You want to do two things:
1. Use a packet filter to force them to use the proxy and not go around it.
2. Use the proxy to them control the content.
A proxy alone can always be avoided by calling the site directly.
-MZ
-- Livingston Enterprises - Chair, Department of Interstitial Affairs Phone: 800-458-9966 510-737-2100 FAX: 510-737-2110 megazone@livingston.com For support requests: support@livingston.com <http://www.livingston.com/> Snail mail: 4464 Willow Road, Pleasanton, CA 94588