14-27

 

ZyWALL 2 Series User’s Guide

 

Table 14-8 Advanced IKE VPN Rule Setup

 

 

LABEL

DESCRIPTION

 

 

Authentication

Select SHA1 or MD5 from the drop-down list box. MD5 (Message Digest 5) and SHA1

Algorithm

(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-1for maximum security.

 

 

SA Life Time

Define the length of time before an IKE SA automatically renegotiates in this field. It may

(seconds)

range from 180 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.

 

 

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.

 

 

Phase 2

 

 

 

Active Protocol

Use the drop-down list box to choose from ESP or AH.

 

 

Encryption

This field is available when you select ESP in the Active Protocol field.

Algorithm

Select DES, 3DES, AES or NULL 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 NULL to set up a tunnel without encryption. When you select NULL, you do not

 

enter an encryption key.

 

 

Authentication

Select SHA1 or MD5 from the drop-down list box. MD5 (Message Digest 5) and SHA1

Algorithm

(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-1for maximum security.

 

 

VPN Screens