[Snort-sigs] Snort not inspecting all traffic sourcing from itself?

Joel Esler jesler at ...435...
Wed Jun 9 16:59:05 EDT 2010


Try adding -k none to your Snort command line.

--
Joel Esler
Sent from my iPhone

On Jun 9, 2010, at 4:45 PM, L0rd Ch0de1m0rt <l0rdch0de1m0rt at ...2420...>  
wrote:

> Hello.  I'm curious.  I am running Snort 2.8.5.1 on an Ubuntu 8.04
> web server and I have the following two very simple rules enabled (and
> nothing else):
>
> alert tcp any any -> any any (msg:"TCP SYN packet seen!"; flags:S;
> classtype:bad-unknown; sid:54002346; rev:1;)
>
> alert tcp any any -> any any (msg:"HTTP GET detected"; content:"GET";
> nocase; classtype:bad-unknown; sid:68000036; rev:1;)
>
> Now before people start complaining, this is for testing only, not
> real rules so no need to criticise them.  Anyway if I make a HTTP GET
> request from a different machine to the Snort machine (which is
> running a web server, remember), both rules fire.  If the Snort
> machine serves up a web page that has the word "GET" in it, the rules
> fire again (different HTTP session).  However, if I log on to the
> Snort machine, fire up a web browser, and start surfing, only the SYN
> rule fires despite the fact that "GET" is clearly in traffic when I do
> a tcpdump on it.  So for some reason, Snort is not inspecting all
> traffic (although some since the SYN rule fired) sourcing from itself.
> Here are my Streams5 options in snort.conf:
>
> preprocessor stream5_global: max_tcp 8192, track_tcp yes, track_udp
> yes, track_icmp no
> preprocessor stream5_tcp: policy windows, detect_anomalies,  
> require_3whs 180, \
>   overlap_limit 10, small_segments 3 bytes 150, timeout 180, \
>    ports client 21 22 23 25 42 53 79 109 110 111 113 119 135 136 137 139 
>  143 \
>        161 445 513 514 587 593 691 1433 1521 2100 3306 6665 6666 6667
> 6668 6669 \
>        7000 32770 32771 32772 32773 32774 32775 32776 32777 32778 32779 
> , \
>    ports both 80 443 465 563 636 989 992 993 994 995 1220 2301 3128
> 6907 7702 7777 7779 7801 7900 7901 7902 7903 7904 7905 \
>        7906 7908 7909 7910 7911 7912 7913 7914 7915 7916 7917 7918
> 7919 7920 8000 8008 8028 8080 8180 8888 9999
> preprocessor stream5_udp: timeout 180
>
> Cheers,
>
> -L0rd Ch0de1m0rt
>
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