A reverse proxy server is a type of server that acts as an intermediary for requests from clients seeking resources from one or more servers. Unlike a forward proxy, which acts on behalf of clients, a reverse proxy acts on behalf of the server or servers it is protecting or interfacing with. Positioned at the edge of a network, it receives initial HTTP connection requests and presents itself as the actual endpoint to the client.
The primary function of a reverse proxy is to serve as a traffic cop for a network, directing incoming requests to the appropriate server or servers behind it. This can include distributing the load evenly across multiple servers (load balancing), caching content to improve performance, handling SSL encryption, and providing a layer of security to shield the origin servers from direct internet access.
By acting as a gateway between users and the application origin server, a reverse proxy handles all policy management and traffic routing. This can help to ensure that only authorized traffic reaches the application servers, protect against attacks such as Distributed Denial of Service (DDoS) attacks, and improve the overall performance and reliability of the application by offloading tasks such as SSL termination and request caching.
Reverse proxies are commonly used in web application architectures, particularly in environments where high availability, security, and scalability are important. Examples of popular reverse proxy software include Nginx, Apache HTTP Server (with mod_proxy), and HAProxy.
In summary, a reverse proxy server is a crucial component in modern network architectures, providing a range of benefits including load balancing, security, and performance enhancements. By acting as an intermediary between clients and servers, it helps to manage traffic, enforce policies, and ensure that applications remain highly available and secure.