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Hi Bryan,</div>
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If I understand correctly, the message, which got lost, was expected to come from the "s_net" source.</div>
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If that is the case, it is normal to lose logs there, as UDP does not provide reliable data transmission.</div>
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<br>
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Logging services have different solutions to this problem, syslog-ng Premium Edition has Advanced Log Transfer Protocol (ALTP).</div>
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You can read more about it here: <a href="https://support.oneidentity.com/technical-documents/syslog-ng-premium-edition/7.0.14/administration-guide/58#TOPIC-1187363">https://support.oneidentity.com/technical-documents/syslog-ng-premium-edition/7.0.14/administration-guide/58#TOPIC-1187363</a></div>
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If I misunderstood the problem, please correct me.</div>
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Have a nice day! <span id="🙂" title=":slight_smile:">🙂</span></div>
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Best regards,</div>
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Attila</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> syslog-ng <syslog-ng-bounces@lists.balabit.hu> on behalf of Klimek, Bryan J. <bklimek@mayo.edu><br>
<b>Sent:</b> Wednesday, June 26, 2019 3:50 PM<br>
<b>To:</b> 'syslog-ng@lists.balabit.hu'<br>
<b>Subject:</b> Re: [syslog-ng] Missing messages</font>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Attila,</span></p>
<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Thank you for your response. I enabled the "stats-level(1)" so I can see the statistics. But the “dropped” counters are all zero.
</span></p>
<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black"> </span></p>
<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">I’ve attached the syslog-ng.conf file for review.</span></p>
<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black"> </span></p>
<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">This syslog-ng instance receives syslog from 2000+ hosts. We create a separate file for every server for every day. We also fork the data to one consolidated file (all traffic
from all hosts into 1 file). We also fork a 3<sup>rd</sup> copy to our SEIM (Security Event Information Management) solution.</span></p>
<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black"> </span></p>
<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">The missing message does not appear in the individual host file, nor does it appear in the consolidate file of all hosts. I’ve never bothered to check with our SEIM people
to see if they are getting the missing message. I just assume they are not.</span></p>
<p class="x_MsoNormal"><span style="font-size:11.0pt; font-family:"Calibri","sans-serif"; color:#1F497D"> </span></p>
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<p class="x_MsoNormal"><b><span style="font-size:10.0pt; font-family:"Verdana","sans-serif"; color:navy">Bryan Klimek</span></b><span style="font-size:11.0pt; font-family:"Calibri","sans-serif"; color:blue">
<br>
</span><span style="font-size:10.0pt; font-family:"Verdana","sans-serif"; color:black">Phone: 507-284-9396</span><span style="font-size:11.0pt; font-family:"Calibri","sans-serif"; color:blue">
<br>
</span><span lang="PT-BR" style="font-size:10.0pt; font-family:"Verdana","sans-serif"; color:black">E-mail:
<a href="mailto:klimek.bryan@mayo.edu">klimek.bryan@mayo.edu</a></span><span lang="PT-BR" style="font-size:11.0pt; font-family:"Calibri","sans-serif"; color:blue">
</span><span style="font-size:11.0pt; font-family:"Calibri","sans-serif"; color:blue"></span></p>
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<p class="x_MsoNormal"><b><span style="font-size:10.0pt; font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt; font-family:"Tahoma","sans-serif""> syslog-ng [mailto:syslog-ng-bounces@lists.balabit.hu]
<b>On Behalf Of </b>Attila Szakacs (aszakacs)<br>
<b>Sent:</b> Monday, June 24, 2019 8:40 AM<br>
<b>To:</b> 'syslog-ng@lists.balabit.hu'<br>
<b>Subject:</b> [EXTERNAL] Re: [syslog-ng] Missing messages</span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Hi Bryan,</span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Thank you for using the syslog-ng mailing list!
</span><span style="font-family:"Segoe UI Symbol","sans-serif"; color:black">🙂</span><span style="font-family:"Calibri","sans-serif"; color:black"></span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Message drop could happen for several reasons. I couple reasons, that suddenly comes up to me:</span></p>
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<li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">The log path has a filter or parser, which does not match for the message.</span></li><li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">The log path has a source, which has a built-in parser (syslog for example), and the message does not match the protocol.</span></li><li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">Flow-control is not enabled and the destination is not alive for a longer period of time.</span></li><li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">Flow-control is configured incorrectly.</span></li><li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">...</span></li></ol>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Saying so, it is hard to come up with one general way to investigate this.</span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">However, I can give you some tips:</span></p>
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<li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">You can set "stats-level(1)" in the global options and use "sbin/syslog-ng-ctl stats", then look for the "dropped" counters.</span></li><li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">You can start syslog-ng in debug mode (./sbin/syslog-ng -Fedtv) and look for the following logs: "Destination queue full, dropping message;" or "UNMATCHED".</span></li><li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">Check if flow-control is enabled and configured properly.</span></li><li class="x_MsoNormal" style="color:black"><span style="font-family:"Calibri","sans-serif"">If you do not want to use flow-control, you can use disk-queue alternatively.</span></li></ol>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">If you could share some parts of your setup and config, where the problem happens, we could give you more insight.</span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Best regards,</span></p>
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<p class="x_MsoNormal"><span style="font-family:"Calibri","sans-serif"; color:black">Attila</span></p>
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<p class="x_MsoNormal"><b><span style="font-size:11.0pt; font-family:"Calibri","sans-serif"; color:black">From:</span></b><span style="font-size:11.0pt; font-family:"Calibri","sans-serif"; color:black"> syslog-ng <syslog-ng-bounces@lists.balabit.hu> on behalf
of Klimek, Bryan J. <bklimek@mayo.edu><br>
<b>Sent:</b> Monday, June 24, 2019 3:05 PM<br>
<b>To:</b> 'syslog-ng@lists.balabit.hu'<br>
<b>Subject:</b> [syslog-ng] Missing messages</span> </p>
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<p class="x_MsoNormal"> </p>
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<p class="x_MsoNormal" style="line-height:12.0pt; background:#FFEB9C"><b><span style="font-size:10.0pt; font-family:"Calibri","sans-serif"; color:#9C6500">CAUTION:</span></b><span style="font-size:10.0pt; font-family:"Calibri","sans-serif"; color:black"> This
email originated from outside of the organization. Do not follow guidance, click links, or open attachments unless you recognize the sender and know the content is safe.</span></p>
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<p class="x_xmsonormal">First time poster, so be gentle.</p>
<p class="x_xmsonormal"> </p>
<p class="x_xmsonormal">We run syslog-ng in our environment as a centralized syslog manager for the archiving of syslog data. We have over 2000+ Unix/Linux systems sending their syslog data with a daily ingest rate of about 10GB per day.</p>
<p class="x_xmsonormal"> </p>
<p class="x_xmsonormal">It was recently pointed out to me that one particular message from one specific host is not getting persisted to the files on our syslog-ng server all the time. That is to say, it is intermittent.</p>
<p class="x_xmsonormal"> </p>
<p class="x_xmsonormal">If one person can find one message that is not making into our syslog-ng archive, I can only assume that we are dropping other messages as well.</p>
<p class="x_xmsonormal"> </p>
<p class="x_xmsonormal">How can I debug if and when messages are being lost and not making into the files on my centralized syslog server?</p>
<p class="x_xmsonormal"> </p>
<p class="x_xmsonormal">Bryan Klimek</p>
<p class="x_xmsonormal">Mayo Clinic</p>
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