Computer networking info.

http://www.tecmint.com/ifconfig-command-examples/

http://www.tecmint.com/20-netstat-commands-for-linux-network-management/

Telnet
Start telnet

• sudo service xinetd restart       'OR'
• sudo /etc/init.d/xinetd restart

xinetd

In computer networking, xinetd (extended Internet 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 extension to or version of inetd, the Internet daemon, thus most modern Linux distributions have switched to it.^[1]

Description[edit]

xinetd listens for incoming requests over a network and launches the appropriate service for that request.^[2] 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 FTP 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.

A super-server or sometimes called a service dispatcher is a type of daemon run generally on Unix-like systems.

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Daemon (computing)

In multitasking computer operating systems, a daemon (/ˈdeɪmən/ or /ˈdiːmən/)^[1] is a computer program that runs as a background process, rather than being under the direct control of an interactive user. Traditionally daemon names end with the letter d: for example, syslogd is the daemon that implements the system logging facility and sshd is a daemon that services incoming SSH connections.

In a Unix environment, the parent process of a daemon is often, but not always, the init process. A daemon is usually created by a process forking a child process and then immediately exiting, thus causing init to adopt the child process. In addition, a daemon, or the operating system, typically must perform other operations, such as dissociating the process from any controlling terminal (tty). Such procedures are often implemented in various convenience routines such as daemon(3) in Unix.

Systems often start daemons at boot time and serve the function of responding to network requests, hardware activity, or other programs by performing some task. Daemons can also configure hardware (like udevdon some GNU/Linux systems), run scheduled tasks (like cron), and perform a variety of other tasks.