Zimbra connect: very strange IP tracing/routing

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Zimbra connect: very strange IP tracing/routing

Postby borepstein » Wed May 06, 2020 10:09 pm

Hello listmates,

We have Zimbra 8.8.15_GA_3928 (build 20200415072015) with Zimbra Connect. The server is located behind a firewall.

Most of the clients are also located behind firewalls or routers using NAT for public communications. That overall would be a fairly common arrangement.

We have discovered that when we were running a group video conference we would on occasion encounter strange issues in that some participants would be unable to participate to others. For example, we would have 3 parties involved: A, B and C. Sometimes a situation would emerge where A could communicate to B but not C and C would be able to communicate to A but not B. So we started investigating.

And so we started investigating. And in the process we have discovered that the server was attempting to communicate to client's private IP addresses as opposed to the public address presented by the NAT. These attempts were naturally not successful and ended up in nothing but dropped packets.

The best theory we could come up with was that the client collects the private IP and communicates it to the server within the actual communication content. The server then attempts communicating to that IP address (not reachable to the server) as opposed to just replying within already established IP connections.

Has anybody encountered this issue? Any idea as to how to remediate?

Any help much appreciated.



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Re: Zimbra connect: very strange IP tracing/routing

Postby rleiker » Fri May 08, 2020 4:15 am

Hi Boris,

You very likely need to setup a STUN/TURN server for use with Zimbra Connect. If you don't already have one setup, refer to: http://forums.zimbra.com/viewtopic.php? ... be6cffa39f

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