[Serusers] Rewriting URI in the Contact field

[Greg Fausak]

What is this device?  Where can I get one? What does it cost?

Thanks :-)

---greg

> -----Original Message-----
> From: serusers-admin at lists.iptel.org 
> [mailto:serusers-admin at lists.iptel.org] On Behalf Of Maxim Sobolev
> Sent: Friday, January 10, 2003 8:15 AM
> To: Jiri Kuthan
> Cc: serusers at lists.iptel.org; kapitan at portaone.com
> Subject: Re: [Serusers] Rewriting URI in the Contact field
> 
> 
> Yes, I know - we have studied all those methods in details. Our
> method of choice is symmetric signalling/symmetric media (aka COMEDIA)
> due to the following reasons:
> 
> 1. Things should work without modifying or reconfiguring existing
> user's infrastructure (NATs) and should be compatible with all
> widely-used NATs.
> 
> 2. We are bound to ata186 as UA. It is compatible with this method.
> Support for other UAs isn't required.
> 
> 3. The calls will be terminated to Cisco GWs, while COMEDIA support
> was recently added into Cisco IOS, so that theoretically the only
> thing we need is to add received/rport support into proxy/registrar
> and update IOS at termination points.
> 
> 4. No media relay is allowed, because this will create excessive
> bandwith load in a single point.
> 
> 5. COMEDIA support is likely to become part of the standard, so that
> our investments into development are protected.
> 
> -Maxim
> 
> On Fri, Jan 10, 2003 at 02:26:07PM +0100, Jiri Kuthan wrote:
> > There is actually a plenty of options how to traverse NATs.
> > Sadly, none of them works in all possible scenarios.
> > 
> > a) STUN -- some phones (kphone for linux, snom hardphones)
> >    have the ability to "fool" NATs to accomplish traversal
> >    using the STUN protocols; particularly good if you cannot
> >    manipulate the NAT
> > b) geek tweaks -- you have a configurable NAT and configurable
> >    phones (there are some of both of them).  you configure static 
> >    port forwarding in the NAT and phones to advertise the
> >    public address in contacts and elsewhere
> > c) ALG -- use a SIP-aware NAT such as PIX or Intertex
> > d) UPnP -- takes UPnP enables phones (snom is) and NATs
> > e) SIP/media relay -- that's a too ugly story
> > 
> > What to choose best depends on your network setting -- can you
> > tweak the NAT, can you afford replacing it with a SIP-enabled
> > one, are the phones you are using configurable or do they use
> > STUN, do you have a server on the public or private NAT side
> > or on each of them, etc.
> > 
> > I remember someone shared with us he was using ser in his
> > network to do the translation of SIP addresses on behalf
> > ot the phones. The ser script was configured to statically
> > rewrite private IP addresses to the public address using
> > replace/textops.
> > 
> > -Jiri
> > 
> > At 01:32 PM 1/10/2003, Maxim Sobolev wrote:
> > >Folks,
> > >
> > >I need an advise on how to better implement one feature, 
> which isn't
> > >currently present in SER. We need to allow UAs behind NAT properly
> > >register with the registrar - by "properly" I mean that 
> host:port portion
> > >of URI in Contact field should not be used, but host:port 
> the request
> > >came from should be used instead. By definition we know 
> that those UAs
> > >will support symmetric SIP signalling, so that this scheme 
> will work just
> > >fine.
> > >
> > >In my opinion there are two ways to do it: either add new 
> rewritecontact*
> > >family of functions similar to rewritehost ones. or add a 
> new flag for
> > >the save() function. This is where I need your help - 
> which implementation
> > >looks better for you (or maybe you have even some better 
> idea), since
> > >we are really interested in inclusion of our changes into 
> the mainline to
> > >reduce our local hacks.
> > >
> > >Regards,
> > >
> > >Maxim
> > >
> > >_______________________________________________
> > >Serusers mailing list
> > >serusers at lists.iptel.org
> > >http://lists.iptel.org/mailman/listinfo/serusers 
> > 
> > --
> > Jiri Kuthan            http://iptel.org/~jiri/ 
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