[Serusers] UA's behind the same NAT

[Atle Samuelsen]

Hi Noel,

Just a tought,
(dont know if your users does this, but just to lighten the aera)

what happens if there is a double NAT here, and you say, that users
behind the same nat (atleast with the logic G wrote) they would have the
same source-ip and the same ruri ip, but would'nt be on the same
physical lan..


see setup :
          B  C
          NAT-->UA2
     A    /
ser - NAT 
         \
         NAT -->UA1
         D  E

A= Public IP
B= NAT1's public IP
C= NAT1's Local Subnet
D= NAT2's public ip
E= NAT2's Local subnet

The from would look like: 
(ua2)
from:blabla<sip:UA2 at C>
(UA1)
from:blublu<sip:UA1 at E>

e.request-uri would be : 
(UA2)
sip:ua2 at A
(UA1)
sip:ua1 at a

SourceIP for both request's would be A, So, you cant really (by this)
know if UA1 and UA2 is behind the same nat, esesially if there is a
double, or triple or so...

-Atle


* Greger V. Teigre <greger at teigre.com> [051110 07:50]:
> Noel,
> If you send the config showing how you do it, it will be easier to comment. 
> :-)
> 
> In general, what you should do is this:
> - Starting from onsip.org configs, there are three locations you need to 
> change: route[4] NAT Traversal, loose route handling and onreply
> - I suggest creating a new route block where you test the src_ip of the 
> message against the looked up location of ruri/domain, i.e. this only works 
> after a successful lookup("location") has been done. This should be the 
> (untested) code snippet:
> avp_write("$ruri/domain", "i:624");
> if (avp_check("i:624","eq/$src_ip")) {
>  setflag(SAME_NAT);
> }
> (NOTE: I'm not sure about how avp_write will handle $ruri/domain as :port 
> is at the end of the domain for ruri after a lookup. You should probably 
> turn on debugging and use avp_print)
> - Then run the test from the NAT traversal route, as well as the loose 
> route (not in onreply) and check for the flag before doing force_rtp_proxy
> - In onreply add && !isflagset(SAME_NAT) to the NAT if test
> 
> No guarantees... This has not been tested.  However, if you can report that 
> it works (or whatever was wrong), I will submit the code piece as a 
> suggestion for the ONsip.org Getting Started document.
> g-)
> 
> 
> ----- Original Message ----- 
> From: "Noel Sharpe" <noels at radnetwork.co.uk>
> To: "'SER Users'" <serusers at lists.iptel.org>
> Sent: Wednesday, November 09, 2005 9:15 PM
> Subject: [Serusers] UA's behind the same NAT
> 
> 
> >Hi All
> >
> >I am trying to improve my proxy setup to force clients behind the same NAT 
> >device to connect each other directly.  My setup is fairly complex, 
> >(rtpproxy / NAT Helper, PSTN gateways,  different peers etc)  but it's 
> >loosely based on the OnSip.org setup.
> >The current config works correctly for all clients, whether behind a NAT 
> >or not, but I'd prefer not to have to use RTP proxy to allow UA's on the 
> >same nat to contact each other.  I've seen the document from the AVPops 
> >module, but I can't get the example to work.  I think the problem is WHERE 
> >I put the avpops config.  As this works on FWD, I think it's possible. 
> >Has anyone got this working?
> >
> >Noel
> >
> >
> >_______________________________________________
> >Serusers mailing list
> >serusers at lists.iptel.org
> >http://lists.iptel.org/mailman/listinfo/serusers
> >
> 
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