How to use Screen Sharing if I don't know the remote Mac's IP address I have the credentials for the Mac, but there is nobody in the room with the machine to check the public IP address.



If I know the public IP, I can connect to the mac. Unfortunately the ISP provides only dynamic IPs, so I guess it changed recently.

Is there any other way to gain access?
Ah! Yeah... your options at this point are limited. The ISP might help you as it's their DHCP that assigned the address; they'd be the only ones that would know that. 

This has happened to me, and as my ISP is comcast, there is no help. 

In the future :), what you need is "Dynamic DNS"; available free from several sources. I use FreeDNS. It's kind of funky, but seems to work reliably. 

The other alternative (to dynamic DNS) is a "roll your own" approach that would require some script-writing on your part. If you're up for that, let me know &amp; we'll go from there.