Thank you Alex and Federico,

I verified, and SO_REUSEPORT is defined on my OS.  I am using Kamailio 5.2 and I set ‘tcp_reuse_port=yes;’ and $fs;  this has been to no avail as ‘ACK’s’ are still using the high port number randomly assigned by Kamailio.

Thank you all for sharing your knowledge!

From: sr-users [mailto:sr-users-bounces@lists.kamailio.org] On Behalf Of Federico Cabiddu
Sent: Friday, May 18, 2018 12:57 AM
To: Kamailio (SER) - Users Mailing List <sr-users@lists.kamailio.org>
Subject: Re: [SR-Users] Transport issue thought

You are right Alex, Linux kernel didn't support SO_REUSEPORT, which allows a socket to be used as source for a tcp connection while is already bound, until version 3.9.

Kamailio's parameter tcp_reuse_port, if enabled and your OS has support for SO_REUSEPORT (so not only Linux but FreeBSD, OSX and others), allows you to use force_send_socket (or $fs) to send messages from a TCP port kamailio is listening to.

Cheers,

Federico

On Fri, May 18, 2018 at 12:28 AM, Alex Balashov <abalashov@evaristesys.com> wrote:

When an outgoing TCP connection is opened, either a port can be
explicitly bound, or it is auto-assigned by the OS's networking stack. I
believe Kamailio does the latter and does not offer options to constrain
the range. If it does, I'm not aware of any apart from this one:

https://www.kamailio.org/wiki/cookbooks/5.1.x/core#tcp_reuse_port

Not sure if it would help in this case, you'd have to give it a try.

On Thu, May 17, 2018 at 10:21:34PM +0000, Wilkins, Steve wrote:

> It appears that the bottom line of my TCP transport not working is that Kamailio is randomly assigning large port numbers to send the TCP traffic out on.
> I am not able to randomly open high ports for this purpose.  Is there a way to tell Kamailio to only use specific ports for this.  I have tried using
> force_send_socket() with Kamailio' s IP, and the port I want to send out on, but this did not work either.  Does this sound like I am on the right track?
>
> Thank you,
> -

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