[Snort-users] snort at a bakeoff.

Chris Green cmg at ...671...
Tue Jan 8 06:36:09 EST 2002


n3m3s1s at ...1284... writes:

> Hi all,
>         I'm running snort in a bakeoff against some other IDSs, and
> I'm getting some funny results.  To begin with, I'm running in the
> foreground just to make sure it's seeing the correct traffic (snort -i
> eth2 -L test.log).  I've included only the web rules, and I have about
> 500 sigs loaded, so it's definitely using the snort.conf that I've
> created.  System and traffic specifics are given below.
>
> 1st Problem: While snort is running, I'd been opening another window
> and doing "snort -r test.log" just to keep an eye on what's going on.
> When I do this, one of two things happen:
>
> 1.  Snort segfaults.  2.  I get real funky results, like only ICMP
> Port Unreachable alerts (if any) and a total packet count of 0 -5.
>

for segfaults, we need a backtrace as explained in BUGS.  Not sure why
you are getting odd errors

Try using a snort commandline like

sbin/snort -A fast -b -l ./log -d -i eth1 and see what happens.

try snort -dev -i eth2 to see full dumps of the traffic on your eth2
interface to make sure it can see everything

The -d is very important to dump the application layer of packets to
match against. For very historical reasons, it isn't the default.

> It doesn't appear that I should be trying to run 2 instances of
>snort concurrently?

You don't say what OS you are on ( I don't know what Dragon uses for
their appliances ). Most OSes can do this but some can't.>
>
> 2nd Problem: If I don't try to run snort a second time and just wait
> for the test to finish, then Ctrl-C, I get a real high drop rate
> (around 50-60%), but the packet counts seem reasonable.  Alerts,
> Logged, and Passed all say 0.

Are there any events that should be logged?

>
> If I run tcpdump on the same interface, I see tons of web traffic, and
> the other IDSs in the bakeoff see it too.  I don't have my snort.conf
> file to show, but for the most part it's pretty vanilla.  I changed my
> home net, and commented out some of the rules (everything except web),
> but other than that it's stock.
>
> I'm a bit at a loss, and any help would be GREATLY appreciated.

We now have your snort.conf, try using one of our command lines and
tell us what OS you are on.
-- 
Chris Green <cmg at ...671...>
"Yeah, but you're taking the universe out of context."




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