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Proxy Servers: Forward, Reverse & Transparent

July 25, 2023

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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

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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

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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.

apigateway

🔄 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.