Tcp-wrappers

tcp-wrappers, aka TCP Wrapper, aka tcpwrappers. A standard package to filter/log incoming TCP requests, and either pass them onto their intended daemon, or otherwise deal with the request.

On Debian, see: apt-cache show tcpd

and some docs are in /usr/share/doc/tcpd

tcp-wrappers was originally written by Wietse Venema, the same fellow who created postfix and The Coroner's Toolkit (TCT) among other tools.

= External links =
 * http://www.centos.org/docs/4/html/rhel-rg-en-4/ch-tcpwrappers.html