Please append a EAP-TLS authentication support into ppp. I would use smart card/certificate authentication form for IPSec client configuration with openswan and pppd on server side. There is existing project that adds EAP TLS support for current versions of pppd with homepage http://www.nikhef.nl/~janjust/ppp/ . thanks
*** This bug has been marked as a duplicate of bug 556407 ***