[Serusers] SER/SEMS behind NAT, advertised_address, sdp_mangle_ip

[Soner Tari]

Hi All,

Our SER server is behind NAT, so we are having all sorts of NAT problems. I 
have tried to read all the information I was able to find on documents, 
maillist archives, and onsip and by googling. And I believe that I were able 
to solve SIP signalling problems by record routing, NAThelper and rtpproxy, 
and some tricks (double record routing) for HT486. So SIP signalling seems 
fine now. But when UAs are connected to sems, they send RTP messages to the 
local IP of SER. I also tried to use another ser instance dedicated to sems, 
but still the same. So I thought it's time to ask a couple of questions to 
the list.

To solve SIP problems, I tried to use advertised_address, but I could not 
see any effect of it, SER still advertises its local IP, afaics. I also 
tried mhomed. Apparently, I don't know how to use this parameter, I thougth 
it would function similar to externip/localnet parameters on Asterisk. So I 
tried solutions mentioned above, with success, as far as I can see. But 
ser.cfg becomes quite complicated. I wish I could use advertised_address 
properly.

To solve RTP problems, I tried to use mangler. But I need to manipulate 
messages sent from SER to the UA, for example 200 OK messages with SDP info. 
But, again I guess I don't know where to use sdp_mangle_ip function. I tried 
to use it in onreply_route without success. Where should I place it in 
ser.cfg? I guess I am missing something obvious. Would advertised_address 
solve this also, if I could have it working for me?

To summarize, I don't care too much about connections from local network 
(btw, I've set SER as DMZ), it's OK if SER forgets its local IP and always 
advertises its public IP. I want SER to put its public IP everywhere in 
every message (SIP/SDP) it sends out. Is there anyway to achive this?

I've done all these on both SER 0.9.4 and 0.10.99 (CVS HEAD a week from 
now), the server is a CentOS 4.1 x86_64.

I would appreciate any help.
Sincerely,
Soner Tari