Forward & Reverse Proxies PDF

106 (Forward & Reverse) Proxies What is a proxy server? (aka Forward proxy) A proxy server is an intermediate piece of software or hardware that sits between the client * *...

106 (Forward & Reverse) Proxies What is a proxy server? (aka Forward proxy) A proxy server is an intermediate piece of software or hardware that sits between the client * * * * * * and the server. * * Clients connect to a proxy to make a request for a service like a web page, file, or * * connection from the server. * Essentially, a proxy server (aka the forward proxy) 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. * * A forward proxy: * * Typically, forward proxies are *used to * *** cache data*, *** *** filter requests, *** *** log requests, *** * or transform requests (by adding/removing headers, encrypting/decrypting, or * *** *** * * * * * * * compressing a resource). * * A forward proxy can hide the identity of the client from the server by sending ** ** **~ ~** requests on behalf of the client. * * In addition to coordinating requests from multiple servers, proxies can also optimize request * * * * * traffic from a system-wide perspective. * * Proxies can combine the same data access requests into one request and then return * ** *** * * * * the result to the user; this technique is called collapsed forwarding. **~* *~** Consider a request for the same data across several nodes, but the data is not in cache. * * * * * * * *  * By routing these requests through the proxy, they can be consolidated into one so that * *** ** * we will only read data from the disk once. Reverse Proxy A reverse proxy retrieves resources from one or more servers on behalf of a client. These * * * * resources are then returned to the client, appearing as if they originated from the proxy * * server itself, thus anonymizing the server. Contrary to the forward proxy, which hides the * * * * client's identity, a reverse proxy hides the server's identity. *** ~ ~*** * A reverse proxy: * In the above diagram, the reverse proxy hides the final server that served the request from * the client. The client makes a request for some content from facebook.com; this request is * served by facebook’s reverse proxy server, which gets the response from one of the backend * * * servers and returns it to the client. * A reverse proxy, just like a forward proxy, can be used for * * * * *** caching, *** *** load balancing, *** * or routing requests to the appropriate servers. * *** *** Summary A proxy is a piece of software or hardware that sits between a client and a server to ** ** *** *** facilitate traffic. A forward proxy hides the identity of the client, whereas a reverse proxy conceals the ** ** * * ** ** * identity of the server. * * So, when you want to protect your clients on your internal network, you should put them * behind a forward proxy; * * * on the other hand, when you want to protect your servers, you should put them behind a * * * * reverse proxy. *