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Re: Using snort to detect if your users are doing interesting things?

  • From: Nils Ketelsen
  • Date: Fri Jun 10 03:06:08 2005

Drew Weaver wrote:

>             Howdy, I am not sure if this is the proper place, if not
> I've noticed you guys know what to do so I'll put the fire retardant
> suit on now. Recently due to growth we have seen an influx of
> "different" and "interesting" types of characters ending up on our
> network. They like to do all sorts of things, port scan /8s spam, setup
> botnets with the controllers hosted on my network.. etc. I'm wondering

There are two basic methods, I guess:

1. You search for specific patterns. For example for somebody pinging
more than n addresses in a specific time frame. If you know what you are
looking for, you can set something up to do it easily.

2. You look for something strange. You will need some kind of
statistical method then. They have a tendency to produce false positives
from time to time, so you better look at the results closely.



> I did have one somewhat silly question.. if you look at the statistics
> of a Fast Ethernet port, and it is doing both 2000 pps out, and 2000 pps
> in (pretty much equal in/out) but hardly any bandwidth at all can anyone
> think of a single application that would mimic that behavior?

DNS-Servers?

Nils
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