VPN

VPN: encapsulating the communication between the two PC’s in an encrypted tunnel that uses strong encryption methods.

IPsec (Internet Protocol Security), is a set of protocols define by the Internet Enginering Task Force (IETF) to provide IP security at the network layer.

IPsec

IPSec based VPN made up of two parts:

• 1. IKE Internet Key Exchange protocol
• 2. ESP Encapsulating Security Payload - IPsec protocols

IKE ist the initial negotiation phase,..
two endpoints agree on whitch methods will be used to provide security for the IP traffic
IKE is used to manage connections, by defining a set of SA (Security Associations)
one SA for each connection.
SAs are unidirectional, ... there are least two for each IPsec connection.