router1(config)# ip nat inside source list 1 interface serial0 overload
router1(config)# interface Ethernet 0
router1(config-if)# ip address 160.10.1.1 255.255.255.0
router1(config-if)# ip nat inside
router1(config-if)# interface serial 0
router1(config-if)# ip address 175.10.1.1 255.255.255.0
router1(config-if)# ip nat outside
router1(config-if)# exit
router1(config)# access-list 1 permit 160.10.1.0 0.0.0 .255