g-suiteoauthopenvpn
Or, maybe any oauth?
All I could find – is 2factor authentication with google.
But I'd like to use Google Apps base for OpenVPN auth.
I believe that it is possible to make something like gitlab. Where you can put your certificate and then use it without login and password.
It's not possible.
Client certificates have to be created by a ca the openvpn server trusts.
Update:
I now had a look at the eFive docs. It seems like eFive OpenVPN Appliance only supports password authentication for clients.
OpenVPN supports client certificates, password authentification and using both together.
And, as I saw looking at the RUT550 docs: PreShared-Key auth, which is not a solution for your problem.
So the answer is: Your devices are both based on OpenVPN, but they are not compatible.
For creating client certs you need the private key (not just the public certificate) of the CA.
I assume You have downloaded an .ovpn file with the information about the vpn.
Create a file in the same folder called auth.txt and insert in its first line the username of your vpn login, in second line the vpn password, e.g.:
admin
master
Save the file and close it. Edit Your .ovpn file: find the line starting with auth-user-pass and add auth.txt. Save the file and close it.
I would write the full path to auth.txt e.g. auth-user-pass /etc/openvpn/auth.txt but (at least on Ubuntu) it also works with just the filename, if in the same folder.
Now You should be able to call sudo openvpn <.ovpn file> without providing credentials (apart from the sudo password).
I based information on here and here
There is a small note how to autorun scripts on system boot: here
Best Answer
While looking for a solution for this I came across Gate. It automates OpenVPN profile creation behind OAuth and supports MFA. It's also got an admin console for user management. Here is a blog post from the developers outlining its use-case and features.
UPDATE 06/2019 - Pritunl is now my go-to solution for this. It supports automatic OpenVPN profile generation behind Google Auth, and provides a cross-platform client that makes setup easy with unique URI's. The user doesn't auth with Google to connect (a PIN can be required) which could be a downside for some, but I find the ease of use great for smaller teams.