Telnet Overviews

Telnet (terminal network or telecommunication network, or Teletype NETwork) is a network protocol used on any network supporting TCP / IP. It belongs to the session layer of the OSI model and the application layer model ARPA. It is standardized by the IETF (RFC 854 and RFC 855). According to the IETF, the purpose of Telnet Protocol is to provide a means of communication very general, bi-directional byte-oriented. 
telnet is a command to create a Telnet session on a remote machine. This command was first available on Unix systems, and then she has appeared on most operating systems. Note that Telnet is not installed by default on Windows Vista and Windows Seven.

Details of the protocol

Telnet is a protocol for client-server based on TCP. Clients usually connect on port 23 of the server.

Default Security.

The next summary of Telnet is that all communication is transmitted unencrypted over the network, including passwords. Of sniffers like tcpdump or Wireshark can intercept the communications of the telnet command. Encrypted protocols like SSH have been developed to provide remote access to replace Telnet and whose interception does not provide data for use in a possible spy.

Relate Link : TCP / IP