#Infra #IaaS #Concepts #Proxy
1. What is a Proxy Server?
- An intermediary server that acts as a middleman between a client and a server.
- Instead of passing requests and responses directly, the proxy server handles them on behalf of either party.
- Used for security, performance optimization, access control, load balancing, and more.
2. Types and Representative Technologies
(1) Forward Proxy
- Positioned in front of the client → handles outbound requests on the client’s behalf.
Why use it?
- Security / Anonymity (hides the real client IP)
- Access control (blocking specific sites within an organization)
- Caching (faster delivery of frequently requested content)
- Bandwidth reduction
Representative Technologies / Products
- Squid Proxy → the most well-known open-source forward proxy
- Apache HTTP Server (mod_proxy) → supports proxy functionality
- Blue Coat ProxySG (enterprise commercial solution)
- Zscaler Internet Access (ZIA) (cloud-based security proxy)
(2) Reverse Proxy
- Positioned in front of the server → handles inbound requests on the server’s behalf.
Why use it?
- Load balancing (distributing traffic across multiple servers)
- Enhanced security (hiding the actual server structure and addresses)
- SSL termination (handling TLS encryption)
- Caching (faster delivery of static files)
- High availability (Failover support)
Representative Technologies / Products
- Nginx → the most widely used open-source reverse proxy
- Apache HTTP Server (mod_proxy, mod_ssl)
- F5 BIG-IP LTM (large-scale enterprise load balancer)
- AWS ALB (Application Load Balancer)
- Cloudflare (CDN + reverse proxy)
3. Comparison Summary
| Category | Forward Proxy | Reverse Proxy |
|---|---|---|
| Position | In front of the client | In front of the server |
| Acts on behalf of? | Client | Server |
| Traffic direction | Outbound (internal → external) | Inbound (external → internal) |
| Primary purpose | Anonymity, access control, caching, bandwidth reduction | Load balancing, security, SSL termination, high availability |
| Representative technologies/products | Squid, Apache mod_proxy, Zscaler, Blue Coat | Nginx, Apache mod_proxy, F5 BIG-IP, AWS ALB, Cloudflare |
[클라이언트] → (포워드 프록시) → 인터넷 → [서버]
(내부망에서 나갈 때)
[클라이언트] → 인터넷 → (리버스 프록시) → [서버]
(외부 요청이 들어올 때)Key Takeaways:
- Forward Proxy is for controlling and securing internal users
- Reverse Proxy is for distributing and securing external traffic
- Their physical position is fundamentally the same → between the client and the server.
- However, their roles and perspectives differ → the name changes based on who they act on behalf of.
- Acting on behalf of the client → Forward Proxy (outbound)
- Acting on behalf of the server → Reverse Proxy (inbound)