ZyWALL 2 Series User’s Guide

Table 37-3Menu 27.1.1.1: IKE Setup

FIELD

DESCRIPTION

EXAMPLE

 

 

 

Encryption

When DES is used for data communications, both sender and receiver must

DES

Algorithm

know the same secret key, which can be used to encrypt and decrypt the

 

 

message or to generate and verify a message authentication code. ZyWALL

 

 

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

MD5 (Message Digest 5) and SHA1 (Secure Hash Algorithm) are hash

SHA1

Algorithm

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

Define the length of time before an IKE Security Association automatically

28800

(Seconds)

renegotiates in this field. It may range from 180 to 3,000,000 seconds (almost

(default)

 

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

DH1

 

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

Press [SPACE BAR] to choose from ESP or AH and then press [ENTER]. See

ESP

 

earlier for a discussion of these protocols.

 

Encryption

Press [SPACE BAR] to choose from NULL, DES, 3DES or AES and then

DES

Algorithm

press [ENTER]. Select NULL to set up a tunnel without encryption.

 

Authentication

Press [SPACE BAR] to choose from SHA1 or MD5 and then press [ENTER].

MD5

Algorithm

 

 

 

 

 

SA Life Time

Define the length of time before an IPSec Security Association automatically

28800

(Seconds)

renegotiates in this field. It may range from 180 to 3,000,000 seconds (almost

(default)

 

35 days).

 

 

 

 

VPN/IPSec Setup

37-13