[OpenSIPS-Users] I need to understand when from opensips ser "TCP Zero Window" message get generated .

[Bogdan-Andrei Iancu]

Hi,

OpenSIPS listens on 5060 for incoming TCP conns, but when connecting (to 
other server) it uses a random / ephemeral port as source of the 
outbound TCP conn - this is normal, how TCP works in most of the cases.

When OpenSIPS is not able to connect anymore, do you see any errors in 
the logs?

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
   https://www.opensips-solutions.com
   https://www.siphub.com

On 13.02.2025 08:59, Sasmita Panda wrote:
> On the same server I can see something different as well .
>
> I have only configured 5060 ports for TCP and UDP in the listen 
> parameter .
> But I can see openisps established connections from different ports 
> rather than 5060 . How is that possible ?
>
> tcp        0      0 172.x.y.z:5060        10.m.n.o:42560   ESTABLISHED 
> 24449/opensips
> tcp        0      0 172.x.y.z:5060        10.a.b.c:35507 ESTABLISHED 
> 24448/opensips
> tcp        0      0 172.x.y.z:58609       10.m.n.o:5060  ESTABLISHED 
> 24450/opensips
> tcp        0      0 172.x.y.z:57323       10.a.b.c:5060  ESTABLISHED 
> 24449/opensips
>
> Here 172.x.y.z is my opensips server and others are gateway IPs . I 
> can understand the TCP connection from the 5060 port .
> How do opensips select other ports here ?
> Is this the default behaviour of opensips ? Or in the latest version 
> the behaviour changes ?
>
>
>
>
>
>
> */Thanks & Regards/*
> /Sasmita Panda/
> /Senior Network Testing and Software Engineer/
> /3CLogic , ph:07827611765/
>
>
> On Thu, Feb 13, 2025 at 10:44 AM Sasmita Panda <spanda at 3clogic.com> wrote:
>
>     Hi ,
>
>
>     I have a server running on opensips 2.2 version (Yes that is very
>     old I know , we are planning to upgrade that in near future ) .
>
>     On that server I have set up the gateways with TCP socket
>     connection . Openisps while sending outbound calls to the gateway
>     give the call in TCP .
>
>     From the last 2/3 months we observed , randomly sometime in 7days
>     or 10/12 days the connection won't get established and calls get
>     affected .
>
>     Once we restart the opensips service things start working fine . 
>     So here is opensips blocking something ? or is it on my linux
>     machine blocking the connection ?
>
>     For the proto_tcp module I have not configured any parameters .
>     just loaded the module . I am hoping the default values must be in
>     use .
>
>     Can anybody suggest to me what I need to debug here ?
>
>     */Thanks & Regards/*
>     /Sasmita Panda/
>     /Senior Network Testing and Software Engineer/
>     /3CLogic , ph:07827611765/
>
>
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