[Asterisk-Users] Multiple IPs and SIP

[Manuel Wenger]

This topic has already been brought up lately, but I'd like to inquire
if there are any news.

I have 2 IP addresses assigned to my ethernet card (eth0 and eth0:0)
that are on 2 different subnets (one public, one private), because our
PSTN gateway provider has established a private link with us using
private addresses. Yes, that's not exactly "clean", 2 ethernet cards
would be better, but it shouldn't make a difference for this issue.

Now the problem: I have asterisk bound to 0.0.0.0 in sip.conf, so it
binds to every address I have. The routes in my system are configured
correctly. But as soon as asterisk tries to send a SIP packet to a
private address, using eth0:0, the following happens:

- the packet actually arrives at my PSTN provider's border gateway
- the sender IP address in the UDP packet is correct, it's my private
address, so linux did its routing job correctly
- the SIP packet contains my public (!) address in the "From" and
"Contact" fields, which is wrong, and confuses our PSTN provider's
gateway, which in turn tries to send the reply to our public address,
which it will never find, because their server is on a private network
only

This has to do with the fact that SIP wants to encode ethernet packet
information in a higher layer, which is somewhat stupid IMHO, but I
think we have to live with this :)

We're using CVS-HEAD-08/24/04 (yes, I have to upgrade sometimes...). Has
this issue been addressed lately, or is it somehow unsolvable?

Thank you everyone
-Manuel
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