Why can't I run OpenVPN on Windows from a non-admin user account?

NOTE: this article is very outdated. You have been able to run OpenVPN as a non-admin user on Windows for many, many years

Historically there have been two reasons:

• Windows does not provide a WHQL-approved method to allow the TAP-Win32 driver to make its virtual device node accessible from a non-admin account.
• OpenVPN needs the ability to add routes to the system routing table. This requires admin privileges.

For more information, see the article "How To Run OpenVPN as a non-admin user in Windows" by Mathias Sundman.