Essential Concepts - Network Protocols (Telnet and SSH)

We have seen the protocols which helps us identify a device uniquely, transfer files between server and client, and help us in E-mail services. But we also use remote connections over internet i.e. control a server from any other device. So here we are going to study the protocol which help us with remote connections.

Telnet :

Telnet is a network protocol that allows you to connect to remote hosts on the internet or on a local network. Telnet is a user command and an underlying TCP/IP protocol for accessing remote computers. Through Telnet, an administrator or another user can access someone else's computer remotely.

On the Web, HTTP and FTP protocols allow you to request specific files from remote computers, but it doesn't allow you to log-in as a user of that computer and control that computer. With Telnet, you log on as a regular user with whatever privileges you may have been granted to the specific application and data on that computer.

A Telnet command request looks like this : 

telnet <hostname or IP> port

Ex : telnet 172.217.6.129   OR   telnet blogspot.in

The result of this request would be an invitation to log on with a userid and a prompt for a password. If accepted, you would be logged on like any user who used this computer every day.

Secure Shell (SSH) :

SSH is a protocol similar to telnet which also facilitates connection to remote hosts for communication. However, SSH has an upper hand over telnet in terms of security.

Telnet was primarily designed to operate within the local network. Local network means computer connected via LAN. One has to access a computer on LAN to steal data or to obtain remote connection. Hence, there was no case of security in Telnet as the attacker needed physical access to computer. But when we use Telnet to get remote connections over Internet, the case of security must be considered. SSH manages to offer total security while connecting to remote hosts on a remote network or Internet.

Hence, SSH, also known as Secure Socket Shell, is a network protocol that provides administrators with a secure way to access a remote computer. Secure Shell provides strong authentication and secure encrypted data communications between two computers connecting over an insecure network such as the Internet.