interface Ethernet0/0
 ip address 192.168.123.3 255.255.255.0
 ip nat inside
 

interface Ethernet0/1
 ip address 200.0.0.1 255.0.0.0
 ip nat outside

ip nat pool POOL 200.0.0.2 200.0.0.3 prefix-length 8
ip nat inside source list 1 pool POOL

access-list 1 permit 192.168.123.0 0.0.0.255