I'm running CentOS 5.5 (basic LAMP with Parallels Power Panel and Plesk) and have thus far neglected security (because it's not my full-time job, there is always something more important on my todo-list). My server does not contain any secret data and also no lives depend on it - Basically what I want is to make sure it does not become part of a botnet, that is "good enough" security in my case.
Anyway, I don't want to become a full-time paranoid admin (like constantly watching and patching everything because of some obscure problem), I also don't care about most security problems like DOS attacks or problems that only exist when using some arcane settings.
I'm in search of a "happy medium", for example a list of known important problems in the default installation of CentOS 5.5 and/or a list of security problems that have actually been exploited - not the typical endless list of buffer overflows that "maybe" a problem in some special case.
The problem that I have with the usually recommended approaches (joining mailing lists, etc.) is that the really important problems (something where an exploit exists, that is exploitable in a common setup and where the attacker can do something really useful - i.e. not a DOS) are completely and utterly swamped by millions of tiny security alerts that surely are important for high-security servers, but not for me.
Thanks for all suggestions!