ZyXEL Communications Prestige 792H, User Manual

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Prestige 792H User’s Guide
VPN Screens 14-17
Table 14-8 VPN IKE: Advanced
LABEL DESCRIPTION
Pre-Shared Key Type your pre-shared key in this field. A pre-shared key identifies a communicating
party during a phase 1 IKE negotiation. It is called "pre-shared" because you have to
share it with another party before you can communicate with them over a secure
connection.
Type from 8 to 31 case-sensitive ASCII characters or from 16 to 62 hexadecimal ("0-
9", "A-F") characters. You must precede a hexadecimal key with a "0x” (zero x),
which is not counted as part of the 16 to 62 character range for the key. For example,
in "0x0123456789ABCDEF", “0x” denotes that the key is hexadecimal and
“0123456789ABCDEF” is the key itself.
Both ends of the VPN tunnel must use the same pre-shared key. You will receive a
“PYLD_MALFORMED” (payload malformed) packet if the same pre-shared key is not
used on both ends.
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 .