interface ethernet 0
ip address 10.28.40.1 255.255.255.0
ip nat inside
!
!
interface serial 0
ip address 155.332.72.178 255.255.255.252
ip nat outside
!
! 
ip nat pool ovrld 55.165.110.2 55.165.110.2 prefix 24
!
!
ip nat inside source list 7 pool ovrld overload 
!
!
access-list 7 permit 10.28.40.0 0.0.0.255