"Host-level security is but one building block when
constructing an in-depth security strategy. As such, it presents
another level of defense against that would-be attacker who has
gotten past your perimeter defenses. When properly implemented,
host-level security also can prevent rogue internal users, ranging
in intent from curious to malicious, from penetrating the server
and gaining unauthorized access.
Besides reducing licensing costs and increasing reliability,
Linux in the server room can offer, under many circumstances, the
most bang for your buck on the performance front. But it can't
promise you security right off the bat: Typically, Linux is no more
or less secure than any other operating system straight out of the
The basics of security boil down to three areas: configuration
issues, patch and version levels, and the number of network
services, and which ones, are running."