ZyXEL Communications ZyXEL ZyWALL 5 - Manual (Page 81)

ZyWALL 5 User’s Guide
80 Chapter 3 Wizard Setup
3.3.4 VPN Status Summary
This read-only screen shows the status of the current VPN setting. Use the summary table to
check whether what you have configured is correct.
Encryption Algorithm 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. 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
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. The minimum value is 180 seconds.
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.
Perfect Forward
Secret (PFS)
Perfect Forward Secret (PFS) is disabled (None) by default in phase 2 IPSec
SA setup. This allows faster IPSec setup, but is not so secure.
Select DH1 or DH2 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.
Next Click Next to continue.
Table 15 VPN Wizard : IPSec Setting (continued)
LABEL DESCRIPTION