Hello

I got an answer from the VOIP provider.

They claim that we have an error in our port forwarding. Because we advertise 5071, but traffic comes from another port.

As I understand, it is however impossible for TCP to send all traffic from just one port.

How is TCP SIP actually supposed to handle a BYE, when the client is behind NAT.

-------------------- Med Liberalistiske Hilsner ----------------------
   Civilingeniør, Kjeld Flarup - Mit sind er mere åbent end min tegnebog
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On 11/4/20 10:00 PM, Kjeld Flarup wrote:

Hello again

I have attached a Capture.

My public IP is 194.255.22.44, and I have a port forward of 5071 in my router

The Raspberry Pi running the Kamailio is on 192.168.2.9 with an alias 192.168.2.40

My listening is setup like this

listen=127.0.0.1:5071
listen=eth0:5071  advertise 194.255.22.44:5071
alias=194.255.22.44:5071

Kamailio is forwarding an invite from a door phone thus I also rewrite FROM:

uac_replace_from("sip:"+$dbr(ra=>[0,1])+"@194.255.22.44:5071");
And the failure route to
$fu = "sip:"+$dbr(ra=>[0,0])+"@194.255.22.44:5071";

In the route doing the INVITE I also set this:

set_advertised_address("194.255.22.44:5071");


Regarding tcp_reuse_port, if I set this I get this error, which I understand is due to the way TCP works.

Nov  4 18:38:41 scantronpbx /usr/sbin/kamailio[15864]: {1 ACK 16191 ACK C2Az-Xm2b0CEPyV5eQuz7yEf9IJo4PyJ} WARNING: <core> [core/tcp_main.c:1061]: tcp_do_connect(): binding to source address 192.168.2.40:5071 failed: Address already in use [98]

I do have tcp_reuse_port=yes with this capture. But much to my surprise, the 200 OK from is send to 37148, but the ACK to it comes from 37150


-------------------- Med Liberalistiske Hilsner ----------------------
    Civilingeniør, Kjeld Flarup - Mit sind er mere åbent end min tegnebog
    Sofienlundvej 6B, 7560 Hjerm, Tlf: 40 29 41 49
    Den ikke akademiske hjemmeside for liberalismen -www.liberalismen.dk
On 11/4/20 1:59 PM, Carsten Bock wrote:
Hi,

I think you are searching for this parameter:

http://www.kamailio.org/wiki/cookbooks/devel/core#tcp_reuse_port

It basically tells the kernel not to choose a new port at random for a new connection, but it will try to reuse the existing port (in your case 5071).

Thanks,
Carsten


--
Carsten Bock I CTO & Founder

ng-voice GmbH

Trostbrücke 1 I 20457 Hamburg I Germany
T +49 40 524 75 93-40 | M +49 179 2021244 I www.ng-voice.com <http://www.ng-voice.com/>

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Managing Directors: Dr. David Bachmann, Carsten Bock



Am Mi., 4. Nov. 2020 um 12:07 Uhr schrieb Kjeld Flarup <kjeld.fla...@liberalismen.dk <mailto:kjeld.fla...@liberalismen.dk>>:

    Hello

    I have a Kamailio running behind NAT, which sends calls to a VOIP
    service provider.

    I have setup the Kamalio to listen on port 5071, and also setup a
    port
    forward in the router.

    Now the problem is that with TCP, 5071 is not used for the
    dialog, but a
    new port is chosen everytime. This means that when the mobile phone
    called hands up, I never sees the BYE, because BYE is a new dialog.


    To which port is the server supposed to send the BYE, and what field
    tells the server this.


-- -------------------- Med Liberalistiske Hilsner
    ----------------------
        Civilingeniør, Kjeld Flarup - Mit sind er mere åbent end min
    tegnebog
        Sofienlundvej 6B, 7560 Hjerm, Tlf: 40 29 41 49
        Den ikke akademiske hjemmeside for liberalismen -
    www.liberalismen.dk <http://www.liberalismen.dk>


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