Key-based authentication in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to generate a new SSH key pair.

Linux CLI

ssh-keygen -t [1] -f ~/.ssh/id_rsa

Drag options to blanks, or click blank then click option'

Aed25519

Brsa

Cecdsa

Ddsa

Attempts:

3 left

💡 Hint

Common Mistakes

Using dsa which is outdated and less secure.

Using rsa without specifying key size.

The ed25519 algorithm is recommended for SSH keys because it is secure and fast.

2fill in blank

medium

Complete the command to copy your public key to the remote server for passwordless login.

Linux CLI

ssh-copy-id -i ~/.ssh/id_rsa.pub [1]@remote_host

Drag options to blanks, or click blank then click option'

Aroot

Bguest

Cadmin

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Using root without permission.

Using guest which may not have SSH access.

You should replace user with your actual username on the remote server.

3fill in blank

hard

Fix the error in the SSH config file to specify the private key file.

Linux CLI

Host remote
  HostName example.com
  User user
  IdentityFile [1]

Drag options to blanks, or click blank then click option'

A~/.ssh/id_rsa

B~/.ssh/config

C~/.ssh/authorized_keys

D~/.ssh/id_rsa.pub

Attempts:

3 left

💡 Hint

Common Mistakes

Using the public key file instead of the private key.

Using unrelated files like config.

The IdentityFile should point to your private key, not the public key or other files.

4fill in blank

hard

Fill both blanks to create a directory and set correct permissions for SSH keys.

Linux CLI

mkdir -p ~/.ssh && chmod [1] ~/.ssh && chmod [2] ~/.ssh/id_rsa

Drag options to blanks, or click blank then click option'

A700

B600

C755

D644

Attempts:

3 left

💡 Hint

Common Mistakes

Setting 755 on private keys, making them world-readable.

Setting 644 on the .ssh directory.

The .ssh directory needs 700 permissions to be accessible only by you. The private key file needs 600 permissions to be readable and writable only by you.

5fill in blank

hard

Fill all three blanks to create an SSH config entry for a server with a custom port and identity file.

Linux CLI

Host myserver
  HostName [1]
  Port [2]
  IdentityFile [3]

Drag options to blanks, or click blank then click option'

A192.168.1.100

B2222

C~/.ssh/my_custom_key

Dexample.com

Attempts:

3 left

💡 Hint

Common Mistakes

Using the public key file for IdentityFile.

Using default port 22 when a custom port is required.

Use the server IP or hostname for HostName, the custom SSH port number for Port, and the path to your private key for IdentityFile.