Ike - 3Com VCX v7111 User Manual

IPSec does not function properly if the gateways IP address is changed on-the-fly
due to the fact that the crypto hardware can only be configured on reset. Therefore,
reset the gateway after you change its IP address.

IKE

IKE is used to obtain the Security Associations (SA) between peers (the gateway and the
application its trying to contact). The SA contains the encryption keys and profile used by the
IPSec to encrypt the IP stream. The IKE table lists the IKE peers with which the gateway
performs the IKE negotiation (up to 20 peers are available).
The IKE negotiation is separated into two phases: main mode and quick mode. The main
mode employs the Diffie-Hellman (DH) protocol to obtain an encryption key (without any prior
keys), and uses a pre-shared key to authenticate the peers. The created channel secures
the messages of the following phase (quick mode) in which the IPSec SA properties are
negotiated.
The IKE negotiation is as follows:
Main mode (the main mode creates a secured channel for the quick mode)
SA negotiation: The peers negotiate their capabilities using two proposals. Each
proposal includes three parameters: Encryption method, Authentication protocol and
the length of the key created by the DH protocol. The keys lifetime is also negotiated
in this stage. For detailed information on configuring the main mode proposals, see
IKE Configuration.
Key exchange (DH): The DH protocol is used to create a phase-1 key.
Authentication: The two peers authenticate one another using the pre-shared key
(configured by the parameter IKEPolicySharedKey).
Quick mode (quick mode negotiation is secured by the phase-1 SA)
SA negotiation: The peers negotiate their capabilities using a single proposal. The
proposal includes two parameters: Encryption method and Authentication protocol.
The lifetime is also negotiated in this stage. For detailed information on configuring
the quick mode proposal, see the SPD table under
Key exchange: a symmetrical key is created using the negotiated SA.
IKE Specifications include:
Authentication mode - pre-shared key only
Main mode is supported for IKE Phase 1
Supported IKE SA encryption algorithms - Data Encryption Standard (DES), 3DES, and
Advanced Encryption Standard (AES)
Hash types for IKE SA - SHA1 and MD5
322
IPSec Configuration.
®
3Com VCX V7111 VoIP Gateway User Guide