OpenVPN bypass on some ports

Solution 1:

After a little more searching, I've found this thread : https://forum.linode.com/viewtopic.php?p=50114&sid=b440414422596bb7dbc96cf7c9ee511f#p50114

I've now modified my "route-up" OpenVPN script as follow, and it's finally working ! I've removed all the others messy rules (iptable PREROUTING, MASQUERADE, etc).

Here is my final "route-up" script :

ip route flush table 100
ip route flush cache

ip rule add from x.x.x.x table 100
ip route add table 100 to y.y.y.y/y dev ethX
ip route add table 100 default via z.z.z.z

Where x.x.x.x is my server's public IP, y.y.y.y/y is the subnet of my server's public IP address, ethX is my server's public Ethernet interface, and z.z.z.z is the default gateway.

Hope this may help someone else.

Solution 2:

After going through the same ordeal myself I found at least one problem with the route-up script.

iptables -t mangle -A PREROUTING ...

should be:

iptables -t mangle -A OUTPUT ...

Read about why here: http://www.iptables.info/en/structure-of-iptables.html

I didn't have to turn on IP forwarding.