The include? function for the IPRange class has an issue processing an input IPRange:
https://github.com/rapid7/nexpose-client/blob/master/lib/nexpose/site.rb#L726

You cannot pass a string or a Ruby IPAddr object in to the include? function because those classes do not respond_to? :from which means the include? function short-circuits immediately.

It looks like the include? function wants an IPRange object as input because it uses the to and from functions. However, passing in an IPRange object results in this stack trace:

It looks like this line causes the issue:
https://github.com/rapid7/nexpose-client/blob/master/lib/nexpose/site.rb#L726

I tested this with Gem 5.0.0 and 3.2.2 using Ruby 2.2.1.