[squid-users] Odd configuration ?

Hi,

I'm the net admin for a small school, and we have been using Squid with
great success for the past year. Internet access is becoming more and more
popular and squid allows us to save a lot of bandwith. However, our network
connection costs us 20$ for every gigabyte sent over the wire, and it is
starting to cost us quite a bit.

Right now, we have a single Squid proxy doing transparent filtering for
everybody. With squid_redirect, it blocks most web ads (which previously
accounted for 20% of our bandwith) and MP3s.

The thing is, administration is pushing for a reduction in internet access
costs. What I want to do is block ads/MP3/EXE/AVI/MOV/RM/ZIP files, which I
estimate, according to the calamaris report, will save us about 30% of
bandwith. I can do that easily with squid_redirect, by adding only a few
regexes. That's not the problem.

The problem is, while most of the time, the students don't have a
legitimate need to access these files, some people - teachers for example,
need to access them. And I'd like to keep transparent proxying active.

Is it possible, to keep transparent proxying active, without necessary
logins, but with the squid_redirect redirector active, and also have a
non-transparent proxy port open, which requires authentication, and offers
unfiltered access ? The authorised users would temporarily configure their
browser to access the traditional proxy.

So:

 -Transparent proxy without authentication offers filtered access
 -Traditional proxy which is unfiltered but requires authentication

Can I do that by running a single copy of squid ? Is there a better way to
do it ? Should I run two copies of squid instead ? Or perhaps even squid
for the filtered access and a lighter proxy for unfiltered access ?

Thanks a lot ! I appreciate any help or suggestions you have..

--
Francois Bradet, Administrateur reseau, Seminaire des Peres Maristes