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<tt>For the below symptoms, I would recommend a watching the
application <br>
port with WireShark.<br>
<br>
This should show any the TLS protocol deviations and any problems
in <br>
handling and establishing the TCP connections.<br>
</tt><br>
<div class="moz-cite-prefix">On 2021-08-19 00:38, David Bowers via
openssl-users wrote:<br>
</div>
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<div class="WordSection1">
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">We have a
server that has around 2025 clients connected at any
instant.
<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">Our
application creates a Server /Listener socket that then is
converted into a Secure socket using OpenSSL library. This
is compiled and built in a Windows x64 environment. We also
built the OpenSSL for the Windows. The Listener socket is
created with a default backlog of 500. The Accept socket is
non-blocking socket and waits for connections<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">Every Client
makes a regular blocking connection to the Server. The
Server accepts the connection after which the Client socket
is converted to a secure socket using the OpenSSL Library.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">The
connections are coming at a rate of about 10 connections
/second ? Not sure about this number.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">We are able
to connect to all the clients in a few minutes and it stays
like that for some time. There constant exchange of
messages between Server(COS) and clients without issues.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">The
application logic is to keep trying to connect every
timeout.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">After maybe
a few hours/days we see the clients dropping connections.
The logs indicate the SSL_Read or SSL_Write on the Server
fails for a client with SSL_Error number 5
(SSL_ERROR_SYSCALL<span
style="font-size:9.5pt;font-family:Consolas;color:#6F008A">)
</span>and the equivalent Windows error of WSATimeOut. We
then observe the WSAECONNRESET as the Client closed
connection. We see this behavior for multiple sites.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">The number
of Clients disconnected starts increasing and we see the
logs in the Client where the server refuses any more
connections form Clients (10061- WSAECONNREFUSED) There is
nothing to indicate this state in the server logs. Our
theory is the backlog is filled and Server refusing further
connections.
<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0in;mso-list:l0 level1 lfo1">We are
trying to find why we get the SSL_Read/SSL_Write Error as it
a Blocking socket. We cannot use to a non-blocking socket
due to platform and application limitation<o:p></o:p></li>
</ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-indent:.5in"><o:p> </o:p></p>
</div>
</blockquote>
<pre class="moz-signature" cols="72">Enjoy
Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S. <a class="moz-txt-link-freetext" href="https://www.wisemo.com">https://www.wisemo.com</a>
Transformervej 29, 2860 Søborg, Denmark. Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded</pre>
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