Need some advice about my openvpn installation (bridging)

karl261

Hi there,

I am looking for some advice for this problem:
I set up openvpn using bridging, which works fine (I can access the internet and other local hosts via the openvpn connection. The plan is to use some SIP-VOIP application over the vpn. Unfortunately it is somehow proprietary and not easy to debug. The application is supposed to connect to the internet gateway on the other end of the tunnel and use its VOIP capabilities.
This VOIP application works fine as long as I am physically at the right network. It connects to the server and I can make phone calls.
Now, using the openvpn tunnel, the application also connects to the server and says ok. I can also place a call (I tried ringing myself) and I can pick up and the connection is establish. BUT: there is no audio, in neither direction.
Actually this is why I set up bridging in the first place, because I thought maybe I need layer 2 traffic for this audio stuff to work. But it still does not work.
The following hosts are involved:
192.168.1.1: Internet gateway and VOIP server
192.168.1.3: openvpn server
192.168.1.222: openvpn client with VOIP client
192.168.1.254: other host that I used to test if I can ping 192.168.1.222. Yes I can.

So, where would I start looking? Any tests I could do?
Of course I can post any conf or log files.

Thanks in advance
Karl

karl261

Hmmm... It might have something to do with multicast and/or igmp. I see packets like this in tcpdump:

23:27:20.298597 IP 192.168.1.1 > 224.0.0.1: igmp query v2
23:27:21.117410 IP 192.168.1.1 > 224.0.0.2: igmp v2 report 224.0.0.2

and

23:25:25.074388 IP 192.168.1.1.5353 > 224.0.0.251.5353: 0 PTR (QM)? 222.1.168.192.in-addr.arpa. (44)
23:25:26.084061 IP 192.168.1.1.5353 > 224.0.0.251.5353: 0 PTR (QM)? 222.1.168.192.in-addr.arpa. (44)
23:25:28.094135 IP 192.168.1.1.5353 > 224.0.0.251.5353: 0 PTR (QM)? 222.1.168.192.in-addr.arpa. (44)
23:25:28.584795 IP 192.168.1.1 > 224.0.0.22: igmp v2 report 224.0.0.22

It seems there is nothing coming back. Do I have to add a special multicast route?

Traffic

Isn't that bonjour ?

karl261

Ah, damn, the igmp get's answered...

23:55:22.085119 IP 192.168.1.222 > 224.0.0.251: igmp v2 report 224.0.0.251

Yes, could be bonjour also. Weird. I need to collect more packages.

P.S. Is there a way to edit a post? So to add something later?

Traffic

Due to incessant spamming .. editing is only available for a short time.

Just add new details or start a new thread if it changes too much !

FYI: This forum is support of openvpn ..
and how can we support some unnamed VOIP app ?

karl261

About the editing: Ok, I see.

About the support: The reasoning here is that I suspect that something is missing in the openvpn tunnel. Since the app is running fine when I am physically in the right net, it should also run over the tunnel bridge. Something seems to be missing or set up in a wrong way. I would like to find out what.

Where else would you ask if not here?

P.S. Still possible to edit. I just tested it: Bonjour works perfektly fine. This cannot the problem. I can connect to some apple airplay service.

Traffic

karl261 wroteWhere else would you ask if not here?

We don't know anything about your VOIP app ..

Pippin

this is why I set up bridging in the first place, because I thought maybe I need layer 2 traffic

As far as I know tap is not needed for VOIP.
So maybe tun is a better option?

karl261

Traffic wrote
karl261 wroteWhere else would you ask if not here?
We don't know anything about your VOIP app ..

That's right. But I suppose there are some openvpn experts here. I'll keep looking! Thanks anyway.

@Pippin: tun does not work in this case, because it would be a different subnet, and the VOIP server (192.168.1.1) cannot have set extra subnet routes.

Traffic

karl261 wroteI suppose there are some openvpn experts here

When you need help with openvpn there are .. :twisted:

For further help .. Please see the Forum rules (top of page)