IPSec [12] provides a set of security services that include access control, data origin authentication and confidentiality. IPSec operates in two modes: (a) Transport Mode where only the payload (the actual data to transfer) of an IP packet is authenticated and encrypted. This mode is appropriate for host to host communication, (b) Tunnel Mode where the entire packet (data and header) is encrypted and authenticated. It is suitable for inter-network communication, remote user access and for inter-host communication. IPSec provides traffic security by using three major protocols: