Our company plan to install IDS to protect our resources, I'm already
read about snort as NIDS, but, that's software based. I'm interesting
with hardware based that will work transparently with our Cisco PIX, no
need to make changes in our firewall. What's your suggestion.
My first piece of advice on this is to ignore any company that says they
deliver a "turnkey" solution. Such a thing doesn't exist.
Any IDS will work with any firewall .. unless, of course, you want to
connect the two together (eg: dynamically ACL the PIX based on what the
IDS sees). That, IMHO, is an invitation do DOS yourself (think .. I
spoof a packet that --looks like an attack-- from your upstream router,
or smtp server, etc). There's dozens of ways to do this, including free
with snort.
You can also examine snort's "inline" mode in which you setup bridging
between two interfaces, and let snort "decide" which packets to forward.
In order to make such a thing redundant, be prepared to do some fancy
H/A stuff with a pair of servers.
And don't forget .. an IDS is certianly not "fix and forget" .. it
requires daily tinkering (new sigs come out daily .. and they're almost
always noisy and require tuning). In most any decent sized network,
having a dedicated admin to chase the IDS alerts and keep an eye on
things is almost a given.
And as for having an IDS "protect" your network .. well .. forget that.
An IDS is great for statistical research and forensics .. but with
botnets and whatnot going SSL, you're time/resources are much better
spent finding your vulnerabilities and patching your hosts.
My $0.02.
Cheers,
Michael Holstein CISSP GCIA
Cleveland State University
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