Xinetd
In computer networking, xinetd (Extended Internet Service Daemon) is an open-source super-server daemon which runs on many Unix-like systems, and manages Internet-based connectivity. It offers a more secure alternative to the older inetd ("the Internet daemon"), which most modern Linux distributions have deprecated. xinetd listens for incoming requests over a network and launches the appropriate service for that request. Requests are made using port numbers as identifiers and xinetd usually launches another daemon to handle the request. It can be used to start services with both privileged and non-privileged port numbers. xinetd features access control mechanisms such as TCP Wrapper ACLs, extensive logging capabilities, and the ability to make services available based on time. It can place limits on the number of servers that the system can start, and has deployable defense mechanisms to protect against port scanners, among other things. On some implementations of Mac OS X, this daemon starts and maintains various Internet-related services, including and telnet. As an extended form of inetd, it offers enhanced security. It replaced inetd in Mac OS X v10.3, and subsequently launchd replaced it in Mac OS X v10.4. However, Apple has retained inetd for compatibility purposes. Configuration of xinetd resides in the default configuration file /etc/xinetd.conf, and configuration of the services it supports resides in configuration files stored in the /etc/xinetd.d directory. The configuration for each service usually includes a switch to control whether xinetd should enable or disable the service. An example configuration file for the RFC 868 time server:
default: off
description: An RFC 868 time server. This protocol provides a
site-independent, machine readable date and time. The Time service sends back
to the originating source the time in seconds since midnight on January first
1900.
This is the tcp version.
service time { disable = yes type = INTERNAL id = time-stream socket_type = stream protocol = tcp user = root wait = no }