Allowing Specific Dynamic IPs

Dec. 20, 2009, 10:01 a.m.

While working on this site, I was faced with an interesting problem. There are certain management-related parts of this site which I want to only be accessible from my computer. Usually, a web developer would use an apache .htaccess file to achieve this, by allowing traffic only from a certain IP. The problem is that I have a dynamically assigned IP address from my ISP. It doesn't change often, but it does change sometimes. It would be a pain to have to update the .htaccess file any time my IP address changed. Then I remembered that my router is configured to update to a dynamicDNS address. Using PHP's gethostbyname function, I did a reverse look-up on my dyndns address, and checked to see if it matched the IP address of the visitor. If it did, I would allow access, otherwise I would deny it. For other people with dynamic IP addresses, you might want to try this out if you ever need to control access to your site.