matwizzle

Last version dates from 2012-11-19, not the fastest of releases - but seems ok. Trend Micro is involved (and offers commercial support).

It doesn't feel heavyweight to me. It does start a bunch of daemons for all of its processing and it has the client->server bit built right in. That may make it feel heavyweight, I guess. But, you don't have to use the client->server stuff if you don't want to. It'll still do all of its magic for you.

Ossec will do a lot out of the box. So, I suggest installing it with the default ruleset and the active-response stuff turned off (the installer will ask you). Then dive into the rules and ossec.conf (knowledge of regex is required).

Documentation @ http://www.ossec.net/doc/index.html

I'd propose using OSSEC over logwatch & fail2ban. Ossec seems to be a bit of an obscure tool, but a thoroughly functional one at that. Logwatch gives a bit too much info at once to interpret properly, while OSSEC will only alert you when something is actually up.

Ossec provides (among some other things):

* Log file monitoring, with severity levels, occurence counting, time-based rules and auto-response. This means (for instance) you get to watch your auth.log for failed login attempts and after 10 failures fire a script to ban him, alert sysop by email or have hubot alert your sysops. Or whatever floats your boat.

* File integrity monitoring. Make sure noone's been mucking around with your files. It has real-time support (through inotify), but if you don't want use that, make sure you store the database it keeps off-server for forensics if need be. Pro-tip: FIM and auto-updates are a tad unnerving.

* It can watch command output. You can use that to make sure the `netstat -tnap` output doesn't change, for instance.

* For larger/more compliant instances, it has a client<->server setup available.