ZyXEL Communications P-661H Series, Руководство пользователя, Страница: 216 / 383

P-661H/HW Series User’s Guide
216 Chapter 13 VPN Screens
13.12 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 125 Two Phases to Set Up the IPSec SA
In phase 1 you must:
• Choose a negotiation mode.
• Authenticate the connection by entering a pre-shared key.
• Choose an encryption algorithm.
Encryption
Algorithm
Select DES , 3DES , AES or NULL from the drop-down list box.
When you use one of these encryption algorithms for data communications, both
the sending device and the receiving device must use the same secret key, which
can be used to encrypt and decrypt the message or to generate and verify a
message authentication code. 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. This implementation of AES uses
a 128-bit key. AES is faster than 3DES .
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 SHA1 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 ZyXEL Device.
Cancel Click Cancel to begin configuring this screen afresh.
Table 84 Edit VPN Policies
LABEL DESCRIPTION