I've installed Strongswan on 2 Google Debian instances in separate projects (actually separate accounts) so there's no route between them on the internal ip's. Ultimately I need to allow VPN connection from outside the Google cloud. I'm pretty much there but can't get a ping to work, and I'm thinking it's due to a route/gateway problem as GC only has a single eth interface which has the internal ip assigned to it.
How do I set up the routing for this? And anything else that may help.