 |
» |
|
|
|
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.SYS | The program file for inetd which is linked to the POSIX file /etc/inetd. | | INCNFSMP.NET.SYS | The 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.SYS | The 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.SYS | The 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. |
Printable version
