Iptables breaks a working VoIP phone?

Kenneth Burgener kenneth at mail1.ttak.org
Mon Oct 29 09:18:04 MDT 2007

Corey Edwards wrote:
> At that point, RTP begins to flow between the two IP addresses
> specified. This is where NAT becomes a problem. If the endpoints aren't
> aware of NAT (which is its design), they will specify their internal
> addresses and the return packets will be silently discarded by some
> router's egress filters. This is one reason why NAT sucks. You can trick
> it using connection tracking and SIP transformations. Or a tool like
> STUN to tell the endpoint what its routeable address actually is. Or a
> proxy which knows how to filter out the RFC1918 addresses and put in the
> correct values.

As I have been reading about it, I saw one comment made by someone else
that seem to indicate that the Linksys is doing some sort of SIP proxy.
 Is there a Linux SIP proxy that can pick up on SIP traffic and just
magically do it's stuff, similar to the Linksys?  I have no way of
configuring the Sipura, so what ever the solution is, it will have to be
transparent to the Sipura device.  The Sipura is setup to sent all
traffic to the default gateway, which happens to of course be either the
Linksys router or the Linux firewall.


More information about the PLUG mailing list