ZyXEL Communications ZYWALL 2 WG, User Manual

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Chapter 3 Wizard Setup
ZyWALL 2WG User’s Guide
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The following table describes the labels in this screen.
3.7 VPN Wizard 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.
Table 19 VPN Wizard: IPSec Setting
LABEL DESCRIPTION
Encapsulation Mode Tunnel is compatible with NAT, Transport is not.
Tunnel mode encapsulates the entire IP packet to transmit it securely. A Tunnel
mode is required for gateway services to provide access to internal systems.
Tunnel mode is fundamentally an IP tunnel with authentication and encryption.
Transport mode is used to protect upper layer protocols and only affects the
data in the IP packet. In Transport mode, the IP packet contains the security
protocol (AH or ESP) located after the original IP header and options, but before
any upper layer protocols contained in the packet (such as TCP and UDP).
IPSec Protocol Select the security protocols used for an SA.
Both
AH and ESP increase ZyWALL processing requirements and
communications latency (delay).
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.