ZyWALL 2 and ZyWALL 2WE

 

Table 27-8 Advanced IKE VPN Rule Setup

LABEL

DESCRIPTION

 

 

 

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

Authentication

(Secure Hash Algorithm) are hash algorithms used to authenticate packet data. The

Algorithm

SHA1 algorithm is generally considered stronger than MD5, but is slower. Select MD5

 

for minimal security and SHA-1for maximum security.

 

 

 

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

 

range from 60 to 3,000,000 seconds (almost 35 days). A short SA Life Time increases

SA Life Time

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 Secrecy (PFS) is disabled (None) by default in phase 2 IPSec SA

Perfect Forward

setup. This allows faster IPSec setup, but is not so secure. Choose from DH1 or DH2 to

enable PFS. DH1 refers to Diffie-Hellman Group 1, a 768 bit random number. DH2

Secrecy (PFS)

refers to Diffie-Hellman Group 2, a 1024 bit (1Kb) random number (more secure, yet

 

 

slower).

 

 

Basic

Click Basic to go to the previous VPN configuration screen.

 

 

Click Apply to save your changes. Click Reset to begin configuring this screen afresh.

27.12Manual Key Setup

Manual key management is useful if you have problems with IKE key management.

27.12.1Security Parameter Index (SPI)

An SPI is used to distinguish different SAs terminating at the same destination and using the same IPSec protocol. This data allows for the multiplexing of SAs to a single gateway. The SPI (Security Parameter Index) along with a destination IP address uniquely identify a particular Security Association (SA). The SPI is transmitted from the remote VPN gateway to the local VPN gateway. The local VPN gateway then uses the network, encryption and key values that the administrator associated with the SPI to establish the tunnel.

Current ZyXEL implementation assumes identical outgoing and incoming SPIs.

27.13Configuring Edit Manual Setup

To edit manual setup, select one of the VPN rules in the VPN Summary screen and click Edit to configure the rule’s settings. The basic IKE rule setup screen opens

27-20

VPN/IPSec Setup