[Openswan Users] VPN connecting two subnets by openswan and zyxel prestige?

[Andre Mueller]

Hello

I think my problem is rather an easy one but nevertheless I am remaining stuck 
with it also having already read "tonnes" of FAQ and configuration samples. 
Therefore I would appreciate very much any helpful suggestions.

My aim is to connect two networks (main office and branch) over IPsec with PSK 
(I know PSK it is rather insecure etc.).  At the head office we have a 
gateway/firewall based on SuSE 10.1 (Kernel 2.6.16) Openswan (2.4.4). At the 
branch office there is a Zyxel Prestige 660 ADSL-Modem/Router. Our situation is 
the following :

main office   [   SuSE Gateway      ]     [  Zyxel Prestige 660 ]

10.0.0.0/16 - 10.0.0.1 = 62.XX.YY.114 ... 212.XX.YY.80 = 10.1.0.1 - 10.1.0.0/16
LAN           eth0       eth2             wan            eth0       LAN


With the Openswan configuration below the branch office Zyxel Router can 
establish an tunnel successfully but unfortunately the intended route between 
both local subnets do not work. On the SuSE Gateway the subnet 10.1.0.0 is bound 
to the public interface eth2 and traffic coming from the branch office over the 
tunnel is showing up at eth2 (iftop -i eth2) and not as it is intended on eth0 
to be route to the local subnet at the head office. So I think I have missed 
something important. I have read the FAQ about multiple tunnels but with the 
Zyxel Prestige 660 I can configure only two VPN connections/tunnels and I would 
like to have the second one as reserve to connect to an additional planed branch 
office.



config setup
         klipsdebug="none"
         plutodebug="none"
         uniqueids=no
         interfaces="ipsec0=eth2"
         dumpdir="/var/log"


conn main_branch
         type=tunnel
         authby=secret
         pfs=no
         left=62.XX.YY.114  # eth2 public interface
         leftsubnet=10.0.0.0/16 # should be on the local interface eth0
         leftnexthop=62.XX.YY.113
         right=212.XX.YY.80
         rightsubnet=10.1.0.0/16
         auto=add
         keyingtries=3


Many thanks in advance, Andre Mueller