables -A FORWARD -o eth1 -i $PLUTO_INTERFACE -d PH_IP_ALICE \
            -s $PLUTO_PEER_CLIENT -j ACCEPT
	iptables -t nat -A POSTROUTING -o $PLUTO_INTERFACE -s PH_IP_ALICE \
	    -d $PLUTO_PEER_CLIENT -j SNAT --to-source $PLUTO_MY_SOURCEIP
	echo "inserted NAT rule mapping PH_IP_ALICE to virtual IP $PLUTO_MY_SOURCEIP" >&2 
	;;
down-client:)
	# connection to my client subnet going down
	# If you are doing a custom version, firewall commands go here.
        iptables -D FORWARD -i eth1 -o $PLUTO_INTERFACE -s PH_IP_ALICE \
            -d $PLUTO_PEER_CLIENT -j ACCEPT
        iptables -D FORWARD -o eth1 -i $PLUTO_INTERFACE -d PH_IP_ALICE \
            -s $PLUTO_PEER_CLIENT -j ACCEPT
         iptables -t nat -D POSTROUTING -o $PLUTO_INTERFACE -s PH_IP_ALICE \
            -d $PLUTO_PEER_CLIENT -j SNAT --to-source $PLUTO_MY_SOURCEIP
        echo "deleted NAT rule mapping PH_IP_ALICE to virtual IP $PLUTO_MY_SOURCEIP" >&2    
	;;
*)	echo "$0: unknown verb \`$PLUTO_VERB' or parameter \`$1'" >&2
	exit 1
	;;
esac