__________       __________                                         _______                                     ___________ 
  /          \     /          \                                       /       \                                   /           \
 | PREROUTING |-->| PREROUTING |--> Routing  ----------------------->| FORWARD |-------------------------------->| POSTROUTING |-->
 |   mangle   |   |   d-nat    |    Decision                         |         |                                 |    s-nat    |
  \__________/     \__________/                                       \_______/                                   \___________/
                                        |                                                                              |
                                        |                                                                              |
                                        |                                                                              |
                                        |                                                                              |
                                        |     _____      _______       ______       ______                   ______    |
                                        |    /     \    |       |     /      \     /      \                 /      \   |
                                        |-->| INPUT |-->| Local |--> | OUTPUT |-->| OUTPUT |--> Routing -->| OUTPUT |--|
                                            |       |   |_______|    | mangle |   | d-nat  |    Decision   |        |    
                                             \_____/                  \______/     \______/                 \______/