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The protection reverse proxy is useful when you must maintain an insecure, proprietary, or legacy system. Direct exposure to the outside world
could lead to a compromise, but putting such systems behind a reverse proxy would extend their lifetime and allow secure operation. A protection
reverse proxy can also actually be useful for all types of web applications since they can benefit from having an HTTP firewall in place, combined
with full traffic logging for auditing purposes.
9.5.1.4 Performance reverse proxy
Finally, you have a good reason to introduce a reverse proxy to increase overall system performance. With little effort and no changes to the actual
web server, a reverse proxy can be added to perform the following operations (as seen in Figure 9-5):
SSL termination, such that SSL communication is terminated at the proxy and the traffic continues unencrypted to the web server
Caching
Compression
Figure 9-5. Performance reverse proxy
Moving these operations to the separate server frees the resources on the web server to process requests. Moreover, the web server (or the
application) may not be able to support these operations. Because the reverse proxy operates on the HTTP level, the additional functionality can be
introduced in front of a web server of any type.
9.5.2. Advanced Architectures
There are three reasons why you would concern yourself with advanced HTTP architectures:
You want to achieve higher availability. Having a system down while the server is being repaired is unacceptable.
The number of users is likely to be greater than one server can support, or is likely to grow (so you desire scalability).
That cool security reverse proxy you put in place centralizes HTTP requests, and you have to deal with the resulting bottleneck in the