Network : Network > Interfaces

Configuring Layer 2 Bridged Mode
Topics:
Configuration Task List for Layer 2 Bridged Mode
Configuring the Common Settings for L2 Bridged Mode Deployments
The following settings need to be configured on your Dell SonicWALL Security Appliance prior to using it in most of the Layer 2 Bridged Mode topologies:
Licensing Services
When the appliance is successfully registered, go to the System > Licenses page and click Synchronize under Manage Security Services Online. This will contact the firewall licensing server and ensure that the appliance is properly licensed.
To check licensing status, go to the System > Status page and view the license status of all the UTM services (Gateway Anti-Virus, Anti-Spyware, and Intrusion Prevention).
Disabling DHCP Server
When using a Dell SonicWALL Security Appliance in Layer 2 Bridged Mode in a network configuration where another device is acting as the DHCP server, you must first disable its internal DHCP engine, which is configured and running by default. On the Network > DHCP Server page, clear the Enable DHCP Server check box, and then click on the Accept button at the top of the screen.
Configuring SNMP Settings
On the System > Administration page, make sure the checkbox next to Enable SNMP is checked, and then click on the Accept button at the top of the screen.
Then, click the Configure button. On the SNMP Settings page, enter all the relevant information for your appliance: the GET and TRAP SNMP community names that the SNMP server expects, and the IP address of the SNMP server. Click OK to save and activate the changes.
Enabling SNMP and HTTPS on the Interfaces
On the Network > Interfaces page, enable SNMP and HTTP/HTTPS on the interface through which you will be managing the appliance.
Enabling Syslog
On the Log > Syslog page, click on the Add button and create an entry for the syslog server. Click OK to save and activate the change.
Activating Security Services on Each Zone
On the Network > Zones page, for each zone you will be using, make sure that the security services are activated.
Then, on the Security Services page for each service, activate and configure the settings that are most appropriate for your environment.
Topics:
Security Services > Gateway Anti-Virus settings
Security Services > Intrusion Prevention settings
Security Services > Anti-Spyware settings
Creating Firewall Access Rules
If you plan to manage the appliance from a different zone, or if you will be using a server such as the HP PCM+/NIM server for management, SNMP, or syslog services, create access rules for traffic between the zones. On the Firewall > Access Rules page, click on the icon for the intersection of the zone of the server and the zone that has users and servers (your environment may have more than one of these intersections). Create a new rule to allow the server to communicate with all devices in that zone.
Configuring Log Settings
On the Log > Settings page, set the priority and other log settings.
Then, go to the Log > Name Resolution page and set the Name Resolution Method to DNS then NetBios. Click Accept to save and activate the change.
Configuring Wireless Zone Settings
When you are using a HP PCM+/NIM system, if it will be managing a HP ProCurve switch on an interface assigned to a WLAN/Wireless zone, you will need to deactivate two features; otherwise, you will not be able to manage the switch. Go to the Network > Zones page and select your Wireless zone. On the Wireless tab, clear the checkboxes next to Only allow traffic generated by a SonicPoint and WiFiSec Enforcement. Click OK to save and activate the change.
Configuring Layer 2 Bridged Mode Procedure
Refer to the L2 Bridge Interface Zone Selection for choosing a topology that best suits your network. In this example, we will be using a topology that most closely resembles the Simple L2 Bridge Topology.
Choose an interface to act as the Primary Bridge Interface. Refer to the L2 Bridge Interface Zone Selection for information in making this selection. In this example, we will use X1 (automatically assigned to the Primary WAN):
Configuring the Primary Bridge Interface
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Select the Network tab, Interfaces folder from the navigation panel.
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Click the Configure icon in the right column of the X1 (WAN) interface.
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Choose an interface to act as the Secondary Bridge Interface. Refer to the L2 Bridge Interface Zone Selection for information in making this selection. In this example, we use X0 (automatically assigned to the LAN):
Configuring the Secondary Bridge Interface
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On the Network > Interfaces page, click the Configure icon in the right column of the X0 (LAN) interface.
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In the IP Assignment drop-down menu, select Layer 2 Bridged Mode.
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In the Bridged to drop-down menu, select the X1 interface.
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Configure management (HTTP, HTTPS, Ping, SNMP, SSH, User Logins, HTTP Redirects).
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You may optionally enable the Block all non-IPv4 traffic setting to prevent the L2 bridge from passing non-IPv4 traffic.
VLAN Filtering
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You may also optionally navigate to the VLAN Filtering tab to control VLAN traffic through the L2 bridge. By default, all VLANs are allowed:
Select Block listed VLANs (blacklist) from the drop-down list and add the VLANs you wish to block from the left pane to the right pane. All VLANs added to the right pane will be blocked, and all VLANs remaining in the left pane will be allowed.
Select Allow listed VLANs (whitelist) from the drop-down list and add the VLANs you wish to explicitly allow from the left pane to the right pane. All VLANs added to the right pane will be allowed, and all VLANs remaining in the left pane will be blocked.
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The Network > Interfaces page displays the updated configuration:
You may now apply security services to the appropriate zones, as desired. In this example, they should be applied to the LAN, WAN, or both zones.
Configuring an L2 Bypass for Hardware Failures
An L2 bypass enables you to perform a physical bypass of the firewall when an interface is bridged to another interface with LAN bypass capability. This allows network traffic to continue flowing if an unrecoverable firewall error occurs.
When the L2 bypass relay is closed, the network cables attached to the bypassed interfaces (X0 and X1) are physically connected as if they were a single continuous network cable. The Engage physical bypass on malfunction option provides the user the choice of avoiding disruption of network traffic by bypassing the firewall in the event of a malfunction.
L2 bypass is only applicable to interfaces in Layer 2 Bridged Mode. The Engage physical bypass on malfunction option only appears when the Layer 2 Bridged Mode option is selected from the Mode / IP Assignment menu. This option does not appear unless a physical bypass relay exists between the two interfaces of the bridge-pair.
When the Engage physical bypass on malfunction option is enabled, the other Layer 2 Bridged Mode options are automatically set as follows:
Block all non-IPv4 traffic – disabled. When enabled, this option blocks all non-IPv4 Ethernet frames. So, this option is disabled.
Never route traffic on this bridge-pair – enabled. When enabled, this option prevents packets from being routed to a network other than the peer network of the bridged pair. So, this option is enabled.
Only sniff traffic on this bridge-pair – disabled. When enabled, traffic received on the bridge-pair interface is never forwarded. So, this option is disabled.
Disable stateful-inspection on this bridge-pair – unchanged. This option is not affected.
To configure an L2 bypass:
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Go to the Network > Interfaces page.
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Click on the Edit icon in the Configure column for the interface you want to configure. The Edit Interface window is displayed.
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Select the Engage physical bypass on malfunction checkbox
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Click OK to configure the interface.
VLAN Integration with Layer 2 Bridged Mode
VLANs are supported on Dell SonicWALL Security Appliances. When a packet with a VLAN tag arrives on a physical interface, the VLAN ID is evaluated to determine if it is supported. The VLAN tag is stripped, and packet processing continues as it would for any other traffic. A simplified view of the inbound and outbound packet path includes the following potentially reiterative steps:
At this point, if the packet has been validated as acceptable traffic, it is forwarded to its destination. The packet egress path includes:
On egress, if the route policy lookup determines that the gateway interface is a VLAN subinterface, the packet is tagged (encapsulated) with the appropriate VLAN ID header. The creation of VLAN subinterfaces automatically updates the firewall’s routing policy table:
The auto-creation of NAT policies, Access Rules with regard to VLAN subinterfaces behave exactly the same as with physical interfaces. Customization of the rules and policies that govern the traffic between VLANs can be performed with customary SonicOS ease and efficiency.
When creating a zone (either as part of general administration, or as a step in creating a subinterface), a checkbox will be presented on the zone creation page to control the auto-creation of a GroupVPN for that zone. By default, only newly created Wireless type zones have Create GroupVPN for this zone enabled, although the option can be enabled for other zone types by selecting the checkbox during creation.
Management of security services between VLAN subinterfaces is accomplished at the zone level. All security services are configurable and applicable to zones comprising physical interfaces, VLAN subinterfaces, or combinations of physical and VLAN subinterfaces.
Gateway Anti-Virus and Intrusion Prevention Services between the different workgroups can easily be employed with the use of VLAN segmentation, obviating the need for dedicated physical interfaces for each protected segment.
VLAN support enables organizations to offer meaningful internal security (as opposed to simple packet filtering) between various workgroups, and between workgroups and server farms without having to use dedicated physical interfaces on the firewall.
Here the ability to assign VLAN subinterfaces to the WAN zone, and to use the WAN client mode (only Static addressing is supported on VLAN subinterfaces assigned to the WAN zone) is illustrated, along with the ability to support WAN Load Balancing and failover. Also demonstrated is the distribution of SonicPoints throughout the network by means of connecting them to access mode VLAN ports on workgroup switches. These switches are then backhauled to the core switch, which then connects all the VLANs to the appliance via a trunk link.
VPN Integration with Layer 2 Bridged Mode
When configuring a VPN on an interface that is also configured for Layer 2 Bridged Mode, you must configure an additional route to ensure that incoming VPN traffic properly traverses the firewall. Navigate to the Network > Routing page, scroll to the bottom of the page, and click on the Add button. In the Add Route Policy window, configure the route as follows:
Destination: custom-VPN-address-object (This is the address object for the local VPN tunnel IP address range.)
Gateway: 0.0.0.0