Snort mailing list archives

Re: Spade ---What gives


From: <bthaler () webstream net>
Date: Wed, 13 Mar 2002 11:26:16 -0500

Something else I noticed:
Even with my usual database output plugin enabled, Snort still creates the "alert" file.

I grep'd this for "spp_anomsensor", and viola!  There's millions of Spade alerts in there.  So evidently Spade was 
working properly,
and it seems that Snort was just not writing the spp_anomsensor alerts to the database.






Sincerely,

Brad T.




----- Original Message -----
From: "James Hoagland" <hoagland () SiliconDefense com>
To: <bthaler () webstream net>; <snort-users () lists sourceforge net>
Sent: Tuesday, March 12, 2002 4:41 PM
Subject: Re: [Snort-users] Spade ---What gives


Hello Brad,

At 2:34 PM -0500 3/12/02, <bthaler () webstream net> wrote:
I enabled Spade as described in the docs, but can't seem to get any
output from it.

In my snort.conf, I am using:
preprocessor spade: 0.005 $SPADEDIR/spade.rcv $SPADEDIR/log.txt 3 50000
preprocessor spade-homenet: 1.1.1.1/20 2.2.2.2/20 3.3.3.3/20
preprocessor spade-adapt3: 0.01 60 168
preprocessor spade-stats: entropy uncondprob condprob


I've tried different values for the threshhold argument, everything
from the default "-1" to the current "0.005".

This looks alright.

My output plugin is:
output database: log, mysql, user=xxx dbname=xxx password=xxx
host=1.1.1.1 sensor_name=xxx

Is there some problem with Spade and the database output plugin?

I cannot speak to these, hopefully someone else can.  What version of
Snort are you using?

In my /var/log/spade/log.txt, I see lots of entries like:
P(dport=80|dip=1234567890)= 1.000000000000
P(dport=80|dip=1234567890)= 0.625000000000
P(dport=443|dip=1234567890)= 0.375000000000
P(dport=80|dip=1234567890)= 1.000000000000
***not the real IPs, of course***

Since the last field is always greater than my threshhold of 0.005,
these should be considered as anamolous by Spade, right?  With a
threshhold of 0.005, and tons of traffic (about 30Mb/s right now), I
should be getting loads of "spp_anomsensor" alerts, right?

You should be.  (However the reported probabilities in the Spade log
file are not the same thing as anomaly scores, which is what
threshold applies to.)

Based on the fact that you are getting entries in log.txt, I would
infer that Spade is receiving packets and processing them.  With your
configuration as shown above, you should be getting many Spade alerts
for the first hour (since 0.005 is a pretty darn low threshold).
After 1 hour adapt3 will make its first adjustment to the threshold,
it will choose a threshold which it thinks will result in 1% of
packets being reported.

I suggest trying to log to a file to see if Spade alerts appear.
This will verify that Spade is sending alerts for your network.

Hope this helps,

   Jim
--
|*      Jim Hoagland, Associate Researcher, Silicon Defense      *|
|*            --- Silicon Defense: IDS Solutions ---             *|
|*  hoagland () SiliconDefense com, http://www.silicondefense.com/  *|
|*   Voice: (530) 756-7317                 Fax: (530) 756-7297   *|

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