Proxy Servers (Forward & Reverse)

A Proxy Server is an intermediary server that sits between a client and a destination server. Instead of the client communicating directly with the server, the request first passes through the proxy. There are two fundamentally different types.

1. Forward Proxy

A Forward Proxy sits in front of the client and acts on behalf of the client.

When a client wants to access example.com, the request goes to the Forward Proxy first. The proxy forwards the request to example.com using the proxy's own IP address. The origin server sees the proxy's IP, not the client's.

Use Cases:

• Anonymity: Hides the client's real IP address from the destination server (like a VPN).
• Content Filtering: Organizations use forward proxies to block employees from accessing social media websites during work hours.
• Bypass Restrictions: Users in censored regions can route traffic through a forward proxy in a different country to access blocked websites.
• Caching: If 100 employees in a company all visit news.com, the forward proxy can cache the page after the first request and serve it locally to the other 99, saving bandwidth.

2. Reverse Proxy

A Reverse Proxy sits in front of the server and acts on behalf of the server. The client has no idea a reverse proxy exists. It thinks it's communicating directly with the origin server.

Use Cases:

• Load Balancing: The reverse proxy distributes incoming requests across multiple backend servers. Nginx and HAProxy are the most popular reverse proxies used as load balancers.
• SSL Termination: The reverse proxy can handle all the computationally expensive SSL/TLS encryption and decryption, offloading this work from the backend servers.
• Caching: The reverse proxy can cache static content (images, CSS, JS files) and serve them directly without ever bothering the backend server.
• Security: The reverse proxy hides the identity and IP addresses of the backend servers from the outside world, protecting them from direct attacks (DDoS protection). Cloudflare is essentially a massive reverse proxy network.
• Compression: The reverse proxy can compress outgoing responses before sending them to the client, reducing bandwidth usage.

3. Forward vs Reverse Proxy Summary