Re: Global proxy autoconfig script?

From: Oskar Pearson <>
Date: Wed, 10 Sep 1997 14:57:57 +0200


We were talking about a global web server that would run a script, and
based on the IP address of the client machine, return a different
java auto-config script.

> >Perhaps his would be good as a sub-routine to each ISP own auto-config
> >file, but is this scalable ? Autooconfig is nothing but a java script,
> >interpreted for EACH object. Is this is BIG, it will be SLOW...
> The Proxy Auto Configuration (PAC) script could be generated by a Perl
We have a related problem:

We have numerous branches spread around the country. We would like to
get a machine in each of those branches to handle traffic for their
area, so that connections don't come all the way over our national
links to get to the cache up here. It would, however, be nice to
not have 1 different config file for each branch (ie settings would be
perfectly uniform) I spent a long time sitting and thinking about this,
and decided that there are basically 4 options:

1) A central auto-config script that runs a CGI on our machines and
decides where they are supposed to go based on the request.

2) We add local routes (local to each branch) that point to
a different cache machine... yucky

3) We modify bind so that it responds with a different IP address
for an A record request based on the address the request came from.

4) Change the way netscape and Explorer work.

I think that 4 is the best option, but it's going to be difficult
(we would need an rfc or something). Here is my idea as to how they would work:

In the reverse DNS ( we add an A record that
points to a 'config-server'. (anyone thought of that before?)

so you have
cacheconfig A

in the reverse zone. Your proxy client then says
"gethostbyname(" and connects
to that machine. It then attempts to connect to that machine using (either
http or a 'cache-config-specific' variant) and asks for a java auto-config

I dig the idea... if you are allowed A records in PTR zones I haven't
tried, but I don't see why you shouldn't be able to have it...

Of course, there might be something in the Internet drafts about auto-config
systems that have been released (I haven't had a chance to look at them,
but look at "ACAP -- Application Configuration Access Protocol",
draft-ietf-acap-spec-06.txt). Perhaps these ideas could be integrated...

So if someone changes IP addresses by dialing up in the UK, it will
talk to that service providers' cache....

Received on Wed Sep 10 1997 - 06:09:06 MDT

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