关键语句

!ACCESS-GROUP FOR WAN INTERFACE

ip access-list extended IN_ACL

 permit tcp any any eq 143 log



!ACL TO MATCH THE FLOW

ip access-list extended REVERSE_PROXY

 permit tcp any any eq 143


!FastEthernet0/0 is a LAN interface

ip nat source list REVERSE_PROXY interface FastEthernet0/0 overload


!NAT PORT MAPPING TO WAN FastEthernet0/1

ip nat source static tcp 192.168.4.X 143 interface FastEthernet0/1 143


!NAT client's source ip to the ip of LAN interface

ip nat source list REVERSE_PROXY interface FastEthernet0/0 overload