Basic authentication in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable basic authentication in the server block.

Nginx

server {
    listen 80;
    location / {
        auth_basic [1];
        auth_basic_user_file /etc/nginx/.htpasswd;
    }
}

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

A"Restricted Area"

Boff

Callow all

Ddeny all

Attempts:

3 left

💡 Hint

Common Mistakes

Using off disables authentication instead of enabling it.

Not using quotes around the realm string causes syntax errors.

The auth_basic directive requires a string to display as the authentication realm. "Restricted Area" is a common example.

2fill in blank

medium

Complete the code to specify the path to the password file for basic authentication.

Nginx

location /secure {
    auth_basic "Secure Area";
    auth_basic_user_file [1];
}

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

A/etc/nginx/.htpasswd

B/var/www/html/index.html

C/etc/passwd

D/usr/local/nginx/conf/nginx.conf

Attempts:

3 left

💡 Hint

Common Mistakes

Using the system's /etc/passwd file instead of the .htpasswd file.

Pointing to a directory or unrelated file causes errors.

The auth_basic_user_file directive points to the password file, usually /etc/nginx/.htpasswd.

3fill in blank

hard

Fix the error in the auth_basic directive to enable basic authentication.

Nginx

location /admin {
    auth_basic [1];
    auth_basic_user_file /etc/nginx/.htpasswd;
}

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

Aoff

Bnone

Ctrue

D"Admin Area"

Attempts:

3 left

💡 Hint

Common Mistakes

Using off disables authentication.

Using unquoted strings causes syntax errors.

The auth_basic directive must have a quoted string to enable authentication. "Admin Area" is correct.

4fill in blank

hard

Fill both blanks to configure basic authentication with a custom realm and password file.

Nginx

location /private {
    auth_basic [1];
    auth_basic_user_file [2];
}

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

A"Private Area"

B/etc/nginx/.htpasswd

C/var/www/html/.htpasswd

D"Public Area"

Attempts:

3 left

💡 Hint

Common Mistakes

Using an incorrect path for the password file.

Not quoting the realm string.

The auth_basic directive needs a quoted realm string, and auth_basic_user_file needs the correct path to the password file.

5fill in blank

hard

Fill all three blanks to create a server block that listens on port 8080 and uses basic authentication with a custom realm and password file.

Nginx

server {
    listen [1];
    location /secure {
        auth_basic [2];
        auth_basic_user_file [3];
    }
}

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

A80

B"Secure Zone"

C/etc/nginx/.htpasswd

D8080

Attempts:

3 left

💡 Hint

Common Mistakes

Using the default port 80 instead of 8080.

Not quoting the realm string.

Incorrect password file path.

The server listens on port 8080, the auth_basic directive uses a quoted realm string, and the password file path is correct.

Practice

1. What is the main purpose of basic authentication in nginx?

easy

A. To speed up the website loading time

B. To encrypt all website traffic automatically

C. To require users to enter a username and password before accessing content

D. To block all users except the server admin

Solution

1. Step 1: Understand basic authentication purpose

   Basic authentication prompts users for a username and password to restrict access.

2. Step 2: Compare options

   Only To require users to enter a username and password before accessing content describes this login prompt function; others describe unrelated features.

3. Final Answer:

   To require users to enter a username and password before accessing content -> Option C

4. Quick Check:

   Basic authentication = login prompt [OK]

Hint: Basic auth means login prompt for access control [OK]

Common Mistakes:

• Confusing basic auth with encryption
• Thinking it speeds up the site
• Assuming it blocks all users except admin

2. Which nginx directive is used to enable basic authentication in a server block?

easy

A. auth_basic_user_file

B. auth_user_file

C. basic_auth_enable

D. auth_basic

Solution

1. Step 1: Identify the directive for enabling basic auth

   The directive auth_basic enables basic authentication and sets the login prompt message.

2. Step 2: Check other directives

   auth_basic_user_file is incorrect; the correct directive for the password file is auth_basic_user_file but the enabling directive is auth_basic.

3. Final Answer:

   auth_basic -> Option D

4. Quick Check:

   Enable basic auth = auth_basic [OK]

Hint: Enable basic auth with auth_basic directive [OK]

Common Mistakes:

• Using auth_basic_user_file to enable auth
• Confusing directive names
• Using non-existent directives

3. Given this nginx config snippet:

location /secure/ {
  auth_basic "Restricted Area";
  auth_basic_user_file /etc/nginx/.htpasswd;
}

What happens when a user tries to access /secure/?

medium

A. User is prompted for username and password

B. User is redirected to /etc/nginx/.htpasswd

C. User accesses content without any prompt

D. User gets a 404 Not Found error

Solution

1. Step 1: Analyze auth_basic directive

   The auth_basic directive enables a login prompt with the message "Restricted Area".

2. Step 2: Analyze auth_basic_user_file directive

   The auth_basic_user_file points to the password file used to verify credentials.

3. Step 3: Determine user experience

   When accessing /secure/, the user is asked for username and password to proceed.

4. Final Answer:

   User is prompted for username and password -> Option A

5. Quick Check:

   auth_basic + user_file = login prompt [OK]

Hint: auth_basic triggers login prompt on matching location [OK]

Common Mistakes:

• Thinking user is redirected to password file
• Assuming no prompt appears
• Expecting 404 error without reason

4. You configured basic authentication but users are not prompted for credentials. Which is the most likely error?

medium

A. Missing auth_basic directive in the location block

B. Password file has wrong permissions

C. Using HTTP instead of HTTPS

D. Incorrect server_name directive

Solution

1. Step 1: Check required directives for basic auth

   Both auth_basic and auth_basic_user_file are needed; missing auth_basic disables the prompt.

2. Step 2: Evaluate other options

   Wrong permissions cause errors but usually show 500 errors; HTTP vs HTTPS affects security but not prompt; server_name unrelated.

3. Final Answer:

   Missing auth_basic directive in the location block -> Option A

4. Quick Check:

   No auth_basic = no login prompt [OK]

Hint: Always include auth_basic to enable prompt [OK]

Common Mistakes:

• Ignoring missing auth_basic directive
• Blaming HTTPS for prompt absence
• Confusing server_name with auth settings

5. You want to protect only the /admin path with basic authentication but allow /admin/public without login. Which nginx config achieves this?

hard

A. Use location /admin/public/ { auth_basic "Admin Area"; } and location /admin/ { auth_basic off; }

B. Use location /admin/ { auth_basic "Admin Area"; auth_basic_user_file /etc/nginx/.htpasswd; } and location /admin/public/ { auth_basic off; }

C. Use location /admin/ { auth_basic off; } only

D. Use location /admin/public/ { auth_basic_user_file /etc/nginx/.htpasswd; } only

Solution

1. Step 1: Protect /admin path with basic auth

   Set auth_basic and auth_basic_user_file in location /admin/ to require login.

2. Step 2: Disable auth for /admin/public

   Override with auth_basic off; in location /admin/public/ to allow open access.

3. Step 3: Confirm correct order and specificity

   More specific location /admin/public/ disables auth, while parent /admin/ requires it.

4. Final Answer:

   Use location /admin/ with auth_basic and location /admin/public/ with auth_basic off -> Option B

5. Quick Check:

   Parent location auth + child location off = selective protection [OK]

Hint: Disable auth in child location with auth_basic off [OK]

Common Mistakes:

• Reversing auth_basic on/off in locations
• Not using auth_basic off to disable
• Only configuring one location