Reverse Proxy

What is a Reverse Proxy?

A Reverse Proxy sits in front of backend servers and forwards client requests to them. Unlike a forward proxy (which acts on behalf of clients), a reverse proxy acts on behalf of servers.

Forward vs Reverse Proxy

Forward Proxy (client-side):
Client ──► [Proxy] ──► Internet ──► Server
           hides client

Reverse Proxy (server-side):
Client ──► Internet ──► [Reverse Proxy] ──► Server
                        hides server

Reverse Proxy Functions

1. Load Balancing

Distribute requests across multiple backend servers.

2. SSL Termination

Handle HTTPS encryption/decryption at the proxy:

Client ──HTTPS──► Reverse Proxy ──HTTP──► Backend
                 (SSL terminates here)

3. Caching

Cache responses to reduce backend load:

Request 1: Client → Proxy → Backend → Response (cached)
Request 2: Client → Proxy → Cached Response (backend not hit)

4. Compression

Compress responses before sending to clients.

5. Security

• Hide backend server details
• Filter malicious requests
• Rate limiting
• Web Application Firewall (WAF)

Common Use Cases

Popular Reverse Proxies

NGINX Example

server {
    listen 80;
    server_name example.com;

    location /api/ {
        proxy_pass http://backend-servers;
    }

    location /static/ {
        root /var/www/static;
    }
}

Interview Tips

• Differentiate forward vs reverse proxy
• Know common functions: SSL termination, caching, load balancing
• Mention security benefits
• Give examples: NGINX, HAProxy, cloud load balancers