Proxy Servers: Forward, Reverse & Transparent

What is a Forward Proxy?

A Forward Proxy acts as a middleman between a client and the internet.

How it works:

• Sits between clients and the public internet.
• Client-facing: It primarily serves the client by forwarding requests to a server.

Use Cases:

• Access Control: Block access to certain websites or restrict internet usage within a company.
• Security: Scan for viruses and block harmful content.
• Monitoring: Log users’ web activity (e.g., employee monitoring).
• Content Filtering
• Caching
• Identity Protection

What is a Reverse Proxy?

A Reverse Proxy sits on the server side and handles requests from clients.

How it works:

• Acts as an intermediary for client requests.
• Primarily serves web servers, sitting in front of one or more.
• Forwards incoming client requests to the appropriate server(s).

Common Tools:

• nginx as a reverse proxy.

Use Case:

• Load balancing across multiple backend servers.
• SSL termination (offloading SSL handshake from app servers).

What is a Transparent Proxy?

A Transparent Proxy intercepts network traffic between a user’s device and the internet without modifying requests or responses.

Characteristics:

• Also called inline, intercepting, or forced proxy.
• No need for users to configure anything—invisible to end-users.

Use Cases:

• Content filtering
• Traffic monitoring
• DDoS protection
• Authentication

Forward Proxy vs Reverse Proxy

Why Use a Proxy for Load Balancing?

Using a reverse proxy for load balancing provides more granular and flexible routing, especially at Layer 7 (Application Layer).

Features:

• Route traffic based on headers, cookies, request content, etc.
• SSL Termination support
• Offloads CPU-intensive tasks like TLS handshake from backend servers

Proxies vs VPN

Note: A VPN is a specialized form of a forward proxy that includes encryption and operates at the system level.

Why Use Proxies in Data Collection?

When making a large number of requests to a server from a single IP, you're likely to get blocked. Proxies allow you to:

• Send traffic using multiple IPs to avoid detection.
• Distribute requests to avoid throttling.
• Scale data scraping or API consumption efficiently.

🔄 Quick Summary

• Forward Proxy: Used by clients to access the internet anonymously or securely.
• Reverse Proxy: Used by servers to manage incoming client traffic.
• Transparent Proxy: Invisible to clients, used for control and monitoring.
• VPN: Encrypted connection for full-device privacy and security.