[Serusers] User ser+nathelper+rtppoxy as outbound server

Jiang zhou zjiang at sipod.com
Fri Sep 3 06:05:42 CEST 2004


I think the normal Nathelper+rtpproxy will have a bug for public ua call a
nated ua.
ua1(pblic ip) ------->ser(nathelper+rtpproxy)----->nat----->ua2

ua2 can call ua1.
The ua2's invite sdp can be modified by nathelper and rewrite the ip/port to
rtpproxy's ip/port . So ua1 send voice to rtpproxy to ua1


Ua1 can't call ua2.
Ua1's Invite message will fail in  nat_uac_test("3") test. So ser dos't
setflag for this invite and don't use the rtpproxy.
Ua2's reply can't be modified by nathelper. So Ua1 find the reply with a
private ip.
So ua2 can't send voice to ua1, only ua1 send voice to ua2.

Is it right?


If use a ser+rtppoxy as a outbound server, I can resovle this issue.


----- Original Message ----- 
From: "Richard" <richard at o-matrix.org>
To: "'Zhou Jiang'" <zjiang at sipod.com>; <serusers at lists.iptel.org>
Sent: Thursday, September 02, 2004 2:52 PM
Subject: RE: [Serusers] User ser+nathelper+rtppoxy as outbound server


> Hi,
>
> I am looking at the same type of setup too.
>
> A local ser runs on the NAT firewall. A UA behind NAT registers with the
> local ser. When a SIP message is sent out to outside world, local ser does
> record route. So it is always in the path and there is not need to change
> SIP contact field. The only thing which needs mangle is the SDP if calling
> the outside world. It should be changed to the local ser's outside ip
> address. Rtpproxy, (if it is capable of doing this), can forward the
traffic
> between inside and outside.
>
> The greatest benefit I can see is that traffic for an intra-office call
> never has to go out. It would be easy to maintain a good quality. Also the
> phone system is still up even if the outside connection is down. Other
> benefits include a distributed registration database.
>
> Any comment?
>
> Richard
>
>
> -----Original Message-----
> From: serusers-bounces at iptel.org [mailto:serusers-bounces at lists.iptel.org] On
> Behalf Of Zhou Jiang
> Sent: Wednesday, September 01, 2004 5:19 PM
> To: serusers at lists.iptel.org
> Subject: [Serusers] User ser+nathelper+rtppoxy as outbound server
>
> I want to cofig ser as a outbound server to resolve all nat problem. The
> follow picture is the system architecture.
>
> uac--nat-->outboud1(ser1+nathelper+rtpproxy)------------->ser(main)
> uac--nat-->outboud2(ser2+nathelper+rtpproxy)-------------|
> uac--nat-->outboud3(ser3+nathelper+rtpproxy)-------------|
>
> Can someone know if ser can rewrite the uac's contact as itself ip address
> and
> forward to main ser? Nathelper can rewrite sdp ip/port to it own ip/port.
> But it
> only rewrite contac with nat's ip and port.
>
> Jiangzhou
>
>
>





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