/etc/inetd.conf
file lists these servers and their usual ports. The inetd
command listens to all of them; when it detects a connection to any such port, it executes the corresponding server program.
/etc/inetd.conf
file describes a server through seven fields (separated by spaces):
/etc/services
file).
stream
for a TCP connection, dgram
for UDP datagrams.
tcp
or udp
.
wait
or nowait
, to tell inetd
whether it should wait or not for the end of the launched process before accepting another connection. For TCP connections, easily multiplexable, you can usually use nowait
. For programs responding over UDP, you should use nowait
only if the server is capable of managing several connections in parallel. You can suffix this field with a period, followed by the maximum number of connections authorized per minute (the default limit is 256).
argv[0]
in C).
Primjer 9.1. Excerpt from /etc/inetd.conf
talk dgram udp wait nobody.tty /usr/sbin/in.talkd in.talkd finger stream tcp nowait nobody /usr/sbin/tcpd in.fingerd ident stream tcp nowait nobody /usr/sbin/identd identd -i
tcpd
program is frequently used in the /etc/inetd.conf
file. It allows limiting incoming connections by applying access control rules, documented in the hosts_access(5) manual page, and which are configured in the /etc/hosts.allow
and /etc/hosts.deny
files. Once it has been determined that the connection is authorized, tcpd
executes the real server (like in.fingerd
in our example). It is worth noting that tcpd
relies on the name under which it was invoked (that is the first argument, argv[0]
) to identify the real program to run. So you should not start the arguments list with tcpd
but with the program that must be wrapped.