Great article!

I used similar technique in ASP/MS SQL web environment about 5 years ago, but I saved some resources and authenticated user's IP in ASP code rater than in MS SQL. I did it pretty much the same way, by comparing user's IP with what stored in the table as allowable range(s) of user IPs. It seemed to be a good method for consortium sites where site licence rater then individual logins are used and maintained.

Thanks, Galina.