Negotiation Discovery Transport Mode in Boundary Mode

The Negotiation Discovery Transport Mode in Boundary Mode IPsec policy scenario requests IPsec transport mode protection for all matching traffic. If the IKE/AuthIP negotiation fails, both inbound and outbound connections are allowed to fallback to clear-text .

This IPsec policy is typically used on machines that are accessed by both IPsec capable and non-IPsec capable machines.

An example of a potential Negotiation Discovery Transport Mode scenario is "Secure all unicast data traffic, except ICMP, using IPsec transport mode and enable negotiation discovery in boundary mode."

To implement this example programmatically, use the following WFP configuration.

At FWPM_LAYER_IKEEXT_V{4|6} setup MM negotiation policy

1. Add one or both of the following MM policy provider contexts.

   • For IKE, a policy provider context of type FWPM_IPSEC_IKE_MM_CONTEXT.
   • For AuthIP, a policy provider context of type FWPM_IPSEC_AUTHIP_MM_CONTEXT.

   Note

   A common keying module will be negotiated and the corresponding MM policy will be applied. AuthIP is the preferred keying module if both IKE and AuthIP are supported.

2. For each of the contexts added in step 1, add a filter with the following properties.

   Filter property	Value
   Filtering conditions	Empty. All traffic will match the filter.
   providerContextKey	GUID of the MM provider context added in step 1.

At FWPM_LAYER_IPSEC_V{4|6} setup QM and EM negotiation policy

1. Add one or both of the following QM transport mode policy provider contexts and set the IPSEC_POLICY_FLAG_ND_BOUNDARY flag.

   • For IKE, a policy provider context of type FWPM_IPSEC_IKE_QM_TRANSPORT_CONTEXT.
   • For AuthIP, a policy provider context of type FWPM_IPSEC_AUTHIP_QM_TRANSPORT_CONTEXT. This context can optionally contain the AuthIP Extended Mode (EM) negotiation policy.

   Note

   A common keying module will be negotiated and the corresponding QM policy will be applied. AuthIP is the preferred keying module if both IKE and AuthIP are supported.

2. For each of the contexts added in step 1, add a filter with the following properties.

   Filter property	Value
   Filtering conditions	Empty. All traffic will match the filter.
   providerContextKey	GUID of the QM provider context added in step 1.

At FWPM_LAYER_INBOUND_TRANSPORT_V{4|6} setup inbound per-packet filtering rules

1. Add a filter with the following properties.

   Filter property	Value
   FWPM_CONDITION_IP_LOCAL_ADDRESS_TYPE filtering condition	NlatUnicast
   action.type	FWP_ACTION_CALLOUT_TERMINATING
   action.calloutKey	FWPM_CALLOUT_IPSEC_INBOUND_TRANSPORT_V{4|6}
   rawContext	FWPM_CONTEXT_IPSEC_INBOUND_PERSIST_CONNECTION_SECURITY

2. Exempt ICMP traffic from IPsec by adding a filter with the following properties.

   Filter property	Value
   FWPM_CONDITION_IP_LOCAL_ADDRESS_TYPE filtering condition	NlatUnicast
   FWPM_CONDITION_IP_PROTOCOL filtering condition	**IPPROTO_ICMP{V6}**These constants are defined in winsock2.h.
   action.type	FWP_ACTION_PERMIT
   weight	FWPM_WEIGHT_RANGE_IKE_EXEMPTIONS

At FWPM_LAYER_OUTBOUND_TRANSPORT_V{4|6} setup outbound per-packet filtering rules

1. Add a filter with the following properties.

   Filter property	Value
   FWPM_CONDITION_IP_LOCAL_ADDRESS_TYPE filtering condition	NlatUnicast
   action.type	FWP_ACTION_CALLOUT_TERMINATING
   action.calloutKey	FWPM_CALLOUT_IPSEC_OUTBOUND_TRANSPORT_V{4|6}
   rawContext	FWPM_CONTEXT_IPSEC_OUTBOUND_NEGOTIATE_DISCOVER

2. Exempt ICMP traffic from IPsec by adding a filter with the following properties.

   Filter property	Value
   FWPM_CONDITION_IP_LOCAL_ADDRESS_TYPE filtering condition	NlatUnicast
   FWPM_CONDITION_IP_PROTOCOL filtering condition	**IPPROTO_ICMP{V6}**These constants are defined in winsock2.h.
   action.type	FWP_ACTION_PERMIT
   weight	FWPM_WEIGHT_RANGE_IKE_EXEMPTIONS

Related topics

Sample code: Using Transport Mode

ALE Layers

Built-in Callout Identifiers

Filtering Conditions

Filtering Layer Identifiers

FWPM_ACTION0

FWPM_PROVIDER_CONTEXT_TYPE