In situations when you unable to connect to remote WS 2008 box via RDS due to Windows Firewall being enabled without inbound RDS rule enabled you may try to enable required firewall rule remotely.
If PS on machine in question is configured for remoting you may open remote PS session on this machine, using following command:
enter-pssession -computername REMOTE_COMPUTER_NAME
If remote PS session opened successfully you may run both PS commands and regular CLI commands for remote machine there. To check inbound RDS rule for Windows firewall use:
netsh advfirewall firewall show rule name=”Remote Desktop (TCP-IN)”
If this role not enabled issue following command to enable it:
netsh advfirewall firewall set rule name=”Remote Desktop (TCP-IN)” new enable=yes
Starting with Windows Server 2012 you may control Windows Firewall with PS commandlets which is much more convenient and easier.