ZyXEL Communications Internet Security Gateway ZyWALL 100, User Manual

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ZyWALL Series Internet Security Gateway
VPN Screens 15-19
Table 15-7 VPN IKE
LABEL DESCRIPTION
Encryption
Algorithm Select DES , 3DES , AES or NULL from the drop-down list box.
The ZyWALL and the remote IPSec router generate an encryption key from the
Diffie-Hellman key exchange. The DES encryption algorithm uses a 56-bit key. Triple
DES (
3DES ) is a variation on DES that uses a 168-bit key. As a result, 3DES is more
secure than DES . It also requires more processing power, resulting in increased
latency and decreased throughput. AES uses a 128-bit key. AES is faster than 3DES
and provides a similar level of security.
Select NULL to set up a tunnel without encryption. When you select NULL , you do
not enter an encryption key.
Authentication
Algorithm Select SHA1 or MD5 from the drop-down list box. MD5 (Message Digest 5) and
SHA1 (Secure Hash Algorithm) are hash algorithms used to authenticate packet
data. The SHA1 algorithm is generally considered stronger than MD5 , but is slower.
Select MD5 for minimal security and SHA-1 for maximum security.
Advanced Click Advanced to configure more detailed settings of your IKE key management.
Apply Click Apply to save your changes back to the ZyWALL.
Reset Click Reset to begin configuring this screen afresh.
15.12 IKE Phases
There are two phases to every IKE (Internet Key Exchange) negotiation – phase 1 (Authentication) and phase
2 (Key Exchange). A phase 1 exchange establishes an IKE SA and the second one uses that SA to negotiate
SAs for IPSec.
Figure 15-6 Two Phases to Set Up the IPSec SA