User's Manual

Chapter 14 VPN
P-2612HW Series User’s Guide
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Phase 2
Active Protocol Use the drop-down list box to choose from ESP or AH.
Encryption
Algorithm
This field is available when you select ESP in the Active Protocol
field.
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 SHA-1 for maximum security.
SA Life Time
(Seconds)
Define the length of time before an IKE SA automatically renegotiates
in this field. It may range from 60 to 3,000,000 seconds (almost 35
days).
A short SA Life Time increases security by forcing the two VPN
gateways to update the encryption and authentication keys. However,
every time the VPN tunnel renegotiates, all users accessing remote
resources are temporarily disconnected.
Encapsulation Select Tunnel mode or Transport mode from the drop-down list box.
Perfect Forward
Secrecy (PFS)
Perfect Forward Secrecy (PFS) is disabled (NONE) by default in phase
2 IPSec SA setup. This allows faster IPSec setup, but is not so secure.
Choose DH1 or DH2 from the drop-down list box to enable PFS. DH1
refers to Diffie-Hellman Group 1 a 768 bit random number. DH2 refers
to Diffie-Hellman Group 2 a 1024 bit (1Kb) random number (more
secure, yet slower).
Back Click Back to return to the previous screen.
Apply Click Apply to save your changes back to the ZyXEL Device and return
to the VPN-IKE screen.
Cancel Click Cancel to return to the VPN-IKE screen without saving your
changes.
Table 83 Security > VPN > Setup > Edit > Advanced Setup (continued)
LABEL DESCRIPTION