Setup of Client -> VPN -> (NAT) -> VPN2 -> Internet

94m3k1n9

Hi,

I'm actually using a Linux 2.6.32-5-amd64 (Debian 6) server, which should NAT between both VPNs.
Both VPNs are working fine if I use them alone.
I'm trying to get the following configuration:
Client PC is running a VPN client to connect to the VPN server at tun1 on the server.
NAT forwards packets from tun1 to tun0.
VPN server is running an openvpn client to connect to VPN2 (tun0 on the first server).
VPN2 server works as exit to the internet.

My problem is that the routing is not working.

My server is configured as VPN2-client (tun0) with IP 10.9.0.42 and gateway 10.9.0.41.
VPN server runs at tun1 in 10.6.0.0/24.

What I tried to do yet:

Enabling packet forwarding in kernel:

echo "1" > /proc/sys/net/ipv4/ip_forward

Tried several iptables configurations from the internet with NAT / POSTROUTING parameters.

I disabled routing features in the the .conf file:

# no routes
route-noexec
route-up /bin/false
script-security 2

so i can reach the server without being connected to VPN2.

Mimiko

Firstly you have to think about tun0 as an internet interface (the second line). Read for example this page: http://serverfault.com/questions/127636/force-local-ip-traffic-to-an-external-interface to route from tun1 to tun0.
Also in your mid-in OpenVPN server you have to use push "redirect-gateway".