[syslog-ng] Syslog-ng don't Listening UDP packets PORT(514) - Problem History

Zoltan Pallagi (zpallagi) Zoltan.Pallagi at oneidentity.com
Fri Nov 8 16:31:36 UTC 2019


Hi,

The most likely reason that another application also listens on this IP:port pair (it is possible in case of UDP and in that case the packet will be captured by the app started later)
Check the output of netstat -anu |grep 514 when syslog-ng does not capture the udp packets. You should see only one line here.

In other case, you should check the debug log of syslog-ng (syslog-ng -Fevd) perhaps there is some useful information.
________________________________
Feladó: syslog-ng <syslog-ng-bounces at lists.balabit.hu>, meghatalmazó: William Luiz Ribeiro Vasconcelos Da Silva <wsilva_ericsson at timbrasil.com.br>
Elküldve: 2019. november 8., péntek 16:28
Címzett: syslog-ng at lists.balabit.hu <syslog-ng at lists.balabit.hu>
Tárgy: [syslog-ng] Syslog-ng don't Listening UDP packets PORT(514) - Problem History

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Good Morning,

  Yesterday, we performed the first test of syslog-ng 3.24 OSE on a RHEL 7.6 VM in our customer's production environment.

  And we identified a very strange behavior.

  We saw through tcpdump that packets were being received by the network card but were not captured by syslog-ng.

  We have a UDP packet send simulator, and when I was pointing my simulator to another IP on the same machine(the users' connection IP), syslog-ng does the capping and consequently the treatment we put into the syslog-ng.conf file.

  What kind of TROUBLESHOOTING we can do in order to identify the reason for syslog-ng to capture packets on the users' connection IP, but for the application connection IP, it doesn't identify anything.

  It is informed by the client at the beginning of our project that syslog should always capture all UDP packets received by the application IP.

  This is the configuration of the "source" we have on this machine in our client's productive environment.


source s_model {
   #udp(port(514));
   udp(ip(10.46.105.34) port(514));
   # udp();
   #network(transport("udp"));
   #network(
   #   ip("10.46.105.34")
   #   transport("udp")
   #);
};

Tks,



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