UDP problem…

I found a peculiar problem while I was setting up an openvpn link the other day. The goal was a simple shared key setup and I started with the sample configuration and modified it a bit to fit the circumstances, I allowed the correct UDP port through the firewall (I think 1194 if I recall correctly) and … it didn’t work. So…. I started over and worked from empty config files and put in the bare minimums… it still didn’t work – no appearance that it was making the connection at all to negotiate the link. I double and triple checked the firewall config/restarted it… nothing Then I decided to try TCP instead of a UDP port. Changed the firewall config to allow the TCP traffic on 1194, adjusted the server and client config and lo and behold it worked. The firewall in question….

Is a VERY old and due for software rebuild Mandrake SNF (Single Network Firewall). I had hoped to be able to go the upgrade route to the MNF series, but license changes there have made the price for them out of reason. (And if I were to do it, I’d have to make too many modifications to make it worth doing). Of course, MNF2 isn’t freely available at all (as per my last check.) So… IPcop may be in the future for that setup.

The bottom line is that there seems to be something funky with UDP and this Mandrake SNF install. The moral of the story may be to consider TCP if you run into problems with a UDP connection over a firewall (and can choose the protocol.)

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