How To Set Up Password Authentication with Nginx on Ubuntu 20.04

Introduction

When setting up a web server, there are often sections of the site that you wish to restrict access to. Web applications often provide their own authentication and authorization methods, but the web server itself can be used to restrict access if these are inadequate or unavailable. In this guide, you’ll password protect assets on an Nginx web server running on Ubuntu 20.04.

Prerequisites

To get started, you will need:

• Access to an Ubuntu 20.04 server environment with a non-root user with sudo privileges in order to perform administrative tasks. To learn how to create such a user, follow the Ubuntu 20.04 initial server setup guide.
• Nginx installed on your system, following Steps 1 and 2 of this guide on how to install Nginx on Ubuntu 20.04.

Step 1 — Creating the Password File

To start out, you need to create a file that will hold your username and password combinations. You can do this by using the OpenSSL utilities that may already be available on your server. Alternatively, you can use the purpose-made htpasswd utility included in the apache2-utils package (Nginx password files use the same format as Apache). Choose the method below that you like best.

Option 1 — Creating the Password File Using the OpenSSL Utilities

If you have OpenSSL installed on your server, you can create a password file with no additional packages. You will create a hidden file called .htpasswd in the /etc/nginx configuration directory to store your username and password combinations.

You can add a username to the file using this command. sammy is used here as the username, but you can use whatever name you’d like:

sudo sh -c "echo -n 'sammy:' >> /etc/nginx/.htpasswd"

Next, add an encrypted password entry for the username by typing:

sudo sh -c "openssl passwd -apr1 >> /etc/nginx/.htpasswd"

You can repeat this process for additional usernames. You can see how the usernames and encrypted passwords are stored within the file by typing:

cat /etc/nginx/.htpasswd

Output
sammy:$apr1$wI1/T0nB$jEKuTJHkTOOWkopnXqC1d1

Option 2 — Creating the Password File Using Apache Utilities

While OpenSSL can encrypt passwords for Nginx authentication, many users find it easier to use a purpose-built utility. The htpasswd utility, found in the apache2-utils package, serves this function well.

Install the apache2-utils package on your server by typing:

sudo apt update
sudo apt install apache2-utils

Now, you have access to the htpasswd command. You can use this to create a password file that Nginx can use to authenticate users. Create a hidden file for this purpose called .htpasswd within your /etc/nginx configuration directory.

The first time you use this utility, you need to add the -c option to create the specified file. Specify a username (sammy in this example) at the end of the command to create a new entry within the file:

sudo htpasswd -c /etc/nginx/.htpasswd sammy

You will be asked to supply and confirm a password for the user.

Leave out the -c argument for any additional users you wish to add:

sudo htpasswd /etc/nginx/.htpasswd another_user

If you view the contents of the file, you can see the username and the encrypted password for each record:

cat /etc/nginx/.htpasswd

Output
sammy:$apr1$lzxsIfXG$tmCvCfb49vpPFwKGVsuYz.
another_user:$apr1$p1E9MeAf$kiAhneUwr.MhAE2kKGYHK.

Step 2 — Configuring Nginx Password Authentication

Now that you have a file with your users and passwords in a format that Nginx can read, you need to configure Nginx to check this file before serving your protected content.

Begin by opening up the server block configuration file that you wish to add a restriction to. For your example, you’ll be using the default server block file installed through Ubuntu’s Nginx package:

sudo nano /etc/nginx/sites-enabled/default

To set up authentication, you need to decide on the context to restrict. Among other choices, Nginx allows you to set restrictions on the server level or inside a specific location.

This example will be for a server level restriction. The auth_basic directive turns on authentication and a realm name to be displayed to the user when prompting for credentials. You will use the auth_basic_user_file directive to point Nginx to the password file you created:

server {
    listen 80 default_server;

     . . .
   
    auth_basic "Restricted Content";
    auth_basic_user_file /etc/nginx/.htpasswd;
}

server {
    listen 80 default_server;

     . . .
   
    location / {
    try_files $uri $uri/ =404;
    auth_basic "Restricted Content";
    auth_basic_user_file /etc/nginx/.htpasswd;
    }
}

Save and close the file when you are finished. Restart Nginx to implement your password policy:

sudo systemctl restart nginx

The directory you specified should now be password protected.

Step 3 — Confirming the Password Authentication

To confirm that your content is protected, try to access your restricted content in a web browser:

http://server_domain_or_IP

You should be presented with a username and password prompt:

If you enter the correct credentials, you will be allowed to access the content. If you enter the wrong credentials or hit “Cancel”, you will see the “Authorization Required” error page:

Conclusion

You should now have everything you need to set up basic authentication for your site. Keep in mind that password protection should be combined with TLS encryption so that your credentials are not sent to the server in plain text. Check out this guide on how to secure Nginx with Let’s Encrypt on Ubuntu 20.04