[OpenSIPS-Users] Media Proxy: Strange behaviour...

[Mauro Davì]

Hi Dan,

I saw,

Dan Pascu ha scritto:
> On 21 Sep 2009, at 13:17, Mauro Davì wrote:
>
>   
>> Thanks Dan.
>>
>> The problem was that Fastweb released a public not assigned IP  
>> Addresses to its customers
>>     
For example an UA connected with Fastweb (Italian operator) received a 
public IP (according to rfc1918)
23.238.97.105 that isn't assigned by IANA 
(http://www.iana.org/assignments/ipv4-address-space/). It's unallocated.
The UA received this IP Address and contacts the SIP Proxy obviusly the 
UA is behind a NAT, the real pubblic IP address
used to connect to Internet was another a Public Assigned IP in my case: 
93.41.132.110.

The who is lookup say:

IP Address 	93.41.132.110 </traceroute/?query=93.41.132.110>
Host 	93-41-132-110.ip81.fastwebnet.it
Location 	IT IT, Italy
City 	Terni, 18 -
Organization 	Fastweb
ISP 	Fastweb
AS Number 	AS12874 Fastweb Autonomous System
Latitude 	42°56'67" North
Longitude 	12°61'67" East
Distance 	874.92 km (543.65 miles)


>> The solution could be to change not only the owner connection  
>> information present in the SDP (to ensure that the connection goes  
>> from the UA to the Media Proxy) but also the owner information (in  
>> this way opensips substitute the faked Fastweb ip address with the  
>> Media Proxy public IP address).
>>
>> Do you agree??
>>     
>
>   
So... In the SDP part of the INVITE I received:

v=0
o=- 3462098794 3462098794 IN IP4 23.238.97.105
s=SJphone
c=IN IP4 23.238.97.105
t=0 0
m=audio 49156 RTP/AVP 8 0 3 98 97 101
c=IN IP4 23.238.97.105
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:3 GSM/8000
a=rtpmap:98 iLBC/8000
a=fmtp:98 mode=20
a=rtpmap:97 iLBC/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=setup:active
a=sendrecv

In wich, the owner information (o=) and the connection information (c=) 
contains the IP address assigned to the UA (23.238.97.105).

When the opensips server received the INVITE it changed the connection 
information and forwarded the INVITE to the destination.
The SDP information contained in the forwarded INVITE was:

v=0
o=- 3462098794 3462098794 IN IP4 23.238.97.105
s=SJphone
c=IN IP4 <MEDIA PROXY PUBLIC IP ADDRESS>
t=0 0
m=audio 30690 RTP/AVP 8 0 3 98 97 101
c=IN IP4 <MEDIA PROXY PUBLIC IP ADDRESS>
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:3 GSM/8000
a=rtpmap:98 iLBC/8000
a=fmtp:98 mode=20
a=rtpmap:97 iLBC/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=setup:active
a=sendrecv

> To be honest, I haven't the slightest idea of what you are talking  
> about...
>
> --
> Dan
>
>
>   

Now... to resolve "my problem", the opensips server need to modify not 
only the SDP connection information (c=), but also the
SDP owner information (o=). In this way the Media Proxy won't send the 
RTP packet to the 23.238.97.105 not assigned IP Address
(that was my problem).

Is this correct?

Thanks a lot and Regards,

    MD
>
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