Add reset interfaces

Reset interfaces interrupt communications picked up through capture interfaces when the traffic matches a rule that terminates connections.

Reset interfaces can deliver TCP resets and ICMP “destination unreachable” messages to interrupt communications picked up through capture interfaces when the traffic matches a rule that terminates connections.

The resets are sent using the source and destination addresses and MAC addresses of the communicating hosts, so an IP address is not mandatory for a reset interface. You can optionally add an IP address if you also want to use this interface for system communications.

VLANs are supported for sending resets, but the correct VLAN is selected automatically. The interface you want to use as the reset interface must not have any manually added VLAN configuration.

You can use an existing system communications interface for sending resets if the reset interface connects to the same networks as the capture interface, and there are no VLANs on the system communications interface.

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

Steps

  1. Right-click an engine element, then select Edit <element type>.
  2. In the navigation pane on the left, select Interfaces.
  3. Create a new Physical Interface.
    • For IPS engines and Layer 2 Firewalls, right-click the empty space and select New Physical Interface.
    • For Firewalls, right-click the empty space and select New > Layer 3 Physical Interface.
  4. Select an Interface ID.
  5. Select the interface type according to the engine role:
    • For IPS engines and Layer 2 Firewalls, select Normal Interface.
    • For Firewalls, select None.
  6. Click OK.

Result

The Physical Interface is added to the interface list.
Note: When you set up the physical network, make sure that the reset interface connects to the same networks as the capture interfaces.

Next steps

Set up the capture interfaces that use this reset interface.

Physical Interface Properties dialog box (IPS engine)

Use this dialog box to define the Physical Interface properties for a Single IPS engine, IPS Cluster, Virtual IPS engine, or Master NGFW Engine in the IPS role.

Note: The available options can vary depending on the type of IPS engine.
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.
Note: Changes to the Master NGFW Engine interface mapping do not affect the Interface IDs that are defined for Virtual NGFW Engines in Virtual Resource elements.
Type

Normal Interface — Corresponds to a single network interface on the engine. Not supported on Virtual IPS engines.

Capture Interface — Network traffic is monitored only. Traffic cannot be blocked.

Inline Interface — The interface is directly on the traffic path so that traffic must always pass through the engine to reach its destination. Only traffic that attempts to pass through Inline Interfaces can be actively filtered.

Zone

(Optional)

Select the network zone to which the interface belongs. Click Select to select an element, or click New to create an element.
MTU

(Optional, not supported on Virtual NGFW Engines)

The maximum transmission unit (MTU) size on the connected link. Either enter a value between 400–65535 or select a common MTU value from the list.

If the interface is a Physical Interface, the same MTU is automatically applied to any VLANs created under it.

The default value (also the maximum standard MTU in Ethernet) is 1500. Do not set a value larger than the standard MTU, unless you know that all devices along the communication path support it.

Note: To set the MTU for a Virtual NGFW Engine, you must configure the MTU for the interface on the Master NGFW Engine that hosts the Virtual NGFW Engine, then refresh the policy on the Master NGFW Engine and the Virtual NGFW Engine.
Comment

(Optional)

 A comment for your own reference.
Option Definition
General tab, Inline Interface Settings or Capture Interface Settings section
Reset Interface

(Capture Interfaces only)

Select the Reset Interface to specify the interface through which TCP connection resets are sent when Reset responses are used in your IPS policy.
Logical Interface Select the Logical Interface.
Note: You cannot use the same Logical Interface element for both Inline and Capture Interfaces on the same engine.
Failure Mode

(Inline Interfaces only)

Select how traffic to the Inline 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.
Note: If there are VLAN Interfaces under the Inline Interface, you must select Bypass.
Note: For Virtual IPS engines, this option is set on the Master NGFW Engine.
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

(Capture or Inline Interfaces only)

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.
Bypass unspecified VLANs

(Master NGFW Engines only)

(Inline Interfaces only)

When this option is selected, traffic from VLANs that are not allocated to any Virtual NGFW Engine is bypassed without inspection. Deselect this option to make the Master NGFW Engine block traffic from VLANs that are not allocated to any Virtual NGFW Engine. We recommend that you keep this option selected if you do not have a specific reason to deselect it.
Option Definition
General tab, Second Interface section

(Inline 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 interface belongs. Click Select to select an element, or click New to create an element.
Second Interface ID

(Inline Interfaces on Master NGFW Engines only)

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, Quality of Service and Bandwidth Management section
QoS Mode

(Optional)

Defines how QoS is applied to the link on this interface.

If Full QoS or DSCP Handling and Throttling is selected, a QoS policy must also be selected. If Full QoS is selected, the throughput must also be defined.

If the interface is a Physical Interface, the same QoS mode is automatically applied to any VLANs created under it.

QoS Policy

(DSCP Handling and Throttling and Full QoS modes only)

The QoS policy for the link on this interface.

If the interface is a Physical Interface, the same QoS policy is automatically selected for any VLANs created under it.

Note: If a Virtual Resource has a throughput limit defined, the interfaces on the Virtual NGFW Engine that use a QoS policy all use the same policy. The policy used in the first interface is used for all the interfaces.
Interface Throughput Limit

(Full QoS mode only)

Enter the throughput for the link on this interface as megabits per second.

If the interface is a Physical Interface, the same throughput is automatically applied to any VLANs created under it.

The throughput is for uplink speed (outgoing traffic) and typically must correspond to the speed of an Internet link (such as an ADSL line), or the combined speeds of several such links when connected to a single interface.

CAUTION:
Make sure that you set the interface speed correctly. When the bandwidth is set, the NGFW Engine always scales the total amount of traffic on this interface to the bandwidth you defined. This scaling happens even if there are no bandwidth limits or guarantees defined for any traffic.
CAUTION:
The throughput for a Physical Interface for a Virtual NGFW Engine must not be higher than the throughput for the Master NGFW Engine interface that hosts the Virtual NGFW Engine. Contact the administrator of the Master NGFW Engine before changing this setting.
Option Definition
General tab, Virtual Resource section

(Master NGFW Engines only)

Virtual Resource

The Virtual Resource associated with the interface. Select the same Virtual Resource in the properties of the Virtual IPS element to add the Virtual NGFW Engine to the Master NGFW Engine.

Only one Virtual Resource can be selected for each Physical Interface. If you want to add multiple Virtual Resources, add VLAN Interfaces to the Physical Interface, then select the Virtual Resource in the VLAN Interface properties.

Allow VLAN Definition in Virtual Engine When selected, allows VLAN Interfaces to be added to the automatically created Physical Interfaces in the Virtual NGFW Engine that is associated with this interface.
Virtual Engine Interface ID Specifies the Interface ID of the Physical Interface in the Virtual NGFW Engine that is associated with this interface.
Option Definition
Advanced tab

(All optional settings)

Override Engine's Default Settings When selected, the default settings of the engine are overridden.
Note: These options cannot be selected if using Capture Interfaces.
SYN Rate Limits
  • Default — The interface uses the SYN rate limits defined for the 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 for the engine on the Advanced Settings branch of the Engine Editor. The engine calculates the number of allowed SYN packets per second and the burst size (the number of allowed SYNs before the engine starts limiting the SYN rate) based on the 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 engine starts limiting the SYN rate.
Tip:

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

Allows you to define the maximum number of separately logged entries.

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.