Practice - 5 Tasks

Answer the questions below

1fill in blank

easy

Complete the code to specify the SSH username in the config file.

Linux CLI

Host example
  User [1]

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

Aadmin

Bssh

Croot

Dguest

Attempts:

3 left

💡 Hint

Common Mistakes

Using a hostname instead of a username.

Leaving the username blank.

Using an invalid username.

✗ Incorrect

The 'User' directive sets the username for SSH connections. Here, 'admin' is the username to use.

2fill in blank

medium

Complete the code to specify the SSH port number in the config file.

Linux CLI

Host example
  Port [1]

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

A22

B21

C443

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using HTTP or FTP ports instead of SSH port.

Leaving the port number out when a non-default port is needed.

✗ Incorrect

The default SSH port is 22. This line sets the port to connect to on the remote server.

3fill in blank

hard

Fix the error in the SSH config line to specify the identity file path.

Linux CLI

Host example
  IdentityFile [1]

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

A/home/user/.ssh/known_hosts

B~/.ssh/id_rsa.pub

C/etc/ssh/ssh_config

D~/.ssh/id_rsa

Attempts:

3 left

💡 Hint

Common Mistakes

Using the public key file instead of the private key.

Using unrelated config or known_hosts files.

✗ Incorrect

The 'IdentityFile' should point to the private key file, usually '~/.ssh/id_rsa'. The public key or config files are incorrect here.

4fill in blank

hard

Fill both blanks to set the hostname and enable compression in the SSH config.

Linux CLI

Host [1]
  Compression [2]

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

Amyserver

Byes

Cno

Dexample.com

Attempts:

3 left

💡 Hint

Common Mistakes

Using a full domain name as the host alias when a simple name is expected.

Setting compression to 'no' when the goal is to enable it.

✗ Incorrect

The 'Host' directive names the SSH alias, here 'myserver'. 'Compression yes' enables data compression for faster transfers.

5fill in blank

hard

Fill all three blanks to create a config that sets the host alias, user, and disables strict host key checking.

Linux CLI

Host [1]
  User [2]
  StrictHostKeyChecking [3]

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

Adevserver

Bdeveloper

Cno

Dyes

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing 'StrictHostKeyChecking' values and setting it to 'yes' when disabling is intended.

Using a username that does not exist on the remote server.

✗ Incorrect

The host alias is 'devserver', the user is 'developer', and 'StrictHostKeyChecking no' disables the prompt for unknown hosts.

Practice

(1/5)

1. What is the main purpose of the Host entry in an SSH config file?

easy

A. To specify the password for the SSH connection

B. To create a shortcut name for an SSH connection

C. To list all IP addresses allowed to connect

D. To define the encryption method used

Solution

Step 1: Understand the role of Host in SSH config
The Host keyword defines a shortcut name for a server, so you can connect using that name instead of typing full details.
Step 2: Compare options
Options B, C, and D do not describe the purpose of Host. Passwords and encryption are handled differently, and allowed IPs are not set here.
Final Answer:
To create a shortcut name for an SSH connection -> Option B
Quick Check:
Host = shortcut name [OK]

Hint: Remember: Host = shortcut name for SSH [OK]

Common Mistakes:

Thinking Host sets password
Confusing Host with IP address list
Assuming Host defines encryption

2. Which of the following is the correct syntax to specify a custom port in an SSH config file?

easy

A. Port: 2222

B. SetPort 2222

C. port=2222

D. Port 2222

Solution

Step 1: Recall SSH config syntax rules
SSH config uses keyword followed by a space and then the value, without colons or equals signs.
Step 2: Check each option
Port 2222 matches the correct syntax: Port 2222. Options A, C, and D use invalid syntax.
Final Answer:
Port 2222 -> Option D
Quick Check:
Keyword + space + value = correct syntax [OK]

Hint: Use space, no colon or equals in SSH config lines [OK]

Common Mistakes:

Using colon after keyword
Using equals sign instead of space
Inventing keywords like SetPort

3. Given this SSH config snippet:

Host myserver
  HostName 192.168.1.10
  User alice
  Port 2200

What command will connect to the server using this config?

medium

A. ssh myserver

B. ssh alice@192.168.1.10 -p 2200

C. ssh 192.168.1.10

D. ssh -p 22 myserver

Solution

Step 1: Understand the config usage
The config defines a shortcut myserver with hostname, user, and port. Using ssh myserver applies all these automatically.
Step 2: Analyze options
ssh myserver uses the shortcut. ssh alice@192.168.1.10 -p 2200 manually specifies user and port but bypasses the config shortcut. ssh 192.168.1.10 misses user and port. ssh -p 22 myserver uses wrong port.
Final Answer:
ssh myserver -> Option A
Quick Check:
Use shortcut name to connect with config settings [OK]

Hint: Use the Host shortcut name to connect easily [OK]

Common Mistakes:

Ignoring the shortcut and typing full command
Using default port 22 instead of configured port
Missing the username from config

4. You wrote this SSH config:

Host test
  HostName 10.0.0.5
  User bob
  Port 22
  IdentityFile ~/.ssh/id_rsa_test

But when you run ssh test, it asks for a password instead of using the key. What is the likely problem?

medium

A. The User should be root, not bob

B. The Port 22 is wrong and should be 2222

C. The IdentityFile path is incorrect or not expanded

D. The HostName must be an IP, not a hostname

Solution

Step 1: Check IdentityFile usage
The IdentityFile path uses ~ which may not expand correctly in SSH config. It should be the full path or use $HOME.
Step 2: Evaluate other options
Port 22 is default and usually correct. User 'bob' is valid if correct user. HostName as IP is valid. So the key problem is likely the path expansion.
Final Answer:
The IdentityFile path is incorrect or not expanded -> Option C
Quick Check:
Use full path for IdentityFile to avoid key not used [OK]

Hint: Use full path, not ~, for IdentityFile in SSH config [OK]

Common Mistakes:

Assuming port 22 is always wrong
Changing user without reason
Confusing hostname format

5. You want to create an SSH config entry that connects to multiple servers with the same user and key but different hostnames. Which is the best way to write this?

hard

A. Host server1 server2 server3\n User admin\n IdentityFile ~/.ssh/admin_key

B. Host server*\n User admin\n IdentityFile ~/.ssh/admin_key

C. Host *\n User admin\n IdentityFile ~/.ssh/admin_key

D. Host server1\n User admin\n IdentityFile ~/.ssh/admin_key\nHost server2\n User admin\n IdentityFile ~/.ssh/admin_key\nHost server3\n User admin\n IdentityFile ~/.ssh/admin_key

Solution

Step 1: Understand grouping hosts in SSH config
You can list multiple hostnames after one Host keyword to apply the same settings to all.
Step 2: Compare options
Host server1 server2 server3\n User admin\n IdentityFile ~/.ssh/admin_key lists all servers in one line, applying user and key once. Host server*\n User admin\n IdentityFile ~/.ssh/admin_key uses wildcard which may match unintended hosts. Host *\n User admin\n IdentityFile ~/.ssh/admin_key applies to all hosts, not just these servers. Host server1\n User admin\n IdentityFile ~/.ssh/admin_key\nHost server2\n User admin\n IdentityFile ~/.ssh/admin_key\nHost server3\n User admin\n IdentityFile ~/.ssh/admin_key repeats same settings multiple times, which is redundant.
Final Answer:
Host server1 server2 server3 User admin IdentityFile ~/.ssh/admin_key -> Option A
Quick Check:
List multiple hosts after one Host for shared settings [OK]

Hint: List multiple hosts after one Host line to share settings [OK]

Common Mistakes:

Using wildcard * too broadly
Repeating same block for each host
Using Host * which applies to all hosts

SSH config file in Linux CLI - Interactive Code Practice

Practice

Solution

Step 1: Understand the role of `Host` in SSH config

Step 2: Compare options

Final Answer:

Quick Check:

Solution

Step 1: Recall SSH config syntax rules

Step 2: Check each option

Final Answer:

Quick Check:

Solution

Step 1: Understand the config usage

Step 2: Analyze options

Final Answer:

Quick Check:

Solution

Step 1: Check IdentityFile usage

Step 2: Evaluate other options

Final Answer:

Quick Check:

Solution

Step 1: Understand grouping hosts in SSH config

Step 2: Compare options

Final Answer:

Quick Check:

Ready to prove it?

Practice

Solution

Step 1: Understand the role of Host in SSH config

Step 2: Compare options

Final Answer:

Quick Check:

Solution

Step 1: Recall SSH config syntax rules

Step 2: Check each option

Final Answer:

Quick Check:

Solution

Step 1: Understand the config usage

Step 2: Analyze options

Final Answer:

Quick Check:

Solution

Step 1: Check IdentityFile usage

Step 2: Evaluate other options

Final Answer:

Quick Check:

Solution

Step 1: Understand grouping hosts in SSH config

Step 2: Compare options

Final Answer:

Quick Check:

Ready to prove it?

Step 1: Understand the role of `Host` in SSH config