Linux Poison shows you how to secure services using TCP_WRAPPERS

Using TCP_WRAPPERS makes securing your servers against outside intrusion is a lot simpler and painless. TCP_WRAPPERS is controlled from two files:

/etc/hosts.allow/etc/hosts.deny
hosts.allow is checked first, and the rules are checked from first to last. If it finds a rule that explicitly allows you in (i.e., a rule allowing your host, domain, subnet mask, etc.) it lets you connect to the service. If it fails to find any rules that pertain to you in hosts.allow, it then goes to check hosts.deny for a rule denying you entry.

  Securing Service using TCP_WRAPPERS