ZyXEL Communications Prestige 653HWI series, User Manual

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Prestige 653HWI Series User’s Guide
VPN Screens 17-17
Table 17-8 VPN IKE: Advanced
LABEL DESCRIPTION
Encryption Algorithm
Select DES or 3DES from the drop-down list box.
When DES is used for data communications, both sender and receiver must know
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.
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.
Key Group
You must choose a key group for phase 1 IKE setup. DH1 (default) refers to Diffie-
Hellman Group 1 a 768 bit random number. DH2 refers to Diffie-Hellman Group 2
a 1024 bit (1Kb) random number.
Phase 2
Active Protocol Use the drop-down list box to choose from
ESP or AH .
Encryption Algorithm
Select DES , 3DES or NULL from the drop-down list box.
When DES is used for data communications, both sender and receiver must know
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.
Select NULL to set up a tunnel without encryption. When you select NULL, you do
not enter an encryption key.