Communication Systems

SSH: Secure Shell or Secure Socket Shell

• Encrypted connection between two hosts over the internet
• SSH key pair:
  1. Public Key : id_.pub eg. id_rsa.pub
  2. Private Key: id_

Q. How to generate an SSH Key pair?

• Use any one algorithm below:

  $ ssh-keygen -t rsa -b 4096
  $ ssh-keygen -t ecdsa -b 521
  $ ssh-keygen -t ed25519
  

• Select the default location and filename. (or, you can choose your own) : eg. .ssh/id_rsa.pub
• You are then prompted to enter a passphrase. (Choose a strong one) (Dont want a passphrase? => Just press ENTER)

• Now, copy the public key to the server! Thats it!

• Note: 1. If you change the default name of the key pair, then you have to explicitly specify that this key should be used for connecting to a specific host. $ ssh -i ~// username@servername 2. For frequent users, you can configure ssh. $ ~/.ssh/config 3. If error, debug using: $ ssh -v