+--------------------------------+
                                   |           pfSense              |
+-------------------------+        |                                |    +---------------------------------------------+
|                         |        |                                |    |                                             |
|    Internet Host1:1883  +<------------------Outbound NAT N:1 <---------+    LAN-Host1:55555 SrcPort Outgoing (Random)|
|                         |        |                                |    |                                             |
+-------------------------+        |                                |    +---------------------------------------------+
                                   |                                |
                                   | Listening PublicIP:55555       |
                                   |                                |
+-------------------------------+  |                                |    +-------------------------------------+
|                               |  |                                |    |                                     |
| Internet Host2:12345 (Random) +-------->Inbound PortNAT+-------------> |    LAN-Host2:55555 DstPort Incoming |
|                               |  |                                |    |                                     |
+-------------------------------+  |                                |    +-------------------------------------+
                                   |                                |
                                   |                                |
                                   +--------------------------------+