HPlogo Configuring and Managing MPE/iX Internet Services > Chapter 2 Internet Daemon

Overview of inetd

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The Internet daemon, or inetd, is the master server that coordinates the use of individual network services on your system. It listens for connection requests from other nodes on the network who want access to a service such as tftpd or bootpd. The Internet daemon checks if the requesting node has permission to use the service, starts the appropriate server if it does and, optionally, records information about the connection request.

Stream Services

The Internet daemon starts servers for both stream services and datagram services. For stream services, which use the TCP/IP protocol, inetd listens for connection requests on stream sockets. When it detects such a request, inetd determines which service the socket corresponds to and invokes a server for it. The server then handles incoming data, providing a reliable, full-duplex bytestream service to the requesting node. Once inetd has invoked the server, it returns to listening for other connection requests.

Datagram Services

For datagram services, which use the UDP/IP protocol, inetd listens for requests on datagram sockets. You can think of a datagram as a connection request and the message all in one package. Unlike the TCP/IP protocol, UDP/IP does not provide any message acknowledgment, flow control or sequencing. It is the simplest possible service with the advantage of low communications overhead. When inetd detects an incoming datagram, it invokes a server for that message. Once a datagram has been delivered, the socket becomes available for another incoming datagram. That is, there is no "connection," simply the delivery and receipt of the datagram. For this reason, datagram service is sometimes referred to as "connectionless" communication.

Internal Services Provided by inetd

The Internet daemon provides several internal trivial services which are described here.
Service

Description

echo

Returns a character to the socket that sent it

discard

Discards all input from socket

chargen

Generates characters and sends them to a socket

daytime

Returns the current time in a format readable by people.

time

Returns current time in a format useful to machines, for example, the number of seconds since Jan 1, 1970.

inetd Files

There are four files of importance as shown in Table 2-1 The Internet Daemon Files, for configuring and using inetd. Once you have installed or updated to version C.60.00 or later, of MPE/iX, these files are located in the NET group of the SYS account.

Table 2-1 The Internet Daemon Files

File

Description
INETD.NET.SYSThe program file for inetd which is linked to the POSIX file /etc/inetd.
INCNFSMP.NET.SYSThe sample configuration file for inetd. You will copy the sample file to INETDCNF.NET.SYS, create a symbolic link from the POSIX file /etc/inetd.conf to INETDCNF.NET.SYS, and edit it as necessary.
INSECSMP.NET.SYSThe sample security file for inetd. You will copy this file to INETDSEC.NET.SYS, create a symbolic link from the POSIX file /usr/adm/inetd.sec to INETDSEC.NET.SYS, and edit it as necessary.
JINETD.NET.SYSThe job file that you will stream to start inetd and abort to stop inetd. You won't need to copy, link, or edit this file.

The remainder of this chapter explains how to copy, link and edit these files to create a working version of the Internet daemon on your system.



Chapter 2 Internet Daemon

inetd Configuration File