On my OpenVPN server, I'm getting messages from OpenVPN like:

 ovpn-server[2455]: host/ IP packet with unknown IP version=15 seen

I have three OpenVPN clients and each of them give this error every minute.

A quick Google search makes it sound like this issue happens when one side is not using compression. But, in my setup, both the clients and the server have compression on.

Some of the clients are 12.04 and some are 12.10. The server is running 12.10, but all of the clients give the error.

Any thoughts on this?

4 Answers 4


I have seen this error when comp-lzo was enabled on the client, but disabled on the server.


I just had this same thing and found that my client configuration was set to: dev tap

While my server configuration was set to dev tun

They were trying to operate in two different modes and getting confused. Might you want to check this between your two configuration files?

I set both of them to what I really had wanted to do which was: dev tun and the logs stopped getting filled up with those errors.

  • 2
    Both the client and server configs have "dev tun" set.
    – nwalke
    Jan 4, 2013 at 15:22
  • I had the linux server set to tun and the windows client set to tap. Thanks a lot for the advice.
    – Gonzalo
    May 18, 2013 at 0:42
  • 5
    This can also happen if you have LZO compression enabled on the client side but not on the server.
    – Léo Lam
    Aug 19, 2015 at 15:09

I had exactly the same issue on a Linode machine - perhaps it is related. There's an investigation and fix by Dan McGee here: http://www.toofishes.net/blog/

echo 'lo' > /sys/module/aoe/parameters/aoe_iflist

I had removed comp lzo from server, but had used comp lzo no in client. Once I removed it from both, no more issues.

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