Redirect "Almost" All IPs to a Static HTML Page

Hi guys,

I realize this isn’t a WPMU Dev (or even a WPMU) question, but I’m hoping someone more familiar with PHP or htaccess can help me out.

I have a WordPress site in development (mysite.com). Although the site is in development, having it “online” makes it easier to collaborate with others who are working on the project with me from different locations. We’re ready to start doing some early promotion and have created a temporarily static page at (mysite.com/index.html) to capture leads, provide basic info, etc. I’d like to use either php (in the generic WordPress index.php file perhaps) or the htaccess file to redirect all visitors who’s IP addresses do not appear on a short list.

If this were just a logical statement, it would be “If IP address is not IP1, IP2 or IP3, redirect to mysite.com/index.html, else view the site normally”. What would be the simplest way to achieve this goal?

Thanks