System Design: Proxies

Question 1

What is a proxy (forward proxy)?

Answer 1

It is a piece of software or hardware that facilitates the request for resources from other servers on behalf of clients, thus anonymizing the client from the server.

Question 2

What are forward proxies used for?

Answer 2

Typically, forward proxies are used to cache data, filter requests, log requests, or transform requests by adding/removing headers. Other uses include:

Anonymizing client IPs, content filtering (eg orgs restrict access to certain sites), bypassing geo location restrictions, malware protection.

Question 3

What is a reverse proxy?

Answer 3

It’s the same things as a forward proxy, except a reverse proxy hides the final server that served the request from the client and sits between the client and server (as opposed to the client and internet).

Question 4

What is a reverse proxy used for?

Answer 4

A reverse proxy, just like a forward proxy, can be used for caching, load balancing, or routing requests to the appropriate servers.

Question 5

What are key differences between and reverse proxy and forward proxy?

Answer 5

Forward proxies are used by clients to access the Internet securely, reverse proxies are used by servers to manage, protect, and optimize incoming requests.

Question 6

Do servers route requests back through load balancers? (Proxies)?

Answer 6

Sometimes, like with Nginx.

Question 7

What are some examples of forward proxies?

Answer 7

Squid: An open-source caching proxy widely used for HTTP, HTTPS, and FTP traffic.

Nginx: Primarily known as a web server, Nginx can also function as a forward proxy when configured appropriately.

Tor (The Onion Router): While primarily known for its network of volunteer-operated servers providing anonymity, Tor also functions as a forward proxy, routing traffic through multiple layers to obscure origin.

Cloudflare Gateway: Offers secure and managed proxy services for enterprise users, focusing on threat protection and secure internet access.

Question 8

What are some examples of reverse proxies.

Answer 8

Nginx – One of the most widely used reverse proxies for load balancing, caching, and security.

AWS Application Load Balancer (ALB) – Handles reverse proxying and traffic distribution in AWS.

Apache HTTP Server (mod_proxy) – Can be configured as a reverse proxy for various protocols.

Cloudflare – Acts as a reverse proxy for security, DDoS protection, and caching.

Question 9

Are responses routed through reverse proxies?

Answer 9

Yes

Question 10

Describe and API gateway.

Answer 10

See image