As far as one true checklists go, I really like NSA Guide to securing RHEL. http://www.nsa.gov/ia/_files/os/redhat/NSA_RHEL_5_GUIDE_v4.2.pdf http://www.nsa.gov

As far as one true checklists go, I really like NSA Guide to securing RHEL. http://www.nsa.gov/ia/_files/os/redhat/NSA_RHEL_5_GUIDE_v4.2.pdf http://www.nsa.gov/ia/_files/os/redhat/NSA_RHEL_5_GUIDE_v4.2... and TLDR version: http://www.nsa.gov/ia/_files/factsheets/rhel5-pamphlet-i731.pdf http://www.nsa.gov/ia/_files/factsheets/rhel5-pamphlet-i731.... It is starting to get a little bit dated (RHEL 5 is quite old), but general rules still apply and usually they explain their reasoning.