ZyXEL Communications VANTAGE CNM - V3.1 User Manual page 262

Chapter 12 VPN Community
Table 124 VPN Management > VPN Community > Add/Edit (continued)
FIELD
Perfect Forward
Secret (PFS)
Enable Replay
Detection
Enable Multiple
Proposals
Apply
Cancel
262
DESCRIPTION
Select whether or not you want to enable Perfect Forward Secrecy (PFS)
and, if you do, which Diffie-Hellman key group to use for encryption. Choices
are:
NONE - disable PFS
DH1 - enable PFS and use a 768-bit random number
DH2 - enable PFS and use a 1024-bit random number
PFS changes the root key that is used to generate encryption keys for each
IPSec SA. It is more secure but takes more time.
As a VPN setup is processing intensive, the system is vulnerable to Denial of
Service (DOS) attacks. The IPSec receiver can detect and reject old or
duplicate packets to protect against replay attacks. Enable replay detection
by selecting this check box.
Select this to allow the Vantage CNM to use any of its phase 2 encryption and
authentication algorithms when negotiating an IPSec SA.
When you enable multiple proposals, the Vantage CNM allows the remote
IPSec router to select which phase 2 encryption and authentication
algorithms to use for the IPSec SA, even if they are less secure than the ones
you configure for the VPN rule.
Clear this to have the Vantage CNM use only the configured phase 2
encryption and authentication algorithms when negotiating an IPSec SA.
Click this to save the changes.
Click this to discard all changes and return to the previous screen.
Vantage CNM User's Guide