Snort mailing list archives
Re: pcre high cpu usage
From: Tomas Heredia <tomas.heredia () activesec biz>
Date: Mon, 18 Oct 2010 19:57:40 -0300
El 18/10/2010 07:27 p.m., Joel Esler escribió:
On Oct 18, 2010, at 5:51 PM, Tomas Heredia wrote:Hi all! Lately, new rules applied to our sensor started to consume too much CPU (not too much, but causing host load to go to 0.4 permanent). I folowed the problem and found it was PCRE causing it. The problem is that this is causing some TREMENDOUS delays in packets... from 50 to 1000 ms, in some packets (doing a ping, 1 every 30 or so packets gets delayed). So, How do yo think "config pcre_match_limit 100" and "config pcre_match_limit_recursion 100" would affect detection? (as false negatives). Do you have any other sugestion (aside from not using pcre rules :-)) to get beter PCRE performance?Are you running in inline mode, or IDS mode? Are you dropping packets?
Excuse me :-) Inline mode. Snort 2.8.6.0 (Ok, planning upgrade anyway). No packets get droped. Just huge delays in some packets. Delay goes off if I put config pcre_match_limit 25 onfigpcre_match_limit_recursion 25 But I don't think it's a good idea. Is it? Thanks! ------------------------------------------------------------------------------ Download new Adobe(R) Flash(R) Builder(TM) 4 The new Adobe(R) Flex(R) 4 and Flash(R) Builder(TM) 4 (formerly Flex(R) Builder(TM)) enable the development of rich applications that run across multiple browsers and platforms. Download your free trials today! http://p.sf.net/sfu/adobe-dev2dev _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- pcre high cpu usage Tomas Heredia (Oct 18)
- Re: pcre high cpu usage Joel Esler (Oct 18)
- Re: pcre high cpu usage Tomas Heredia (Oct 18)
- Re: pcre high cpu usage Alex Kirk (Oct 18)
- Re: pcre high cpu usage Tomas Heredia (Oct 19)
- Re: pcre high cpu usage Alex Kirk (Oct 19)
- Re: pcre high cpu usage Tomas Heredia (Oct 19)
- Re: pcre high cpu usage Alex Kirk (Oct 19)
- Re: pcre high cpu usage Tomas Heredia (Oct 19)
- Re: pcre high cpu usage Tomas Heredia (Oct 18)
- Re: pcre high cpu usage Joel Esler (Oct 18)