I was wondering about the port vera is using to access the device behind my “natting” router
I think it uses something like NAT keep-alive to avoid port forwarding.
Correct. It creates a connection to findvera.com first, and then just keeps that connection alive.
The good thing about that is there is no configuration needed on your router to get that connection up, or to access the interface via findvera.com.
This approach works well in simple applications, but you can’t imagine (well, may be you can) how much trouble it creates in VoIP…
True.
This approach works well in simple applications, but you can't imagine (well, may be you can) how much trouble it creates in VoIP...
Can you clarify? You mean Vera interferes with your VOIP? It shouldn’t.
Vera uses ssh to make a connection to the findvera.com server as a ‘tunnel’ back in. It’s very low bandwidth to keep the tunnel open. The NetworkMonitor does a loopback ping every 60 seconds just to be sure the connection didn’t die, and if it did, it closes and reopens the ssh tunnel.
No, of course it doesn’t. What I meant is that the keep-alive approach used in VoIP created more troubles then good. Different routers had different UDP timeouts, so sometimes NAT dropped the port when it wasn’t expected, and it couldn’t work when signaling and media streams were coming from different IPs, etc
But it’s all irrelevant for Vera, as from architectural perspective it’s much more straight forward then VoIP. Timeout problem still can apply though…