<div dir="ltr">On Sun, May 12, 2013 at 2:54 PM, Spencer Thomason <span dir="ltr"><<a href="mailto:spencer@5ninesolutions.com" target="_blank">spencer@5ninesolutions.com</a>></span> wrote:<br><div class="gmail_extra">
<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">The phones periodically send a TCP ACK ping to<br>
Freeswitch which goes unanswered and then phone then tears down the TCP<br>
connection. I'm not at all a TCP expert but should Freeswitch be<br>
responding to this unsolicited ACK?</blockquote><div><br></div><div style>I've been working with TCP for 25 years, and this is the first I have heard of ACK ping. A quick Google search told me that this technique involves sending a normal TCP ACK packet (which all TCP packets except the initial one have, by the way) to a random TCP port. The host will then respond with a RST packet. (Which means reset the connection because the ACK was not sent to an established connection.)</div>
<div style><br></div><div style>However, a firewall may filter and discard these random ACK packets. Since they're not part of "normal" TCP, no one cares.</div><div style><br></div><div style>In answer to your question, this is in the TCP layer much deeper than Freeswitch. There is nothing Freeswitch can do at this level.</div>
<div style><br></div><div style>-- </div><div style>Steve</div></div></div></div>