[SC.LUG] transparent proxy with a single box and iptables

[Robert Marshall]

Maybe someone here can unbaffle me....

I'm trying to do web filtering, I have a single linux box that isn't
attached to anything else (other than the internet :-))

I'm using squid and dansguardian which works fine when setting a proxy
via the browser except that I can't get transparent proxy to work

I think that with a single box I need something  like

iptables -t nat -A OUTPUT -p tcp --dport 80 -j REDIRECT --to-port 8080

(dansguardian uses port 8080), this works fine and blocks unwanted
sites.

Unfortunately - of course - if a site isn't blocked - the request gets
sent round the forwarding loop again and squid kills it

What am I missing? do I need to do something via iptables so that it
recognises something emerging from squid or do I need to change
squid.conf somehow

All advice very welcome!

Robert
-- 
We must collect our thoughts.  For the unexpected is always upon us.  In the
street.  At the door.  On a stage.			Thank you, Mr. Berio.