[vishnu]

You can use telnet to connect to any computer on the network that has a telnet server that is listening for connections. The difference between telnet and ssh is that the telnet communication is not encrypted. That's why you should only use telnet on trusted networks. ssh packets are encrypted, probably (depending on your version) at 256 bit, which, while not uncrackable, is close enough to deter all but the most determined crackers.