SSH automation in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to connect to a remote server using SSH.

Bash Scripting

ssh [1]@example.com

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

Auser

Bpassword

Croot

Dlocalhost

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'password' instead of username in the SSH command.

Using 'localhost' which connects to the local machine, not remote.

The SSH command requires the username before the @ symbol to connect to the remote server.

2fill in blank

medium

Complete the code to run a command remotely over SSH.

Bash Scripting

ssh [e-mail] '[1]'

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

Als -l

Bcd /home

Cmkdir new_folder

Dexit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'exit' which closes the SSH session instead of running a command.

Using 'cd /home' which changes directory but does not produce output.

The command 'ls -l' lists files in long format on the remote server.

3fill in blank

hard

Fix the error in the SSH command to copy a file from local to remote.

Bash Scripting

scp [1] [e-mail]:/home/user/

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

Aexample.com

B/home/user/file.txt

[e-mail]

Dfile.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Adding user or host before the local file name causes errors.

Using a remote path as the source file.

The local file name 'file.txt' should be specified without user or host prefix.

4fill in blank

hard

Fill both blanks to create an SSH key pair and copy the public key to the remote server.

Bash Scripting

ssh-keygen -t [1] -f ~/.ssh/id_[2] -N ''

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

Arsa

Bdsa

Ced25519

Decdsa

Attempts:

3 left

💡 Hint

Common Mistakes

Using outdated key types like 'dsa'.

Mismatching key type and file name.

The modern recommended key type is 'ed25519', and the file name matches the key type.

5fill in blank

hard

Fill all three blanks to copy the SSH public key to the remote server for passwordless login.

Bash Scripting

cat ~/.ssh/id_[1].pub | ssh [2]@example.com 'mkdir -p ~/.ssh && cat >> ~/.ssh/[3]'

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

Arsa

Buser

Cauthorized_keys

Ded25519

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong key file name.

Using wrong remote username.

Appending to wrong file instead of 'authorized_keys'.

The public key file is 'id_ed25519.pub', the username is 'user', and the keys are appended to 'authorized_keys'.

Practice

1. What is the main benefit of using SSH keys for automation instead of passwords?

easy

A. It allows passwordless login for automated scripts.

B. It makes the connection slower but more secure.

C. It requires manual password entry every time.

D. It disables encryption for faster transfers.

Solution

1. Step 1: Understand SSH key usage

   SSH keys allow scripts to connect without typing passwords manually.

2. Step 2: Compare with password login

   Password login needs manual input, which breaks automation.

3. Final Answer:

   It allows passwordless login for automated scripts. -> Option A

4. Quick Check:

   SSH keys enable passwordless login = B [OK]

Hint: SSH keys = no password prompts for scripts [OK]

Common Mistakes:

• Thinking SSH keys slow down connection
• Assuming passwords work without manual input
• Believing SSH keys disable encryption

2. Which of the following is the correct syntax to copy a local file file.txt to a remote server using SSH automation?

easy

A. ssh file.txt user@remote:/path/

B. scp file.txt user@remote:/path/

C. ssh-copy file.txt user@remote:/path/

D. copy file.txt user@remote:/path/

Solution

1. Step 1: Identify the command for secure copy

   scp is used to copy files over SSH securely.

2. Step 2: Check other options

   ssh runs commands, ssh-copy is not a valid command, and copy is not for SSH.

3. Final Answer:

   scp file.txt user@remote:/path/ -> Option B

4. Quick Check:

   Use scp to copy files over SSH = A [OK]

Hint: Use scp to copy files remotely [OK]

Common Mistakes:

• Using ssh instead of scp for file copy
• Typing ssh-copy which is invalid
• Using copy command which is local only

3. What will be the output of this command if the remote server is reachable and the user has SSH key access?
ssh user@remote 'echo Hello from remote'

medium

A. Connection timed out.

B. Permission denied (publickey).

C. Hello from remote

D. ssh: Could not resolve hostname remote: Name or service not known

Solution

1. Step 1: Understand the command

   The command runs echo Hello from remote on the remote server via SSH.

2. Step 2: Check conditions

   If the server is reachable and SSH keys are set, the command outputs the echoed text.

3. Final Answer:

   Hello from remote -> Option C

4. Quick Check:

   SSH runs remote echo command = Hello from remote [OK]

Hint: SSH runs remote commands and shows output [OK]

Common Mistakes:

• Assuming permission denied without checking keys
• Confusing hostname errors with command output
• Thinking SSH command outputs nothing

4. You wrote this script to automate a remote command:

ssh user@remote 'uptime'

But it fails with "Permission denied (publickey)". What is the most likely fix?

medium

A. Generate SSH keys and add the public key to remote's authorized_keys.

B. Change the command to ssh user@remote uptime without quotes.

C. Use scp instead of ssh to run commands.

D. Restart the remote server to reset SSH.

Solution

1. Step 1: Understand the error

   "Permission denied (publickey)" means SSH keys are missing or not accepted.

2. Step 2: Fix SSH key setup

   Generate SSH keys locally and add the public key to ~/.ssh/authorized_keys on remote.

3. Final Answer:

   Generate SSH keys and add the public key to remote's authorized_keys. -> Option A

4. Quick Check:

   Permission denied means missing keys = A [OK]

Hint: Add your public key to remote authorized_keys [OK]

Common Mistakes:

• Removing quotes does not fix permission errors
• Using scp instead of ssh for commands
• Restarting server won't fix key issues

5. You want to automate running multiple commands on a remote server via SSH in one script. Which is the best way to do this?

hard

A. Use a single SSH command with multiple commands separated by semicolons inside quotes.

B. Run separate SSH commands for each remote command in the script.

C. Use scp to send commands instead of SSH.

D. Copy a script file to remote and run it with one SSH command.

Solution

1. Step 1: Consider multiple commands execution

   Running many commands inline can be complex and error-prone.

2. Step 2: Use script file for clarity and reuse

   Copying a script file to remote and running it via SSH is cleaner and easier to maintain.

3. Final Answer:

   Copy a script file to remote and run it with one SSH command. -> Option D

4. Quick Check:

   Script file on remote is best for multiple commands = C [OK]

Hint: Send script file and run remotely for many commands [OK]

Common Mistakes:

• Running many commands inline can cause quoting errors
• Running separate SSH commands is slower and complex
• Using scp to send commands is incorrect