Checking current IP from the command line in Linux

wget -q -O - checkip.dyndns.org | sed -e 's/[^0-9.]//g'

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