Re: Global proxy autoconfig script?

From: Andreas Strotmann <>
Date: Wed, 10 Sep 1997 16:22:50 +0200


funny, I posted a very similar question to the German academic proxy cache
mailing list six weeks ago. Here's the technique that I proposed to solve
this problem.

First, note that the original poster of this question had noticed that
users complained that their proxy configs don't work any more when they
change ISPs. Second, this assumes that we're talking about auto-configs,
i.e. there are WWW servers involved.

Given this, here's my proposal for a scenario how this might work. Easy,
fast, reliable;-)

- User accesses IN via ISP1 using auto-config URL for ISP2
- User's browser asks ISP2's WWW server for auto-config file
- ISP2's web server runs a little script that does as follows:
  - case 1: request stems from client in ISP2 domain
    => return ISP2 auto-config.  Done.
  - case 2: otherwise
    => return redirect to an upstream registry of auto-config URLs
    - User's browser automatically looks up new URL of registry
    - this URL corresponds to a script again:
      - case 1: request comes from a client in a domain registered
        => return redirect to registered auto-config URL (which may
           be the URL of a lower-level registry)
      - case 2: else, there's an upstream register for autoconfig URLs
        => return redirect to upstream register; iterate
      - case 3: still can't resolve
        => return standard auto-config with "DIRECT" to all.
- eventually, ISP1's auto-config script will be downloaded from ISP1's
  webserver.  Note that ISP1 may use the selfsame technique to distribute
  the load of his/her clients among proxies.
The overhead is OK since the script is loaded into a browser about once
per session or so.
Of course, a global recommendation on writing such scripts would also be
Just my $0.02
Andreas Strotmann       / ~~~~~~ \________________A.Strotmann@Uni-Koeln.DE
Universitaet zu Koeln  /| University of Cologne   \
Regionales Rechenzentrum| Regional Computer Center \
Robert-Koch-Str. 10    /|    Tel: +49-221-478-5524 |\   Home: -221-4200663
D-50931  Koeln        __|__  FAX: +49-221-478-5590 |__________~~~~~~~~~~~~   
Received on Wed Sep 10 1997 - 07:24:50 MDT

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