hello there
i implemented this kind of configuration at my network and it is working great.
first of all you should make acl's :
acl for your user B :
acl User-B src "/Admin/Squid/User-B"
acl for your user C :
acl User-C src "/Admin/Squid/User-C"
acl for the web-sites that user B can Access :
acl B-sites url_regex "/Admin/Squid/B-sites"
in the User-B acl file you should put the computer name of the computers that need access only to some sites
in the User-C acl file you should put the computer name of the computers that will have no access to the web
in the B-sites acl file you should put the
the sites that you wish to enable for user-B
Ok now that we have all the acl files ready we should put the http_acess Directive in the right formation try :
http_access deny User-C
http_access allow B-sites User-B
http_access deny User-B
good Luck !!
Sababa