I think that question most scary one for linux community because Ive asked same question in many forums unfortunately still no answer!! I dont think linux uncapable to do this. If I can not find solution for that I am gonna say bye bye linux for our servers.. I hope some one in there knows the answer of question below. Regards Question: I am using Ubuntu Server 8.04+Squid+Dansguardian for filtering our school's internet. Recently I can give permission to the machine IPs so they can access to the internet without limitation of dansguardian. Ip based permission is not usefull and I need user based permission but dansguardian needs something for that (I think LDAP). My Active Directory Domain controllers have Win 2003 Enterprise. If I make it more clear certain users should pass dansguardian filtering does not matter which ever machine they logged in.