[Serusers] NAT

Richard richard at o-matrix.org
Wed Aug 25 19:51:28 CEST 2004


You can either use nathelper or mediaproxy. Check the documentation on these
two modules. There are good explanation on why/how.

-----Original Message-----
From: serusers-bounces at iptel.org [mailto:serusers-bounces at lists.iptel.org] On
Behalf Of Michael Shuler
Sent: Wednesday, August 25, 2004 7:44 AM
To: 'Michael Shuler'; serusers at lists.iptel.org
Subject: RE: [Serusers] NAT

Anyone have an explanation or did this email miss the list?

----------------------------------------

Michael Shuler, C.E.O.
BitWise Systems, Inc.
682 High Point Lane
East Peoria, IL 61611
Office: (217) 585-0357
Cell: (309) 657-6365
Fax: (309) 213-3500
E-Mail: mike at bwsys.net
Customer Service: (877) 976-0711 

> -----Original Message-----
> From: serusers-bounces at lists.iptel.org 
> [mailto:serusers-bounces at lists.iptel.org] On Behalf Of Michael Shuler
> Sent: Tuesday, August 24, 2004 5:50 PM
> To: serusers at lists.iptel.org
> Subject: [Serusers] NAT
> 
> 
> I'm trying to understand the NAT process, can someone tell me 
> if this is
> correct
> 
> Here is my original INVITE from client IP 123.123.123.123 
> which is received
> from port 5002 (because its behind a NAT router): 
> 
> INVITE sip:2175850357 at sip2.bwsys.net;user=phone SIP/2.0
> Via: SIP/2.0/UDP 192.168.100.2:5060;branch=z9hG4bK-4qxhdyvuyz6t;rport
> From: "Mike's Springfield snom 1"
> <sip:MikeSnom1 at sip2.bwsys.net>;tag=k91lt5ydem
> To: <sip:2175850357 at sip2.bwsys.net;user=phone>
> Call-ID: 3c275253ad55-krb7eduyhd2m at 192-168-100-2
> CSeq: 1 INVITE
> Max-Forwards: 70
> Contact: <sip:MikeSnom1 at 192.168.100.2:5060;line=rygvn8mw>
> P-Key-Flags: keys="3"
> User-Agent: snom200-3.42
> Accept-Language: en
> Accept: application/sdp
> Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, 
> SUBSCRIBE, PRACK,
> MESSAGE, INFO
> Allow-Events: talk, hold, refer
> Supported: timer, 100rel, replaces
> Session-Expires: 3600
> Content-Type: application/sdp
> Content-Length: 256
> 
> v=0
> o=root 20147217 20147217 IN IP4 192.168.100.2
> s=call
> c=IN IP4 192.168.100.2
> t=0 0
> m=audio 10048 RTP/AVP 18 0 8 101
> a=rtpmap:18 g729/8000
> a=rtpmap:0 pcmu/8000
> a=rtpmap:8 pcma/8000
> a=rtpmap:101 telephone-event/8000
> a=fmtp:101 0-15
> a=sendrecv
> 
> 
> 
> Now this invite is going to get forwarded to my TNT (with a 
> public IP) which
> has SIP capabilities and hands of PRI to a phone switch.  So 
> to make NAT
> support work what would this message look like after being 
> proxied and NAT
> "adjusted" and what function in SER would be needed to make 
> the changes
> happen?
> 
> Now I know the proxy should be able to learn the port that 
> the INVITE comes
> in on and can send SIP messages back via the learned port, 
> but I do not
> understand how the RTP stream works when NAT is involved.  My 
> guess is that
> anything what says 192.168.100.2 (the NAT'ed IP) needs to get 
> changed to the
> proxy's public IP of 198.88.216.87:5060.  This would include 
> the Via and
> Contact.  Now the SDP "c" line has to be changed because it says
> 192.168.100.2 but it should be changed to 123.123.123.123 (the clients
> learned IP).  Now that leaves us to the problem of the RTP 
> port.  The client
> says it wants to receive on 10048, but how does the generic 
> NAT router know
> that the snom wants this port opened?
> 
> 
> ----------------------------------------
> 
> Michael Shuler, C.E.O.
> BitWise Systems, Inc.
> 682 High Point Lane
> East Peoria, IL 61611
> Office: (217) 585-0357
> Cell: (309) 657-6365
> Fax: (309) 213-3500
> E-Mail: mike at bwsys.net
> Customer Service: (877) 976-0711 
> 
> _______________________________________________
> Serusers mailing list
> serusers at lists.iptel.org
> http://lists.iptel.org/mailman/listinfo/serusers
> 

_______________________________________________
Serusers mailing list
serusers at lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers




More information about the sr-users mailing list