Open WIFI often allow only traffic via http and https ports. This gist contains steps to allow you to ssh to a machine by first creating a VM, switching the ssh port to listen to port 80. So now, you can ssh (port 80) into the VM, in order to ssh (port 22) into your desired machine.
original gist by guillochon, this Fork contains reformatted steps, and I switched OS from CentOs to Ubuntu... just as an exercise to get famaliarized with GCP.
https://gist.github.com/guillochon/eeaa54b328952d260472c14c559f698a