[Serdev] ipv6 to ipv4 proxying

[Maxim Sobolev]

Bert Vermeulen wrote:

> Maxim Sobolev wrote:
> 
>> You will have to use nathelper/rtpproxy for this. The latest version 
>> from the cvs supports so-called "bridge" mode, so that it can act as a 
>> gateway between two networks. There is even a sample config file 
>> available modules/nathelper/examples/4to6.cfg for such functionality.
> 
> 
> Unfortunately, this requires rtpproxy from CVS, which is broken at the 
> moment. I've had no luck getting this working.

It doesn't mean that it is broken.

> In any case, I must disagree that this is the way to go. Quite simply 
> SER supports IPv6 in theory only; actually turning it on breaks all 
> connectivity to non-IPv6 registered clients. In other words, enabling 
> IPv6 in SER makes it an IPv6-only SIP proxy.

Huh? What makes you think so??? You can specify both IPv4 address to 
listen for SIP packers as well as IPv6 addresses. This in no way will 
make SER "an IPv6-only SIP proxy" or break IPv4 or IPv6 connectivity, at 
least if the config is correct and you don't try to contact IPv4 client 
using IPv6 and vice versa ;).

> It seems wrong to have a simple "listen" directive that makes the server 
> listen on IPv6, yet this breaks everything unless you then also set up:
> 
> - an undocumented RTP proxy
> - an equally undocumented nathelper module
> - two extra tables in the database, created manually
> - a bunch of logic in the config file to make it all work together

Well, no offence, but it is how free software works. You are getting 
software for free, you are getting no technical support, you may or may 
not get documentation, you may or may not get a help from the mailing list.

If you want a solution that "just works" in your specific environment, 
then you should consider buying proffesional consulting service. I am 
sure you will have zero problems finding person who for reasonable 
anount of money will help you to setup IPv4<->IPv6 SIP/RTP bridge.

> A client that uses IPv4 to register can be assumed to not support IPv6 
> at all, since IPv6-aware clients "prefer" IPv6. Therefore, the SIP proxy 
> that is about to connect the two together can be sure the call is going 
> to fail.

Why? I can't follow your logic here. The proxy can use IPv4 to talk to 
IPv4 clients and IPv6 to talk to IPv6 clients.

> Instead of relaying the INVITE through as is, knowing that 
> it'll fail eventually, wouldn't it be more interesting to e.g. at least 
> replace the request's
> "IN IP6 <ipv6 address>" with "IN IP4 <resolved hostname>"? This gives 
> the IPv4-only client at the other end at least a fighting chance to 
> complete the call.

This is actually what nathelper/rtpproxy in bridge mode do.

-Maxim