I've never tried this, but could you enable access from a given hostname rather than IP address, and then use a dynamic DNS system like http://www.noip.com/ htt

I've never tried this, but could you enable access from a given hostname rather than IP address, and then use a dynamic DNS system like http://www.noip.com/ http://www.noip.com/ to automatically update a hostname when your IP address changes? Two downsides I can see are that a) you would be vulnerable to DNS poisoning attack on the server side, but that would be the equivalent to just opening it up to all IPs, and b) dynamic DNS systems can take a short while to refresh the DNS record and/or it can get cached by your servers up-stream DNS servers. Some tinkering with your server to make it always use the authoritive DNS servers for your dynamic DNS hostname would help with that. I'm just thinking out loud, I've never tried any of that!