Reverse Proxy Server

1
ReverseProxy Server

• Local Government Webmasters Meeting
• March 22, 2007 - Seattle, Washington
• Prepared by Steven NiedermeyerWeb Systems
  Analyst, City of Bellingham

2
Overview

• What is a reverse proxy server?
• Business case highlights
• Examples of available solutions
• Considerations when implementing
• Additional resources

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What is a reverse proxy server (RPS)?

• Wikipedia defines a reverse proxy as
• A proxy server that is installed within the
  neighborhood of one or more servers.
  Typicallyutilized in front of webservers. All
  connections coming from the Internet addressed to
  one of the webservers are routed through the
  proxy server, which may either deal with the
  request itself or pass the request wholly or
  partially to anotherwebserver.

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Example Reverse Proxy Network Diagram
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Business Case Highlights

• Benefits of a reverse proxy server
• Cost of implementation
• Potential risks of implementation
• Potential risks if not implemented

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Benefits of an RPS

• Increased Security
• Single SSL certificate
• Caching and compression
• Central access logs for reporting

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Increased Security

• A reverse proxy may be used to prevent Internet
  clients from having direct access to less secure
  web servers or applications located on isolated
  networks or intranets.

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Single SSL certificate

• A reverse proxy server may act as a single point
  for all secure connections. You only need to buy
  one SSL certificate.

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Caching and Compression

• A reverse proxy can
• Offload other webservers by caching static
  content, such as images.
• Compress content before delivering it to site
  visitors to optimize load times.

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Central access logs

• A reverse proxy server allows for
• Centralized logging of web traffic
• Single format for access logs
• Simplified reporting and tracking of performance
  measures.

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Cost of Implementation

• The purchase price of a reverse proxy server
  solution ranges from free to over tens of
  thousands of dollars depending on the needs of
  the agency. Staff time must be invested in
  implementation, training, and establishing
  policies to govern the management of this key
  component of an agencies web presence.
• The City of Bellingham implemented a solution for
  just over 11,000 (9,000 server, 1,500 backup
  license and FTP software, 1,000 consulting to
  enable a web application to work with the reverse
  proxy server)

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Potential Risks of Implementation

• Implementing a reverse proxy server
• Creates a single point of failure for all of your
  webservers unless you include load balancing in
  your solution
• Existing web applications may need to be modified
  in order to work correctly

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Potential Risks If Not Implemented

• Not implementing a reverse proxy server
• May increase your risk of a security breach
• May increase your operating costs for SSL
  certificates

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Examples of Available Solutions

• Solutions vary widely but the following are a
  couple of examples
• Basic solution Apache HTTP Linux/Windows
  Server 2003
• Advanced solution Microsoft Internet Security
  Application Server (ISA)

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Considerations When Implementing

• Set up a test environment
• Provision a backup server with the same
  configuration as your primary reverse proxy
  server
• Keep detailed documentation as reverse proxy
  servers may require extensive configuration

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Additional Resources

• Product Examples
• Apache Software Foundationhttp//httpd.apache.org
  /
• Microsoft http//www.microsoft.com/isaserver/defau
  lt.mspx
• General concepts
• Wikipediahttp//en.wikipedia.org/wiki/Reverse_pro
  xy