Hello,
I needed to setup jupyterhub on a cluster which - due to data security requirements and policy - the incoming connections to the compute resources in the private IP space from the submission host have to be restricted to a limited number of predefined ports on which the compute nodes can be reached.

I did not seem to be able to control that feature within the existing code for the batchspawner.
I solved the problem with the following change in a fork of the repo
pontiggi@50428e8
in which I added an additional option, configurable in jupyterhub_config.py , to set the port range for the spawned singleuser servers. something like for example
c.BatchSpawnerBase.ports = '40000-41000'

I was wondering if there was any other way already existing in the orignal code base to achieve the same goal, with some option I might have missed.
Or, if there is not such option, if you are interested in incorporating this in the upstream code. In which case I'll be happy to cleanup the code as needed according to your guidelines and open a pull request.

Thanks for any advise or feedback
Best
Francesco