[asterisk-users] PJSIP, NAT and STUN/ICE

[O. Hartmann]

Am Mon, 9 Oct 2017 15:07:46 -0700
John Kiniston <johnkiniston at gmail.com> schrieb:

> Well, I can answer one of your questions.
> 
> To see the current external_media_address and external_signalling_address
> from the CLI you can issue a 'pjsip show transport <transport-name>'
> 
> Your router could have a built in sip helper that is rewriting the contact
> for your packets.
> 
> On Mon, Oct 9, 2017 at 2:56 PM, O. Hartmann <ohartmann at walstatt.org> wrote:
> 
> > I'm quite new to Asterisk and using Asterisk 13 on FreeBSD current.
> > Asterisk is behind a
> > NAT router, the physical setup is very much a trivial one. The Asterisk
> > PBX is supposed
> > to act as the telephone gateway for several VoIP/SIP phones.
> >
> > I'm using throughout pjsip as configuration, I have no experience with
> > chan_sip since I
> > started recently using Asterisk for several SoHo and lab's projects. So be
> > alarmed, there
> > may come some noobish questions.
> >
> > When planning and setting up the Asterisk, I had to deal with NAT. The
> > Asterisk config
> > object of type=transport knows about essential entries:
> >
> > local_net=                      192.168.254.1/24
> > bind=                           192.168.254.1:5060
> > external_media_address=         dyndns FQDN
> > external_signaling_address=     dyndns FQDN
> > direct_media=                   no
> > rtp_symmetric=                  yes
> > force_rport=                    yes
> >
> > dyndns FQDN is the FQDN of my broadband access point provided by some
> > dynamical DNS
> > provider.
> >
> > This setup is not working properly with when external_media_address= and
> > external_signaling_address= are set that way, but commenting out both
> > makes all of the
> > ITSP which provides me with service happy.
> >
> > I think, at this point I have no idea of the concept or, there is simply a
> > missing link,
> > even a (dangerously) misconfigured router - on which the Asterisk runs.
> > When
> > external_xxxx_xxxx are not set, I suppose they're set to 0.0.0.0/0.0.0.0,
> > aren't they,
> > implying that they listen on all configured IPs?
> >
> > If so, is there a way to show the setting of external_media_address= and
> > external_signaling_address= on the CLI?
> >
> > When using PJSIP with the setting excluding attributes external_xxx_xxx,
> > does pjsip do
> > some magic to traverse the NAT in a proper way? At this very moment, I do
> > not understand
> > how things would work avoiding setting external_media_address= and
> > external_signaling_address=. The Asterisk 13 I'm running is supposed to be
> > bound to IP
> > 192.168.254.1, which is routed to the gateway.
> >
> > My problem is, I don not understand why the communication is working
> > fluently with both
> > external_xxx_xxx atrributes commeneted out which I suppose to be crucial -
> > following the
> > Asterisk 13 documentation!
> >
> > Maybe someone can sched some light onto this. I think, my view on the
> > matter is
> > completely confused.
> >
> > Thanks in advance,
> >
> > oh
> >
> > Another point
> >
> > --
> > _____________________________________________________________________
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> >
> > Check out the new Asterisk community forum at: https://community.asterisk.
> > org/
> >
> > New to Asterisk? Start here:
> >       https://wiki.asterisk.org/wiki/display/AST/Getting+Started
> >
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> >  
> 
> 
> 
Thank you for your answer.

This is the output of 

pjsip show transport transport-nat-udp (name of the transport object defined):

 external_media_address     : 
 external_signaling_address : 
 external_signaling_port    : 0

It is set, as expected, to nothing since I didn't set anything to make it work. I guess,
from this point, Asterisk figures somehow out itself how to traverse the NAT (in my
simple standard setup). 

I'm just curious. Maybe I'm on the wrong page here and the setup I have is that common,
that those extra options doesn't matter and NAT is easily circumferenced. As I said in my
introduction, Asterisk and pjsip are new to me (and I have no experience with
chan_sip) ;-).

Kind regards,

oh
-- 
O. Hartmann

Ich widerspreche der Nutzung oder Übermittlung meiner Daten für
Werbezwecke oder für die Markt- oder Meinungsforschung (§ 28 Abs. 4 BDSG).
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