[SR-Users] fix_nated_sdp()

[Carsten Bock]

Hi Bernhard,

have you checked the SDP which is going to and from the
Freeswitch-Server? Is it modified?

If yes: You may want to check your NAT-Firewall. A working (but not
nice) solution might be to relay the RTP through an proxy in this
case...
If No: Verify the result of "nat_uac_test": Why is it returning "false"?

Carsten

2011/1/25 Bernhard Suttner <bernhard.suttner at winet.ch>:
> Hi,
>
> someone has an idea?
>
> Thanks in advance!
>
> Best regards,
> Bernhard
>
> -----Ursprüngliche Nachricht-----
> Von: sr-users-bounces at lists.sip-router.org [mailto:sr-users-bounces at lists.sip-router.org] Im Auftrag von Bernhard Suttner
> Gesendet: Montag, 24. Januar 2011 20:38
> An: sr-users at lists.sip-router.org
> Betreff: [SR-Users] fix_nated_sdp()
>
> Hi,
>
> I have a question about the fix_nated_sdp() function. Different devices (phones, pbxes, gateways) are using Kamailio as SBC. The SBC does t_relay() the message to a pool of FreeSWITCH Servers.
>
> The scenario does work quite well but:
>
> if a call is initiated from one of the freeswitch server, pass it through kamailio to the PBX and the PBX does have a forwarding back to kamailio and in the end to freeswitch I have no audio because the PBX is behind a NAT and uses private ip addresses in all the SDP of 200 OK and 183 Session Progress. Therefore FreeSWITCH could not do the (very cool) RTP Auto-Adjustment (check if IP in incoming packet is different to the IP in the SDP) to detect the real IP address.
>
> Therefore I have to use fix_nated_sdp(). I am not sure, what this function could break therefore I want to be very sure and use it only, if really necessary. Test which User-Agent or Server the peer (in this example the PBX) has, is not really possible because some devices does not send this header.
>
> What do you think about the follwoing pseudo code:
>
> if (method==INVITE && has_sdp() && nat_uac_test(8)) fix_nated_sdp(3)
>
> and within the onreply route:
>
> if (status=~(180|183|200) && has_sdp() && nat_uac_test(8)) fix_nated_sdp(3)
>
> Somebody has a better idea to handle this? What could go wrong?
>
> Thanks in advance.
>
> Best regards,
> Bernhard Suttner
>
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