Recommending an IDS system

["Matthew MacAulay" <matthew.macaulay () cobweb co uk>]

Hello,

I have been tasked with looking at and recommending an IDS system for my
company.

I have been looking at open source products (Snort) which seems to be a
very good system with a lot of community support. My problem is we are
an ASP. We want connections to be able to reach our systems for the
services we provide. I want to be able to monitor over 100 internet
facing servers (behind Firewalls and load balancers) and alert / and
possibly block non normal traffic / detected attack signatures. 

After doing some reading into different methods IDS v IPS, Host v
Network, I favour a combination, we have at anyone time up to 50,000
concurrent connections to our systems so I have a problem of scale. One
Snort box is just not going to cut it!

Looking at how I can "tap" into the network traffic has been partially
solved by using IDSVLANS which is supported by our Switch hardware.
(Nortel 8600) So an IDSVLAN could be setup for each of our existing
VLANS and a couple of load balanced IDS boxes per IDSVLAN to alert to a
central server to produce reports / alert / wake people up.... Sounds
great.

Though I have not looked at it in as much detail as network based IDS, I
expect I can get a hosts based IDS to also alert (SNMP or what ever) to
a central server to again produce reports / alerts / wake people up.

I am interested to here what systems you use to do IDS / IPS. Do you
have in place IDS systems for platforms of a larger or similar scale? I
would like to here from people have who have faced similar challenges.

Questions I keep asking myself:

Am I trying to do too much, should I just concentrate on host based IDS?

Is network based IDS the right way to go?
Or am I right in trying to do both?
Should I be using an open source product to do ID?
Are there commercial products which can do what I want?

Your thoughts, recommendations and pointers to further reading are
welcome.

Regards,

Mat.


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