Proxies & Reverse Proxies

Overview

Proxies are intermediary servers that sit between clients and servers. A forward proxy acts on behalf of clients, while a reverse proxy acts on behalf of servers.

They provide additional functionality like security, caching, load balancing, and anonymity.

Key Concepts

Forward Proxy

Sits between clients and the internet. Clients send requests to the proxy, which forwards them to servers. Hides client identity.

Reverse Proxy

Sits between the internet and servers. Receives client requests and forwards to appropriate backend servers. Hides server architecture.

Load Balancing

Reverse proxies can distribute incoming requests across multiple backend servers.

How It Works

Forward Proxy Flow: Client → Forward Proxy → Internet → Server Server sees proxy IP, not client IP

Reverse Proxy Flow: Client → Internet → Reverse Proxy → Backend Servers Client doesn't know which server handled request

Common reverse proxies: Nginx, HAProxy, Apache

Use Cases

Forward Proxy: Corporate networks controlling internet access

Forward Proxy: VPNs hiding user location

Reverse Proxy: Load balancing across multiple servers

Reverse Proxy: SSL termination (handling HTTPS encryption)

Reverse Proxy: Caching static content

Reverse Proxy: Security and DDoS protection

Best Practices

Use multiple proxies for redundancy

Implement health checks for backend servers

Configure appropriate timeouts

Enable compression for text-based content

Set up proper logging and monitoring

Use connection pooling to backend servers

Implement rate limiting and DDoS protection

Interview Tips

What Interviewers Look For

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Explain the difference: forward proxy for clients, reverse proxy for servers
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Discuss common reverse proxy tools: Nginx, HAProxy, Apache
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Mention use cases: load balancing, caching, SSL termination, security
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Talk about how reverse proxies improve scalability and availability
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Explain how proxies can be a single point of failure and mitigation strategies