Website Security Headers Explained: A Complete Guide

What Are Security Headers?

HTTP security headers are instructions sent by your web server that tell browsers how to handle your website content. They protect against cross-site scripting (XSS), clickjacking, MIME type sniffing, and other common web attacks.

Essential Security Headers

Strict-Transport-Security (HSTS)

Forces browsers to only connect to your site via HTTPS. This prevents protocol downgrade attacks and cookie hijacking.

Strict-Transport-Security: max-age=31536000; includeSubDomains

Content-Security-Policy (CSP)

Controls which resources the browser is allowed to load. This is your strongest defense against XSS attacks.

Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'

X-Content-Type-Options

Prevents browsers from MIME-type sniffing, which can lead to XSS attacks through file uploads.

X-Content-Type-Options: nosniff

X-Frame-Options

Prevents your site from being embedded in iframes, protecting against clickjacking attacks.

X-Frame-Options: DENY

Referrer-Policy

Controls how much referrer information is sent when navigating away from your site.

Referrer-Policy: strict-origin-when-cross-origin

Permissions-Policy

Restricts which browser features your site can use (camera, microphone, geolocation, etc.).

Permissions-Policy: camera=(), microphone=(), geolocation=()

How to Check Your Headers

Sentrix's security scanning feature automatically checks all of these headers and more. Run a scan on your website to get a detailed report of missing headers, misconfigured CORS, SSL issues, and exposed sensitive files.

Common Mistakes

Missing HSTS - Even with HTTPS enabled, users can still be redirected to HTTP without HSTS
Overly permissive CSP - Using unsafe-inline and unsafe-eval defeats the purpose of CSP
Exposing server information - Server and X-Powered-By headers reveal your technology stack to attackers
Wildcard CORS - Setting Access-Control-Allow-Origin: * with credentials enabled is a critical vulnerability

Next Steps

Start by running a Sentrix security scan on your website. The scan will identify missing headers and provide specific remediation steps. Implementing these headers takes minutes but significantly improves your security posture.