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9.6. El superservidor inetd

Inetd (frecuentemente llamado «superservidor de internet») es un servidor de servidores. Ejecuta a pedido servidores rara vez utilizados para que no tengan que ejecutar continuamente.
El archivo /etc/inetd.conf enumera estos servidores y sus puertos usuales. El programa inetd escucha en todos estos puertos y cuando detecta una conexión a uno de ellos ejecuta el programa servidor correspondiente.
Cada línea significativa del archivo /etc/inetd.conf describe un servidor con siete campos (separados con espacios):
The following example illustrates some use-cases after installing talkd, nullidentd (ident-server), and fingerd:

Ejemplo 9.1. Extracto de /etc/inetd.conf

#:BSD: Shell, login, exec and talk are BSD protocols.
talk   dgram   udp     wait    nobody.tty   /usr/sbin/in.talkd      in.talkd
ntalk  dgram   udp     wait    nobody.tty   /usr/sbin/in.ntalkd     in.ntalkd

#:INFO: Info services
ident  stream  tcp     nowait  nobody       /usr/sbin/nullidentd    nullidentd
finger stream  tcp     nowait  nobody       /usr/sbin/tcpd          /usr/sbin/in.fingerd
The 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.