Introduction

The LEMP software stack is a group of software that can be used to serve dynamic web pages and web applications. This is an acronym that describes a Linux operating system, with an Nginx web server. The backend data is stored in the MySQL database and the dynamic processing is handled by PHP.

In this guide, you'll install a LEMP stack on a Debian server using the packages provided by the operating system.

Prerequisites

To complete this guide, you will need:

• A Debian 8 server with a non-root user with sudo privileges. You can set up a user with these privileges in our Initial Server Setup with Debian 8 guide.

Step 1 — Install the Nginx Web Server

In order to display web pages to our site visitors, we are going to employ Nginx, a modern, efficient web server.

All of the software we will be using for this procedure will come directly from Debian's default package repositories. This means we can use the apt package management suite to complete the installation.

Since this is our first time using apt for this session, we should start off by updating our local package index. We can then install the server:

sudo apt-get update
sudo apt-get install nginx

On Debian 8, Nginx is configured to start running upon installation.

If you have the ufw firewall running, you will need to allow connections to Nginx. You should enable the most restrictive profile that will still allow the traffic you want. Since we haven't configured SSL for our server yet, in this guide, we will only need to allow traffic on port 80.

You can enable this by typing:

sudo ufw allow 'Nginx HTTP'

You can verify the change by typing:

sudo ufw status

You should see HTTP traffic allowed in the displayed output:

Output
Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Nginx HTTP                 ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Nginx HTTP (v6)            ALLOW       Anywhere (v6)

Now, test if the server is up and running by accessing your server's domain name or public IP address in your web browser. If you do not have a domain name pointed at your server and you do not know your server's public IP address, you can find it by typing one of the following into your terminal:

ip addr show eth0 | grep inet | awk '{ print $2; }' | sed 's/\/.*$//'

This will print out a few IP addresses. You can try each of them in turn in your web browser.

As an alternative, you can check which IP address is accessible as viewed from other locations on the internet:

curl -4 icanhazip.com

Type one of the addresses that you receive in your web browser. It should take you to Nginx's default landing page:

http://server_domain_or_IP

If you see the above page, you have successfully installed Nginx.

Step 2 — Install MySQL to Manage Site Data

Now that we have a web server, we need to install MySQL, a database management system, to store and manage the data for our site.

You can install this easily by typing:

sudo apt-get install mysql-server

You will be asked to supply a root (administrative) password for use within the MySQL system, and you'll need to confirm that password.

The MySQL database software is now installed, but its configuration is not exactly complete yet.

To secure the installation, we can run a simple security script that will ask whether we want to modify some insecure defaults. Begin the script by typing:

sudo mysql_secure_installation

You will be asked to enter the password you set for the MySQL root account. Then you'll be asked you if you want to change that password. If you are happy with your current password, enter N for "no" at the prompt:

Using existing password for root.

Setting the root password ensures that nobody can log into the MySQL
root user without the proper authorisation.

You already have a root password set, so you can safely answer 'n'.

Change the root password? [Y/n] n
 ... skipping.

For the rest of the questions the script asks, you should press Y, followed by the ENTER key at each prompt. This will remove some anonymous users and the test database, disable remote root logins, and load these new rules so that MySQL immediately respects the changes you have made.

At this point, your database system is now set up and secured. Let's set up PHP.

Step 3 — Install PHP for Processing

We now have Nginx installed to serve our pages and MySQL installed to store and manage our data. However, we still don't have anything that can generate dynamic content. That's where PHP comes in.

Since Nginx does not contain native PHP processing like some other web servers, we will need to install fpm, which stands for "fastCGI process manager". We will tell Nginx to pass PHP requests to this software for processing. We'll also install an additional helper package that will allow PHP to communicate with our MySQL database backend. The installation will pull in the necessary PHP core files to make that work.

These packages aren't available in the default repositories due to licensing issues, so we'll have to modify the repository sources to pull them in.

Open /etc/apt/sources.list in your text editor:

sudo nano /etc/apt/sources.list

Then, for each source, append the contrib and non-free repositories to each source. Your file should look like the following after you've made those changes:

...
deb http://mirrors.digitalocean.com/debian jessie main contrib non-free
deb-src http://mirrors.digitalocean.com/debian jessie main contrib non-free

deb http://security.debian.org/ jessie/updates main contrib non-free
deb-src http://security.debian.org/ jessie/updates main contrib non-free

# jessie-updates, previously known as 'volatile'
deb http://mirrors.digitalocean.com/debian jessie-updates main contrib non-free
deb-src http://mirrors.digitalocean.com/debian jessie-updates main contrib non-free

Save and exit the file. Then update your sources:

sudo apt-get update

Then install the php5-fpm and php5-mysql modules:

sudo apt-get install php5-fpm php5-mysql

We now have our PHP components installed, but we need to make a slight configuration change to make our setup more secure.

Open the main php-fpm configuration file with root privileges:

sudo nano /etc/php5/fpm/php.ini

Look in the file for the parameter that sets cgi.fix_pathinfo. This will be commented out with a semi-colon (;) and set to "1" by default.

This is an extremely insecure setting because it tells PHP to attempt to execute the closest file it can find if the requested PHP file cannot be found. This basically would allow users to craft PHP requests in a way that would allow them to execute scripts that they shouldn't be allowed to execute.

We will change both of these conditions by uncommenting the line and setting it to "0" like this:

cgi.fix_pathinfo=0

Save and close the file when you are finished.

Now, we just need to restart our PHP processor by typing:

sudo systemctl restart php5-fpm

This will implement the change that we made.

Step 4 — Configure Nginx to Use the PHP Processor

Now, we have all of the required components installed. The only configuration change we still need is to tell Nginx to use our PHP processor for dynamic content.

We do this on the server block level (server blocks are similar to Apache's virtual hosts). Open the default Nginx server block configuration file by typing:

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

Currently, with the comments removed, the Nginx default server block file looks like this:

server {
    listen 80 default_server;
    listen [::]:80 default_server;

    root /var/www/html;
    index index.html index.htm index.nginx-debian.html;

    server_name _;

    location / {
        try_files $uri $uri/ =404;
    }
}

We need to make some changes to this file for our site.

• First, we need to add index.php as the first value of our index directive so that files named index.php are served, if available, when a directory is requested.
• We can modify the server_name directive to point to our server's domain name or public IP address.
• For the actual PHP processing, we just need to uncomment a segment of the file that handles PHP requests. This will be the location ~\.php$ location block, the included fastcgi-php.conf snippet, and the socket associated with php-fpm.
• We will also uncomment the location block dealing with .htaccess files. Nginx doesn't process these files. If any of these files happen to find their way into the document root, they should not be served to visitors.

The changes that you need to make are in red in the text below:

server {
    listen 80 default_server;
    listen [::]:80 default_server;

    root /var/www/html;
    index index.php index.html index.htm index.nginx-debian.html;

    server_name your_server_ip;

    location / {
        try_files $uri $uri/ =404;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/var/run/php5-fpm.sock;
    }

    location ~ /\.ht {
        deny all;
    }
}

When you've made the above changes, you can save and close the file.

Test your configuration file for syntax errors by typing:

sudo nginx -t

If any errors are reported, go back and recheck your file before continuing.

When you are ready, reload Nginx to make the necessary changes:

sudo systemctl reload nginx

Step 5 — Create a PHP File to Test Configuration

Your LEMP stack should now be completely set up. We can test it to validate that Nginx can correctly hand .php files off to our PHP processor.

We can do this by creating a test PHP file in our document root. Open a new file called info.php within your document root in your text editor:

sudo nano /var/www/html/info.php

Type or paste the following lines into the new file. This is valid PHP code that will return information about our server:

<?php
  phpinfo();
?>

When you are finished, save and close the file.

Now, you can visit this page in your web browser by visiting your server's domain name or public IP address followed by /info.php:

http://server_domain_or_IP/info.php

You should see a web page that has been generated by PHP with information about your server:

If you see a page that looks like this, you've set up PHP processing with Nginx successfully.

After verifying that Nginx renders the page correctly, it's best to remove the file you created as it can actually give unauthorized users some hints about your configuration that may help them try to break in.

For now, remove the file by typing:

sudo rm /var/www/html/info.php

You can always regenerate this file if you need it later.

Conclusion

You should now have a LEMP stack configured on your Debian server. This gives you a very flexible foundation for serving web content to your visitors.