IPsec Negotiation Using the IKE Protocol
IKE negotiates IPsec tunnels between two IPsec peers. This negotiation can be done using a combination of main-mode and quick-mode exchanges or a combination of aggressive-mode and quick-mode exchanges. This section looks at the various packets and message types that are used in these exchanges to do the negotiation. We will look at three types of negotiations that IKE carries out:
Main mode using preshared key authentication followed by quick-mode negotiation
Main mode using digital signature authentication followed by quick-mode negotiation
Aggressive mode using preshared key authentication followed by quick-mode negotiation
In addition to these types, the following types of negotiations can also take ...