Atmosphere uses a standard OpenStack security group rule set to govern default Atmosphere access. By default, Atmosphere limits the privileged ports (under port 1024) to
Though these ports are accessible, that doesn’t mean anything is running there. On Jetstream Featured images, typically the only listener running is sshd – which is required both for deployment and access to the VM.
In non-privileged ports (over 1024), there are no restrictions placed by Atmosphere. Typically, the only ports you might find open above 1024 will be the Xvnc ports for the web desktop functionality.
Some instances like the R and Shiny Server instance will have port 3838 open.
It is unlikely that other ports under 1024 will be opened upon request.