ZyWALL 2 Series User’s Guide

 

Table 14-8 Advanced IKE VPN Rule Setup

 

 

LABEL

DESCRIPTION

 

 

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.

 

 

Encapsulation

Select Tunnel mode or Transport mode from the drop-down list box.

 

 

Perfect Forward

Perfect Forward Secrecy (PFS) is disabled (NONE) by default in phase 2 IPSec SA setup.

Secrecy (PFS)

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

 

down list box 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).

 

 

Apply

Click Apply to save your changes back to the ZyWALL and return to the Edit VPN Rule

 

screen.

 

 

Cancel

Click Cancel to return to the Edit VPN Rule screen without saving your changes.

 

 

14.14Manual Key Setup

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

14.14.1Security 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 ZyWALL implementation assumes identical outgoing and incoming SPIs.

14.15Configuring Edit Manual Setup

To edit manual setup, click Edit in the VPN Rules screen to configure the VPN settings.

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VPN Screens