RE: SIM solution - Objectives ?
"Marcus J. Ranum" <[email protected]>
| Newsgroups | gmane.comp.sysutils.loganalysis |
|---|---|
| Message-ID | <[email protected]> |
Here's another point to ponder, which I like to hop up and down about when I'm doing my "intrusion prevention" workshop at Interop... When you're setting up your firewall you should design in intrusion detection by using overlapping permit/deny+LOG rules in the firewall. It's cheap, fast, *AND* good! For example, if you have a DMZ and traffic from the DMZ toward the internal network is getting matched by a default internet incoming rule - consider installing a superceeding rule that applies to your DMZ with logging turned on. That way you get notified when your web server starts strobing SSH ports on internal hosts. :) Or, perhaps an superceeduing outbound deny +LOG rule from your DMZ to the internet for everything except the minimum set of services your DMZ needs. My preceeding comments should emphatically not be taken to mean that I think you shouldn't log denies! If it's worth denying, it's worth logging - and that's a fact. But in today's environment, with all the HTTP tunnelling crapware and malware, it's really really really important to be looking at stuff like "top permitted destinations" and things like that! In fact I strongly recommend grabbing blacklists from places like squidguard.org and joining your destinations of permitted HTTP against the "spyware sites" blacklist to produce lists of internal machines that are making calls out to such sites. Useful? mjr.