ZyXEL Communications Prestige 661H Series, User Manual

Page: 407 / 547

Prestige 661H/HW Series User’s Guide
407 Chapter 42 VPN/IPSec Setup
Figure 263
Menu 27.1.1.1KE Setup
The following table describes the fields in this menu.
Menu 27.1.1.1 - IKE Setup
Phase 1
Negotiation Mode= Main
PSK=
Encryption Algorithm = AES
Authentication Algorithm = SHA1
SA Life Time (Seconds)= 28800
Key Group= DH1
Phase 2
Active Protocol = ESP
Encryption Algorithm = AES
Authentication Algorithm = MD5
SA Life Time (Seconds)= 28800
Encapsulation = Tunnel
Perfect Forward Secrecy (PFS)= None
Press ENTER to Confirm or ESC to Cancel:
Table 139 Menu 27.1.1.1 IKE Setup
FIELD DESCRIPTION
Phase 1
Negotiation
Mode
Press [SPACE BAR] to choose from Main or Aggressive and then press [ENTER].
See earlier for a discussion of these modes. Multiple SAs connecting through a
secure gateway must have the same negotiation mode.
PSK Prestige gateways authenticate an IKE VPN session by matching pre-shared keys.
Pre-shared keys are best for small networks with fewer than ten nodes. Enter your
pre-shared key here. Enter up to 31 characters. Any character may be used, including
spaces, but trailing spaces are truncated.
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
The Prestige and the remote IPSec router generate an encryption key from the Diffie-
Hellman key exchange. Prestige 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 slightly
increased latency and decreased throughput.
This implementation of
AES uses a 128-bit key. AES is faster than 3DES .
Press [SPACE BAR] to choose from DES , 3DES or AES and then press [ENTER].
Authentication
Algorithm
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 slightly slower.
Press [SPACE BAR] to choose from SHA1 or MD5 and then press [ENTER].
SA Life Time
(Seconds)
Define the length of time before an IKE Security Association 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.