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I am attempting to make a VPN connection to a third party VPN site, then forward traffic from my internal computers (ssh and ping for now) out to the VPN site using IPTables.

3rd Party <-> (tun0/eth0)Linux VPN Box(eth1) <-> Windows7TestBox

I am running on CentOS 6.3 Linux and have two network connections eth0->public eth1->private. I am running vpnc-0.5.3-4 which is currently connecting to my destination.

When I connect I am able to ping the destination IPAddresses but that is as far as I can get.

ping -I tun0 success

ping -I eth0 fail

ping -I eth1 fail

I have my private network Windows 7 test box set up to have the eth1 (private) network of my VPN Server as its gateway and can ping him fine. I need IPTables to send the Windows 7 traffic out the VPN tunnel.

I have tried for a few days many different IPTables configurations from this site and others, either the other examples are too simple or overly complicated. The only thing this server is doing is connecting to the VPN and forwarding all traffic.

So we can "flush" everything and start from scratch here. It is a blank slate.


echo "Define variables"


echo "Zero out all counters"

$ipt -Z

$ipt -t nat -Z

$ipt -t mangle -Z

echo "Flush all active rules, delete all chains"

$ipt -F

$ipt -X

$ipt -t nat -F

$ipt -t nat -X

$ipt -t mangle -F

$ipt -t mangle -X




$ipt -t nat -A POSTROUTING -o tun0 -j MASQUERADE

$ipt -A FORWARD -i eth1 -o eth0 -j ACCEPT

$ipt -A FORWARD -i eth0 -o eth1 -j ACCEPT

$ipt -A FORWARD -i eth0 -o tun0 -j ACCEPT

$ipt -A FORWARD -i tun0 -o eth0 -j ACCEPT

Again I have done many variations of the above and many other rules from other posts but haven't been able to move forward. It seems like such a simple task, and yet....

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