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.

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 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 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 Engine are overridden.
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 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.

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.