Guide to Setting the "Cross-Origin-Resource-Policy" Header

Contents

What Does This Header Do?

The Cross-Origin-Resource-Policy (CORP) header controls who can load resources (e.g., images, scripts, or styles) from your website. By restricting access to same-origin or trusted origins, this header helps prevent unauthorized usage of your resources.

Steps to Set the Header

1. If You Use a Web Server (e.g., Apache, Nginx, etc.)

For Apache:

  1. Open your website's configuration file (or .htaccess file if you use one).
  2. Add the following line, replacing same-origin with the appropriate policy: 
    Header set Cross-Origin-Resource-Policy "same-origin"
  3. Save the file and restart the Apache server to apply changes.

For Nginx:

  1. Open your website's configuration file (e.g., /etc/nginx/sites-available/your-site).
  2. Add the following line inside the server block, replacing same-origin with the appropriate policy: 
    add_header Cross-Origin-Resource-Policy "same-origin";
  3. Save the file and restart Nginx to apply changes using: 
    sudo systemctl restart nginx

2. If You Use a Programming Language:

For PHP:

header("Cross-Origin-Resource-Policy: same-origin");

For Node.js:

Use a middleware like helmet to set the header automatically:

const helmet = require('helmet');
app.use(helmet.crossOriginResourcePolicy({ policy: 'same-origin' }));

Or set it manually:

app.use((req, res, next) => {
  res.setHeader('Cross-Origin-Resource-Policy', 'same-origin');
  next();
});

For Python (Flask):

from flask import Flask, Response

app = Flask(__name__)

@app.after_request
def set_headers(response):
    response.headers['Cross-Origin-Resource-Policy'] = 'same-origin'
    return response

3. Verify the Header

After setting the header, test your website to ensure it’s working:

  1. Open your website in a browser.
  2. Use the developer tools (right-click > Inspect > Network tab) to view the HTTP headers.
  3. Look for the Cross-Origin-Resource-Policy header with the correct value.

Why It Matters

Setting this header protects your resources from being accessed or abused by unauthorized third parties, reducing potential misuse or security risks.