Difference between Forward and reverse proxies

Forward and reverse proxies are both intermediaries that handle requests between clients and servers, but they serve different purposes and operate in distinct contexts. Here’s a detailed comparison:

Forward Proxy

A forward proxy acts on behalf of clients (or a network of clients) to access servers on the internet. It is often used to provide privacy, security, and caching for client requests.

Key Characteristics of a Forward Proxy:

1. Client-side Proxy:

   • Sits between the client and the external servers.
   • Clients know about the forward proxy and direct their requests to it.

2. Client Privacy and Anonymity:

   • Hides the client’s IP address from the destination server.
   • Can be used to access restricted or geo-blocked content.

3. Content Filtering:

   • Can block access to certain websites or content based on policies.
   • Often used in corporate or educational environments to enforce usage policies.

4. Caching:

   • Stores copies of frequently accessed resources to reduce load times and save bandwidth.
   • Improves performance for the client by serving cached content instead of retrieving it from the destination server each time.

5. Security:

   • Can scan outgoing requests and incoming responses for malware.
   • Controls and monitors internet usage within a network.

Example Scenario:

A company wants to ensure that its employees cannot access certain websites and also wants to save bandwidth by caching frequently accessed content. It sets up a forward proxy to handle all internet traffic from the employees' computers.

Reverse Proxy

A reverse proxy acts on behalf of servers to handle requests from clients. It is often used for load balancing, caching, and improving security for the servers.

Key Characteristics of a Reverse Proxy:

1. Server-side Proxy:

   • Sits between the client and the internal servers.
   • Clients are unaware of the reverse proxy’s presence and interact with it as if it were the actual server.

2. Load Balancing:

   • Distributes incoming client requests across multiple backend servers to ensure no single server is overwhelmed.
   • Enhances scalability and reliability of the service.

3. Caching:

   • Stores copies of responses from backend servers to serve future requests quickly.
   • Reduces load on backend servers and improves response times for clients.

4. Security:

   • Acts as a barrier between clients and backend servers, protecting the servers from direct exposure to the internet.
   • Can provide SSL termination, offloading the SSL/TLS processing from the backend servers.

5. Application Firewall:

   • Can inspect incoming traffic for malicious requests and protect against various types of attacks (e.g., DDoS, SQL injection).

Example Scenario:

A high-traffic website uses a reverse proxy to distribute incoming requests among multiple web servers, ensuring high availability and performance. The reverse proxy also handles SSL termination, offloading the cryptographic processing from the backend servers.

Comparison Table

Feature	Forward Proxy	Reverse Proxy
Position	Between client and external servers	Between client and internal servers
Purpose	Privacy, security, content filtering, caching	Load balancing, security, caching, SSL termination
Client Awareness	Clients are aware and direct requests to it	Clients are unaware, think they interact with the server directly
Use Case Example	A company filtering employee internet access	A website distributing load across multiple servers
Anonymity	Hides client IP from destination server	Hides backend server details from clients
Caching	Stores frequently accessed client content	Stores server responses to improve client access times
Security Role	Scans outgoing/incoming client traffic	Protects backend servers, inspects incoming client traffic