ZyXEL p-2802h-i1 Guia Do Utilizador
Chapter 14 VPN Screens
P-2802H(W)(L)-I Series User’s Guide
200
14.12.3 Perfect Forward Secrecy (PFS)
Enabling PFS means that the key is transient. The key is thrown away and replaced by a brand
new key using a new Diffie-Hellman exchange for each new IPSec SA setup. With PFS
enabled, if one key is compromised, previous and subsequent keys are not compromised,
because subsequent keys are not derived from previous keys. The (time-consuming) Diffie-
Hellman exchange is the trade-off for this extra security.
This may be unnecessary for data that does not require such security, so PFS is disabled
(None) by default in the ZyXEL Device. Disabling PFS means new authentication and
encryption keys are derived from the same root secret (which may have security implications
in the long run) but allows faster SA setup (by bypassing the Diffie-Hellman key exchange).
new key using a new Diffie-Hellman exchange for each new IPSec SA setup. With PFS
enabled, if one key is compromised, previous and subsequent keys are not compromised,
because subsequent keys are not derived from previous keys. The (time-consuming) Diffie-
Hellman exchange is the trade-off for this extra security.
This may be unnecessary for data that does not require such security, so PFS is disabled
(None) by default in the ZyXEL Device. Disabling PFS means new authentication and
encryption keys are derived from the same root secret (which may have security implications
in the long run) but allows faster SA setup (by bypassing the Diffie-Hellman key exchange).
14.13 Configuring Advanced IKE Settings
Click Advanced Setup in the VPN Setup-Edit screen to open this screen.
Figure 112 Advanced VPN IKE
The following table describes the fields in this screen.
Table 78 Advanced VPN IKE
LABEL
DESCRIPTION
VPN - IKE
Protocol
Enter 1 for ICMP, 6 for TCP, 17 for UDP, etc. 0 is the default and signifies any
protocol.