• Table of contents
• Trusted Network Connect (TNC) HOWTO
  • Architecture
  • TNC Configuration
  • TNC Integrity Measurement Collectors and Verifiers
  • TNC Deployment
  • Certification
  • Presentations

Trusted Network Connect (TNC) HOWTO¶

The Trusted Computing Group (TCG) has defined and released an open architecture and a growing set of standards for endpoint integrity called Trusted Network Connect.

Architecture¶

strongSwan supports both the older XML-based IF-TNCCS 1.1 "TNC Client-Server Interface" and the latest IF-TNCCS 2.0 "TLV Binding" but currently not the IF-TNCCS SoH 1.0 "State of Health Protocol Bindings" used by Microsoft's Network Access Protection (NAP) framework. The new strongSwan "Test" and "Scanner" IMC/IMV pairs support the IF-M 1.0 "TLV Binding" standard.

The TCG IF-M 1.0 protocol is equivalent to the IETF "Posture Attribute (PA) Protocol Compatible with Trusted Network Connect" (PA-TNC) defined by RFC 5792 and the TCG IF-TNCCS 2.0 protocol is equivalent to the IETF "Posture Broker (PB) Protocol Compatible with Trusted Network Connect" (PB-TNC) defined by RFC 5793. Both RFCs are part of the IETF's "Network Endpoint Assessment" (NEA) framework defined by RFC 5209.

As a transport protocol to exchange IF-TNCCS 1.1 or IF-TNCCS 2.0 messages between TNC Client and TNC Server, strongSwan uses the EAP-TNC method defined by IF-T "Protocol Bindings for Tunneled EAP Methods 1.1". EAP-TNC as an inner non-secure protocol is then encapsulated in an outer encrypted and authenticated IKEv2-EAP-TTLS tunnel.

TNC Configuration¶

By activating the appropriate plugins, a strongSwan VPN Client can act as a TNC Client and a strongSwan VPN Gateway can take on either the role of a "Policy Enforcement Point" (PEP) only which forwards all EAP-TTLS packets via EAP-RADIUS to an external AAA-Server or alternatively can additionally act as a TNC Server.

• Configuration as a TNC Client

• Configuration as a TNC Server

• Configuration as a PEP with EAP-RADIUS Interface

TNC Integrity Measurement Collectors and Verifiers¶

strongSwan can dynamically load any number of Integrity Measurement Collectors (IMCs) and Integrity Measurement Verifiers (IMVs) that adhere to the IF-IMC 1.2 and IF-IMV 1.2 interface specifications, respectively. These interfaces are implemented by the tnc-imc and tnc-imv plugins, respectively.

• Attestation PTS-IMC

• Attestation PTS-IMV

TNC Deployment¶

• IF-TNCCS 1.1 support was first introduced in October 2010 with the strongSwan 4.5.0 release. The tnccs-11 charon plugin originally used Mike McCauley's libtnc library but the code was refactored with the strongSwan 4.5.1 release to use the tnc-imc and tnc-imv plugins and now implements the IF-TNCCS 1.1 protocol directly by including Mike McCauley's libxml statements.
  A strongSwan VPN Gateway configured as a PEP can connect to a FreeRADIUS server running the TNC@FHH plugin.

  - Example 1a: TNC Client - TNC Server with password-based EAP-MD5 client authentication
  - Example 1b: TNC Client - PEP - FreeRADIUS

• IF-TNCCS 2.0 support was introduced in February 2011 with the strongSwan 4.5.1 release. The tnccs-20 charon plugin was implemented by HSR master student Sansar Choinyambuu and does not make use of the libtnc library at all. Communication with IMCs and IMVs is handled by the tnc-imc or tnc-imv plugin, respectively.

  - Example 2a: TNC Client - TNC Server with password-based EAP-MD5 client authentication
  - Example 2b: TNC Client - TNC Server with certificate-based EAP-TLS client authentication

• Using the tnccs-dynamic plugin, a strongSwan VPN gateway can act as a TNC Server handling both the IF-TNCCS 1.1 and IF-TNCCS 2.0 protocols by dynamically detecting the protocol version chosen by the TNC Client.

  - Example 3: TNC Client - TNC Server with dynamic IF-TNCCS 1.1/2.0 protocol detection.

• IF-M 1.0 support was introduced in August 2011 with the strongSwan 4.5.3 release. The strongSwan "Test" and "Scanner" IMC/IMV pairs which communicate with each other via the IF-M TLV-based protocol can be used either in conjunction with a strongSwan TNC Client or TNC Server, respectively, or as stand-alone dynamic libraries imc-test.so, imc-scanner.so, imc-attestation.so, imv-test.so, imv-scanner.so, and imv-attestation.so with any third party TNC Client or TNC Server product having an IF-IMC or IF-IMV interface, respectively.

• IF-MAP 2.0 prototype support was introduced in August 2011 with the strongSwan 4.6.0dr1 developers release. Using the tnc-ifmap plugin strongSwan acts as a MAP Client sending IPsec authentication metadata to a MAP Server via an Apache Axis2/C SOAP interface. For details see our TNC IF-MAP HOWTO.

• Support of the TCG Attestation PTS Protocol: Binding to IF-M was introduced in November 2011 with the strongSwan 4.6.2dr1 release and was developed by HSR master student Sansar Choinyambuu. Using the Attestation PTS-IMC / Attestation PTS-IMV pair, file and TPM-based functional component measurements can be executed remotely.

  - Example 4: TNC Client with PTS-IMC - TNC Server with PTS-IMV.

Certification¶

The IF-IMC interface of the strongSwan 4.5.2 TNC Client (TNCC) and the IF-IMV interface of the strongSwan 4.5.2 TNC Server (TNCS) were successfully certified by the Trusted Computing Group (TCG). We also participated in the May 2011 Plugfest in Chantilly, Virginia, USA, where we tested IF-PEP interoperability.

Presentations¶

• TCG Members Meeting June 2011 Munich: The strongSwan IPsec Solution with TNC Support.