netsh firewall add portopening TCP 3389 RDP enable subnet
netsh firewall add portopening UDP 3389 RDP enable subnet
netsh firewall add portopening TCP 3389 blah enable any
To disable the Windows Firewall enter: netsh firewall set opmode disable.
You can also manage a server core Firewall via the Firewall snap-in for MMC Vista and Server 2008
