Fewer than one in twenty security professionals has the core competence and the foundation knowledge to take a system all the way from a completely unknown state of security through mapping, vulnerability testing, password cracking, modem testing, vulnerability patching, firewall tuning, instrumentation, virus detection at multiple entry points, and even through back-ups and configuration management.
Stephen Northcutt, Network Intrusion Detection: An Analysts' Handbook
infosec, sans, security