HP-UX Internet Services Administrator's Guide (February 2007)

system? However, the terms local and remote are limited in their description of complex
communications, such as when a local system logs on to a remote system and then the
remote system logs back on to the local system. At that point, which is the local system
and which is the remote system?
A better solution is to use the terms client and server. The term client refers to a process
that is requesting a service from another process. The term server refers to a process
or host that performs operations requested by local or remote hosts that are running
client processes.
HP has implemented a super-server known as the Internet daemon, inetd. This
program acts like a switchboard; that is, it listens for any request and activates the
appropriate server based on the request.
A typical network service consists of two co-operating programs. The client program
runs on the requesting system. The server program runs on the system with which you
want your system to communicate. The client program initiates requests to
communicate. The server program accepts requests for communication. For example,
the network service rlogin is the client program that requests a login to a remote
HP-UX or other UNIX system. When the request to log in is received on the remote
host by inetd, inetd invokes the server program for rlogin (called rlogind) to
handle the service request.
Flowchart Format
The flowcharts in this section each have a corresponding set of labeled explanations.
You can follow the flowcharts alone or follow the flowcharts and read the explanations
for more detail. The explanations are on the pages that follow each flowchart.
Troubleshooting Tips 81