I have a Windows XP Professional box, that runs Hamachi on it. The users that outside the office use Hamachi to get VPN access. I would like to secure the Remote Desktop access by limiting it to only the LAN users and users that are connected using Hamachi. Is that something that I can do on XP? If so, please tell how it's done. Thanks.
I'm assuming this machine is setup behind a firewall/nat device in which case your need to restrict access to the device is minimal. This also assumes you do not have NAT transversal ports open to the machine is question.
There is a good article on securing VNC in very much the same way that was posted on Life Hacker a couple of years ago Secure VNC with Hamachi. I'll just run through the items you need to do differently.
In Step 4 (which is detailed in the screenshots), instead of TightVNC Server, you will look for the Program/Service Remote Desktop.
When entering the Change Scope dialog, you will want to enter 192.168.1.0/255.255.255.0,126.96.36.199/255.0.0.0 (replacing 192.168.1.0 with your local subnet & mask)
That should get you access to the RDP Server via Hamachi and Local Lan only.