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Chapter 3 Wizard Setup
ZyWALL 2WG User’s Guide
92
Figure 30
VPN Wizard: IKE Tunnel Setting
The following table describes the labels in this screen.
Table 18
VPN Wizard: IKE Tunnel Setting
LABEL
DESCRIPTION
Negotiation Mode
Select
Main Mode
for identity protection. Select
Aggressive Mode
to allow
more incoming connections from dynamic IP addresses to use separate
passwords.
Note: Multiple SAs (security associations) connecting through a
secure gateway must have the same negotiation mode.
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
.
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.
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.
DH5
refers to Diffie-Hellman Group 5
a 1536-bit random number.
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.