Service Ports?

I noticed that there is a tab called “Ports” in the firewall section of winbox. Some of the options (h323, gre, pptp) were disabled and I was wondering what that meant? I have been having some trouble with a customers VPN, and was wondering if by enabling these options it might fix the issue? If this might fix the problem do I have to enable the service port for each router gre/vpn traffic moves across?

Does anyone know what the service ports do and how they work?

I use a 1-1 NAT setup on my network if this makes any difference.

Thanks,
Ken

These are NAT helpers to provide correct NAT traversal
http://www.mikrotik.com/docs/ros/2.8/ip/conserv||0.7552533992583437

Thanks for the link to the documentation. I have already read the documentation and I don’t feel that it explains how the NAT “helpers” work and when to use them.

Thanks,
Ken