"SSL-based VPNs were designed to eliminate the need for complex configurations on the user's PC. Unfortunately, that was before the dangers of public WiFi networks and tougher regulatory requirements came into being. Thanks to WiFi, many attacks that were difficult are now quite simple. In particular, a man-in-the-middle attack can intercept SSL-encrypted traffic, rendering SSL-based VPNs useless - even if it's protected by a typical one-time password system. The man-in-the-middle can easily feed the one-time password into the SSL-based VPN within the alloted time.
"In order to thwart this attack, mutual authentication is required. Mutual authentication means that the user is validated to the site and the site is validated to the user..."
