Secure Shell, commonly known as SSH and Telnet are the network protocols that serves the same purpose that is to provide remote access to the system in order to establish some sort of communication between the systems. They are both used to connect to remote servers in order to facilitate some sort of communications. When you ssh to trasnfer data between a system, the data will be send in the encrypted form, where the hacker cannot encode or decode it. While you telnet, the data send between the system is alphabetical format(ASCII), where every one can understand.
Difference between Telnet and SSH
SSH:SSH stands for Secure Shell and it is now only major protocol to access the network devices and servers over the internet. SSH encrypts the data being transferred between the systems so it cannot be Decoded by the Hackers. SSH also uses a public key for the authentication of users accessing a server and it is a great practice providing security. SSH is mostly used in all popular operating systems like Unix, Solaris, Red-Hat Linux, CentOS, Ubuntu etc. SSH uses public and private keys, to identify hosts and users. By default SSH runs on port 22, however it can be easily changed.
On a Linux system, SSH can be easily installed using yum:
# yum -y install openssh-server openssh-clients
Telnet: The data transferred between the systems is in Plain text (ASCII form) and not in encrypted format which is the major security concern. So the data can be easily read by anybody in the network and can hack the system. Telnet is mostly used in Private network as it’s highly insecure to use in Public network. Telnet does not use Authentication which is again a security issue. Telnet is the joint abbreviation of Telecommunications and Networks and it is a networking protocol best known for UNIX platform. Telnet runs on port 23.
On a Linux system, telnet can be easily installed using yum:
# yum install telnet