Basic authentication in Nginx - Mini Project: Build & Apply

Basic Authentication Setup with Nginx

📖 Scenario: You are setting up a simple web server using Nginx. To protect a specific area of your website, you want to add basic authentication so that only users with a username and password can access it.

🎯 Goal: Learn how to configure basic authentication in Nginx by creating a password file, setting the auth_basic_user_file directive, applying the authentication to a location block, and verifying the setup.

📋 What You'll Learn

Create a password file with a user entry

Add the auth_basic_user_file directive for the password file path

Configure Nginx to use basic authentication for a location

Print the final Nginx configuration snippet

💡 Why This Matters

🌍 Real World

Basic authentication is commonly used to protect admin pages or sensitive areas on websites without complex login systems.

💼 Career

Knowing how to configure basic authentication in Nginx is a key skill for DevOps engineers managing web servers and securing web applications.

1

Create the password file

Create a file called /etc/nginx/.htpasswd with the exact content user:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/ which represents the username user and a hashed password.

Nginx

# Create the password file with the exact content
# Your code here

Hint

This line is the content of the password file. It stores the username and hashed password for basic authentication.

2

Add the auth_basic_user_file directive

In your Nginx configuration, set the auth_basic_user_file directive to /etc/nginx/.htpasswd.

Nginx

user:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/
# Define the auth_basic_user_file directive below
# Your code here

Hint

This directive specifies the path to the password file for authentication.

3

Configure basic authentication in Nginx

Add a location /secure block in the Nginx configuration that enables basic authentication with the message "Restricted Area" and the auth_basic_user_file directive for the password file.

Nginx

user:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/
auth_basic_user_file /etc/nginx/.htpasswd;
# Add location /secure block with basic authentication below
# Your code here

Hint

The location block protects the /secure path with basic authentication.

4

Print the final Nginx configuration

Print the entire Nginx configuration snippet including the password file content, the variable, and the location block exactly as shown.

Nginx

user:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/
auth_basic_user_file /etc/nginx/.htpasswd;

location /secure {
    auth_basic "Restricted Area";
    auth_basic_user_file /etc/nginx/.htpasswd;
}
# Print the full configuration below
# Your code here

Hint

Use a print statement to show the full configuration exactly as it is.

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