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<p class="MsoNormal">If you are using UDP, understand that there is no “guarantee of delivery”. You can see if you are having any UDP packet loss by running ‘netstat -su’. Look for the number associated with ‘receive buffer errors'.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">If ‘receive buffer errors' Is not zero, then you are losing messages. Understand that the ‘receive buffer errors' Is cumulative and only goes up and is never reset until a reboot. So if you want to “watch” the number, you need to query
it on a daily basis to understand how many packets you are losing per day.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Bryan<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> syslog-ng <syslog-ng-bounces@lists.balabit.hu> <b>
On Behalf Of </b>Daniel Ehrlich<br>
<b>Sent:</b> Tuesday, June 15, 2021 12:49 AM<br>
<b>To:</b> Syslog-ng users' and developers' mailing list <syslog-ng@lists.balabit.hu><br>
<b>Subject:</b> [EXTERNAL] Re: [syslog-ng] Tips to diagnose missing syslog messages?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Thanks Laci,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Yes this is syslog-ng as a receiver, from a network source of UDP 514.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">The destination is files on the local drive.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">The network path is allowed by firewall as we receive several messages, though some go missing.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">For example, some hosts send every minute and only 5 of the 15 might make it to the dest file.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I may be overloading the listener with 3-500 events per second?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I think I am running syslog-ng 3.5 from RedHat repos.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I was sure if the multi-threaded option would help?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Thanks<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Daniel<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> syslog-ng <<a href="mailto:syslog-ng-bounces@lists.balabit.hu">syslog-ng-bounces@lists.balabit.hu</a>> on behalf of Laszlo Szemere (lszemere) <<a href="mailto:Laszlo.Szemere@oneidentity.com">Laszlo.Szemere@oneidentity.com</a>><br>
<b>Sent:</b> Tuesday, 15 June 2021 12:34 AM<br>
<b>To:</b> Syslog-ng users' and developers' mailing list <<a href="mailto:syslog-ng@lists.balabit.hu">syslog-ng@lists.balabit.hu</a>><br>
<b>Subject:</b> Re: [syslog-ng] Tips to diagnose missing syslog messages?</span> <o:p>
</o:p></p>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black">Hello Daniel,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> If I understand you correctly: you have a problem that one of your Syslog-ng server is not receiving a log message. (Not that you do not receive a message FROM one
of your Syslog-ng server.)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> From my experience: In those cases when someone tries to diagnose an issue where Syslog-ng do not receive a message, it is always a good first step to determine
if the message actually reaches Syslog-ng or not.<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> i.e.: in case of a network source, try to receive the message with a simple netcat command. (Maybe the message was dropped by a firewall before reaching your machine,
and Syslog-ng has nothing to do with it.) At this point we do not really care about the format of the message.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> If you made sure that those messages are reaching the application, we should try to diagnose Syslog-ng itself. For that we will need some information about your
setup.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> i.e.:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> - your platform<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> - version of Syslog-ng (Where it is obtained from? i.e. local build)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> - Related config parts. (including the source driver which is expected to receive the logs)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> - How do you start Syslog-ng? (i.e.: as a service)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black">Best regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black">Laci<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> syslog-ng <<a href="mailto:syslog-ng-bounces@lists.balabit.hu">syslog-ng-bounces@lists.balabit.hu</a>> on behalf of Daniel Ehrlich <<a href="mailto:Daniel.Ehrlich@usq.edu.au">Daniel.Ehrlich@usq.edu.au</a>><br>
<b>Sent:</b> Wednesday, June 9, 2021 07:24<br>
<b>To:</b> Syslog-ng users' and developers' mailing list <<a href="mailto:syslog-ng@lists.balabit.hu">syslog-ng@lists.balabit.hu</a>><br>
<b>Subject:</b> [syslog-ng] Tips to diagnose missing syslog messages?</span> <o:p>
</o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<div style="border:solid #9C6500 1.0pt;padding:2.0pt 2.0pt 2.0pt 2.0pt">
<p class="MsoNormal" style="line-height:12.0pt;background:#FFEB9C"><b><span style="font-size:10.0pt;color:#9C6500">CAUTION:</span></b><span style="font-size:10.0pt;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.<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
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<div>
<div>
<p class="MsoNormal">Hi Everyone,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<div>
<p class="MsoNormal">Does anyone have some diagnostic tips to offer to diagnose why syslog messages are not being received?<o:p></o:p></p>
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<div>
<p class="MsoNormal">I have syslog-ng on a few servers but one is losing messages (others syslog-ng servers might be dropping that I am unaware off).<o:p></o:p></p>
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<div>
<p class="MsoNormal">Not sure if there is some options I should add to the conf or diag commands or load specifications I should check?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Options:<br>
options { <o:p></o:p></p>
<div>
<p class="MsoNormal"> chain_hostnames(no);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> create_dirs (yes);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> dir_perm(0755);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> dns_cache(yes);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> keep_hostname(yes);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> log_fifo_size(2048);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> log_msg_size(8192);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> perm(0644);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> time_reopen (10);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> use_dns(yes);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> use_fqdn(yes);<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> flush_lines(100);<o:p></o:p></p>
</div>
<p class="MsoNormal">};<o:p></o:p></p>
</div>
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<p class="MsoNormal"><o:p> </o:p></p>
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<div>
<p class="MsoNormal">Also adding the flag-control flag to the log stanza.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Thanks<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Daniel<o:p></o:p></p>
</div>
</div>
<div>
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