How to tell what process has a specific port open on Linux?

netstat -lnp --inet inet -4 -6

lsof -i :123

Windows Firewall from the command line

netsh firewall show state

netsh firewall set opmode mode=DISABLE

netsh firewall set opmode mode=ENABLE exceptions=DISABLE

netsh firewall set opmode mode=ENABLE exceptions=ENABLE

More about it: http://support.microsoft.com/kb/947709