DirectAccess and NAT
If you did, and you tried to use UAG, you were welcomed to a big disappoint, because that scenario just wasn’t support. So while you would have loved to have DirectAccess, there was no way you could support the public IP address requirement.
The good news is that with Windows Server 2012 you can!
Check out this article by Richard Hicks’ who gives you the details:
DEBRA LITTLEJOHN SHINDER
MVP (Enterprise Security)