This network is allocated to be used from IETF only. So I don't think it should be detected from a NAT check, it is not meant to be used as a source or destination.
+----------------------+---------------------------------+ | Attribute | Value | +----------------------+---------------------------------+ | Address Block | 192.0.0.0/24 [2] | | Name | IETF Protocol Assignments | | RFC | Section 2.1 of this document | | Allocation Date | January 2010 | | Termination Date | N/A | | Source | False | | Destination | False | | Forwardable | False | | Global | False | | Reserved-by-Protocol | False | +----------------------+---------------------------------+