[squid-users] proxy auth

Hi

Im trying to achieve the following.

I allow proxy access without authentication for my users, I have 1 office
that I want to deny access unless they provide a username and password.

I have a very large amount of subnets and do not specify them in squid.conf
so basicly have a

http_access allow all

The IP address I want to enforce to use an username/password is 192.168.0.50
so have

acl restricted src 192.168.0.50/32

authenticate_program /usr/bin/ncsa_auth /usr/etc/passwd

acl passwd proxy_auth test_user
http_access allow passwd

Ive tried a few combinations and want to say

http_access deny restricted (unless they have provided a username/password)

I realise I could do something like this

acl all_subnets src "file.with.list.of.all.subnets"
acl passwd proxy_auth passwd

http_access allow all_subnets
http_access allow passwd
http_access deny all

But its not really going to be possible for me to list all the subnets for
internal reasons.

So the question is can I enforce proxy_auth for a certain IP address?

Thanks

Paul

-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.