Catching user switching and getting current active user from root on linux

[mpnordland]

ok, I'll give one more chance.
First, to pacify those who hate google groups: What is a good usenet
client?
second, How should I set up this proxy so that when a connection is
made, it request's authentication, and then log's the request, if
authentication is not gotten, how do I have it block (or firewall) the
request? Furthermore, I would like for the proxy to be squid. So all
of the nitty gritty should have to do with squid.