4 May
2009
4 May
'09
6:07 p.m.
2009/5/4 Dubravko Caric <dubravko_caric(a)yahoo.com>om>:
There is a really easy way to detect if a router is performing SIP ALG:
- Configure you UA in the LAN with *no* STUN/ICE, just private IP.
- Capture a INVITE/REGISTER from that UA in the proxy (in the public network).
- Check if "Via" and/or "Contact" headers contain the router public
IP
instead of the UA private IP.
- If so, you are behind a *fucking* router with SIP ALG enabled.
If you can dissable it (by web, telnet...) please add that information
to the wiki page:
http://www.voip-info.org/wiki/view/Routers+SIP+ALG
(or sent it to me directly and I'll add it).
Let me understand:
- UA1 sends "200 OK" and when you capture it in the proxy it has port
31479 in Contact header, is it?
- When this "200 OK" leaves the proxy it has 0 in Contact header, is it?
--
Iñaki Baz Castillo
<ibc(a)aliax.net>
Questions:
- Does this router use the painful SIP ALG?
http://www.voip-info.org/wiki/view/Routers+SIP+ALG
didn't find anything regarding SIP and ALG in the device specification but I did find
this http://www.easyofficephone.com/support/router-compatibility#linksys_wrt54g:
"This router is not recommended for use with voice over ip services
using the stock firmware from Linksys. This model router is known to
damage and modify SIP packets in such a way that it prevents voice over
ip packets from being formatted correctly and can cause a multitude of
problems."
i'll check everything once more... How is possible
that the proxy replaces 31479 with 0 ???
You must be doing something wrong with the Contact header.
i'm
not doing any manipulation with Contact header, all other scenarios are
working fine as long as I don't use two clients behind this specific
router.