Scenario
machine A (192.168.100.1) provides resource A on port 8888
machine B (192.168.200.1) needs to access resource A
without modifying machine B (not allowed), create machine C and have any traffic to machine C on port 8888 forwarded to machine A. Then tell machine B that machine C is machine A and nobody is the wiser. None of the examples I found online had this working properly.