[stunnel-users] Username authentication

I want to try to use stunnel as a "simple" client vpn. It solves all of my encryption issues but I would like to verify a username/password before it lets the traffic through. I didn't see any patches or hacks out there that did this. Has this been attempted before or am I on my own. I would also be interested in other solutions based on openssl that are not network device level VPNs clients. Already using client side certificates and I know that is the normal SSL authentication mechanism.... Thanks. -Joe