With a network interface card or running PPP, you can connect your machine to a local area network, or the Internet and have access to many additional services and network utilities. Linux provides two methods of making available network services from a host. Heavily used services will usually be run stand-alone . This means the service process does all the management and listening on a socket or port. These must come first.
Most services however run through inetd .
It listens on many ports, and when a connection to a port is requested, it starts up the process associated with that port. If you need them, uncomment them. Note that we use tcpd to control access to the ftp daemon. The tcpd program is a wrapper program that can be set up to monitor incoming requests for telnet, finger, ftp and other Internet services. When all is well, tcpd runs the appropriate server program and goes away.