Blocking only one site of a Domain with SQUID

Hello everyone,

I'd like to know how to block just one site of a domain using squid.


Example:


I want to give access to all sites of the "mydomain.org" domain, except

the xxx site.
So, the following sites would be accessible:


www.mydomain.org
intranet.mydomain.org
cbs.mydomain.org
top.mydomain.org
......


But the following site would be blocked:


xxx.mydomain.org


How could I do this?


Thanks!