MIB approach

Reverse mapping information can be obtained using the following command:

tools dump nat deterministic-mapping outside-ip <ipv4-address> router <router-instance> outside-port <[1..65535]>
 <ipv4-address>       : a.b.c.d
 <router-instance>    : <router-name> | <service-id>
                        router-name    - "Base"
                        service-id     - [1..2147483647]

Example:

tools dump nat deterministic-mapping outside-ip 10.0.0.2 router "Base" outside-port 2333 

Output:

Inside router 10 ip 10.0.5.171 -- outside router Base ip 10.0.0.2 port 2333 at Mon Jan 7 10:02:02 PST 2013