#!/bin/sh # # A post-up/down hook to automatically create/delete a 'sec' VLAN # device, and a dedicated, host-scoped, IP for IPSec (v4 only). # # Copyright 2013 Guilhem Moulin # # Licensed under the GNU GPL version 3 or higher. # set -ue PATH=/usr/sbin:/usr/bin:/sbin:/bin ifsec=sec0 ipsec=172.16.0.1/32 # /!\ This mark much match that in /usr/local/sbin/update-firewall.sh. secmark=0xA99 # Ignore the loopback interface and non inet4 families. [ "$IFACE" != lo -a "$ADDRFAM" = inet ] || exit 0 # Only the device with the default, globally-scoped route, is of # interest here. [ "$( /bin/ip -4 route show to default scope global \ | sed -nr '/^default via \S+ dev (\S+).*/ {s//\1/p;q}' )" \ = \ "$IFACE" ] || exit 0 case "$MODE" in start) # Don't create $ifsec if it's already there if ! /bin/ip -o link show | grep -qE "^[0-9]+:\s+$ifsec"; then # Create a new VLAN $IFACE on physical device $ifsec. This is # required otherwise charon thinks the left peer is that # host-scoped, non-routable IP. /bin/ip link add link "$IFACE" name "$ifsec" type vlan id 2713 /bin/ip address add "$ipsec" dev "$ifsec" scope host /bin/ip link set dev "$ifsec" up fi # If a packet retained its mark that far, it means it has # been SNAT'ed from $ipsec, and didn't have a xfrm # association. Hence we nullroute it to avoid to leak data # intented to be tunneled through IPSec. /!\ The priority # must be >220 (strongSwan IPSec's policy) since xfrm lookup # must take precedence. /bin/ip rule add fwmark "$secmark" table 666 priority 666 || true /bin/ip route add prohibit default table 666 || true ;; stop) if /bin/ip -o link show | grep -qE "^[0-9]+:\s+$ifsec"; then # Deactivate the VLAN /bin/ip link set dev "$ifsec" down fi # Delete the 'prohibit' rule /bin/ip rule del fwmark "$secmark" table 666 priority 666 || true /bin/ip route flush table 666 ;; esac