inetd.conf File Format for TCP/IP

Purpose

Defines how the inetd daemon handles internet service requests.

Description

The /etc/inetd.conf file is the default configuration file for the inetd daemon. This file helps you specify the daemons to start by default and supply the arguments that correspond to the required style of functioning for each daemon. This file is part of TCP/IP in Network Support Facilities.

If you change the /etc/inetd.conf file, run the refresh -s inetd or kill -1 InetdPID command to inform the inetd daemon of the changes to its configuration file. The inetd.conf file specifies which daemons start by default and supplies arguments determining the style of functioning for each daemon.

The inetd daemon controls the following daemons:

The ftpd, rlogind, rexecd, rshd, talkd, telnetd, and uucpd daemons are started by default. The tftpd, fingerd, and comsat daemons are not started by default unless they are uncommented in the /etc/inetd.conf file.

Service Requests

The following internet service requests are supported internally by the inetd daemon and are used for debugging:

Item	Description
`ECHO`	Returns data packets to a client host.
`DISCARD`	Discards received data packets.
`CHARGEN`	Discards received data packets and sends predefined or random data.
`DAYTIME`	Sends the current date and time in user-readable form.
`TIME`	Sends the current date and time in machine-readable form.

The inetd daemon reads its configuration file only when the inetd daemon starts, when the inetd daemon receives a SIGHUP signal, or when the SRC refresh -s inetd command is entered. Each line in the inetd configuration file defines how to handle one internet service request only.

Each line is of the form:

ServiceName SocketType ProtocolName Wait/NoWait UserName ServerPath ServerArgs.

The fields must be separated either with spaces or tabs and convey the following meanings:

Item	Description
`ServiceName`	Contains the name of an internet service that is defined in the etc/services file. For services provided internally by the inetd daemon, this name must be the official name of the service. That is, the name must be identical to the first entry on the line that describes the service in the /etc/services file.
`SocketType`	Contains the name for the type of socket that is used for the service. Possible values for the `SocketType` parameter are: `stream` Specifies that a stream socket is used for the service. `dgram` Specifies that a datagram socket is used for the service. `sunrpc_tcp` Specifies that a Sun remote procedure call (RPC) socket is used for the service, over a stream connection. `sunrpc_udp` Specifies that a Sun RPC socket is used for the service, over a datagram connection.
`ProtocolName`	Contains the name of an internet protocol that is defined in the /etc/protocols file. For example, use the `tcp` value for a service that uses TCP/IP and the `udp` value for a service that uses the User Datagram Protocol (UDP).
`Wait/NoWait/SRC`	Contains either the `wait`, the `nowait`, or the `SRC` instruction for datagram sockets and the nowait instruction for stream sockets. The `Wait/NoWait/SRC` field determines whether the inetd daemon waits for a datagram server to release the socket before continuing to listen at the socket. The `SRC` instruction works like wait, but instead of forking and waiting for the child to die, it does a `startsrc` on the subsystem and stores information about the starting of the service. When the service is removed from the `inetd.conf` file and inetd is restarted, the service then has a `stopsrc` issued to the service to stop it. If `DEBUG`[`=level`] is specified after `wait` or `nowait`, the SO_DEBUG socket debugging flag will be turned on for this service. If `level` is specified, the trace level is set to the specified level; otherwise the level is set to `normal`. Valid values for `level` are `min`, `normal`, or `detail`.
`UserName`	Specifies the user name that the inetd daemon uses to start the server. This variable allows a server to be given less permission than the root user.
`ServerPath`	Specifies the full path name of the server that the inetd daemon uses to execute to provide the service. For services that the inetd daemon provides internally, this field must be internal.
`ServerArgs`	Specifies the command line arguments that the inetd daemon uses to execute the server. The maximum number of arguments is five. The first argument specifies the name of the server used. If the `SocketType` parameter is `sunrpc_tcp` or `sunrpc_udp`, the second argument specifies the program name, and the third argument specifies the version of the program. For services that the inetd daemon provides internally, this field must be empty.

Examples

The following are example entries in the /etc/inetd.conf file for an inetd daemon:

Uses the ftpd daemon for servicing ftp requests
Uses the talkd daemon for ntalk requests
Uses the telnetd daemon for telnet requests, sets the SO_DEBUG flag for sockets that are used for this service, and sets the trace level for these sockets to normal.

Provides time requests internally.

ftp;stream tcp nowait root /usr/sbin/ftpd ftpd
ntalk dgram udp wait root /usr/sbin/talkd talkd
telnet stream tcp6 nowait|DEBUG root /usr/sbin/telnetd telnetd -a
time stream tcp nowait root internal
time dgram udp wait  root internal

Files

Item	Description
etc/services	Defines the sockets and protocols that are used for internet services.
/etc/protocols	Defines the internet protocols that are used on the local host.