Network Working Group P. Sangster Internet Draft Symantec Corporation Intended status: Proposed Standard K. Narayan Expires: April 2009 Cisco Systems October 6, 2008 PA-TNC: A Posture Attribute Protocol (PA) Compatible with TNC draft-ietf-nea-pa-tnc-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on January 6, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This document specifies PA-TNC, a Posture Attribute Protocol identical to the Trusted Computing Group's IF-M 1.0 protocol. The document then evaluates PA-TNC against the requirements defined in the NEA Requirements specification. Sangster & Narayan Expires April 6, 2009 [Page 1] Internet-Draft PA-TNC October 2008 Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [1]. Table of Contents 1. Introduction.................................................3 1.1. Relationship to Trusted Network Connect..................3 1.2. Prerequisites............................................4 1.3. Message Diagram Conventions..............................4 2. Design Considerations........................................4 2.1. Standard Attribute Namespace for Interoperability........4 2.2. Vendor Defined Namespace for Differentiation and Agility 5 2.3. Use of TLV Based Encoding for Efficiency.................5 3. PA-TNC Message Protocol......................................6 3.1. PA-TNC Messaging Model...................................6 3.2. PA-TNC Relationship to PB-TNC............................7 3.3. PA-PB Posture Collector and Posture Validator Identifiers8 3.4. PA-TNC Messages in PB-TNC................................9 3.5. IETF Standard PA Subtypes................................9 3.6. PA-TNC Field Types......................................10 3.7. PA-TNC Message Header Format............................10 4. PA-TNC Attributes...........................................11 4.1. PA-TNC Attribute Header.................................11 4.2. IETF Standard PA-TNC Attribute Types....................13 4.2.1. Attribute Request..................................15 4.2.2. Product Information................................16 4.2.3. Numeric Version....................................17 4.2.4. String Version.....................................19 4.2.5. Operational Status.................................21 4.2.6. Port Filter........................................22 4.2.7. Installed Packages.................................24 4.2.8. PA-TNC Error.......................................26 4.2.8.1. Invalid Parameter Error Code...................27 4.2.8.2. Version Not Supported Error Code...............28 4.2.8.3. Attribute Type Not Supported Error Code........29 4.2.9. Assessment Result..................................30 4.2.10. Remediation Instructions..........................31 4.2.10.1. IETF Standard PA-TNC Remediation Parameters Types..................................................32 4.2.11. Forwarding Enabled................................33 4.2.12. Factory Default Password Enabled..................34 4.3. Vendor-Defined Attributes...............................35 5. Evaluation Against NEA Requirements.........................35 Sangster & Narayan Expires April 6, 2009 [Page 2] Internet-Draft PA-TNC October 2008 5.1. Evaluation Against Requirement C-1......................35 5.2. Evaluation Against Requirement C-2......................36 5.3. Evaluation Against Requirement C-3......................36 5.4. Evaluation Against Requirement C-4......................36 5.5. Evaluation Against Requirement C-5......................36 5.6. Evaluation Against Requirement C-6......................36 5.7. Evaluation Against Requirement C-7......................37 5.8. Evaluation Against Requirement C-8......................37 5.9. Evaluation Against Requirement C-9......................37 5.10. Evaluation Against Requirement C-10....................38 5.11. Evaluation Against Requirement C-11....................38 5.12. Evaluation Against Requirement PA-1....................38 5.13. Evaluation Against Requirement PA-2....................38 5.14. Evaluation Against Requirement PA-3....................39 5.15. Evaluation Against Requirement PA-4....................39 5.16. Evaluation Against Requirement PA-5....................39 5.17. Evaluation Against Requirement PA-6....................40 6. Security Considerations.....................................40 6.1. Trust Relationships.....................................40 6.1.1. Posture Collector..................................40 6.1.2. Posture Validator..................................40 6.1.3. Posture Broker Client, Posture Broker Server.......41 6.2. Security Threats........................................41 6.2.1. Attribute Theft....................................41 6.2.2. Message Fabrication................................42 6.2.3. Attribute Modification.............................42 6.2.4. Attribute Replay...................................42 6.2.5. Attribute Insertion................................42 6.2.6. Denial of Service..................................43 7. Privacy Considerations......................................43 8. IANA Considerations.........................................44 8.1. IETF Standard PA Subtypes...............................44 8.2. Registry for IETF Standard PA-TNC Attribute Types.......44 8.3. Registry for IETF Standard PA-TNC Error Codes...........45 8.4. Registry for IETF Standard Remediation Parameter Types..45 9. Acknowledgments.............................................46 10. References.................................................46 10.1. Normative References...................................46 10.2. Informative References.................................46 Appendix A: Use Cases..........................................46 A.1. Initial Client triggered assessment.....................46 A.1.1. Message Contents...................................48 A.1.1.1. N/W Join.......................................48 A.1.1.2. Request Posture (Req Post.)....................48 A.1.1.3. Vendor X Patch Posture (VndrX Patch Posture)...48 A.1.1.4. OS Posture.....................................49 A.1.1.5. Posture Report.................................49 Sangster & Narayan Expires April 6, 2009 [Page 3] Internet-Draft PA-TNC October 2008 A.1.1.6. Verify Posture.................................49 A.1.1.7. OS Posture Result (OS Reslt)...................50 A.1.1.8. Vendor X Patch Result (VndrX Patch Result).....50 A.1.1.9. Assessment Result (Assess Result)..............50 A.1.1.10. Posture Result (OS PRslt & Vndr X Post PResult)50 A.2. Server initiated Assessment with Remediation............51 A.2.1. Message Contents...................................52 A.2.1.1. N/W Join.......................................52 A.2.1.2. Create Posture Request (Create Posture Req.)...52 A.2.1.3. Vendor Y AV Posture Request (Vndr Y AV Posture Req)...................................................53 A.2.1.4. Vendor X AV Posture Request (Vndr X AV Posture Req)...................................................53 A.2.1.5. Posture Request................................54 A.2.1.6. Posture Request (Vndr X AV Post Req & Vndr Y AV Post Req)...............................................54 A.2.1.7. Vendor Y AV Posture (Vndr Y AV Posture)........54 A.2.1.8. Vendor X AV Posture (Vndr X AV Posture)........54 A.2.1.9. Posture Response...............................55 A.2.1.10. Verify Posture................................55 A.2.1.11. Vendor Y AV Posture Result (Vndr Y AV Post Result)................................................55 A.2.1.12. Vendor X AV Posture Result (Vndr X AV Post Reslt) .......................................................56 A.2.1.13. Assessment Result (Assess Result).............56 A.2.1.14. Posture Result (Vndr X AV Post Reslt & Vndr Y AV Post Reslt).............................................56 A.3. Client triggered re-assessment..........................56 A.3.1. Message Contents...................................58 A.3.1.1. Enable VPN Client (Enble)......................58 A.3.1.2. Notify Status Change (VPN Status Change).......58 A.3.1.3. Notify Posture Change (Posture Change).........58 A.3.1.4. Request Posture (Req. Post)....................58 A.3.1.5. Inspect/Request Info (Ins/Rq Info).............58 A.3.1.6. Vendor X VPN Posture (VPNX Post)...............58 A.3.1.7. Vendor Y VPN Posture (VPNY Post)...............59 A.3.1.8. Posture Report.................................60 A.3.1.9. Verify Posture (Vrfy Post.)....................60 A.3.1.10. VPN Posture Result (VPN PRslt)................60 A.3.1.11. Assessment Result (Assess Result).............61 A.3.1.12. Posture Result (VPN PRslt)....................61 Author's Address...............................................61 Intellectual Property Statement................................61 Disclaimer of Validity.........................................61 Sangster & Narayan Expires April 6, 2009 [Page 4] Internet-Draft PA-TNC October 2008 1. Introduction This document specifies PA-TNC, a Posture Attribute Protocol (PA) identical to the Trusted Computing Group's IF-M 1.0 protocol [6]. The document then evaluates PA-TNC against the requirements defined in the NEA Requirements specification [7]. 1.1. Relationship to Trusted Network Connect Starting in 2004, the Trusted Computing Group (TCG) has defined and published the Trusted Network Connect (TNC) architecture and standards for network access control. These standards enable multi-vendor interoperability throughout the TNC architecture and have been widely adopted and deployed. In order to avoid the development of multiple incompatible standards in this area, the TCG offered several of its TNC standards to the IETF as candidates for standardization in the IETF also. This document is one of those standards, known in the IETF as PA-TNC and in the TCG as IF-M 1.0. PA-TNC and IF-M 1.0 are equivalent. Consistent with IETF's requirements for standards track documents, the TCG has authorized the editors of this document to offer the specification to the IETF without restriction. As with other Internet-Drafts, the IETF Trust owns the copyright to this document. The IETF may modify this document, ignore it, publish it as an RFC, or take any other action. If the IETF decides to adopt a version of this document as an RFC, the TCG plans to publish a specification for an equivalent TNC protocol to ensure continued compatibility. 1.2. Prerequisites This document does not define an architecture or reference model. Instead, it defines a protocol that works within the reference model described in the NEA Overview and Requirements specification. The reader is assumed to be thoroughly familiar with that document. No familiarity with TCG specifications is assumed. 1.3. Message Diagram Conventions This specification defines the syntax of PA-TNC messages using diagrams. Each diagram depicts the format and size of each field in bits. Implementations MUST send the bits in each diagram as they are shown, traversing the diagram from top to bottom and then from left to right within each line (which Sangster & Narayan Expires April 6, 2009 [Page 5] Internet-Draft PA-TNC October 2008 represents a 32-bit quantity). Multi-byte fields representing numeric values must be sent in network (big endian) byte order. Descriptions of bit field (e.g. flag) values are described referring to the position of the bit within the field. These bit positions are numbered from the most significant bit through the least significant bit so a one octet field with only bit 0 set has the value 0x80. 2. Design Considerations This section discusses some of the key design considerations for the PA protocol. 2.1. Standard Attribute Namespace for Interoperability The PA protocol requires the use of two categories of namespaces: component types (AKA PA Subtypes) and attributes. Each of these namespace categories needs to contain well known, interoperable names with defined syntax and semantics co- existing with names for vendor defined private extensions. Similarly, each namespace category needs to be readily extensible without repeated coordination yet avoids naming conflicts. The PA-TNC and PB-TNC protocols provide for multiple orthogonal namespaces for each category that exist without overlap by including a SMI Private Enterprise Number (PEN) field to identify the definer of namespace of the associated field. This allows the IETF NEA WG to define a set of standard component types and attribute types while allowing vendors to each create additional names outside of the IETF standard namespace. Over time, vendor defined names might be proposed for standardization and thus migration into the IETF namespace. The PB-TNC protocol defines an IETF standard namespace (using vendor-id=0) that allows for definition of standard component types (e.g. Operating System, Firewall, Anti-Virus) using the PA Subtype field (see section 3.2. Similarly, PA-TNC defines a set of standard attributes in section 4.2. that represent the most common capabilities (attributes) of these types of components across a variety of vendor implementations. The standard namespace allows NEA deployments with both open source and vendor provided NEA implementations to support a consistent set of policies across their environment based on these standard attributes. The standard attributes can be used with a variety of endpoints (hosts, printers, mobile devices) that are running Sangster & Narayan Expires April 6, 2009 [Page 6] Internet-Draft PA-TNC October 2008 applications and operating systems (defined by the PA Subtypes) from a variety of vendors. 2.2. Vendor Defined Namespace for Differentiation and Agility The endpoint is a very dynamic environment in terms of rate of new features being deployed and attacks that are crafted against existing and new applications such as: viruses, worms, malware, and spyware. It is difficult to imagine the standard namespaces to being able to keep pace with this rapidly changing environment. Vendors typically differentiate themselves by moving rapidly to provide unique mechanisms to address such threats and their ability to deal with changes in an agile manner. The PA-TNC and PB-TNC protocols allows for creation of vendor defined namespace(s) where each namespace allows use of vendor defined PA Subtypes to identify non-standard applications or operating system variants and vendor defined attributes describing new aspects of each type of component. The vendor namespaces will allow NEA deployments to craft compliance policies using a mixture of attributes from both the IETF standard namespace and vendor defined namespaces that may include multiple vendors representing the various hardware and software components present on the endpoints. The PA-TNC protocol's use of vendor-id to identify the namespace of each attribute allows Posture Collectors to support some or all of the IETF standard attributes plus optionally a set of vendor defined attributes (potentially from more then one vendor-id namespace). For instance, an open source anti-virus Posture Collector might be written that supports all of the IETF standard attributes used to describe a local anti-virus component and a subset of multiple anti-virus manufacturers' vendor defined attributes. This Posture Collector might therefore be able to interoperate with Posture Validators from multiple vendors. Conversely, a simple Posture Collector might be written to ignore any vendor defined attributes requested and only return standard attributes that it supports. If the vendor provided Posture Validator's policy allows for this subset to be considered compliant, then these simple Posture Collectors can be used to perform a successful assessment. 2.3. Use of TLV Based Encoding for Efficiency The PA-TNC protocol has chosen to employ a binary encoding using a type-length-value (TLV) structure. TLV encoding was preferred over the use of a textual encoding format such as XML to provide a more efficient utilization of the potentially constrained Sangster & Narayan Expires April 6, 2009 [Page 7] Internet-Draft PA-TNC October 2008 bandwidth available between the NEA Client and NEA Server (see NEA Overview and Architecture [7]). Efficiency was a primary criteria for this choice with consideration given to both: 1. Optimization of the bits-on-the-wire to accommodate NEA requirements for assessment over low bandwidth or high latency links (C-8) and allow for the PT protocol to run over existing network access protocols (PT-4, C-11) that are constrained by packet size. 2. Optimization of CPU utilization on the endpoint to accommodate for low power endpoints such as mobile devices. The choice of TLV encoding does not preclude the use of XML- based attribute values within the vendor namespaces or future standard attributes. It is conceivable that certain vendors may utilize XML encoding for extensibility within their namespace when the above considerations are less applicable to their technologies. Attributes encoded within the vendor defined namespace using alternate encoding such as XML will be opaque to NEA software only supporting standard attributes and will be processed primarily by the vendor defined components (collector/validator). 3. PA-TNC Message Protocol This section discusses the use of the PA-TNC message and its attributes, and specifies the syntax and semantics for the PA- TNC message header. The details of each attribute included within the PA-TNC payload are specified in section 4.2. 3.1. PA-TNC Messaging Model PA-TNC messages are carried by the PB-TNC protocol [5], which provides a multi-roundtrip reliable transport and end-to-end message delivery to subscribed (interested) parties using a variety of underlying network protocols. PA-TNC is unaware of these underlying PT transport protocols being used below PB-TNC. The interested parties consist of Posture Collectors on the NEA Client and Posture Validators associated with the NEA Server that have registered to receive messages about particular types of components (e.g. anti-virus) during an assessment. The PA- TNC messaging protocol operates synchronously within an assessment session, with Posture Collectors and Posture Validators taking turns sending one or more messages to each other. Each PA-TNC message may contain one or more attributes Sangster & Narayan Expires April 6, 2009 [Page 8] Internet-Draft PA-TNC October 2008 associated with the functional component identified in the component type (PA Subtype) of the PB protocol. Posture Collectors may only send PA-TNC messages to Posture Validators and vice versa. No Posture Collector to Posture Collector or Posture Validator to Posture Validator messaging is allowed to occur. Each Posture Collector or Posture Validator may send several PA-TNC messages in succession before indicating that it has completed its response to the Posture Broker Client or Posture Broker Server respectively. As necessary, the Posture Broker Client and Posture Broker Server will batch these messages prior to sending them over the network. PB-TNC provides a publish/subscribe model of message exchange. This means that, at any given point in time, zero or more subscribers for a particular type of message may be present on a Posture Broker Client or Posture Broker Server. This is beneficial, since it allows one Posture Collector or Posture Validator to combine multiple functions (like anti-virus and personal firewall) by subscribing to both TNC standard component types. It also allows multiple Posture Collectors or Posture Validators to support the same components, such as two anti- virus Posture Validators that are each used to manage their own respective anti-virus client software. However, this publish/subscribe model has some possible negative side effects. When a Posture Collector or Posture Validator initially sends a PA-TNC message, it does not know whether it will receive many, one, or no PA-TNC messages from the other side. For many types of assessments, this is acceptable, but in some cases a more direct channel binding between a particular Posture Collector and Posture Validator pair is necessary. For example, a Posture Validator may wish to provide remediation instructions to a particular Posture Collector that it knows is capable of remediating a non-compliant component. This can be accomplished using the exclusive delivery PB-TNC capability to limit distribution of a message to a single Posture Collector by including the target Posture Collector Identifier in the PA-PB header. 3.2. PA-TNC Relationship to PB-TNC This section summarizes the major elements of a PA-TNC message as they might appear inside of a PB-TNC message. The double line (===) in the diagram below indicates the separation between the PB-TNC and PA-TNC protocols. The PA-TNC portion of the message is delivered to each Posture Collector or Posture Sangster & Narayan Expires April 6, 2009 [Page 9] Internet-Draft PA-TNC October 2008 Validator registered to receive messages containing a particular message type. Note that PB-TNC is capable of carrying multiple PB-TNC and PA-TNC messages in a single PB-TNC batch. See the PB-TNC specification [5] for more information on its capabilities. One important linkage between the PA-TNC and PB-TNC protocols is the PA message type (PA Message Vendor ID and PA Subtype) that is used by the Posture Broker Client and Posture Broker Server to route messages to interested Posture Collectors and Posture Validators. The message type indicates the software component (component type) that is associated with the attributes included inside the PA-TNC message. Therefore, Posture Collectors and Posture Validators written to support an assessment of a particular component can register to receive messages about the component and thus participate in its assessment. Each Posture Collector and Posture Validator MUST only send PA-TNC messages containing attributes that pertain to the software component defined in the message type of the message. This ensures that only the appropriate Posture Collectors and Posture Validators that support a particular type of component will receive attributes related to that component. If a PA-TNC message contained a mix of attributes about different components and a message type of only one of those components, the message would only be delivered to parties interested in the component type included in the message type, so other interested recipients wouldn't see those attributes. The message type is comprised of 2 fields: a PA Message Vendor ID and a PA Subtype. The PA Message Vendor ID identifies the vendor or other organization that defined this message type. The PA Subtype identifies the message type more specifically within the set of message types defined by that vendor. This specification defines several IETF Standard PA Subtypes to be used with a PA Message Vendor ID of zero (0). Within this specification, the PA Subtype field is used to indicate the type of component (e.g. firewall) involved with the message's attributes. Therefore for clarity the PA subtype will be referred to as the "component type" in this specification. Vendor-defined name spaces may use other semantics for the PA Subtype field as this is outside the scope of this specification. Sangster & Narayan Expires April 6, 2009 [Page 10] Internet-Draft PA-TNC October 2008 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PB-TNC Header | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PB-TNC Message of type PB-PA-Message | |(includes: PA Message Vendor ID, PA Subtype, and other fields| | used by Posture Broker Client and Posture Broker Server for | | routing) | =============================================================== +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Message Header | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Attribute | | (e.g. Product Information) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Attribute | | (e.g. Operational Status) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 Overview: PB-TNC batch that contains a PA-TNC Message For example, if a Posture Broker Client sent a PB-TNC batch that contained a PA-TNC message with a message type indicating firewall component, this message would be routed by the Posture Broker Server to Posture Validators registered to assess firewalls. Each registered Posture Validator would receive a copy of the PA-TNC message including the PA-TNC header and set of attributes. It is important that each of the attributes included in the PA-TNC message be associated with the firewall component because only the Posture Collector and Posture Validator interested in firewalls will receive such messages. If the above message contained both firewall and operating system attributes inside a PA-TNC message with a component type of firewall, then any Posture Collector and Posture Validator registered to receive operating system messages would not receive those attributes, as the messages would only be delivered to those registered for firewall messages. 3.3. PA-PB Posture Collector and Posture Validator Identifiers The PA-PB header contains several fields important to the processing of a received PA message. The PA Vendor ID and Subtype are described in the PB-TNC specification and above in section 3.2. Also present in the PA-PB header is a pair of fields that identify the Posture Collector and/or Posture Validator involved in the exchange. These fields are used for performing exclusive Sangster & Narayan Expires April 6, 2009 [Page 11] Internet-Draft PA-TNC October 2008 delivery of messages as described in section 3.1 and as an indicator for correlation of received attributes. Correlation of attributes is necessary when the sending Posture Collector provides posture for multiple implementations of a single type of component during an assessment, so the recipient Posture Validators need to know which attributes are describing the same implementation. For example, a single Posture Collector might report attributes on two installed VPN implementations on the endpoint. Because the individual attributes do not include an indication of which VPN product they are describing, the recipient needs something to perform this correlation. Therefore, for this example, the VPN Posture Collector would need to obtain two Posture Collector Identifiers from the Posture Broker Client and consistently use one with each of the implementations during an assessment. The VPN Posture Collector would group all the attributes associated with a particular VPN implementation into a single PA-PB message and send the message using the Posture Collector Identifier it designates as going with the particular implementation. This approach allows the recipient to recognize when attributes in future assessment messages also describe the same component implementation. 3.4. PA-TNC Messages in PB-TNC As depicted in section 3.2. a PA-TNC message consists of a PA- TNC header followed by a sequence of one or more attributes. The PA-TNC message header (described in section 3.6. and the header for each of the PA-TNC attributes (specified in section 4.1) have a fixed type-length-value (TLV) format. Each PA-TNC message MAY contain a mixture of standards-based and vendor- defined attributes identifiable using the type portion of the attribute header. All Posture Collectors and Posture Validators compliant with this specification MUST be capable of processing multiple attributes in a received PA-TNC message. A Posture Collector or Posture Validator that receives a PA-TNC message can use the attribute header's length field to skip any attributes that it does not understand, unless the attribute is marked as mandatory to process. 3.5. IETF Standard PA Subtypes This section defines several IETF Standard PA Subtypes. Each PA subtype defined here identifies a specific component relevant to the endpoint's posture. This allows a small set of generic PA- TNC attributes (e.g. Product Information) to be used to describe Sangster & Narayan Expires April 6, 2009 [Page 12] Internet-Draft PA-TNC October 2008 a large number of different components (e.g. operating system, anti-virus, etc.). It also allows Posture Collectors and Posture Validators to specialize in a particular component and only receive PA-TNC messages relevant to that component. Value Name Definition ----- ---- ---------- 0 Testing Reserved for use in specification examples, experimentation and testing. 1 Operating System Operating system running on the endpoint 2 Anti-Virus Host-based anti-virus software 3 Anti-Spyware Host-based anti-spyware software 4 Anti-Malware Host-based anti-malware (e.g. anti- bot) software not included within anti-virus or anti-spyware components 5 Firewall Host-based firewall 6 IDPS Host-based Intrusion Detection and/or Prevention Software (IDPS) 7 VPN Host-based Virtual Private Networking (VPN) software 8 NEA Client NEA client software These PA subtypes must be used in a PB-PA message with a PA Message Vendor ID of zero (0) indicating an IETF standard type of component (as described in the PB-TNC specification [5]). If these PA subtype values are used with a different PA Message Vendor ID, they have a completely different meaning that is not defined in this specification. 3.6. PA-TNC Field Types This section describes some commonly used primitive types found in the value field of attributes. The value field for each attribute is typically a structure composed of several data items. Many of these data items share a common syntax and/or encoding. In order to consolidate the description of these Sangster & Narayan Expires April 6, 2009 [Page 13] Internet-Draft PA-TNC October 2008 common syntax or encoding rules, this section defines type definitions that are to be applied. Type Name Description --------- ----------- OctetArray Variable number of octets containing binary data. Integer 32-bit unsigned value in network (big endian) byte order String OctetArray that contains a human readable text encoded in UTF-8 transformation format [2] IPv4Address OctetArray composed of 4 octets starting with the most significant octet. IPv6Address OctetArray composed of 16 octets starting with the most significant octet. TimeString An RFC 3339 [4] compliant ASCII string expressed in Coordinated Universal Time (UTC) time. VersionNum OctetArray composed of 2 Integer typed values where the initial Integer contains the major version and the second contains the minor version. 3.7. PA-TNC Message Header Format This section describes the format and semantics of the PA-TNC header. Every PA-TNC message MUST start with a PA-TNC header. The PA-TNC header provides a common context applying to all of the attributes contained within the PA-TNC payload. The payload consists of a sequence of assessment attributes described in section 4.2. Sangster & Narayan Expires April 6, 2009 [Page 14] Internet-Draft PA-TNC October 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Version This field indicates the version of the format for the PA-TNC message. This version is intended to allow for evolution of the PA-TNC message header and payload in a manner that can easily be detected by message recipients. PA-TNC message senders MUST set this field to 0x01 for all PA-TNC messages that comply with formats and requirements described in version 1.0 of this specification. Implementations responding to a PA-TNC message containing a supported version SHOULD use the same Version number to minimize the risk of version incompatibility. Message senders MAY send an empty PA-TNC message with the Version value set to 0 in order to discover the PA-TNC protocol versions supported by peer recipients, for more information see PA-TNC Error Code description in section 4.2.8. Message recipients MUST NOT support version 0 and MUST NOT interpret the contents (after the Version field) of a PA-TNC message containing a version number that the recipient does not support. Message recipients MUST respond to a PA-TNC message with an unsupported version by sending a Version Not Supported error code in a PA-TNC Error attribute. PA-TNC message initiators supporting multiple PA-TNC protocol versions SHOULD be able to alter which version of PA-TNC message they send based on prior message exchanges with a particular peer Posture Collector or Posture Validator. Reserved Reserved for future use. This field MUST be set to 0 on transmission and ignored upon reception. Message Identifier This field contains a value that uniquely identifies this message, differentiating it from others sent by a particular Sangster & Narayan Expires April 6, 2009 [Page 15] Internet-Draft PA-TNC October 2008 PA-TNC message sender within this assessment. This value can be included in a response message to indicate which message was received and caused the response. For example, this field is included in the PA-TNC error messages so the party who receives the error message can determine which of the messages they had sent caused the error. PA-TNC message senders MUST NOT send the same message identifier more than once during an assessment. Message identifiers may be randomly generated or sequenced as long as values are not repeated during an assessment message exchange. PA-TNC message recipients are not required to check for duplicate message identifiers. 4. PA-TNC Attributes This section defines the PA-TNC attributes that can be carried within a PA-TNC message. The initial section defines the standard attribute header that appears at the start of each attribute in a PA-TNC message. The second section defines each of the IETF Standard PA-TNC attributes and the final section discusses how vendor-defined PA-TNC attributes can be used within a PA-TNC message. Vendor-defined PA-TNC attributes use the vendor's SMI Private Enterprise Number in the Attribute Type field. A PA-TNC message MUST contain a PA-TNC header (defined in section 3.7. followed by a sequence of zero or more PA-TNC attributes. All PA-TNC attributes MUST begin with a standard PA-TNC attribute header, as defined in section 4.1. The contents of PA-TNC attributes vary widely, depending on their attribute type. Section 4.2. defines the IETF Standard PA-TNC Attributes. Section 4.3. discusses how vendor-specific PA-TNC attributes can be defined. 4.1. PA-TNC Attribute Header Following the PA-TNC message header is a sequence of zero or more attributes. All PA-TNC attributes MUST begin with the standard PA-TNC attribute header defined in this subsection. Each attribute described in this specification is represented by a TLV tuple. The TLV tuple includes an attribute identifier comprised of the Vendor ID and Attribute Type (type), the TLV tuple's overall length and finally the attribute's value. The use of TLV representation was chosen due to its flexibility and extensibility and use in other standards. Recipients of an attribute can use the attribute type fields to determine the Sangster & Narayan Expires April 6, 2009 [Page 16] Internet-Draft PA-TNC October 2008 precise syntax and semantics of the attribute value field and the length to skip over an unrecognized attribute. The length field is also beneficial when a variable length attribute value is provided. The TLV format does not contain an explicit TLV format version number, so every attribute included in a particular PA-TNC message MUST use the same TLV format. Using the PA-TNC message version number to indicate the format of all TLV attributes within a PA-TNC message allows for future versioning of the TLV format in a manner detectable by PA-TNC message recipients. Similarly, requiring all TLV attribute formats to be the same within a PA-TNC message also assures that recipients compliant with a particular PA-TNC message version can at least parse every attribute header and use the length to skip over unrecognized attributes. Finally all attribute TLVs within a PA-TNC message MUST pertain to the same implementation of the component. This restriction is relevant when a single Posture Collector is reporting on multiple implementations of a component, so must send multiple PA-TNC messages each including only the attributes describing a single implementation. For more information on how Posture Collectors should handle multiple implementations see section 3.3. Every PA-TNC 1.0 compliant TLV attribute MUST use the following TLV format: 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | PA-TNC Attribute Vendor ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Attribute Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Attribute Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attribute Value (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Flags This field defines flags impacting the processing of the associated attribute. Bit 0 (0x80) is the NOSKIP flag. Any Posture Collector or Posture Validator that receives an attribute with this flag set to 1 but does not support this attribute MUST NOT process Sangster & Narayan Expires April 6, 2009 [Page 17] Internet-Draft PA-TNC October 2008 any part of the PA-TNC message and SHOULD respond with an Attribute Type Not Supported error in a PA-TNC error message. In order to avoid taking action on a subset of the attributes only to later find an unsupported attribute with the NOSKIP flag set, recipients of a multi-attribute PA-TNC message might need to scan all of the attributes prior to acting upon any attribute. When the NOSKIP flag is set to 0, recipients SHOULD skip any unsupported attributes and continue processing the next attribute. Bit 1-7 are reserved for future use. These bits MUST be set to 0 on transmission and ignored upon reception. PA-TNC Attribute Vendor ID This field indicates the owner of the name space associated with the PA-TNC Attribute Type. This is accomplished by specifying the 24 bit SMI Private Enterprise Number Vendor ID of the party who owns the Attribute Type name space. IETF Standard PA-TNC Attribute Types MUST use zero (0) in this field. The PA-TNC Attribute Vendor ID 0xffffff is reserved. Posture Collectors and Posture Verifiers MUST NOT send PA-TNC messages in which the PA-TNC Attribute Vendor ID has this reserved value (0xffffff). If a Posture Collector or Posture Verifier receives a message in which the PA-TNC Attribute Vendor ID has this reserved value (0xffffff), it SHOULD respond with an Invalid Parameter error code in a PA-TNC Error attribute. PA-TNC Attribute Type This field defines the type of the attribute included in the Attribute Value field. This field is qualified by the PA-TNC Attribute Vendor ID field so that a particular PA-TNC Attribute Type value (e.g. 327) has a completely different meaning depending on the value in the PA-TNC Attribute Vendor ID field. If the PA-TNC Attribute Vendor ID field has the value zero (0) then the PA-TNC Attribute Type field contains an IETF Standard PA-TNC Attribute Type, as listed in the IANA Sangster & Narayan Expires April 6, 2009 [Page 18] Internet-Draft PA-TNC October 2008 registry. Section 4.2. of this specification defines the initial set of IETF Standard PA-TNC Attribute Types. The PA-TNC Attribute Type 0xffffffff is reserved. Posture Collectors and Posture Verifiers MUST NOT send PA-TNC messages in which the PA-TNC Attribute Type has this reserved value (0xffffffff). If a Posture Collector or Posture Verifier receives a message in which the PA-TNC Attribute Type has this reserved value (0xffffffff), it SHOULD respond with an Invalid Parameter error code in a PA-TNC Error attribute. PA-TNC Attribute Length This field contains the length in octets of the entire PA-TNC Attribute including the PA-TNC Attribute Header (the fields Flags, PA-TNC Attribute Vendor ID, PA-TNC Attribute Type, and PA-TNC Attribute Length). Therefore, this value MUST always be at least 12. Any Posture Collector or Posture Verifier that receives a message with a PA-TNC Attribute Length field whose value is less than 12 SHOULD respond with an Invalid Parameter PA-TNC error code. Implementations that do not support the specified PA-TNC Attribute Type can use this length to skip over this attribute to the next attribute. Note that while this field is 4 octets the maximum usable attribute length is likely to be less than 2^32-1 due to limitations of the underlying protocol stack specifically PB-TNC's length field includes 32 bytes of other headers which reduce the maximum size available to PA-TNC since they both use 4 octet length fields. Attribute Value This field varies depending on the particular type of attribute being expressed. The contents of this field for each of the IETF Standard PA-TNC Attribute Types are defined in section 4.2. 4.2. IETF Standard PA-TNC Attribute Types This section defines an initial set of IETF Standard PA-TNC Attribute Types. These Attribute Types MUST always be used with a PA-TNC Vendor ID of zero (0). If these PA-TNC Attribute Type values are used with a different PA-TNC Vendor ID, they have a Sangster & Narayan Expires April 6, 2009 [Page 19] Internet-Draft PA-TNC October 2008 completely different meaning that is not defined in this specification. The following table briefly describes each attribute and defines the numeric value to be used in the PA-TNC Attribute Type field of the PA-TNC Attribute Header. Later subsections provide detailed specifications for each PA-TNC Attribute Value. Number Name Description ------ ---- ----------- 0 Testing Reserved for use in specification examples, experimentation and testing. 1 Attribute Request Contains a list of attribute type values defining the attributes desired from the Posture Collectors. 2 Product Information Manufacturer and product information for the component. 3 Numeric Version Numeric version of the component. 4 String Version String version of the component. 5 Operational Status Describes whether the component is running on the endpoint. 6 Port Filter Lists the set of ports (e.g. TCP port 80 for HTTP) that are allowed or blocked on the endpoint. 7 Installed Packages List of software packages installed on endpoint that provide the requested component. 8 PA-TNC Error PA-TNC message or attribute processing error. 9 Assessment Result Result of the assessment performed by a Posture Validator. Sangster & Narayan Expires April 6, 2009 [Page 20] Internet-Draft PA-TNC October 2008 10 Remediation Instructions for remediation Instructions generated by a Posture Validator. 11 Forwarding Enabled Indicates whether packet forwarding has been enabled between different interfaces on the endpoint. 12 Factory Default Indicates whether the endpoint Password has a factory default password enabled. The following subsections discuss the usage, format and semantics of the Attribute Value field for each IETF Standard PA-TNC Attribute Type. 4.2.1. Attribute Request This PA-TNC Attribute Type allows a Posture Validator to request certain attributes from the registered set of Posture Collectors. All Posture Collectors that implement any of the IETF Standard PA Subtypes defined in this specification SHOULD support receiving and processing this attribute type for at least those PA subtypes. Posture Collectors that receive and process this attribute MAY choose to send all, a subset or none of the requested attributes but MUST NOT send attributes that were not requested (except error attributes). All Posture Validators that implement any of the IETF Standard PA Subtypes defined in this specification SHOULD support sending this attribute type for at least those PA subtypes. Posture Verifiers MUST NOT include this attribute type in an Attribute Request attribute. It does not make sense for a Posture Verifier to request that a Posture Collector send an Attribute Request attribute. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 1. Sangster & Narayan Expires April 6, 2009 [Page 21] Internet-Draft PA-TNC October 2008 The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. Note that this diagram shows two attribute types. The actual number of attribute types included in an Attribute Request attribute can vary from one to a large number (limited only by the maximum message and length supported by the underlying PT transport protocol). However, each Attribute Request MUST contain at least one attribute type. Because the length of a PA-TNC Attribute Vendor ID paired with a PA-TNC Attribute Type and a one octet Reserved field is always 8 octets, the number of requested attributes can be easily computed using the PA-TNC Attribute Length field by subtracting the number of octets in the PA-TNC Attribute Header and dividing by 8. If the PA-TNC Attribute Length field is invalid, Posture Collectors SHOULD respond with an Invalid Parameter PA-TNC error code. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | PA-TNC Attribute Vendor ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Attribute Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | PA-TNC Attribute Vendor ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Attribute Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved Reserved for future use. This field MUST be set to 0 on transmission and ignored upon reception. PA-TNC Attribute Vendor ID This field contains the SMI Private Enterprise Number of the organization that controls the name space for the following PA-TNC Attribute Type. This field enables IETF Standard PA- TNC Attributes and vendor-defined PA-TNC Attributes to be used without potential collisions. Any IETF Standard PA-TNC Attribute Types defined in section 4.2. MUST use zero (0) in this field. Vendor-defined Sangster & Narayan Expires April 6, 2009 [Page 22] Internet-Draft PA-TNC October 2008 attributes MUST use the SMI Private Enterprise Number of the organization that defined the attribute. PA-TNC Attribute Type The PA-TNC Attribute Type field (together with the PA-TNC Vendor ID field) indicates the specific attribute requested. Some IETF Standard PA-TNC Attribute Types MUST NOT be requested using this field (e.g. requesting a PA-TNC Error attribute). This is explicitly indicated in the description of those PA-TNC Attribute Types. Any Posture Collector or Posture Validator that receives an Attribute Request containing one of the prohibited Attribute Types SHOULD respond with an Invalid Parameter error in a PA-TNC error message. 4.2.2. Product Information This PA-TNC Attribute Type contains identifying information about a product that implements the component specified in the PA Subtype field, as described in section 3.5. For example, if the PA Subtype is Anti-Virus, this attribute would contain information identifying an anti-virus product installed on the endpoint. All Posture Collectors that implement any of the IETF Standard PA Subtypes defined in this specification MUST support sending this attribute type, at least for those PA subtypes. Whether a particular Posture Collector actually sends this attribute type SHOULD still be governed by local privacy and security policies. All Posture Validators that implement any of the IETF Standard PA Subtypes defined in this specification MUST support receiving this attribute type, at least for those PA subtypes. Posture Validators MUST NOT send this attribute type. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 2. The value in the PA-TNC Attribute Length field will vary, depending on the length of the Product Name field. However, the value in the PA-TNC Attribute Length field MUST be at least 17 because this is the length of the fixed size fields in the PA-TNC Attribute Header and the fixed size fields in this attribute type. If the PA-TNC Attribute Length field is less than the size of these fixed length fields, implementations SHOULD respond with an Invalid Parameter PA-TNC error code. Sangster & Narayan Expires April 6, 2009 [Page 23] Internet-Draft PA-TNC October 2008 This attribute type includes both numeric and textual identifiers for the organization that created the product (the "product creator") and for the product itself. For automated processing, numeric identifiers are superior because they are less ambiguous and more efficient. However, numeric identifiers are only available if the product creator has assigned them. Therefore, a textual identifier is also included. This textual identifier has the additional benefit that it may be easier for humans to read (although this benefit is minimal since the primary purpose of this attribute is automated assessment). The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Product Vendor ID | Product ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Product ID | Product Name (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Product Vendor ID This field contains the SMI Private Enterprise Number for the product creator. If the SMI PEN for the product creator is unknown or if the product creator does not have an SMI PEN, the Product Vendor ID field MUST be set to 0 and the identity of the product creator SHOULD be included in the Product Name along with the name of the product. Product ID This field identifies the product using a numeric identifier assigned by the product creator. If this Product ID value is unknown or if the product creator has not assigned such a value, this field MUST be set to 0. If the Product Vendor ID is 0, this field MUST be set to 0. In any case, the name of the product SHOULD be included in the Product Name field. Note that a particular Product ID value (e.g. 635) will have completely different meanings depending on the Product Vendor ID. Each Product Vendor ID defines a different space of Product ID values. Product creators are encouraged to publish lists of Product ID values for their products. Sangster & Narayan Expires April 6, 2009 [Page 24] Internet-Draft PA-TNC October 2008 Product Name This variable length field contains a UTF-8 [2] string identifying the product (e.g. "Symantec Norton AntiVirus(TM) 2008") in enough detail to unambiguously distinguish it from other products from the product creator. Products whose creator is known, but does not have a registered SMI Private Enterprise Number, SHOULD be represented using a combination of the creator name and full product name (e.g. "Ubuntu(R) IPtables" for the IPtables firewall in the Ubuntu distribution of Linux). If the product creator's SMI Private Enterprise Number is included in the Product Vendor ID field, the product creator's name may be omitted from this field. The length of this field can be determined by starting with the value in the PA-TNC Attribute Length field in the PA-TNC Attribute Header and subtracting the size of the fixed length fields in that header (12) and the size of the fixed length fields in this attribute (5). If the PA-TNC Attribute Length field is less than the size of these fixed length fields, implementations SHOULD respond with an Invalid Parameter PA- TNC error code. 4.2.3. Numeric Version This PA-TNC Attribute Type contains numeric version information for a product on the endpoint that implements the component specified in the PA Subtype field, as described in section 3.5. For example, if the PA Subtype is Operating System, this attribute would contain numeric version information for the operating system installed on the endpoint. The version information in this attribute is associated with a particular product, so Posture Validators are expected to also possess the corresponding Product Information attribute when interpreting this attribute. All Posture Collectors that implement the IETF Standard PA Subtype for Operating System SHOULD support sending this attribute type, at least for the Operating System PA subtype. Other Posture Collectors MAY support sending this attribute type. Whether a particular Posture Collector actually sends this attribute type SHOULD still be governed by local privacy and security policies. All Posture Validators that implement the IETF Standard PA Subtype for Operating System SHOULD support receiving this attribute type, at least for the Operating System PA subtype. Other Posture Validators MAY support receiving this attribute type. A Posture Validator that does not support Sangster & Narayan Expires April 6, 2009 [Page 25] Internet-Draft PA-TNC October 2008 receiving this attribute type SHOULD simply ignore attributes with this type. Posture Validators MUST NOT send this attribute type. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 3. The value in the PA-TNC Attribute Length field MUST be 28. If the PA-TNC Attribute Length field is less than the size of these fixed length fields, implementations SHOULD respond with an Invalid Parameter PA-TNC error code. This attribute type includes numeric values for the product version information, enabling Posture Validators to do comparative operations on the version. Some Posture Collectors may not be able to determine some or all of this information for a product. However, this attribute can be especially useful for describing the version of the operating system, where numeric version numbers are generally available. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Major Version Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Minor Version Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Build Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Service Pack Major | Service Pack Minor | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Major Version Number This field contains the major version number for the product, if applicable. If unused or unknown, this field SHOULD be set to 0. Minor Version Number This field contains the minor version number for the product, if applicable. If unused or unknown, this field SHOULD be set to 0. Sangster & Narayan Expires April 6, 2009 [Page 26] Internet-Draft PA-TNC October 2008 Build Number This field contains the build number for the product, if applicable. This may provide more granularity than the minor version number, as many builds may occur leading up to an official release, and all these builds may share a single major and minor version number. If unused or unknown, this field SHOULD be set to 0. Service Pack Major This field contains the major version number of the service pack for the product, if applicable. If unused or unknown, this field SHOULD be set to 0. Service Pack Minor This field contains the minor version number of the service pack for the product, if applicable. If unused or unknown, this field SHOULD be set to 0. 4.2.4. String Version This PA-TNC Attribute Type contains string version information for a product on the endpoint that implements the component specified in the PA Subtype field, as described in section 3.5. For example, if the PA Subtype is Firewall, this attribute would contain string version information for a host-based firewall product installed on the endpoint (if any). The version information in this attribute is associated with a particular product, so Posture Validators are expected to also possess the corresponding Product Information attribute when interpreting this attribute. All Posture Collectors that implement any of the IETF Standard PA Subtypes defined in this document MUST support sending this attribute type, at least for those PA subtypes. Other Posture Collectors MAY support sending this attribute type. Whether a particular Posture Collector actually sends this attribute type SHOULD still be governed by local privacy and security policies. All Posture Validators that implement any of the IETF Standard PA Subtypes defined in this document MUST support receiving this attribute type, at least for those PA subtypes. Other Posture Validators MAY support receiving this attribute type. Posture Validators MUST NOT send this attribute type. Sangster & Narayan Expires April 6, 2009 [Page 27] Internet-Draft PA-TNC October 2008 For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 4. The value in the PA-TNC Attribute Length field will vary, depending on the length of the Component Version Number, Internal Build Number, and Configuration Version Number fields. However, the value in the PA-TNC Attribute Length field MUST be at least 15 because this is the length of the fixed size fields in the PA-TNC Attribute Header and the fixed size fields in this attribute type. If the PA-TNC Attribute Length field is less than the size of these fixed length fields or does not match the length indicated by the sum of the fixed length and variable length fields, implementations SHOULD respond with an Invalid Parameter PA-TNC error code. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version Len | Product Version Number (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Build Num Len | Internal Build Number (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Config. Len | Configuration Version Number (Variable Length)| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Version Len This field defines the number of octets in the Product Version Number field. If the product version number is unavailable or unknown, this field MUST be set to 0 and the Product Version Number field will be zero length (effectively not present). Product Version Number This field contains a UTF-8 string identifying the version of the component (e.g. "1.12.23.114"). This field MUST be sized to fit the version string and MUST NOT include extra octets for padding or NUL character termination. Various products use a wide range of different formats and semantics for version strings. Some use alphabetic characters, white space, and punctuation. Some consider version "1.21" to be later than version "1.3" and some Sangster & Narayan Expires April 6, 2009 [Page 28] Internet-Draft PA-TNC October 2008 earlier. Therefore, the syntax and semantics of this string are not defined. Build Num Len This field defines the number of octets in the Internal Build Number field. For products where the internal build number is unavailable or unknown, this field MUST be set to 0 and the Internal Build Number field will be zero length (effectively not present). Internal Build Number This field contains a UTF-8 string identifying the engineering build number of the product. This field MUST be sized to fit the build number string and MUST NOT include extra octets for padding or NUL character termination. The syntax and semantics of this string are not defined. Config. Len This field defines the number of octets in the Configuration Version Number field. If the product version number is unavailable or unknown, this field MUST be set to 0 and the Product Version Number field will be zero length (effectively not present). Configuration Version Number This field contains a UTF-8 string identifying the version of the configuration used by the component. This version SHOULD represent the overall configuration version even if several configuration policy files or settings are used. Posture Collectors MAY include multiple version numbers in this single string if a single version is not practical. This field MUST be sized to fit the version string and MUST NOT include extra octets for padding or NUL character termination. Various products use a wide range of different formats for version strings. Some use alphabetic characters, white space, and punctuation. Some consider version "1.21" to be later than version "1.3" and some earlier. In addition, some Posture Collectors may place multiple configuration version numbers in this single string. Therefore, the syntax and semantics of this string are not defined. Sangster & Narayan Expires April 6, 2009 [Page 29] Internet-Draft PA-TNC October 2008 4.2.5. Operational Status This PA-TNC Attribute Type describes the operational status of a product that can implement the component specified in the PA Subtype field, as described in section 3.5. For example, if the PA Subtype is Anti-Spyware, this attribute would contain information about the operational status of a host-based anti- spyware product that may or may not be installed on the endpoint. Posture Collectors that implement the IETF Standard PA Subtype for Operating System or VPN MAY support sending this attribute type for those PA subtypes. Posture Collectors that implement other IETF Standard PA Subtypes defined in this specification SHOULD support sending this attribute type for those PA subtypes. Other Posture Collectors MAY support sending this attribute type. Whether a particular Posture Collector actually sends this attribute type SHOULD still be governed by local privacy and security policies. Posture Validators that implement the IETF Standard PA Subtype for Operating System or VPN MAY support receiving this attribute type, at least for those PA subtypes. Posture Validators that implement other IETF Standard PA Subtypes defined in this specification SHOULD support receiving this attribute type, at least for those PA subtypes. Other Posture Validators MAY support receiving this attribute type. A Posture Validator that does not support receiving this attribute type SHOULD simply ignore attributes with this type. Posture Validators MUST NOT send this attribute type. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 5. The value in the PA-TNC Attribute Length field MUST be 36. If the PA-TNC Attribute Length field does not have this value, implementations SHOULD respond with an Invalid Parameter PA-TNC error code. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. Sangster & Narayan Expires April 6, 2009 [Page 30] Internet-Draft PA-TNC October 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status | Result | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Last Use | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Last Use (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Last Use (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Last Use (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Last Use (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Status This field gives the operational status of the product. The following table lists the values currently defined for this field. As described in section 8. the IANA maintains a registry of valid values for this field so that new values can be defined. Value Description ----- ----------- 0 Unknown or other 1 Not installed 2 Installed but not operational 3 Operational If a Posture Validator receives a value for this field that it does not recognize, it SHOULD treat this value as equivalent to the value 0. Result This field contains the result of the last use of the product. The following table lists the values currently defined for this field. As described in section 8. the IANA maintains a registry of valid values for this field so that new values can be defined. Sangster & Narayan Expires April 6, 2009 [Page 31] Internet-Draft PA-TNC October 2008 Value Description ----- ----------- 0 Unknown or other 1 Successful use with no errors detected 2 Successful use with one or more errors detected 3 Unsuccessful use (e.g. aborted) Posture Collectors SHOULD set this field to 0 if the Status field contains a value of 1 (Not installed) or 2 (Installed but not operational). If a Posture Validator receives a value for this field that it does not recognize, it SHOULD treat this value as equivalent to the value 0. Reserved This field is reserved for future use. The field MUST be set to 0 on transmission and ignored upon reception. Last Use This field contains the date and time of the last use of the component. The Last Use date and time MUST be represented as an RFC 3339 [4] compliant ASCII string in Coordinated Universal Time (UTC) time with the additional restrictions that the 't' delimiter and the 'z' suffix MUST be capitalized and fractional seconds (time-secfrac) MUST NOT be included. Leap seconds are permitted and Posture Validators MUST support them. The last use string MUST NOT be NUL terminated or padded in any way. If the last use time is not known, not applicable, or cannot be represented in this format, the Posture Collector MUST set this field to the value "0000-00- 00T00:00:00Z" (allowing this field to be fixed length). Not that this particular reserved value is NOT a valid RFC 3339 date and time and MUST NOT be used for any other purpose in this field. This encoding produces a string that is easy to read, parse, and interpret. The format (more precisely defined in RFC 3339) is YYYY-MM-DDTHH:MM:SSZ, resulting in one and only one representation for each second in UTC time from year 0000 to year 9999. For example, 9:05:00AM EST (GMT-0500) on January 19, 1995 can be represented as "1995-01-19T14:05:00Z". The length of this field is always 20 octets. Sangster & Narayan Expires April 6, 2009 [Page 32] Internet-Draft PA-TNC October 2008 4.2.6. Port Filter This PA-TNC Attribute Type provides the list of port numbers and associated protocols (e.g. TCP and UDP) that are currently blocked or allowed by a host-based firewall on the endpoint. Posture Collectors that implement the IETF Standard PA Subtype for Firewall or VPN SHOULD support sending this attribute type for those PA subtypes. Posture Collectors that implement other IETF Standard PA Subtypes defined in this specification MUST NOT support sending this attribute type for those PA subtypes. Other Posture Collectors MAY support sending this attribute type, if it is appropriate to their PA subtype. Whether a particular Posture Collector actually sends this attribute type SHOULD still be governed by local privacy and security policies. Posture Validators that implement the IETF Standard PA Subtype for Firewall or VPN SHOULD support receiving this attribute type, at least for those PA subtypes. Posture Validators that implement other IETF Standard PA Subtypes defined in this specification MUST NOT support receiving this attribute type for those PA subtypes. Other Posture Validators MAY support receiving this attribute type. A Posture Validator that does not support receiving this attribute type SHOULD simply ignore attributes with this type. Posture Validators MUST NOT send this attribute type. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 6. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. Note that this diagram shows two Protocol/Port Number pairs. The actual number of Protocol/Port Number pairs included in a Port Filter attribute can vary from one to a large number (limited only by the maximum message and length supported by the underlying PT transport protocol). However, each Port Filter attribute MUST contain at least one Protocol/Port Number pair. Because the length of a Protocol/Port Number pair with the Reserved field and B flag is always 4 octets, the number of Protocol/Port Number pairs can be easily computed using the PA- TNC Attribute Length field by subtracting the number of octets in the PA-TNC Attribute Header and dividing by 4. If the PA-TNC Attribute Length field is invalid, Posture Validators SHOULD respond with an Invalid Parameter PA-TNC error code. Sangster & Narayan Expires April 6, 2009 [Page 33] Internet-Draft PA-TNC October 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved |B| Protocol | Port Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved |B| Protocol | Port Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved This field is reserved for future use. It MUST be set to 0 on transmission and ignored upon reception. B Flag (Blocked or Allowed Port) This single bit field indicates whether the following port is blocked or allowed. This bit MUST be set to 1 if the protocol and port combination is blocked. Otherwise this field MUST be set to 0. This field was provided to allow for more abbreviated reporting of the port filtering policy (e.g. when all ports are blocked except a few, the Posture Collector can just list the few that are allowed). Posture Collectors MUST NOT provide a mixed list of block and non-blocked ports for a particular protocol. To be more precise, a Posture Collector MUST NOT include two Protocol/Port Number pairs in a single Port Filter attribute where the protocol number is the same but the B flag is different. Also, Posture Collectors MUST NOT list the same Protocol and Port Number combination twice in a Port List attribute. Posture Collectors MAY list all blocked ports for one protocol and all allowed ports for a different protocol in a single Port List attribute, using the B flag to indicate whether each entry is blocked. For example, a Posture Collector might list all the blocked TCP ports but only list the allowed UDP ports. However it MUST NOT list some blocked TCP ports and some other allowed TCP ports. Protocol This field contains the protocol number being blocked or allowed. The values used in this field are the same ones used in the IPv4 Protocol and IPv6 Next Header fields. The IANA already maintains a registry of these values. Sangster & Narayan Expires April 6, 2009 [Page 34] Internet-Draft PA-TNC October 2008 Port Number This field contains the port number being blocked or allowed. The values used in this field are specific to the protocol identified by the Protocol field. The IANA maintains registries for TCP and UDP port numbers. 4.2.7. Installed Packages This PA-TNC Attribute Type contains a list of the installed packages that comprise a product on the endpoint that implements the component specified in the PA Subtype field, as described in section 3.5. This allows a Posture Validator to check which packages are installed for a particular product and which versions of those packages are installed. Posture Collectors that implement any of the IETF Standard PA Subtypes defined in this document SHOULD support sending this attribute type for those PA subtypes. Other Posture Collectors MAY support sending this attribute type, if it is appropriate to their PA subtype. Whether a particular Posture Collector actually sends this attribute type SHOULD still be governed by local privacy and security policies. Posture Validators that implement any of the IETF Standard PA Subtypes defined in this document SHOULD support receiving this attribute type, at least for those PA subtypes. Other Posture Validators MAY support receiving this attribute type. A Posture Validator that does not support receiving this attribute type SHOULD simply ignore attributes with this type. Posture Validators MUST NOT send this attribute type. This attribute type can be quite long, especially for the Operating System PA subtype. This can cause problems, especially with 802.1X and other limited transport protocols. Therefore, Posture Collectors SHOULD NOT send this attribute unless specifically requested to do so using the Attribute Request attribute or otherwise configured to do so. Also, Posture Validators SHOULD NOT request this attribute unless the transport protocol in use can support the large amount of data that may be sent in response. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 7. The value in the PA-TNC Attribute Length field will vary, depending on the number of packages and the length of the Package Name and Package Version Number fields for those packages. However, the value in the PA-TNC Attribute Length Sangster & Narayan Expires April 6, 2009 [Page 35] Internet-Draft PA-TNC October 2008 field MUST be at least 16 because this is the length of the fixed size fields in the PA-TNC Attribute Header and the fixed size fields in this attribute type. If the PA-TNC Attribute Length field is less than the size of these fixed length fields or does not match the length indicated by the sum of the fixed length and variable length fields, implementations SHOULD respond with an Invalid Parameter PA-TNC error code. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. Note that this diagram shows an attribute containing information on one package. The actual number of package descriptions included in an Installed Packages attribute is indicated by the Package Count field. This value may vary from zero to a large number (up to 65535, if the underlying PT transport protocol can support that many). If this number is not sufficient, specialized patch management software should be employed which can simply report compliance with a pre-established patch policy. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Package Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Pkg Name Len | Package Name (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version Len | Package Version Number (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved This field is reserved for future use. The field MUST be set to 0 on transmission and ignored upon reception. Package Count This field is an unsigned 16-bit integer that indicates the number of packages listed in this attribute. For each package so indicated, a Pkg Name Len, Package Name, Version Len, and Package Version Number field is included in the attribute. Pkg Name Len Sangster & Narayan Expires April 6, 2009 [Page 36] Internet-Draft PA-TNC October 2008 This field is an unsigned 8-bit integer that indicates the length of the Package Name field in octets. This field may be zero if a Package Name is not available. Package Name This field contains the name of the package associated with the product. This field is a UTF-8 encoded character string whose octet length is given by the Pkg Name Len field. This field MUST NOT include extra octets for padding or NUL character termination. The syntax and semantics of this name are not specified in this document, since they may vary across products and/or operating systems. Posture Collectors MAY list two packages with the same name in a single Installed Packages attribute. The meaning of doing so is not defined here. Version Len This field is an unsigned 8-bit integer that indicates the length of the Package Version Number field in octets. This field may be zero if a Package Version Number is not available. Package Version Number This field contains the version string for the package named in the previous Package Name field. This field is a UTF-8 encoded character string whose octet length is given by the Version Len field. This field MUST NOT include extra octets for padding or NUL character termination. The syntax and semantics of this version string are not specified in this document, since they may vary across products and/or operating systems. Posture Collectors MAY list two packages with the same Package Version Number (and even the same Package Name and Package Version Number) in a single Installed Packages attribute. The meaning of doing so is not defined here. 4.2.8. PA-TNC Error This PA-TNC Attribute Type contains an error code and supplemental information regarding an error pertaining to PA- TNC. All Posture Collectors and Posture Validators that implement any of the IETF Standard PA Subtypes defined in this specification Sangster & Narayan Expires April 6, 2009 [Page 37] Internet-Draft PA-TNC October 2008 MUST support sending and receiving this attribute type, at least for those PA subtypes. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 8. The value in the PA-TNC Attribute Length field will vary, depending on the length of the Error Information field. However, the value in the PA-TNC Attribute Length field MUST be at least 20 because this is the length of the fixed size fields in the PA-TNC Attribute Header and the fixed size fields in this attribute type. A PA-TNC error code SHOULD be sent with the same PA Message Vendor ID and PA Subtype used by the PA-TNC message that caused the error so that the error code is sent to the party who sent the offending PA-TNC message. Other measures (such as setting PB-TNC's EXCL flag and Posture Collector Identifier or Posture Validator Identifier fields) SHOULD also be taken to attempt to ensure that only the party who sent the offending message receives the error. When a PA-TNC error code is received, the recipient MUST NOT respond with a PA-TNC error code because this could result in an infinite loop of errors. Instead, the recipient MAY log the error, modify its behavior to attempt to avoid the error (attempting to avoid loops or long strings of errors), ignore the error, terminate the assessment, or take other action as appropriate (as long as it is consistent with the requirements of this specification). Posture Verifiers MUST NOT include this attribute type in an Attribute Request attribute. It does not make sense for a Posture Verifier to request that a Posture Collector send a PA- TNC Error attribute. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. Sangster & Narayan Expires April 6, 2009 [Page 38] Internet-Draft PA-TNC October 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | PA-TNC Error Code Vendor ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Error Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Error Information (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved This field is reserved for future use. This field MUST be set to 0 on transmission and ignored upon reception. PA-TNC Error Code Vendor ID This field contains the SMI Private Enterprise Number for the organization that defined the PA-TNC Error Code that is being used in the attribute. For IETF Standard PA-TNC Error Code values this field MUST be set to zero (0). PA-TNC Error Code This field contains the PA-TNC Error Code being reported in this attribute. Note that a particular PA-TNC Error Code value will have completely different meanings depending on the PA-TNC Error Code Vendor ID. Each PA-TNC Error Code Vendor ID defines a different space of PA-TNC Error Code values. When the PA-TNC Error Code Vendor ID is set to zero (0), the PA-TNC Error Code is an IETF Standard PA-TNC Error Code. The IANA maintains a registry for these values. The following table lists the IETF Standard PA-TNC Error Codes defined in this specification: Value Description ----- ----------- 0 Reserved 1 Invalid Parameter 2 Version Not Supported 3 Attribute Type Not Supported The next few subsections of this document provide detailed definitions of these error codes. Sangster & Narayan Expires April 6, 2009 [Page 39] Internet-Draft PA-TNC October 2008 Error Information This field provides additional context for the error. The contents of this field vary based on the PA-TNC Error Code Vendor ID and PA-TNC Error Code. Therefore, whenever a PA-TNC Error Code is defined, the format of this field for that error code must also be defined. The definitions of IETF Standard PA-TNC Error Codes on the next few pages provide good examples of such definitions. The length of this field can be determined by the recipient using the PA-TNC Attribute Length field by subtracting the length of the fixed-length fields in the PA-TNC Attribute Header and the fixed-length fields in this attribute. 4.2.8.1. Invalid Parameter Error Code The Invalid Parameter error code is an IETF Standard PA-TNC Error Code (value 1) that indicates that the sender of this error code has detected an invalid value in a PA-TNC message sent by the recipient of this error code in the current assessment. For this error code, the Error Information field contains the first 8 octets of the PA-TNC message that contained the invalid parameter and an offset indicating the position within that message of the invalid parameter. The following diagram illustrates the format and contents of the Error Information field for this error code. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Offset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Version This field MUST contain an exact copy of the Version field in the PA-TNC Message Header of the PA-TNC message that caused this error. Sangster & Narayan Expires April 6, 2009 [Page 40] Internet-Draft PA-TNC October 2008 Reserved This field MUST contain an exact copy of the Reserved field in the PA-TNC Message Header of the PA-TNC message that caused this error. Message Identifier This field MUST contain an exact copy of the Message Identifier field in the PA-TNC Message Header of the PA-TNC message that caused this error. Offset This field MUST contain an octet offset from the start of the PA-TNC Message Header of the PA-TNC message that caused this error to the start of the value that caused this error. For instance, if the first PA-TNC attribute in the message had an invalid PA-TNC Attribute Length (e.g. 0), this value would be 16. 4.2.8.2. Version Not Supported Error Code The Version Not Supported error code is an IETF Standard PA-TNC Error Code (value 2) that indicates that the sender of this error code does not support the PA-TNC version number included in the PA-TNC Message Header of a PA-TNC message sent by the recipient of this error code in the current assessment. For this error code, the Error Information field contains the first 8 octets of the PA-TNC message that contained the unsupported version as well as Max Version and Min Version fields that indicate which PA-TNC version numbers are supported by the sender of the error code. The sender MUST support all PA-TNC versions between the Min Version and the Max Version, inclusive (i.e. including the Min Version and the Max Version). When possible, recipients of this error code SHOULD send future messages to the Posture Collector or Posture Validator that originated this error message with a PA-TNC version number within the stated range. Any party that is sending the Version Not Supported error code SHOULD include that error code as the only PA-TNC attribute in a PA-TNC message with version number 1. All parties that send PA- TNC messages SHOULD be able to properly process a message that meets this description, even if they cannot process any other Sangster & Narayan Expires April 6, 2009 [Page 41] Internet-Draft PA-TNC October 2008 aspect of PA-TNC version 1. This ensures that a PA-TNC version exchange can proceed properly, no matter what versions of PA-TNC the parties implement. The following diagram illustrates the format and contents of the Error Information field for this error code. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Copy of Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max Version | Min Version | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Version This field MUST contain an exact copy of the Version field in the PA-TNC Message Header of the PA-TNC message that caused this error. Copy of Reserved This field MUST contain an exact copy of the Reserved field in the PA-TNC Message Header of the PA-TNC message that caused this error. Message Identifier This field MUST contain an exact copy of the Message Identifier field in the PA-TNC Message Header of the PA-TNC message that caused this error. Max Version This field MUST contain the maximum PA-TNC version supported by the sender of this error code. Min Version This field MUST contain the minimum PA-TNC version supported by the sender of this error code. Reserved Sangster & Narayan Expires April 6, 2009 [Page 42] Internet-Draft PA-TNC October 2008 Reserved for future use. This field MUST be set to 0 on transmission and ignored upon reception. 4.2.8.3. Attribute Type Not Supported Error Code The Attribute Type Not Supported error code is an IETF Standard PA-TNC Error Code (value 3) that indicates that the sender of this error code does not support the PA-TNC Attribute Type included in the Error Information field. This PA-TNC Attribute Type was included in a PA-TNC message sent by the recipient of this error code in the current assessment. For this error code, the Error Information field contains the first 8 octets of the PA-TNC message that contained the unsupported attribute type as well as a copy of the attribute type that caused the problem. The following diagram illustrates the format and contents of the Error Information field for this error code. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | PA-TNC Attribute Vendor ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PA-TNC Attribute Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Version This field MUST contain an exact copy of the Version field in the PA-TNC Message Header of the PA-TNC message that caused this error. Copy of Reserved This field MUST contain an exact copy of the Reserved field in the PA-TNC Message Header of the PA-TNC message that caused this error. Message Identifier Sangster & Narayan Expires April 6, 2009 [Page 43] Internet-Draft PA-TNC October 2008 This field MUST contain an exact copy of the Message Identifier field in the PA-TNC Message Header of the PA-TNC message that caused this error. Flags This field MUST contain an exact copy of the Flags field in the PA-TNC Attribute Header of the PA-TNC attribute that caused this error. PA-TNC Attribute Vendor ID This field MUST contain an exact copy of the PA-TNC Attribute Vendor ID field in the PA-TNC Attribute Header of the PA-TNC attribute that caused this error. PA-TNC Attribute Type This field MUST contain an exact copy of the PA-TNC Attribute Type field in the PA-TNC Attribute Header of the PA-TNC attribute that caused this error. 4.2.9. Assessment Result This PA-TNC attribute contains the final assessment result from a particular Posture Validator. This attribute might be returned to a Posture Collector for information purposes such as when an endpoint is compliant. Similarly, the Assessment Result attribute could be sent to indicate a non-compliant result where specific actions are needed to bring an endpoint into compliance with the network's policies. These actions could be defined in other PA- TNC attributes such as Remediation Instructions sent to the Posture Collector. All Posture Collectors that support an IETF standard PA Subtype defined in this specification SHOULD support receiving and processing the Assessment Result attribute. All Posture Validators that implement an IETF standard PA Subtype defined in this specification SHOULD support sending the Assessment Result attribute. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 9. Sangster & Narayan Expires April 6, 2009 [Page 44] Internet-Draft PA-TNC October 2008 The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Assessment Result | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Assessment Result This 32-bit field MUST contain one of the following values Value Description ----- ----------- 0 Posture Validator assessed the endpoint component to be compliant with policy 1 Posture Validator assessed the endpoint component to be non-compliant with policy but the difference from compliant was minor. 2 Posture Validator assessed the endpoint component to be non-compliant with policy and the assessed difference was very significant. 3 Posture Validator was unable to determine policy compliance of an endpoint component due to an error. 4 Posture Validator was unable to determine whether the assessed endpoint component was compliant with policy based on the attributes provided by the Posture Collector(s) 4.2.10. Remediation Instructions This PA-TNC attribute sent by the Posture Validator to the Posture Collector(s) contains remediation instructions for updating a particular component to make the endpoint compliant with the assessment policies. A Posture Validator might choose to send more then one Remediation Instructions attributes in some circumstances (e.g. both a URI and a human readable message are necessary) to remediate one or more components. This attribute supports the inclusion of either an IETF Standard or vendor specific remediation instruction. Sangster & Narayan Expires April 6, 2009 [Page 45] Internet-Draft PA-TNC October 2008 All Posture Collectors that implement an IETF standard PA Subtype defined in this specification SHOULD support receiving and processing the Remediation Instructions attribute. All Posture Validators that implement an IETF standard PA Subtype defined in this specification SHOULD support sending this attribute type. Posture Collectors and Posture Validators supporting other non-IETF standard components MAY support this attribute. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 10. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Remediation Parameters Vendor ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remediation Parameters Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remediation Parameters (Variable Length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved (8 bits) The Reserved bits MUST be set to 0 on transmission and ignored on reception. Remediation Parameters Vendor ID (24 bits) The Remediation Parameters Vendor ID field identifies a vendor by using the SMI Private Enterprise Number (PEN). Any organization can receive its own unique PEN from IANA, the Internet Assigned Numbers Authority. The Remediation Parameters Vendor ID qualifies the Remediation Parameters Type field so that each vendor has 2^32 separate Remediation Parameters Types available for its use. Remediation Parameters Types standardized by the IETF are always used with the value zero (0) in this field. Remediation Parameters Type (32 bits) The Remediation Parameters Type field identifies the different types of remediation instructions that can be contained in the Sangster & Narayan Expires April 6, 2009 [Page 46] Internet-Draft PA-TNC October 2008 Remediation Parameters field. IANA maintains a registry of IETF Standard PA-TNC Remediation Parameters Types. A list of IETF Standard PA-TNC Remediation Parameters Types defined in this specification appears later in this section. New vendor-specific remediation instructions can be created by adding new Remediation Parameters Types (those used with a non- zero Remediation Parameters vendor ID) without IETF or IANA involvement. Remediation Parameters (variable length) The Remediation Parameters field contains the actual remediation instructions for the Posture Collector. 4.2.10.1. IETF Standard PA-TNC Remediation Parameters Types This subsection defines several PA-TNC Remediation Parameters Types that have been standardized by the IETF. Remediation-URI Posture Validators can include a Remediation-URI in the PA message by creating a Remediation Instructions attribute with: Remediation Parameters Vendor ID = 0 Remediation Parameters Type = 1 Remediation Parameters = URI The Remediation Parameters field in the Remediation Instructions attribute MUST contain a URI, as described in RFC 3986 [9]. This URI SHOULD contain instructions to update a particular component so that it might result in the component being compliant with the policies in future assessments. Remediation-String Posture Validators can include a Remediation-String in the PA message by creating a Remediation Instructions attribute with: Remediation Parameters Vendor ID = 0 Remediation Parameters Type = 2 Remediation Parameters = UTF-8 encoded string Sangster & Narayan Expires April 6, 2009 [Page 47] Internet-Draft PA-TNC October 2008 The Remediation Parameters field in the Remediation Instructions attribute MUST contain a UTF-8 encoded string. This string should contain human-readable instructions for remediation that MAY be displayed to the user by the Posture Collector. The Remediation String SHOULD be localized in the user's preferred language when known and supported by the NEA Server. 4.2.11. Forwarding Enabled This PA-TNC attribute indicates whether the endpoint is forwarding traffic between interfaces. Endpoints that forward traffic between networks connected to multiple network interfaces may be considered non-compliant (and a security risk) in some enterprise network deployments. For example, an endpoint with multiple connected network interfaces might allow traffic from an interface connected to a public network to be forwarded through another interface carrying a VPN session to a protected enterprise network. This attribute is currently envisioned to be specific to reporting posture for the operating system component, however could be useful for other future types of components. Posture Collectors that implement the IETF standard PA Subtype for Operating System SHOULD support sending the Forwarding Enabled attribute. Posture Collectors that do not implement the Operating System PA Subtype defined in this specification SHOULD NOT send the Forwarding Enabled attribute unless if it is appropriate to their PA Subtype. Whether a particular Posture Collector actually sends this attribute type SHOULD still be governed by local privacy and security policies. Posture Validators that implement the IETF standard PA Subtype for Operating System SHOULD support receiving the Forwarding Enabled attribute type. Posture Validators supporting components other than Operating System MAY support receiving this attribute type if it is appropriate to their PA Subtype. A Posture Validator that does not support receiving this attribute type SHOULD simply ignore attributes with this type. Posture Validators MUST NOT send this attribute type. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 11. Sangster & Narayan Expires April 6, 2009 [Page 48] Internet-Draft PA-TNC October 2008 The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Forwarding Enabled | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Forwarding Enabled This 32-bit field MUST contain one of the following values Value Description ----- ----------- 0 Disabled - Endpoint is not forwarding traffic. 1 Enabled - Endpoint is forwarding traffic. 2 Unknown - Unable to determine whether endpoint is forwarding traffic. 4.2.12. Factory Default Password Enabled This PA-TNC attribute indicates whether the endpoint has a factory default password enabled for use. Some types of endpoints include a default static password for used to gain privileged access to the endpoint. If this password is not changed or disabled before the endpoint is accessible on the network, it's often easy to compromise the endpoint. Posture Collectors that implement the IETF standard PA Subtype for Operating System SHOULD support sending the Factory Default Password Enabled attribute. Posture Collectors that implement other IETF Standard PA Subtypes defined in this specification SHOULD NOT support sending this attribute type for those PA subtypes. Other Posture Collectors MAY support sending this attribute type, if it is appropriate to their PA subtype. Whether a particular Posture Collector actually sends this Sangster & Narayan Expires April 6, 2009 [Page 49] Internet-Draft PA-TNC October 2008 attribute type SHOULD still be governed by local privacy and security policies. Posture Validators that implement the IETF standard PA Subtype for Operating System SHOULD support receiving the Factory Default Password Enabled attribute. Other Posture Validators MAY support receiving this attribute type. A Posture Validator that does not support receiving this attribute type SHOULD simply ignore attributes with this type. Posture Validators MUST NOT send this attribute type. For this attribute type, the PA-TNC Attribute Vendor ID field MUST be set to zero (0) and the PA-TNC Attribute Type field MUST be set to 12. The following diagram illustrates the format and contents of the Attribute Value field for this attribute type. The text after this diagram describes the fields shown here. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Factory Default Password Enabled | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Factory Default Password Enabled This 32-bit field MUST contain one of the following values Value Description ----- ----------- 0 Endpoint does not have a factory default password enabled. 1 Endpoint has a factory default password enabled. 4.3. Vendor-Defined Attributes This section discusses the use of vendor-defined attributes within PA-TNC. The PA-TNC protocol was designed to allow for vendor-defined attributes to be used as a replacement where a standard attribute could be used. In some cases even the standard attributes allow for vendor-defined information to be included. It is envisioned that over time as particular vendor- Sangster & Narayan Expires April 6, 2009 [Page 50] Internet-Draft PA-TNC October 2008 defined attributes become popular, an equivalent standard attribute could be added allowing for broader interoperability. This specification does not define vendor-defined attributes, but rather highlights how such attributes can be used with PA- TNC without the potential for name space collisions or misinterpretations. In order to avoid collisions, PA-TNC uses the well-established SMI Private Enterprise Numbers as Vendor IDs to define separate name spaces for important fields within a PA-TNC message. For example, to ensure the uniqueness of attribute types while providing for vendor extensions, vendor- defined attribute types include the vendor's unique Vendor ID, to indicate the intended name space for the attribute type, followed by the attribute type. IETF Standard PA-TNC Attribute Types use a Vendor ID of zero (0). SMI Private Enterprise Numbers are used to provide a separate identifier space for each vendor. The IANA provides a registry for SMI Private Enterprise Numbers. Any organization (including non-profit organizations, governmental bodies, etc.) can obtain one of these numbers at no charge and thousands of organizations have done so. Within this document, SMI Private Enterprise