[syslog-ng] Filter matching not working
Gabor Nagy (gnagy)
Gabor.Nagy at oneidentity.com
Thu Dec 3 08:16:30 UTC 2020
Hello!
I just took a quick look on the config and on the internal logs. Couldn't be that "f_discreg" is not included in a log path?
Another thing that could be is parsing: your "s_net" source will try to parse incoming messages as either BSD or Syslog format.
If you've just tested the filter by sending in the message "default send string", then syslog-ng will parse it, which results that MSG macro will not contain "default send string".
With trace level logging you can debug how does the message being parsed (-t command line option), and to disable parsing on the source side use the flags("no-parse") option.
See an example:
[2020-12-03T09:14:51.016256] Incoming log entry; line='default send string'
[2020-12-03T09:14:51.016290] Initial message parsing follows;
[2020-12-03T09:14:51.016322] Setting value; name='PROGRAM', value='default', msg='0x7f24a8005f30'
[2020-12-03T09:14:51.016334] Setting value; name='LEGACY_MSGHDR', value='default ', msg='0x7f24a8005f30'
[2020-12-03T09:14:51.016341] Setting value; name='MESSAGE', value='send string', msg='0x7f24a8005f30'
Regards,
Gabor
________________________________
From: syslog-ng <syslog-ng-bounces at lists.balabit.hu> on behalf of Saqib M <saqib.m at cummins.com>
Sent: Thursday, December 3, 2020 1:48
To: syslog-ng at lists.balabit.hu <syslog-ng at lists.balabit.hu>
Subject: [syslog-ng] Filter matching not working
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Greetings –
I have been trying to create a very basic filter that looks up a string in the incoming log. However, it would not match any filter and would go to the default filter. I have tried both match() and message(), neither worked for me. Please let me know if you think I am missing something.
Following are the chunks from the syslog-ng.conf
source s_net {
# All syslog traffic on port 514 - this is direct from network devices.
udp(port (514));
network(transport("tcp") max-connections(20000) log_iw_size(100000000) ); # tags("fortigate", "cisco", "default") );
};
filter f_discreg { message("default send string") };
log { source(s_net); filter(f_dlptracker); destination(d_dlptracker); flags(final); };
Here is the log from the test I ran.
[2020-12-02T22:00:36+0000] Incoming log entry; source='s_net#0', line='default send string'
[2020-12-02T22:00:46+0000] Filter node evaluation result; filter_result='not-match', filter_type='OR'
[2020-12-02T22:00:46+0000] Filter rule evaluation result; filter_result='not-match', filter_rule='f_tanium'
[2020-12-02T22:00:46+0000] Filter rule evaluation begins; filter_rule='f_palo_alto'
[2020-12-02T22:00:46+0000] Filter node evaluation result; filter_result='not-match'
[2020-12-02T22:00:46+0000] Filter node evaluation result; filter_result='not-match'
[2020-12-02T22:00:46+0000] Filter node evaluation result; filter_result='not-match'
[2020-12-02T22:00:46+0000] Filter node evaluation result; filter_result='not-match', filter_type='OR'
[2020-12-02T22:00:46+0000] Filter node evaluation result; filter_result='not-match', filter_type='OR'
[2020-12-02T22:00:46+0000] Filter rule evaluation result; filter_result='not-match', filter_rule='f_palo_alto'
[2020-12-02T22:00:46+0000] Filter rule evaluation begins; filter_rule='f_dlptracker'
[2020-12-02T22:00:46+0000] Filter node evaluation result; filter_result='not-match'
[2020-12-02T22:00:46+0000] Filter rule evaluation result; filter_result='not-match', filter_rule='f_dlptracker'
[2020-12-02T22:00:46+0000] Outgoing message; destination='d_fallback#0', message='2020-12-02T22:00:46+00:00 172.17.236.3 default send string\x0a'
Regards,
Saqib M
Cybersecurity Co-op
Global Cybersecurity Technologies
Email: saqib.m at cummins.com<mailto:saqib.m at cummins.com>
Cummins Inc.
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