..preferrably to apply to only specific ports.
PPTP uses port 1723/TCP, and requires
GRE protocol support in the Router. I doubt supporting this will be a problem for the Almond+, however I question the wisdom of using
PPTP in the first place, as it relies on Microsoft CHAPv2 which is inherently insecure, and can be compromised in under 4 hours, using freely available tools available on the Internet. See:
http://www.cloiudcracker.com.
IPSec or
OpenVPN would be far better (ie more secure) choices. IMHO PPTP is depreciated, and should
never be used by
anyone, regardless of their Operating System. (Microsoft's later OS entries support PPTP right "out of the box").
My opinion is not gospel, so feel free to make any choices you feel are suitable for your network. I would however recommend that you do a
Google search for "
PPTP insecurities", which will provide more that
1.7 Million results.
I personally do not recommend PPTP to anyone under any circumstances. It is completely insecure!