I want to use my database for saving users instead of Auth0 storage, but my DB may be available only in the subnetwork and I cannot make it public due to strong security requirements. Is there some way to use this feature for me? Maybe we can provide a connection throughout the VPN/IPsec tunnel or something?
I don’t think a VPN/tunnel would work well, you’d have to set it up each time a DB script is run (like a login or a registration).
The usual approach is to host an API on the same subnet as your DB, protect the API with security such as access tokens, or certificates, and invoke that API from the custom DB scripts.