interface GigabitEthernet0/0
 description Internet Facing Interface
 ip address 194.#.133.12 255.255.255.0
 ip access-group secure_internet_connection in
!
ip access-list extended secure_internet_connection
 permit gre any host 194.#.133.12
 permit esp any host 194.#.133.12
 permit ahp any host 194.#.133.12
 permit udp any host 194.#.133.12 eq isakmp