How to Enable TLS 1.3 in Apache on Debian 10

TLS 1.3 is a version of the Transport Layer Security (TLS) protocol that was published in 2018 as a proposed standard in RFC 8446. It offers security and performance improvements over its predecessors.

This guide will demonstrate how to enable TLS 1.3 using the Apache web server on Debian 10.

Requirements

• Vultr Cloud Compute (VC2) instance running Debian 10 (Buster).
• A valid domain name and properly configured A/AAAA/CNAME DNS records for your domain.
• A valid TLS certificate. We will get one from Let's Encrypt.
• Apache version 2.4.36 or greater.
• OpenSSL version 1.1.1 or greater.

Before you begin

Check the Debian version.

lsb_release -ds
# Debian GNU/Linux 10 (buster)

Create a new non-root user account with sudo access and switch to it.

adduser johndoe --gecos "John Doe"
usermod -aG sudo johndoe
su - johndoe

NOTE: Replace johndoe with your username.

Set up the timezone.

sudo dpkg-reconfigure tzdata

Ensure that your system is up to date.

sudo apt update && sudo apt upgrade -y

Install the needed packages.

sudo apt install -y zip unzip curl wget git socat

Install the acme.sh client and obtain a TLS certificate from Let's Encrypt

Install acme.sh.

sudo mkdir /etc/letsencrypt
git clone https://github.com/Neilpang/acme.sh.git
cd acme.sh 
sudo ./acme.sh --install --home /etc/letsencrypt --accountemail your_email@example.com
cd ~
source ~/.bashrc

Check the version.

/etc/letsencrypt/acme.sh --version
# v2.8.2

Obtain RSA and ECDSA certificates for your domain.

# RSA
sudo /etc/letsencrypt/acme.sh --issue --standalone -d example.com --ocsp-must-staple --keylength 2048
# ECC/ECDSA
sudo /etc/letsencrypt/acme.sh --issue --standalone -d example.com --ocsp-must-staple --keylength ec-256

NOTE: Replace example.com in commands with your domain name.

Create sensible directories to store your certs and keys in. We will use /etc/letsencrypt.

sudo mkdir -p /etc/letsencrypt/example.com
sudo mkdir -p /etc/letsencrypt/example.com_ecc

Install and copy certificates to /etc/letsencrypt.

# RSA
sudo /etc/letsencrypt/acme.sh --install-cert -d example.com --cert-file /etc/letsencrypt/example.com/cert.pem --key-file /etc/letsencrypt/example.com/private.key --fullchain-file /etc/letsencrypt/example.com/fullchain.pem 
# ECC/ECDSA
sudo /etc/letsencrypt/acme.sh --install-cert -d example.com --ecc --cert-file /etc/letsencrypt/example.com_ecc/cert.pem --key-file /etc/letsencrypt/example.com_ecc/private.key --fullchain-file /etc/letsencrypt/example.com_ecc/fullchain.pem

After running the above commands, your certificates and keys will be in the following locations:

• RSA: /etc/letsencrypt/example.com
• ECC/ECDSA: /etc/letsencrypt/example.com_ecc

Install Apache

Apache added support for TLS 1.3 in version 2.4.36. Debian 10 system comes with Apache and OpenSSL that support TLS 1.3 out of the box, so there is no need to build a custom version.

Download and install the latest 2.4 branch of Apache via the apt package manager.

sudo apt install -y apache2

Check the version.

sudo apache2 -v
# Server version: Apache/2.4.38 (Debian)
# Server built:   2019-04-07T18:15:40

Configure Apache for TLS 1.3

Now that we have successfully installed Apache, we are ready to configure it to start using TLS 1.3 on our server.

First, enable the SSL module.

sudo a2enmod ssl

Restart Apache.

sudo systemctl restart apache2

Run sudo vim /etc/apache2/sites-available/example.com.conf, and populate the file with the following basic configuration.

<IfModule mod_ssl.c>
  <VirtualHost *:443>
    ServerName example.com

    SSLEngine on
    SSLProtocol all -SSLv2 -SSLv3

    # RSA
    SSLCertificateFile "/etc/letsencrypt/example.com/fullchain.pem"
    SSLCertificateKeyFile "/etc/letsencrypt/example.com/private.key"
    # ECC
    SSLCertificateFile "/etc/letsencrypt/example.com_ecc/fullchain.pem"
    SSLCertificateKeyFile "/etc/letsencrypt/example.com_ecc/private.key"

  </VirtualHost>
</IfModule>

Save the file and exit.

Activate the new configuration file by linking the file to the sites-enabled directory.

sudo a2ensite example.com.conf

Check the configuration.

sudo apachectl configtest

Reload Apache.

sudo systemctl reload apache2

Open your site via HTTPS protocol in your web browser. To verify TLS 1.3, you can use browser dev tools or SSL Labs service. The screenshots below show Chrome's security tab with TLS 1.3 in action.

You have successfully enabled TLS 1.3 in Apache on your Debian 10 server. The final version of TLS 1.3 was defined in August 2018, so there’s no better time to start adopting this new technology.