SSH key generation (ssh-keygen) in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the ssh-keygen command?

The ssh-keygen command creates a pair of keys (a public key and a private key) used to securely connect to remote computers without using passwords.

beginner

What files are created by default when you run ssh-keygen without options?

By default, ssh-keygen creates two files in your ~/.ssh/ folder: id_rsa (private key) and id_rsa.pub (public key).

beginner

Why should you keep your private key safe and never share it?

The private key is like a secret password. If someone else gets it, they can access your remote computers as if they were you. Only share the public key.

beginner

How do you add a passphrase to your SSH key during generation?

When running ssh-keygen, it asks for a passphrase. You can type a secret phrase to add extra protection to your private key.

intermediate

What is the command to generate an SSH key with RSA algorithm and 4096 bits key size?

Use ssh-keygen -t rsa -b 4096 to create a strong RSA key with 4096 bits length.

What does the ssh-keygen command generate?

A A configuration file for SSH

B A password for SSH login

C A new SSH server

D A pair of public and private keys

ssh-keygen creates a pair of keys used for secure SSH authentication.

Where are SSH keys stored by default after running ssh-keygen?

A /usr/bin/

B /etc/ssh/

C ~/.ssh/

D /var/log/

SSH keys are saved in the ~/.ssh/ directory in your home folder.

Which file contains the public key after generating SSH keys?

A id_rsa.pub

B id_rsa

C authorized_keys

D config

The public key is saved in the file ending with .pub, usually id_rsa.pub.

What is the benefit of adding a passphrase to your SSH key?

A Automatically uploads the key to servers

B Adds extra security by encrypting the private key

C Allows multiple users to share the key

D Makes the key generation faster

A passphrase encrypts your private key, so even if stolen, it cannot be used without the passphrase.

How do you specify the key type and size when generating an SSH key?

A ssh-keygen -t rsa -b 4096

B ssh-keygen --type rsa --size 2048

C ssh-keygen -key rsa -size 1024

D ssh-keygen -generate rsa 4096

The correct syntax is ssh-keygen -t rsa -b 4096 to specify RSA type and 4096 bits.

Explain the process and purpose of generating SSH keys using ssh-keygen.

Think about how you can log in to a remote computer safely without typing a password every time.

Describe how to generate a strong SSH key with a passphrase and where the keys are stored.

Remember the command syntax and the default folder for SSH keys.