Here I am going to explain, how to enable Key and Password based authentication in linux instances of Google Cloud. This can be applied on other Cloud or standalone Linux instances. But do check manuals 🙂
When i say Key + Password, I am not referring passphrase which we give while created Private/Publich SSH key. I am referring to multiple auth methods where system will be first authenticated via PubKey and then via Password.
If your Pubkey is not matching it won’t allow you to login. If password not matching then also it won’t allow you to login. You must use exact same credentials which you configured.
I am not explaining here how to create SSH keys or password, I am assuming you already know that.