P-662H/HW-D Series User’s Guide

 

Table 95 Advanced VPN Policies

 

 

 

 

LABEL

DESCRIPTION

 

 

 

 

Authentication

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

 

Algorithm

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-1for maximum security.

 

SA Life Time

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

 

(Seconds)

It may range from 60 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

 

Secrecy (PFS)

SA setup. 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 ZyXEL Device and return to the

 

 

VPN-IKE screen.

 

Cancel

Click Cancel to return to the VPN-IKEscreen without saving your changes.

 

 

 

16.14 Manual Key Setup

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

16.14.1 Security 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.

16.15 Configuring Manual Key

You only configure VPN Manual Key when you select Manual in the IPSec Key Mode field on the VPN IKE screen. This is the VPN Manual Key screen as shown next.

Chapter 16 VPN Screens

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