SSH Protocol

Saksham
Me

What is SSH protocol?

SSH

It is also referred to as Secure Shell, is a method for secure remote login from one computer to another. It is an alternative to telnet and rlogin

SSH

 It protects the communications security and integrity with strong encryption.

Me

How does it work?

SSH

– It works in client server model.

– The SSH client drives the connection setup and uses public key cryptography to verify the identity of the SSH server. 

– Once a connection is established data that is transmitted is encrypted according to the parameters negotiated in the setup. 

SSH

After the setup phase is done, SSH protocol uses strong symmetric encryption and hashing algorithms to ensure the privacy and integrity of the data that is exchanged.

RFC – Link

From SSH.com
Me

What are the options to initiate SSH?

SSH

Amongst the several methods available the most common ones are passwords and public key authentication.

SSH

In most of automation cases the public key authentication method is preferred. (ANSIBLE uses it)

Me

Is it driven via a cryptographic key pair – public key and private key?

SSH

Duh?

The keys used for authentication are called SSH keys.

Configure the public key on a server to authorize access and grant anyone who has a copy of the private key access to the server.

Me

But WHY Public key?

SSH

– Why not – It is passwordless login, and yet more secure?

– The motivation for using public key authentication over simple passwords is security.

– Public key authentication provides cryptographic strength that even extremely long passwords can not offer

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