In this exercise, the objective is to enforce HTTP Strict Transport Security (HSTS) on an Apache web server. This is an update to the SSL/ TLS certificate deployment as documented here.

From Wikipedia, HSTS 'allows web servers to declare that web browsers (or other complying user agents) should only interact with it using secure HTTPS connections, and never via the insecure HTTP protocol'.


  • The Apache mod_headers extension must be enabled.
  • All HTTP trafic on the web server must be redirected to HTTPS.
  • All subdomains must be served over HTTPS. This includes the www subdomain.
  • The web server must continuously be accessible through HTTPS. Failure to meet this requirement could break access to the website for an extended period of time.


In the SSL/ TLS configuration file, the following segment should be amended. In Apache, this is located by default at /etc/httpd/conf.d/ssl.conf.

# HSTS (mod_headers is required) (15768000 seconds = 6 months)
Header always set Strict-Transport-Security "max-age=15768000"

After restarting Apache, the website should be ready for submission to the Chrome HSTS preload list. This list is supported by most major browsers.

At the time of posting, this site contains no errors and is pending submission to the list.


As of 25th August 2016, this site is included in Chrome's HSTS preload list. In practice no modern browser should permit an insecure HTTP connection to the website.

Update 2

The max-age field value was updated to 31536000 (31536000 seconds = 1 year) to reflect the new minimum age required by the HSTS preload list.