Create Self-Signed SSL certificate for Apache in Ubuntu

Introduction

TLS, or transport layer security, and its predecessor SSL, which stands for secure sockets layer, are web protocols used to wrap normal traffic in a protected, encrypted wrapper.

Using this technology, servers can send traffic safely between the server and clients without the possibility of the messages being intercepted by outside parties. The certificate system also assists users in verifying the identity of the sites that they are connecting with.

In this guide, we will show you how to set up a self-signed SSL certificate for use with an Apache web server on an Ubuntu 16.04 server.

Prerequisites

Before you begin, you should have a non-root user configured with sudo privileges. You can learn how to set up such a user account by following our initial server setup for Ubuntu 16.04.

You will also need to have the Apache web server installed. If you would like to install an entire LAMP (Linux, Apache, MySQL, PHP) stack on your server, you can follow our guide on setting up LAMP on Ubuntu 16.04. If you just want the Apache web server, skip the steps pertaining to PHP and MySQL in the guide.

When you have completed the prerequisites, continue below.

Step 1: Create the SSL Certificate

TLS/SSL works by using a combination of a public certificate and a private key. The SSL key is kept secret on the server. It is used to encrypt content sent to clients. The SSL certificate is publicly shared with anyone requesting the content. It can be used to decrypt the content signed by the associated SSL key.

We can create a self-signed key and certificate pair with OpenSSL in a single command:

As we stated above, these options will create both a key file and a certificate. We will be asked a few questions about our server in order to embed the information correctly in the certificate.

Fill out the prompts appropriately. The most important line is the one that requests the Common Name (e.g. server FQDN or YOUR name). You need to enter the domain name associated with your server or, more likely, your server’s public IP address.

The entirety of the prompts will look something like this:

Both of the files you created will be placed in the appropriate subdirectories of the /etc/ssl directory.

While we are using OpenSSL, we should also create a strong Diffie-Hellman group, which is used in negotiating Perfect Forward Secrecy with clients.

We can do this by typing:

This may take a few minutes, but when it’s done you will have a strong DH group at /etc/ssl/certs/dhparam.pem that we can use in our configuration.

Step 2: Configure Apache to Use SSL

We have created our key and certificate files under the /etc/ssl directory. Now we just need to modify our Apache configuration to take advantage of these.

We will make a few adjustments to our configuration:

  1. We will create a configuration snippet to specify strong default SSL settings.
  2. We will modify the included SSL Apache Virtual Host file to point to our generated SSL certificates.
  3. (Recommended) We will modify the unencrypted Virtual Host file to automatically redirect requests to the encrypted Virtual Host.

When we are finished, we should have a secure SSL configuration.

Create an Apache Configuration Snippet with Strong Encryption Settings

First, we will create an Apache configuration snippet to define some SSL settings. This will set Apache up with a strong SSL cipher suite and enable some advanced features that will help keep our server secure. The parameters we will set can be used by any Virtual Hosts enabling SSL.

Create a new snippet in the /etc/apache2/conf-available directory. We will name the file ssl-params.conf to make its purpose clear:

For our purposes, we can copy the provided settings in their entirety. We will just make two small changes.

Set the SSLOpenSSLConfCmd DHParameters directive to point to the Diffie-Hellman file we generated earlier. Also, take a moment to read up on HTTP Strict Transport Security, or HSTS, and specifically about the “preload” functionality. Preloading HSTS provides increased security, but can have far reaching consequences if accidentally enabled or enabled incorrectly. In this guide, we will not preload the settings, but you can modify that if you are sure you understand the implications, add below in “/etc/apache2/conf-available/ssl-params.conf” file:

Save and close the file when you are finished.

Modify the Default Apache SSL Virtual Host File

Next, let’s modify /etc/apache2/sites-available/default-ssl.conf, the default Apache SSL Virtual Host file. If you are using a different server block file, substitute it’s name in the commands below.

Before we go any further, let’s back up the original SSL Virtual Host file:

Now, open the SSL Virtual Host file to make adjustments:

Inside, with most of the comments removed, the Virtual Host file should look something like this by default:

 

We will be making some minor adjustments to the above file. We will set the normal things we’d want to adjust in a Virtual Host file (ServerAdmin email address, ServerName, etc.), adjust the SSL directives to point to our certificate and key files, and uncomment one section that provides compatibility for older browsers.

As it stands now, the server will provide both unencrypted HTTP and encrypted HTTPS traffic. For better security, it is recommended in most cases to redirect HTTP to HTTPS automatically. If you do not want or need this functionality, you can safely skip this section.

To adjust the unencrypted Virtual Host file to redirect all traffic to be SSL encrypted, we can open the /etc/apache2/sites-available/000-default.conf file:

Inside, within the VirtualHost configuration blocks, we just need to add a Redirect directive, pointing all traffic to the SSL version of the site:

Save and close the file when you are finished.

Step 3: Enable the Changes in Apache

Now that we’ve made our changes and adjusted our firewall, we can enable the SSL and headers modules in Apache, enable our SSL-ready Virtual Host, and restart Apache.

We can enable mod_ssl, the Apache SSL module, and mod_headers, needed by some of the settings in our SSL snippet, with the a2enmod command:

Next, we can enable our SSL Virtual Host with the a2ensite command:

We will also need to enable our ssl-params.conf file, to read in the values we set:

At this point, our site and the necessary modules are enabled. We should check to make sure that there are no syntax errors in our files. We can do this by typing:

The first line is just a message telling you that the ServerName directive is not set globally. If you want to get rid of that message, you can set ServerName to your server’s domain name or IP address in /etc/apache2/apache2.conf. This is optional as the message will do no harm.

If your output has Syntax OK in it, your configuration file has no syntax errors. We can safely restart Apache to implement our changes.

Step 4: Test Encryption

Open your web browser and type https:// followed by your server’s domain name or IP into the address bar.┬áBecause the certificate we created isn’t signed by one of your browser’s trusted certificate authorities, you will likely see a scary looking warning.┬áThis is expected and normal. We are only interested in the encryption aspect of our certificate, not the third party validation of our host’s authenticity. Click “ADVANCED” and then the link provided to proceed to your host anyways.

You should be taken to your site. If you look in the browser address bar, you will see a lock with an “x” over it. In this case, this just means that the certificate cannot be validated. It is still encrypting your connection.

If you configured Apache to redirect HTTP to HTTPS, you can also check whether the redirect functions correctly:

http://server_domain_or_IP

If this results in the same icon, this means that your redirect worked correctly.

Step 5: Change to a Permanent Redirect

If your redirect worked correctly and you are sure you want to allow only encrypted traffic, you should modify the unencrypted Apache Virtual Host again to make the redirect permanent.

Open your server block configuration file again:

Find the Redirect line we added earlier. Add permanent to that line, which changes the redirect from a 302 temporary redirect to a 301 permanent redirect:

Save and close the file.

Check your configuration for syntax errors:

  • sudo apache2ctl configtest

When you’re ready, restart Apache to make the redirect permanent:

  • sudo systemctl restart apache2

Conclusion

You have configured your Apache server to use strong encryption for client connections. This will allow you serve requests securely, and will prevent outside parties from reading your traffic.

If you have a suggestion or issue with the above commands, please leave a comment below:

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