ZyXEL P-335U User Guide - Page 155

The remote IPSec router must also have NAT traversal, enabled. See, for more, information.

Page 155 highlights

P-334U/P-335U User's Guide The following table describes the labels in this screen. Table 53 Security > VPN > Rule Setup: IKE (Advanced) LABEL DESCRIPTION Property Active Select this check box to activate this VPN policy. This option determines whether a VPN rule is applied before a packet leaves the firewall. Keep Alive Select this check box to have the ZyXEL Device automatically reinitiate the SA after the SA lifetime times out, even if there is no traffic. The remote IPSec router must also have keep alive enabled in order for this feature to work. NAT Traversal Select this check box to enable NAT traversal. NAT traversal allows you to set up a VPN connection when there are NAT routers between the two IPSec routers. Note: The remote IPSec router must also have NAT traversal enabled. See Section 13.1.2.5 on page 143 for more information. IPSec Keying Mode Protocol Number Enable Replay Detection DNS Server (for IPSec VPN) Local Policy You can use NAT traversal with ESP protocol using Transport or Tunnel mode, but not with AH protocol nor with manual key management. In order for an IPSec router behind a NAT router to receive an initiating IPSec packet, set the NAT router to forward UDP ports 500 and 4500 to the IPSec router behind the NAT router. Select IKE or Manual from the drop-down list box. IKE provides more protection so it is generally recommended. Manual is a useful option for troubleshooting if you have problems using IKE key management. Enter 1 for ICMP, 6 for TCP, 17 for UDP, etc. 0 is the default and signifies any protocol. 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. Select YES from the drop-down menu to enable replay detection, or select NO to disable it. If there is a private DNS server that services the VPN, type its IP address here. The ZyXEL Device assigns this additional DNS server to the ZyXEL Device's DHCP clients that have IP addresses in this IPSec rule's range of local addresses. A DNS server allows clients on the VPN to find other computers and servers on the VPN by their (private) domain names. Local IP addresses must be static and correspond to the remote IPSec router's configured remote IP addresses. Two active SAs can have the same configured local or remote IP address, but not both. You can configure multiple SAs between the same local and remote IP addresses, as long as only one is active at any time. In order to have more than one active rule with the Secure Gateway Address field set to 0.0.0.0, the ranges of the local IP addresses cannot overlap between rules. If you configure an active rule with 0.0.0.0 in the Secure Gateway Address field and the LAN's full IP address range as the local IP address, then you cannot configure any other active rules with the Secure Gateway Address field set to 0.0.0.0. Chapter 13 IPSec VPN 155

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P-334U/P-335U User’s Guide
Chapter 13 IPSec VPN
155
The following table describes the labels in this screen.
Table 53
Security > VPN > Rule Setup: IKE (Advanced)
LABEL
DESCRIPTION
Property
Active
Select this check box to activate this VPN policy. This option determines
whether a VPN rule is applied before a packet leaves the firewall.
Keep Alive
Select this check box to have the ZyXEL Device automatically reinitiate the SA
after the SA lifetime times out, even if there is no traffic. The remote IPSec
router must also have keep alive enabled in order for this feature to work.
NAT Traversal
Select this check box to enable NAT traversal. NAT traversal allows you to set
up a VPN connection when there are NAT routers between the two IPSec
routers.
Note:
The remote IPSec router must also have NAT traversal
enabled. See
Section 13.1.2.5 on page 143
for more
information.
You can use NAT traversal with
ESP
protocol using
Transport
or
Tunnel
mode, but not with
AH
protocol nor with manual key management. In order for
an IPSec router behind a NAT router to receive an initiating IPSec packet, set
the NAT router to forward UDP ports 500 and 4500 to the IPSec router behind
the NAT router.
IPSec Keying Mode
Select
IKE
or
Manual
from the drop-down list box.
IKE
provides more
protection so it is generally recommended.
Manual
is a useful option for
troubleshooting if you have problems using
IKE
key management.
Protocol Number
Enter 1 for ICMP, 6 for TCP, 17 for UDP, etc. 0 is the default and signifies any
protocol.
Enable Replay
Detection
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. Select
YES
from the drop-down menu
to enable replay detection, or select
NO
to disable it.
DNS Server (for
IPSec VPN)
If there is a private DNS server that services the VPN, type its IP address here.
The ZyXEL Device assigns this additional DNS server to the ZyXEL Device's
DHCP clients that have IP addresses in this IPSec rule's range of local
addresses.
A DNS server allows clients on the VPN to find other computers and servers on
the VPN by their (private) domain names.
Local Policy
Local IP addresses must be static and correspond to the remote IPSec router's
configured remote IP addresses.
Two active SAs can have the same configured local or remote IP address, but
not both. You can configure multiple SAs between the same local and remote IP
addresses, as long as only one is active at any time.
In order to have more than one active rule with the
Secure Gateway Address
field set to
0.0.0.0
, the ranges of the local IP addresses cannot overlap between
rules.
If you configure an active rule with
0.0.0.0
in the
Secure Gateway Address
field and the LAN’s full IP address range as the local IP address, then you
cannot configure any other active rules with the
Secure Gateway Address
field
set to
0.0.0.0
.