How Linux Works

The inetd Daemon

Implementing stand-alone servers for every single service is somewhat inefficient, because each server must know all about the network interface API, have its own port configuration system, and so on. In many respects, the API for talking to TCP is not much different than the standard I/O system. TCP servers read from network ports and return output back to those ports—this is similar to the behavior of cat with no arguments in Using the Shell is similar.

The inetd daemon is a superserver that standardizes network port access and interfaces between regular programs and network ports. After you start inetd, it reads the inetd.conf file and then listens on the network ports defined in that file, attaching a newly started process ...