SSH expandable to Secure Shell is a secure protocol for the network system administrators to log into a remote server or computer. It is program that carries out commands and moves files from one computer to another on the internet. SSH uses port 22 to connect the two machines on the internet. It is a very useful technique for a network administrator to access their business server remotely from any other location. It is an effective way to create connections on the net maintaining privacy without any hacker intrusion. It ensures highest possible authentication and secured communication like passwords, public keys and other similar sensitive data over insecure network channels like the internet. It is an improvement upon the Telnet to transfer information in a more secure form. Because of its high capabilities of encrypting everything it receives and sends it is widely used to secure all insecure connections.
Features of SSH:
- The entire communication that takes place is encrypted and prevents snooping by unwanted intruders. - It has the mechanism to check there is no tampering in the information being shared between the two machines - It allows the users to reconfirm that it is the same server connection that they had been connecting to in the previous occasions. - It allows the users to login and administer their accounts and perform functions like file transfer and running applications on the remote computer. - SSH is compatible to all the operating systems like UNIX, Windows and Mac.
How does it work:
To establish a SSH connection the first need is to make a secure connection between the server and the client. The client authenticates the server connection and this creates a secured symmetric channel between the client and the server. The client gets a prompt on the screen when they login for the first time to reconfirm the connection.
Public key authentication: it is a strong and most secure method where the client has a public key and a private key. The private key is stored on the machine the client’s logins from while the public key is on the server they are connecting with. The SSH uses the public key to encrypt and lock the communication and it can only be unlocked by the private key.
Password Authentication: It is the easiest way of authentication. The user/ client specifies a user name and a password. That is encrypted through the symmetric key that is only known to the two of them.