Snort mailing list archives
Re: Slow Start Times (5 minutes +)
From: JJC <cummingsj () gmail com>
Date: Thu, 10 Nov 2011 06:57:01 -0700
There are certainly optimizations... I would, however, be curious about how much memory that your system has and how much is being used... Could be a simple sizing issue... and 17K rules is a ton of rules! On Wed, Nov 9, 2011 at 3:02 PM, Eoin Miller < eoin.miller () trojanedbinaries com> wrote:
Scripted the creation of a lot of signatures to look for some specific domain/host names inside of http_header and noticed that snort now seems to take quite a while to start up when these signatures are loaded (5 minutes). Example rules: alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"ALERT"; content:"domain1.com|0D 0A|"; http_header; sid:1; rev:1;) alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"ALERT"; content:"domain2.com|0D 0A|"; http_header; sid:2; rev:1;) alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"ALERT"; content:"domain3.com|0D 0A|"; http_header; sid:3; rev:1;) ... and so on and so forth ... While snort is starting up, the processor is pegged at 100% for this time period until it drops privs to deamonize and processes the pcap file in no time at all after it gets rolling. I did some simple analysis just using the 'time' command and processing a VERY small pcap (like ~10 packets) file with various numbers of rules to see how long it took. Below is the number of example style rules and the time it took for snort to start up and process the ~10 packet file: 01000 rules: real 0m2.089s user 0m1.000s sys 0m0.097s 02000 rules: real 0m3.324s user 0m2.200s sys 0m0.132s 03000 rules: real 0m4.909s user 0m3.766s sys 0m0.150s 04000 rules: real 0m6.878s user 0m5.705s sys 0m0.179s 05000 rules: real 0m9.288s user 0m8.063s sys 0m0.231s 06000 rules: real 0m12.267s user 0m11.035s sys 0m0.236s 07000 rules: real 0m16.034s user 0m14.767s sys 0m0.266s 08000 rules: real 0m20.464s user 0m19.148s sys 0m0.318s 09000 rules: real 0m27.713s user 0m26.380s sys 0m0.332s 10000 rules: real 0m37.173s user 0m35.811s sys 0m0.363s 11000 rules: real 0m52.529s user 0m51.074s sys 0m0.457s 12000 rules: real 1m17.307s user 1m15.771s sys 0m0.526s 13000 rules: real 1m45.878s user 1m44.328s sys 0m0.530s 14000 rules: real 2m34.341s user 2m32.678s sys 0m0.648s 15000 rules: real 3m23.892s user 3m22.185s sys 0m0.685s 16000 rules: real 4m11.174s user 4m9.279s sys 0m0.850s 17000 rules: real 4m54.605s user 4m52.632s sys 0m0.915s This doesn't seem entirely normal for this few rules, I am guessing there is some review/optimization for the pattern matching that is going on when the sigs all end/share similar patterns that causes this? Total shot in the dark with that guess for the reason for the extended start up times. -- Eoin ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ 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 Please visit http://blog.snort.org to stay current on all the latest Snort news!
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Current thread:
- Slow Start Times (5 minutes +) Eoin Miller (Nov 09)
- Re: Slow Start Times (5 minutes +) JJC (Nov 10)
- Re: Slow Start Times (5 minutes +) Eoin Miller (Nov 10)
- Re: Slow Start Times (5 minutes +) JJC (Nov 10)