Re: [Linphone-users] hoping for help in protocol analyzation

[Boris]

Hej again Dennis,

here i am again with some more things to report.

Finally, with all circumstances in mind, I do believe that it should be 
possible to make linphone work without changing the network environment 
or adding a network service like siproxd.

So I am focussing on the working hardphone Panasonic KX-UT133 in the 
first step.

Am 23.09.21 um 22:17 schrieb Boris:
> Hej Dennis,
>
> thanks for your hints. This is so much, I will need some time to follow....
>
> Am 22.09.21 um 18:19 schrieb Dennis Filder:
> > It would be very interesting to know how these other SIP clients learn
> > the public IP address.  LEAF has tcpdump, so it should be easy to
> > figure out.  I suspect that they contact a hard-coded publically
> > reachable STUN server or do other tricks like that.

I tcpdumped the LAN and WAN interfaces of the leaf-box during 
initialization of the hardphone. And in fact, there is a response from 
cx.dtst.de that contains like SIP Status 200 OK and it contains the 
public IP.
As far as I understand, there is no STUN server within that communication.

I did't publish the pcap files for they seem to contain some private 
data. So, if needed, I could send them with PM or so....

> > As for TNG working and DT not working I assume that TNG is your ISP
>
> yes
>
> > which means it can rewrite your outgoing SIP packets on the fly at the
> > next hop with a transparent SIP proxy because it knows both your phone
> > number and your currently assigned IP address.  I read about Telekom
> > doing it this way, and while it sure is convenient it isn't really how
> > SIP was intended to be used because it usually also allows any
> > stranger walking into your home to plug in an IP phone and perform
> > calls on your bill without having to authenticate against the SIP
> > provider. 
>
> No. I got some (one for each phone number) credentials from TNG to 
> authorizw against their SIP server.
>
> If SIP packets would be rewritten, LinPhone, Twinkle and the Panasonic 
> HardPhone wouldn't be able to reach the DT server?
>
> > That's something to keep in mind.  It also gives people
> > wrong ideas about how SIP is designed to work.
>
> I obviously belong to exactly these people - regardless of who or what 
> is responsible for this.

What do you think could be the next step?

Thanks and regards,


Boris