Jep, nije tek tako lako dati jedinstven recept za sigurnost.
Potraži malo po netu, čim ukucaš centos security, dobićeš puno toga.
Npr.
http://www.linux-books.us/centos_0004.php (free knjiga, malo starija doduše)
Postoje neke opšte smernice, iptables i SELinux konfiguracija, dodatni alati...
Tu je i sigurnost pojedinačnih servisa, audit i brdo toga.
Pogledaj i ovo:
http://www.bastille-unix.org/
Citat:
Bastille currently supports the Red Hat (Fedora Core, Enterprise, and Numbered/Classic), SUSE, Debian, Gentoo, and Mandrake distributions, along with HP-UX. It also supports Mac OS X. Bastille's focuses on letting the system's user/administrator choose exactly how to harden the operating system. In its default hardening mode, it interactively asks the user questions, explains the topics of those questions, and builds a policy based on the user's answers. It then applies the policy to the system. In its assessment mode, it builds a report intended to teach the user about available security settings as well as inform the user as to which settings have been tightened.