Telnet

telnet (TErminal NETwork or TELecommunication NETwork, or TELetype NETwork) is a Protocole network used on any network supporting the protocol TCP/IP. It belongs to the session layer of OSI model and to the application layer of the ARPA model. It is standardized by IETF (RFC 854 and RFC 855). According to, IETF, the goal of protocol telnet is to very provide to means of communication general practitioner, bidirectional and directed Octet.

telnet is also an order making it possible to create a session telnet on a distant machine. This order was available initially on the systems Unix then it appeared on the majority of the operating systems.

Details of the protocol

Telnet is a protocol of the type Client-serveur based on TCP. The customers generally connect themselves on the port 23 of the waiter.

Use

One of the major uses of the order telnet was to connect itself to waiters telnet, which required an identifier, then a password, and gave a line of order on the distant machine in exchange. For that it required the launching of a demon on the machine host, often called telnetd.

The order telnet remains a very practical order to test waiters. Considering the flexibility of the program, it is possible to use the order telnet to establish an interactive connection TCP with other services such as smtp or HTTP.

Defect of safety

The basic side of telnet makes that any communication is transmitted in light on the network, passwords included/understood. Sniffer S like Tcpdump or Wireshark make it possible to intercept the communications of the order telnet. Quantified protocols as HS was developed to provide a distant access replacing telnet and whose interception does not provide any data usable to a possible spy.

See too

PuTTY : a customer telnet, HS and Rlogin
HS

External bonds

telnetd : a demon telnet written in Java

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