Prestige 334W User’s Guide

 

 

Table 16-8 VPN IKE: Advanced

 

 

 

 

 

LABEL

DESCRIPTION

 

 

 

 

 

 

 

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

 

 

Authentication

SHA1 (Secure Hash Algorithm) are hash algorithms used to authenticate packet

 

 

Algorithm

data. The SHA1 algorithm is generally considered stronger than MD5, but is

 

 

 

slower. Select MD5 for minimal security and SHA-1 for 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

 

 

SA Life Time

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.

 

 

 

 

 

 

 

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

 

 

Perfect Forward

SA 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

 

 

Secrecy (PFS)

 

 

number. DH2 refers to Diffie-Hellman Group 2, a 1024 bit (1Kb) random number

 

 

 

 

 

 

(more secure, yet slower).

 

 

 

 

 

 

Basic

Select Basic to go to the previous VPN configuration screen.

 

 

 

 

 

 

Apply

Click Apply to save your changes.

 

 

 

 

 

 

Reset

Click Reset to begin configuring this screen afresh.

 

 

 

 

 

16.13Manual Key Setup

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

16.13.1Security 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.

VPN Screens

16-25