|
|
Internet Key Exchange IKE transparently negotiates encryption and authentication keys. The two SonicWALL appliances authenticate the IKE VPN session by matching preshared keys and IP addresses or Unique Firewall Identifiers.
Select -Add New SA- from the Security Association menu.
Select IKE using Preshared secret from the IPSec Keying Mode menu.
Enter a descriptive name for the Security Association, such as "Palo Alto Office" or "NY Headquarters", in the Name field.
Make sure the Disable This SA box is unchecked to enable this VPN policy.
Enter the primary VPN gateway address in the IPSec Primary Gateway Name or Address field. You can add a secondary VPN gateway address in the IPSec Secondary Gateway Name or Address field. This address must be valid, and should be the NAT Public IP Address if the remote SonicWALL uses Network Address Translation (NAT). If the remote SonicWALL uses a dynamic IP address, you can enter "0.0.0.0" in the IPSec Gateway Address field or you can enter the dynamic IP address of the remote SonicWALL. With SonicWALL's Flexible VPN feature, the remote SonicWALL initiates IKE negotiation in Aggressive Mode because it has a dynamic IP address, and authenticates using the SA Names and Unique Firewall Identifiers rather than the IP addresses. Therefore, the SA Name for the SonicWALL must match the opposite SonicWALL Unique Firewall Identifier.
Select Main Mode from the Exchange menu.
Select Group 2 from the Phase 1 DH Group menu.
Define the length of time before an IKE Security Association automatically renegotiates in the SA Life time (secs) field.
Tip! 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, users accessing remote resources are disconnected. Therefore,
the default SA Life Time of 28,800 seconds (8 hours) is recommended.
Select the 3DES or AES-128, AES-192, or AES 256 options from the Phase1 Encryption/Authentication menu.
Select Use this SA as the default route for all Internet traffic if all remote VPN connections access the Internet through this SA. You can only configure one SA to use this feature. If you do not select this feature, go to Step 13.
Select Destination network obtains IP addresses using DHCP through this SA if the remote network obtains its IP addresses from this SA. If you do not select this feature, go to Step 13.
Select Specify destination networks below if the VPN destination is a specific IP address and click Add New Network. The VPN Destination Network window is displayed.
Type the IP address of the remote network in the Network field. This address is a private address if the remote LAN has enabled NAT.
Type the subnet mask of the remote network in the Subnet mask field.
Click Advanced Settings and select the boxes that apply to your SA:
Enable Keep Alive - Allows the VPN tunnel to remain active or maintain its current connection by listening for traffic on the network segment between the two connections. Interruption of the signal forces the tunnel to renegotiate the connection.
Try to bring up all possible SAs - If multiple SAs are configured on the SonicWALL, select this feature to have the SonicWALL renegotiate the tunnels if they lose communication with the SonicWALL.
Require authentication of local users - Requires that all outbound VPN traffic on this SA is from an authenticated user. Unauthenticated traffic is not allowed on the VPN tunnel.
Require authentication of remote users - requires that all inbound traffic on this SA is from an authenticated user. Unauthenticated traffic is not allowed on the VPN tunnel.
Remote users behind VPN gateway - Select this feature if remote users have a VPN tunnel terminating on the VPN gateway.
Remote VPN clients with XAUTH - Select this feature if remote users require authentication using XAUTH and are accessing the SonicWALL via a VPN client.
Enable Windows Networking (NetBIOS) broadcast - Computers running Microsoft Windows® communicate with one another through NetBIOS broadcast packets. Select the Enable Windows Networking (NetBIOS) broadcast check box to access remote network resources by browsing the Windows® Network Neighborhood.
Apply NAT and firewall rules - This feature allows a remote site’s LAN subnet to be hidden from the corporate site, and is most useful when a remote office’s network traffic is initiated to the corporate office. The IPSec tunnel is located between the SonicWALL WAN interface and the LAN segment of the corporation. To protect the traffic, NAT (Network Address Translation) is performed on the outbound packet before it is sent through the tunnel, and in turn, NAT is performed on inbound packets when they are received. By using NAT for a VPN connection, computers on the remote LAN are viewed as one address (the SonicWALL public address) from the corporate LAN. If the SonicWALL uses the Standard network configuration, using this check box applies the firewall access rules and checks for attacks, but not NAT.
Forward packets to remote VPNs - Selecting the Forward Packets to Remote VPNs check box for a Security Association allows the remote VPN tunnel to participate in the SonicWALL routing table. Inbound traffic is decrypted and can now be forwarded to a remote site via another VPN tunnel. Normally, inbound traffic is decrypted and only forwarded to the SonicWALL LAN or a specific route on the LAN specified on the Routes tab located under the Advanced section. Enabling this feature allows a network administrator to create a “hub and spoke” network configuration by forwarding inbound traffic to a remote site via a VPN security association. To create a “hub and spoke” network, enable the Forward Packets to Remote VPNs check box for each Security Association in your SonicWALL. Traffic can travel from a branch office to a branch office via the corporate office.
Enable Perfect Forward Secrecy - This setting increases the renegotiation time of the VPN tunnel. By enabling Perfect Forward Secrecy, a hacker using brute force to break encryption keys is not able to obtain other or future IPSec keys. During the phase 2 renegotiation between two SonicWALL appliances or a Group VPN SA, an additional Diffie-Hellman key exchange is performed. Enable Perfect Forward Secrecy adds incremental security between gateways.
Phase 2 DH Group - If Enable Perfect Forward Secrecy is enabled, select the type of Diffie-Hellman (DH) Key Exchange (a key agreement protocol) to be used during phase 2 of the authentication process to establish preshared keys. Groups 1, 2, and 5 use Modular-Exponentiation with different prime lengths as listed below:
Group - Prime Size (bits)
Group 1 - 768
Group 2 - 1024
Group 5 - 1536
Tip! If
network connection speed is an issue, select Group 1. If network security
is an issue, select Group 5. To compromise between speed and security, select
Group 2.
Default LAN Gateway - The Default LAN Gateway field allows the network administrator to specify the IP address of the default LAN route for incoming IPSec packets for this SA. Incoming packets are decoded by the SonicWALL and compared to static routes configured in the SonicWALL. Since packets can have any IP address destination, it is impossible to configure enough static routes to handle the traffic. For packets received via an IPSec tunnel, the SonicWALL looks up a route for the LAN. If no route is found, the SonicWALL checks for a Default LAN Gateway. If a Default LAN Gateway is detected, the packet is routed through the gateway. Otherwise, the packet is dropped.
Click Delete This SA to delete the current SA. A dialog box is displayed asking you to confirm the deletion of this VPN policy. Click OK to proceed with the deletion.