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HTTP: The Definitive Guide

Cover of HTTP: The Definitive Guide by David Gourley... Published by O'Reilly Media, Inc.

Where Do Proxies Go?

The previous section explained what proxies do. Now let's talk about where proxies sit when they are deployed into a network architecture. We'll cover:

  • How proxies can be deployed into networks

  • How proxies can chain together into hierarchies

  • How traffic gets directed to a proxy server in the first place

Proxy Server Deployment

You can place proxies in all kinds of places, depending on their intended uses. Figure 6-11 sketches a few ways proxy servers can be deployed.

Egress proxy (Figure 6-11a)

You can stick proxies at the exit points of local networks to control the traffic flow between the local network and the greater Internet. You might use egress proxies in a corporation to offer firewall protection against malicious hackers outside the enterprise or to reduce bandwidth charges and improve performance of Internet traffic. An elementary school might use a filtering egress proxy to prevent precocious students from browsing inappropriate content.

Access (ingress) proxy (Figure 6-11b)

Proxies are often placed at ISP access points, processing the aggregate requests from the customers. ISPs use caching proxies to store copies of popular documents, to improve the download speed for their users (especially those with high-speed connections) and reduce Internet bandwidth costs.

Surrogates (Figure 6-11c)

Proxies frequently are deployed as surrogates (also commonly called reverse proxies) at the edge of the network, in front of web servers, where they can field all of the ...

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