I assume you're using Apache from the mention of httpd.conf, in which case you're looking for this. I've never implemented it myself I'm afraid.
One thing to be cautious of is proxy servers -- everyone on the same ISP may look like they're coming from one IP address. One way to mitigate this is to put the downloads you want to limit on a port number other than 80 (8080 is common). That will fix it for users behind a transparent proxy, and only leave problems for users who have explicit proxies assigned. There's not much you can do about those unless you want to implement a cookie-based system of some sort yourself.
Last edited by Tuttle; May 10th, 2005 at 09:51 AM.
Safe computing is a habit, not a toolkit.