Re: Transparent caching

From: Todd Graham Lewis <>
Date: Thu, 2 Jan 1997 19:52:47 -0500 (EST)

On Wed, 18 Dec 1996, Paul M. Hoogsteder wrote:

> Does anyone know transparent-cache implementations in software, or is
> anyone working on something like that? (Other than the Interceptor).
> 75% of our network-traffic goes to personal users who dialin with PPP, of
> which probably 90% is either ftp or http. Setting up a transparent cache
> can save us thousands of dollars every month (at $0.30 USD for every
> megabyte).

Linux has a really neat transparent proxy option whereby all packets which
meet certain criteria (say, destination port = 80) can be redirected to a
local process (say, squid).

It would be really easy to take squid and make it aware of this option.
Once it accepts the connection, it has to do a getsockopt on the
connection to discover the intended destination. Some pseudocode:

$remaddr = getsockopt(whatever);
s#GET document/wherever.html#GET http://$remaddr/document/wherever.html#g;

And that's it. Just put one of these in each of your dial-in locations,
tell your ciscos to do TOS routing and redirect all port 80 traffic to
your cache, and you're done.

I've been meaning to do it for a while, but unfortunately, I couldn't code
my way out of a wet paper sack. 8^(

If anyone's interested, I have some documents on the option, and I could
offer a hand with the Linux parts. Feel free to mail me.

Todd Graham Lewis Linux! Core Engineering
Mindspring Enterprises (800) 719 4664, x2804
Received on Thu Jan 02 1997 - 17:06:52 MST

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