# Add layer 2 physical interfaces for NGFW Engines in the Firewall/VPN role

Layer 2 physical interfaces on NGFW Engines in the Firewall/VPN role provide traffic inspection.

##

Layer 2 physical interfaces have definitions for the corresponding logical interface that the interface belongs to. The logical interface represents one or more network interfaces that capture the traffic for inspection.

On inline IPS interfaces and inline Layer 2 Firewall interfaces, you must select a logical interface for each inline interface.

Note: You cannot use the same logical interface to represent both inline IPS interfaces and inline Layer 2 Firewall interfaces.

For capture interfaces, the configuration depends on the deployment.

- When a capture interface is connected to a switch SPAN port, you must select a logical interface for each capture interface. You can optionally select the same logical interface for more than one capture interface.
- When a network TAP device is used, you must select the same logical interface for two capture interfaces. The monitored traffic going to different directions is captured through these two related network interfaces and is then combined into a complete traffic flow on the logical interface.

To define a capture interface, you must select a reset interface for it. You can use Layer 3 physical interfaces that meet the following requirements as reset interfaces:

- The Layer 3 physical interface connects to the same networks as the capture interfaces.
- There are no VLANs on the Layer 3 physical interface.

For more details about the product and how to configure features, click Help or press F1.

## Steps

1. Right-click a Single Firewall or Firewall Cluster and select Edit <element type>.
2. In the navigation pane on the left, select Interfaces.
3. Right-click the empty space and select New > Layer 2 Physical Interface.
4. From the Type drop-down list, select the interface type.
5. Define the physical interface properties.
   Note: You cannot select the same logical interface for a capture interface and an inline interface on the same NGFW Engine.
   CAUTION:
   Using Bypass as the Failure Mode requires a fail-open network interface card. If the ports that represent the interfaces cannot fail open, policy installation fails on the NGFW Engine. Bypass mode is not compatible with VLAN retagging. In network environments where VLAN retagging is used, normal mode is automatically enforced.
6. Click OK.

## Layer 2 Physical Interface Properties dialog box (Firewall)

Use this dialog box to define the layer 2 physical interface properties for a Single Firewall or Firewall Cluster.

Option | Definition
--- | ---
General tab
Interface ID | The Interface ID automatically maps to a physical network port of the same number during the initial configuration of the engine. The mapping can be changed as necessary through the engine’s command line interface.
Type | Capture Interface — Network traffic is monitored only. Traffic cannot be blocked. A connection can be terminated by sending a TCP Reset response. Inline IPS Interface — The interface is directly on the traffic path so that traffic passes through the interface to reach its destination. Inline Layer 2 Firewall Interface — The interface is directly on the traffic path so that traffic passes through the interface to reach its destination.
Zone (Optional) | Select the network zone to which the Physical Interface or Second Interface belongs. To browse for a Zone element, select Select. To create a Zone element, select New.

Option | Definition
--- | ---
General tab, Second Interface section (Inline IPS Interfaces and Inline Layer 2 Firewall Interfaces only)
ID | Select a Second Interface ID. The Interface ID is mapped to a physical network port of the same number during the initial configuration of the engine.
Zone (Optional) | Select the network zone to which the Second Interface belongs. To browse for a Zone element, select Select. To create a Zone element, select New.
Second Interface ID | Select a Second Interface ID. The Interface ID is mapped to a physical network port of the same number during the initial configuration of the engine.

Option | Definition
--- | ---
General tab, Inline Interface Settings or Capture Interface Settings section
Reset Interface | (When Type is Capture Interface) Select the Reset Interface to specify the interface through which TCP connection resets are sent when Reset responses are used in your policy.
Logical Interface | Specifies the Logical Interface. You cannot use the same Logical Interface element for both Inline and Capture Interfaces on the same Virtual NGFW Engine.
Failure Mode (Inline IPS Interfaces only) | Select how traffic to the Inline IPS Interface is handled if the engine goes offline. Bypass — traffic is allowed through the Inline Interface without inspection. Normal — traffic is not allowed through the Inline Interface. CAUTION: Using bypass mode requires a fail-open network interface card. If the ports that represent the interfaces cannot fail open, policy installation fails on the NGFW Engine. Bypass mode is not compatible with VLAN retagging. In network environments where VLAN retagging is used, normal mode is automatically enforced.
Inspect unspecified VLANs | Select this option to make the engine inspect traffic from VLANs that are not included in the engine’s interface configuration. We recommend that you keep this option selected if you do not have a specific reason to deselect it.
Inspect QinQ | Select this option to make the engine inspect double-tagged VLAN traffic as defined in IEEE 802.1Q. We recommend that you keep this option selected if you do not have a specific reason to deselect it.

Option | Definition
--- | ---
Advanced tab (All optional settings) Note: These settings are not available for Capture Interfaces.
Override Engine's Default Settings | When selected, the default settings of the NGFW Engine are overridden.
SYN Rate Limits | Default — The interface uses the SYN rate limits defined for the NGFW Engine on the Advanced Settings branch of the Engine Editor. None — Disables SYN rate limits on the interface. Automatic — This is the recommended mode if you want to override the general SYN rate limits defined on the Advanced Settings branch of the Engine Editor. The NGFW Engine calculates the number of allowed SYN packets per second and the burst size (the number of allowed SYNs before the NGFW Engine starts limiting the SYN rate) based on the NGFW Engine’s capacity and memory size. Custom — Enter the values for Allowed SYNs per Second and Burst Size.
Allowed SYNs per Second | Defines the number of allowed SYN packets per second.
Burst Size | The number of allowed SYNs before the NGFW Engine starts limiting the SYN rate. We recommend that you set the burst size to be at least one tenth of the Allowed SYNs per Second value. If the burst size is too small, SYN rate limits do not work. For example, if the value for Allowed SYNs per Second is 10000, set the value for Burst Size to at least 1000.
Enable Log Compression | By default, each generated Antispoofing and Discard log entry is logged separately and displayed as a separate entry in the Logs view. Log Compression settings allow you to define the maximum number of separately logged entries. When the defined limit is reached, a single antispoofing log entry or Discard log entry is logged. The single entry contains information about the total number of the generated Antispoofing log entries or Discard log entries. After this log entry, the logging returns to normal and all generated entries are once more logged and displayed separately. Log Compression is useful when the routing configuration generates a large volume of antispoofing logs or the number of Discard logs becomes high. For each event type, Antispoofing or Discard, you can define: Log Rate (Entries/s) — The maximum number of entries per second. The default value for antispoofing entries is 100 entries/s. By default, Discard log entries are not compressed. Burst Size (Entries) — The maximum number of matching entries in a single burst. The default value for antispoofing entries is 1000 entries. By default, Discard log entries are not compressed.
Set to Default | Returns all changes to the log compression settings to the default settings.