+ 0 Votes Nope gechurch Updated - February 28, 2013 at 10:31pm PST There's no way for a web server to do this to a client machine. If you want to control the users browser application you first need control of their PC. You'll need to install web filtering software on the users PCs before the fact. Even then, I doubt you will be able to do what you want. You can easily block all Internet traffic except to web site XYZ, but I don't think you will be able to block or allow access to other sites based on whether that user is at your site. Perhaps you could do some custom coding; write a helper program that monitors for traffic to website XYZ. When it sees it, it would change the settings on the Internet filtering software into "allow access to XYZ site only" mode. When the user closes out of the site your helper program sees the connection close and would set the Internet filtering software into "allow all" mode. This would be kludgly, would require the user to properly log out of the site (not just close the browser), would require XYZ site to have permissions to save a file to the users PC, and would require the content filter to have different profiles and allow programmatic switching of profiles to work. Best of luck to you making all of those things happen. I'd say it's at the least far more trouble than it's worth.