Linux / Unix
http://www.cyberciti.biz/tips/linux-unix-bsd-openssh-server-best-practices.html
http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html
http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html
http://www.cyberciti.biz/tips/howto-log-user-activity-using-process-accounting.html
http://www.gnu.org/software/acct/manual/html_mono/accounting.html
http://linoxide.com/linux-how-to/linux-interview-questions-answers/