The Cisco Easy VPN Remote feature provides for automatic management of the following details:
Negotiating tunnel parameters, such as addresses, algorithms, and lifetime.
Establishing tunnels according to the parameters that were set.
Automatically creating the NAT or Port Address Translation (PAT) and associated access lists that are needed, if any.
Authenticating users, that is, ensuring that users are who they say they are by way of usernames, group names, and passwords.
Managing security keys for encryption and decryption.
Authenticating, encrypting, and decrypting data through the tunnel.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t15/ftezvpnr.htm
