ZyXEL Communications P-662HW-61 User Manual page 235

Prestige 662HW Series User's Guide
Table 73 VPN IKE: Advanced Setup (continued)
LABEL
End
Phase 1
Negotiation Mode
Pre-Shared Key
Encryption
Algorithm
Authentication
Algorithm
SA Life Time
(Seconds)
Key Group
Phase 2
Active Protocol
235
DESCRIPTION
Enter a port number in this field to define a port range. This port number must be
greater than that specified in the previous field. If Remote Start Port is left at 0,
End will also remain at 0.
Select Main or Aggressive from the drop-down list box. Multiple SAs connecting
through a secure gateway must have the same negotiation mode.
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.
Select DES, 3DES or AES 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 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.
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.
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.
Use the drop-down list box to choose from ESP or AH.
Chapter 19 VPN Screens