[Serusers] NAT

[Michael Shuler]

In the nat helper module it says:

1.5.1. fix_nated_sdp(mode)
Rewrites Contact HF to contain request's source address:port. 

Meaning of the parameters is as follows:

mode - 0x01 (add direction=active), 0x02 (rewrite media IP address with
source address of the message). 



I understand what 0x02 is doing, can someone explain what 0x01 is actually
doing?



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

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: Richard [mailto:richard at o-matrix.org] 
> Sent: Wednesday, August 25, 2004 12:51 PM
> To: 'Michael Shuler'; serusers at lists.iptel.org
> Subject: RE: [Serusers] NAT
> 
> 
> 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 lists.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
> > 
> 
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