Reverse Web Proxy

Reverse Web Proxy

This article explains about what a reverse web proxy is and examples of reverse proxy.
Examples include:
Microsoft ISA Server
Apache proxy_mod module
Sun iPlanet
Hardware load balancers with SSL Acceleration features
Stateful inspection or SSL acceleration routines that assume incoming traffic is HTTPS will cause
problems when the traffic is ICA in SSL. Notice in the figure above that the HTTPS connection from
the client is terminated at the proxy server, and a new HTTP(S) connection is initiated between the
proxy and the target server. This setup implies that the destination server is an HTTP server: neither
MetaFrame Presentation Server nor Secure Gateway is an HTTP server.
Allpurpose Reverse Proxy (NAT)
A firewall that supports Network Address Translation (NAT) can be thought of as an all-purpose
reverse proxy server. Clients connect to the firewall address and their traffic is transparently
forwarded to a different host on the secure network. Network Address Translation is powerful
because it requires no client logic and works with any protocol. The only requirement is that the client
must connect to the firewall address instead of the actual target server address.
NAT offers little or no security, since all network traffic arriving at the firewall is forwarded to the
configured destination server. Often, NAT is used when joining disparate trusted networks as an
alternative to re-addressing or subnetting.
Transparent Proxy
The term Transparent Proxy is used to refer to a proxy service that runs locally on a client machine,
intercepts outbound network traffic, and routes the traffic through a proxy server. Applications
running on the client device need not be configured with the address of the target proxy server,
because the traffic interception takes place at a relatively low layer of the network stack.

For example, the Advanced Gateway Client included with MetaFrame Secure Access Manager 2.2 is
a secure transparent proxy that intercepts traffic at the WinSock level. This design allows a client
application such as Outlook.exe to route traffic through the proxy without any explicit application
configuration. In this example, Outlook is not aware that its traffic is being intercepted and
redirected through a secure tunnel.
The Citrix Extranet Client for Windows was another example of a transparent localhost proxy.