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Understood, I though it was quite strange to see these unsolicited
ACKs from the Polycoms followed by a RST.<br>
<br>
Thanks,<br>
Spencer<br>
<br>
<br>
On 05/13/2013 02:07 PM, Steven Schoch wrote:
<blockquote
cite="mid:CAOkuKdcOqW1exccJZKSYmZKMaSihbLcETdYcrxYUH8vGwJnZgg@mail.gmail.com"
type="cite">
<div dir="ltr">On Sun, May 12, 2013 at 2:54 PM, Spencer Thomason <span
dir="ltr"><<a moz-do-not-send="true"
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>
<br>
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</pre>
</blockquote>
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