Proxy Gateway Support in NCSA Mosaic for Microsoft Windows

This document will describe how to set up NCSA Mosaic for MS Windows
to use proxy gateways.  Note:  proxy gateways are currently only
supported in Windows Mosaic version 2.0a2 and later.



What is a Proxy Gateway?

A proxy gateway allows Mosaic to pass on a network request (in the form
of a URL) to an outside agent which will perform the request for Mosaic, 
and return the results to Mosaic.  The intended effect of this is to 
allow Mosaic clients that are sealed off from the internet to pass their 
network requests off to a trusted agent that can access the internet for 
Mosaic.  A user of a Mosaic client using a proxy gateway should feel as 
if they were directly connected to the internet.



How is it Implemented?

Proxy gateways in Mosaic are expected to talk the HTTP/1.0 protocol.  The URL
that Mosaic wants to access is passed to the proxy in the form of an HTTP/1.0
GET request.  The proxy then accesses the URL, and returns its results back
to Mosaic.

Proxy gateways are currently implemented on a per access method basis.  This
means each URL access method can send its requests to a different proxy.
The current access methods are ftp, gopher, wais, news, and http.

To add proxy gateway support into Windows Mosaic, you must add a section to
your mosaic.ini file of the format:


[proxy information]
http_proxy=http://aixtest.cc.ukans.edu:911/
ftp_proxy=http://aixtest.cc.ukans.edu:911/
wais_proxy=http://aixtest.cc.ukans.edu:911/
gopher_proxy=http://aixtest.cc.ukans.edu:911/



Where do I get a Proxy Gateway?

Not surprising, since client support for proxy gateways has just come
out, there aren't a lot of proxy gateways out there.  Since proxy
gateways are expected to be used to pass through firewalls, you need
to trust your proxy gateway, the best way to get a gateway you
trust is to write it yourself.


Now that we have CGI, hopefully someone will write a proxy gateway CGI 
module, and then you can turn your favorite HTTP server into a proxy gateway.  
For more information see http://hoohoo.ncsa.uiuc.edu/cgi/overview.html.