Use the netsh advfirewall command. For example, to enable remote management from any MMC snap-in, type the following:

netsh advfirewall firewall set rule group=”Remote Administration” new enable=yes

After installing Windows Server 2008 Core you might want to disable the integrated firewall. You can perfom that by using the following command:

netsh firewall set opmode mode=disable
This disables the integrated firewall completely and should only be used in isolated environments, e. g. you have a corporate firewall or the core server stands in an isolated test environment.