transparent proxy

From: Oskar Pearson <>
Date: Tue, 7 Oct 1997 18:40:10 +0200

Hi Guys

I have created a new mailing list (called
specifically for the function of implementing cisco-cache like
features under linux using squid, or, in fact, any other reasonable
cache software for linux. There will be other implications,
which is why I am mailing this to the following lists - for people who
may be interested. Please excuse duplicate copies if you are on multiple

To fill people in on the cisco cache function:

The cisco cache allows people with a cisco 7000 router to run IOS
software that allows you to redirect all requests for web pages (or port
80) to one or more cisco-cache machines. The cisco decides which
machine to forward requests to by using the destination IP address
in conjunction with the number of available proxies. If it finds the
proxy is down, it then sends to a different cache.

It occured to me why the cisco cache splits the networking into 256
sections based on IP-address rather than a hash of the URL - it's simply
because the redirect function of the Cisco 7000's doesn't work at the
http level, but only the IP-level... it takes the destination URL and
decides which machine to forward it to, and then that machine is supposed
to do the transparency. This was worrying people on squid-users the other

I would like to implement the same thing under linux, where if a packet
is destined to to port 80, it can be redirected to a set of hosts that
load-balance, allowing for one single machine to do routing, and
as many others as needed to handle the actual squid process.
This means that we can have a user-level process that periodically checks
that the squid hosts are up, and will add and remove them from the
list of available proxies.

Currently linux can redirect connections transparently as long as the
proxy-software is running on the same machine... I want to be able to
split the function onto multiple machines.

I would appreciate it if anyone interested would subscribe.. it's
going to be a 'short-term-low-volume-list' (I hope) set to perform
a specific function. Note that the linux-transparency stuff was initially
ported from BSD (AFAIK) so it should be possible to port the outcome to
other OS's.

To subscribe, mail '' with the word 'subscribe' in
the body... there should be no subject.

To unsubscribe, mail '' with the word 'unsubscribe' in
the body... there should be no subject.


Received on Tue Oct 07 1997 - 09:46:34 MDT

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