Terminal Services Gateway

We were looking for some solution where we can centralize every RDP session coming from outside (especially for vendor access), and we ended up with 2 choices: Citrix or Terminal Services Gateway (now known as Remote Desktop Services Gateway). Considering we already have licenses for Terminal Services, we are taking the latter. If you don't know what it is, here's a brief explanation.

Windows Server Terminal Services uses Remote Desktop Protocol (RDP) to enable the connections from clients to the terminal server, which uses port 3389. If you need to access a terminal server from outside the internal network (intranet), you have two options for doing so. You can either enable port 3389 through your firewall to specific servers (which isn’t a good idea), or, more commonly, clients connect to the corporate network via VPN, which can then enable the RDP session in a secure manner.