Snort mailing list archives
Snort only partially alerting.
From: Frank Calone <fc10011001 () gmail com>
Date: Wed, 12 Jun 2013 11:33:58 -0400
Hi. I am trying to get a new standalone Snort server operational on a CentOS box. I have two network cards that Snort is monitoring. We also have Snort running on an appliance, supplied by a 3rd party vendor. Snort has been useful on the appliance but it doesn’t support session capture, hence our using a dedicated server. The problem I’m having is I am getting alerts on the appliance but not on the full blown Snort server for the 2 rules we want to focus on. I have looked at the configuration settings and I do not see anything that could explain this. I have turned up performance monitoring and it actually looks like the new server is mostly idle (Here is a snapshot from perfmon). usr[0] sys[0] idle[0] 4.752 1.404 93.845 5.768 1.335 92.897 5.562 1.515 92.923 5.607 1.509 92.884 I have essentially the same 2 rules setup on both systems looking for executable files. Sometimes both systems will alert, though most of the time the new server misses the traffic. Nothing much is showing up in the syslog either. I am getting an occasional syslog entry as follows: Jun 11 16:16:35 security03 snort[11616]: S5: Pruned session from cache that was using 1060353 bytes (stale/timeout). (redacted).98.242 57787 --> 50.58.123.18 80 (0) : LWstate 0x9 LWFlags 0x41e007 Jun 11 16:17:56 security03 snort[11616]: S5: Pruned session from cache that was using 1307810 bytes (stale/timeout). (redacted).99.239 65232 --> 152.180.0.17 80 (0) : LWstate 0x9 LWFlags 0x45e007 However, I’ve only had about 10 of these type messages during a 1.5 hour interval though the rate goes up during peak work hours (24 in 1.5 hr). I set memcap (at max value) in stream5_global to 1073741824, max_tcp 393216 and stream_tcp5 timeout to 600. To test the alerting, we downloaded an executable file via web. Snort on the appliance alerted but Snort on the server did not. There were no errors in Syslog at the time of the download. Our server has 4 GB main memory and 4 dual processors. Help please. Frank
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Current thread:
- Snort only partially alerting. Frank Calone (Jun 12)
- Re: Snort only partially alerting. Joel Esler (Jun 12)
- Re: Snort only partially alerting. Frank Calone (Jun 14)
- Re: Snort only partially alerting. beenph (Jun 14)
- Re: Snort only partially alerting. Frank Calone (Jun 14)
- Re: Snort only partially alerting. Joel Esler (Jun 12)