Snort mailing list archives

Re: not detecting common intrusion


From: Cearns Angela <acearns () yahoo com>
Date: Wed, 26 Jun 2002 17:54:21 -0700 (PDT)

Thank you Erek:

I'm indeed pouring thru the doc at the snort website.
Erek, I'm a student at the University of Colorado
doing research on DDOS and various mitigation methods.
I'm currently building a testbed to simulate DDoS
attack and trying to find out a better way to respond
to the attack. One area of my research focus is rate
limiting. Can I ask you and the mailing list
participants for some personal advice?

Would it be useful to add a X processor to snort to do
a bandwidth consumption type of detection? Or is there
a much easier way to detect "bandwidth usage beyond a
certain threshold" that it's really not worth it to
add it to snort? 

What about adding a rate limiting capability to snort
thru X processor as an "action" to the detection of
"bandwidth overuse"? Will this be a useful feature or
is it just easier for people to configrue rate
limiting through iptables?

Erek, I don't mean to bombard you with questions but
I've been pounding my head for weeks. Thank you so
much for your help. 

With sincere gratitude,
Ang

--- Erek Adams <erek () theadamsfamily net> wrote:
On Wed, 26 Jun 2002, Cearns Angela wrote:

Thanks Erek

:)  No problem.

Pardon my ignorance, but if snort doesn't detect
"bandwidth consumption" attacks - floods, what do
the
"dos.rules" and "ddos.rules" included in the
snort.conf file detect? (May be I should learn to
read
the rules files better)...

It's not ignorance, it's just something you haven't
"learned" yet. :)

I'd say 90% of the rules in (d)dos.rules are simply
matching for known
patterns of the (d)dos attacks.  IOW, when you fire
off dos type fred, there
is a specific pattern of bits associated with the
fred attack.

Try to keep in mind how snort works.  Frame comes
over the wire, pcap brings
it into snort, snort looks at the frame and makes
some decisions based on it.
Now granted, that's oversimplified, but that's the
gist of it.

The snort.org website has some good technical docs
on how/what's going on
under the hood.  If you're really interested, that's
where you might want to
pursuse reading a bit more.

Cheers!

-----
Erek Adams
Nifty-Type-Guy
TheAdamsFamily.Net





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