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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.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. |
