Not sure I understand the use case here.
You are looking for a way to pass an IP address and get the returned hostname and put it in a FlowFile attribute?
The QueryDNS does not require any additional "special permissions" to use it. I have never tried using this processor myself.
There are no other DNS specific processor designed to perform such task, you could need utilize the executeStreamCommand, ExecuteScript, or ExecuteGroovyScript processors to execute the system level command to return your reverse DNS lookup results.
Execute based processor will require an additional layer of authorization since the processor is executed like every other processor as the NiFi service user (this means that ANY access the NiFi service user has will be accessible by the NiFi dataflow using these processors).
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