Intrusion Detection Exchange B. Feinstein Format Guardent, Inc. Internet-Draft G. Matthews Expires: December 16, 2002 CSC/NASA Ames Research Center J. White MITRE Corporation June 17, 2002 The Intrusion Detection Exchange Protocol (IDXP) draft-ietf-idwg-beep-idxp-05 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 December 16, 2002. Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. Abstract This memo describes the Intrusion Detection Exchange Protocol (IDXP), an application-level protocol for exchanging data between intrusion detection entities. IDXP supports mutual-authentication, integrity, and confidentiality over a connection-oriented protocol. The protocol provides for the exchange of IDMEF messages, unstructured text, and binary data. The IDMEF message elements are described in the Intrusion Detection Message Exchange Format (IDMEF) [4], a companion document of the Intrusion Detection Exchange Format (IDWG) Feinstein, et al. Expires December 16, 2002 [Page 1] Internet-Draft The IDXP June 2002 working group of the IETF. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 2. The Model . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1 Connection Provisioning . . . . . . . . . . . . . . . . . . 6 2.2 Data Transfer . . . . . . . . . . . . . . . . . . . . . . . 8 2.3 Connection Teardown . . . . . . . . . . . . . . . . . . . . 9 2.4 Trust Model . . . . . . . . . . . . . . . . . . . . . . . . 9 3. The IDXP Profile . . . . . . . . . . . . . . . . . . . . . . 11 3.1 IDXP Profile Overview . . . . . . . . . . . . . . . . . . . 11 3.2 IDXP Profile Identification and Initialization . . . . . . . 11 3.3 IDXP Profile Message Syntax . . . . . . . . . . . . . . . . 12 3.4 IDXP Profile Semantics . . . . . . . . . . . . . . . . . . . 12 3.4.1 The IDXP-GREETING Element . . . . . . . . . . . . . . . . . 12 3.4.2 The OPTION Element . . . . . . . . . . . . . . . . . . . . . 14 3.4.3 The IDMEF-MESSAGE Element . . . . . . . . . . . . . . . . . 14 4. IDXP Options . . . . . . . . . . . . . . . . . . . . . . . . 15 4.1 The channelPriority Option . . . . . . . . . . . . . . . . . 16 4.2 The streamType Option . . . . . . . . . . . . . . . . . . . 17 5. Fulfillment of IDWG Communications Protocol Requirements . . 20 6. IDXP Option Registration Template . . . . . . . . . . . . . 23 7. Initial Registrations . . . . . . . . . . . . . . . . . . . 24 7.1 Registration: The IDXP Profile . . . . . . . . . . . . . . . 24 7.2 Registration: The System (Well-Known) TCP port number for IDXP . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 7.3 Registration: The channelPriority Option . . . . . . . . . . 24 7.4 Registration: The streamType Option . . . . . . . . . . . . 25 8. The DTDs . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8.1 The IDXP DTD . . . . . . . . . . . . . . . . . . . . . . . . 26 8.2 The channelPriority Option DTD . . . . . . . . . . . . . . . 27 8.3 The streamType DTD . . . . . . . . . . . . . . . . . . . . . 28 9. Reply Codes . . . . . . . . . . . . . . . . . . . . . . . . 30 10. Security Considerations . . . . . . . . . . . . . . . . . . 31 10.1 Use of the TUNNEL Profile . . . . . . . . . . . . . . . . . 31 10.2 Use of Underlying Security Profiles . . . . . . . . . . . . 31 References . . . . . . . . . . . . . . . . . . . . . . . . . 32 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 32 A. IANA Considerations . . . . . . . . . . . . . . . . . . . . 34 B. History of Significant Changes . . . . . . . . . . . . . . . 35 B.1 Significant Changes Since beep-idxp-04 . . . . . . . . . . . 35 B.2 Significant Changes Since beep-idxp-03 . . . . . . . . . . . 35 B.3 Significant Changes Since beep-idxp-02 . . . . . . . . . . . 35 B.4 Significant Changes Since beep-idxp-01 . . . . . . . . . . . 36 Feinstein, et al. Expires December 16, 2002 [Page 2] Internet-Draft The IDXP June 2002 B.5 Significant Changes Since beep-idxp-00 . . . . . . . . . . . 36 C. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 38 Full Copyright Statement . . . . . . . . . . . . . . . . . . 39 Feinstein, et al. Expires December 16, 2002 [Page 3] Internet-Draft The IDXP June 2002 1. Introduction IDXP is specified, in part, as a Blocks Extensible Exchange Protocol (BEEP) [8] "profile". BEEP is a generic application protocol framework for connection-oriented, asynchronous interactions. Features such as authentication and confidentiality are provided through the use of other BEEP profiles. Accordingly, many aspects of IDXP (e.g., confidentiality) are provided within the BEEP framework. 1.1 Purpose IDXP provides for the exchange of IDMEF [4] messages, unstructured text, and binary data between intrusion detection entities. Addressing the security-sensitive nature of exchanges between intrusion detection entities, underlying BEEP security profiles should be used to offer IDXP the required set of security properties. See Section 5 for a discussion of how IDXP fulfills the IDWG communication protocol requirements. See Section 10 for a discussion of security considerations. IDXP is primarily intended for the exchange of data created by intrusion detection entities. IDMEF [4] messages should be used for the structured representation of this intrusion detection data, although IDXP may be used to exchange unstructured text and binary data. 1.2 Profiles There are several BEEP profiles discussed, the first of which we define in this memo: The IDXP Profile The TUNNEL Profile [7] The Simple Authentication and Security Layer (SASL) Family of Profiles (c.f., Section 4.1 of [8]) The TLS Profile (c.f., Section 3.1 of [8]) 1.3 Terminology 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 [2]. Throughout this memo, the terms "analyzer" and "manager" are used in Feinstein, et al. Expires December 16, 2002 [Page 4] Internet-Draft The IDXP June 2002 the context of the Intrusion Detection Message Exchange Requirements [9]. In particular, Section 3.2 of [9] defines the meaning of a collection of intrusion detection terms. The terms "peer", "initiator", "listener", "client", and "server", and the characters "I", "L", "C", and "S" are used in the context of BEEP [8]. In particular, Section 2.1 of BEEP discusses the roles that a BEEP peer may perform. The term "Document Type Declaration" is abbreviated as "DTD" and is defined in Section 2.8 of the Extensible Markup Language (XML) [3]. Note that the term "proxy" is specific to IDXP, and does not exist in the context of BEEP. The term "intrusion detection" is abbreviated as "ID". Feinstein, et al. Expires December 16, 2002 [Page 5] Internet-Draft The IDXP June 2002 2. The Model 2.1 Connection Provisioning Intrusion detection entities using IDXP to transfer data are termed IDXP peers. Peers can exist only in pairs, and these pairs communicate over a single BEEP session with one or more BEEP channels opened for transferring data. Peers are either managers or analyzers, as defined in Section 3.2 of [9]. The relationship between analyzers and managers is potentially many- to-many. I.e., an analyzer MAY communicate with many managers; similarly, a manager MAY communicate with many analyzers. Likewise, the relationship between different managers is potentially many-to- many, so that a manager MAY receive the alerts sent by a large number of analyzers by receiving them through intermediate managers. Analyzers MUST NOT establish IDXP exchanges with other analyzers. An IDXP peer wishing to establish IDXP communications with another IDXP peer does so by opening a BEEP channel, which may entail initiating a BEEP session. A BEEP security profile offering the required security properties SHOULD initially be negotiated (see Section 10 for a discussion of security considerations). Following the successful negotiation of the BEEP security profile, IDXP greetings are exchanged and connection provisioning proceeds. In the following sequence a peer 'Alice' initiates an IDXP exchange with the peer 'Bob'. Alice Bob ---------------- xport connect[1] ------------------> <-------------------- greeting ----------------------> <-------------start security profile[2] -------------> <-------------------- greeting ----------------------> <------------------ start IDXP[3] -------------------> Notes: [1] 'Alice' initiates a transport connection to 'Bob', triggering the exchange of BEEP greeting messages. [2] both entities negotiate the use of a BEEP security profile. [3] both entities negotiate the use of the IDXP profile. In between a pair of IDXP peers may be an arbitrary number of proxies. A proxy may be necessary for administrative reasons, such as running on a firewall to allow restricted access. Another use Feinstein, et al. Expires December 16, 2002 [Page 6] Internet-Draft The IDXP June 2002 might be one proxy per company department, which forwards data from the analyzer peers in the department onto a company-wide manager peer. A BEEP tuning profile MAY be used to create an application-layer tunnel that transparently forwards data over a chain of proxies. The TUNNEL profile [7] SHOULD be used for this purpose; see [7] for more detail concerning the options available to setup an application-layer tunnel using TUNNEL, and see Section 10.1 for a discussion of TUNNEL related security considerations. TUNNEL MUST be offered as a tuning profile for the creation of application-layer tunnels. The TUNNEL profile MUST offer the use of some form of SASL authentication (c.f., Section 4.1 of [8]). Once a tunnel has been created a BEEP security profile offering the required security properties SHOULD be negotiated, followed by negotiation of the IDXP profile. The following sequence shows how TUNNEL might be used to create an application-layer tunnel through which IDXP would operate. A peer 'Alice' initiates the creation of a BEEP session using the IDXP profile with the entity 'Bob' by first contacting 'proxy1'. In the greeting exchange between 'Alice' and 'proxy1', the TUNNEL profile is selected, and subsequently the use of the TUNNEL profile is extended to reach through 'proxy2' to 'Bob'. Alice proxy1 proxy2 Bob -- xport connect --> <---- greeting -----> -- start TUNNEL ---> - xport connect[1] -> <----- greeting -----> --- start TUNNEL ---> --- xport connect --> <----- greeting -----> --- start TUNNEL ---> <----- [2] ------ <------- ------- <------ ------- <------------------------- greeting --------------------------> <------------------ start security profile -------------------> <------------------------- greeting --------------------------> <------------------------ start IDXP -------------------------> Notes: [1] Instead of immediately acknowledging the request from 'Alice' to start TUNNEL, 'proxy1' attempts to establish use of TUNNEL with 'proxy2'. 'proxy2' also delays its acknowledgment to 'proxy1'. Feinstein, et al. Expires December 16, 2002 [Page 7] Internet-Draft The IDXP June 2002 [2] 'Bob' acknowledges the request from 'proxy2' to start TUNNEL, and this acknowledgment propagates back to 'Alice' so that a TUNNEL application-layer tunnel is established from 'Alice' to 'Bob'. 2.2 Data Transfer Between a pair of ID entities communicating over a BEEP session, one or more BEEP channels MAY be opened using the IDXP profile. If desired, additional BEEP sessions MAY be established to offer additional channels using the IDXP profile. However, in most situations additional channels using the IDXP profile SHOULD be opened within an existing BEEP session, as opposed to provisioning a new BEEP session containing the additional channels using the IDXP profile. Peers assume the role of client or server on a per-channel basis, with one acting as the client and the other as the server. A peer's role of client or server is determined independent of whether the peer assumed the role of initiator or listener during the BEEP session establishment. Clients and servers act as sources and sinks, respectively, for exchanging data. In a simple case, an analyzer peer sends data to a manager peer. E.g., +----------+ +----------+ | | | | | |****** BEEP session ******| | | | | | | Analyzer | ----- IDXP profile ----> | Manager | | (Client) | | (Server) | | | | | | |**************************| | | | | | +----------+ +----------+ Use of multiple BEEP channels in a BEEP session facilitates categorization and prioritization of data sent between IDXP peers. For example, a manager 'M1', sending alert data to another manager, 'M2', may choose to open a separate channel to exchange different categories of alerts. 'M1' would act as the client on each of these channels, and manager 'M2' can then process and act on the incoming alerts based on their respective channel categorizations. See Section 4 for more detail on how to incorporate categorization and/or prioritization into channel creation. Feinstein, et al. Expires December 16, 2002 [Page 8] Internet-Draft The IDXP June 2002 +----------+ +----------+ | | | | | |*************** BEEP session ***************| | | | | | | | -- IDXP profile, network-based alerts ---> | | | Manager | | Manager | | M1 | ---- IDXP profile, host-based alerts ----> | M2 | | (Client) | | (Server) | | | ------ IDXP profile, other alerts -------> | | | | | | | |********************************************| | | | | | +----------+ +----------+ 2.3 Connection Teardown An IDXP peer may choose to close an IDXP channel under many different circumstances (e.g., an error in processing has occurred). To close a channel, the peer sends a "close" element (c.f., Section 2.3.1.3 of [8]) on channel zero indicating which channel is being closed. An IDXP peer may also choose to close an entire BEEP session by sending a "close" element indicating that channel zero is to be closed. Section 2.3.1.3 of [8] offers a more complete discussion of the circumstances under which a BEEP peer is permitted to close a channel and the mechanisms for doing so. It is anticipated that due to the overhead of provisioning an application-layer tunnel and/or a BEEP security profile, BEEP sessions containing IDXP channels will be long-lived. Additionally, the repeated overhead of IDXP channel provisioning (i.e., the exchange of IDXP greetings) may be avoided by keeping IDXP channels open even while data is not actively being exchanged on them. These are recommendations and, as such, IDXP peers may choose to close and re-provision BEEP sessions and/or IDXP channels as they see fit. 2.4 Trust Model In our model, trust is placed exclusively in the IDXP peers. Proxies are always assumed to be untrustworthy. A BEEP security profile is used to establish end-to-end security between pairs of IDXP peers, doing away with the need to place trust in any intervening proxies. Only after successful negotiation of the underlying security profile are IDXP peers to be trusted. Only BEEP security profiles offering at least the protections required by Section 5 of [9] should be used to secure a BEEP session containing channels using the IDXP profile. See Section 3 of [8] for the registration of the TLS profile, an example of a BEEP security profile meeting the requirements of Feinstein, et al. Expires December 16, 2002 [Page 9] Internet-Draft The IDXP June 2002 Section 5 of [9]. See Section 5 for a discussion of how IDXP fulfills the IDWG communications protocol requirements. Feinstein, et al. Expires December 16, 2002 [Page 10] Internet-Draft The IDXP June 2002 3. The IDXP Profile 3.1 IDXP Profile Overview The IDXP profile provides a mechanism for exchanging information between intrusion detection entities. A BEEP tuning profile MAY be used to create an application-layer tunnel that transparently forwards data over a chain of proxies. The TUNNEL profile [7] SHOULD be used for this purpose; see [7] for more detail concerning the options available to setup an application-layer tunnel using TUNNEL, and see Section 10.1 for a discussion of TUNNEL related security considerations. TUNNEL MUST be offered as a tuning profile for the creation of application-layer tunnels. The TUNNEL profile MUST offer the use of some form of SASL authentication (c.f., Section 4.1 of [8]). The TLS profile SHOULD be used to provide the required combination of mutual-authentication, integrity, and confidentiality for the IDXP profile. For further discussion of application-layer tunnel and security issues see Section 2.1 and Section 10. The IDXP profile supports several elements of interest: o The "IDXP-Greeting" element identifies an analyzer or manager at one end of a BEEP channel to the analyzer or manager at the other end of the channel. o The "Option" element is used to convey optional channel parameters between peers during the exchange of "IDXP-Greeting" elements. This element is OPTIONAL. o The "IDMEF-Message" element carries the structured information to be exchanged between the peers. 3.2 IDXP Profile Identification and Initialization The IDXP profile is identified as http://iana.org/beep/transient/idwg/idxp in the BEEP "profile" element during channel creation. During channel creation, "IDXP-Greeting" elements MUST be mutually exchanged between the peers. An "IDXP-Greeting" element MAY be contained within the corresponding "profile" element in the BEEP "start" element. Including an "IDXP-Greeting" element in the initial "start" element has exactly the same semantics as passing it as the first "MSG" message on the channel. If channel creation is successful, then before sending the corresponding reply, the BEEP Feinstein, et al. Expires December 16, 2002 [Page 11] Internet-Draft The IDXP June 2002 peer processes the "IDXP-Greeting" element and includes the resulting response in the reply. This response will be an "ok" element or an "error" element. The choice of which element is returned is dependent on local provisioning of the peer. 3.3 IDXP Profile Message Syntax BEEP messages in the profile MUST have a MIME Content-Type [5] of "text/xml", "text/plain", or "application/octet-stream". The syntax of the individual elements is specified in Section 8.1 and Section 5 of [4]. 3.4 IDXP Profile Semantics Each BEEP peer issues the "IDXP-Greeting" element using "MSG" messages. The "IDXP-Greeting" element MAY contain one or more "Option" sub-elements, conveying optional channel parameters. Each BEEP peer then issues "ok" in "RPY" messages or "error" in "ERR" messages. (See Section 2.3.1 of [8] for the definitions of the "error" and "ok" elements.) An "error" element MAY be issued within a "RPY" message when piggy-backed within a BEEP "profile" element. See section 3.4.1 for an example of an "error" element being issued within a "RPY" message. Based on the respective client/server roles negotiated during the exchange of "IDXP-Greeting" elements, the client sends data using "MSG" messages. Depending on the MIME Content-Type, this data may be an "IDMEF-Message" element, plain text, or binary. The server then issues "ok" in "RPY" messages or "error" in "ERR" messages. 3.4.1 The IDXP-GREETING Element The "IDXP-Greeting" element serves to identify the analyzer or manager at one end of the BEEP channel to the analyzer or manager at the other end of the channel. The "IDXP-Greeting" element MUST include the role of the peer on the channel (client or server) and the Uniform Resource Identifier (URI) [1] of the peer. Additionally, the "IDXP-Greeting" element MAY include the fully qualified domain name (c.f., [6]) of the peer. One or more "Option" sub-elements MAY be present. An "IDXP-Greeting" element MAY be sent by either peer at any time. The peer receiving the "IDXP-Greeting" MUST respond with an "ok" (indicating acceptance), or an "error" (indicating rejection). A peer's identity and role on a channel and any optional channel parameters are, in effect, specified by the most recent "IDXP- Greeting" it sent that was answered with an "ok". An "IDXP-Greeting" may be rejected (with an "error" element) under Feinstein, et al. Expires December 16, 2002 [Page 12] Internet-Draft The IDXP June 2002 many circumstances. These include, but are not limited to, authentication failure, lack of authorization to connect under the specified role, the negotiation of an inadequate ciphersuite, or the presence of a channel option that must be understood but was unrecognized. For example, a successful creation with an embedded "IDXP-Greeting" might look like this: I: MSG 0 10 . 1592 187 I: Content-Type: text/xml I: I: I: I: ]]> I: I: I: END L: RPY 0 10 . 1865 91 L: Content-Type: text/xml L: L: L: ]]> L: L: END L: MSG 0 11 . 1956 61 L: Content-Type: text/xml L: L: L: END I: RPY 0 11 . 1779 7 I: Content-Type: text/xml I: I: I: END Feinstein, et al. Expires December 16, 2002 [Page 13] Internet-Draft The IDXP June 2002 A creation with an embedded "IDXP-Greeting" that fails might look like this: I: MSG 0 10 . 1776 185 I: Content-Type: text/xml I: I: I: I: ]]> I: I: I: END L: RPY 0 10 . 1592 182 L: Content-Type: text/xml L: L: L: 'http://example.com/eve' must first L: negotiate the TLS profile ]]> L: L: END 3.4.2 The OPTION Element If present, the "Option" element MUST be contained within an "IDXP- Greeting" element. An individual "IDXP-Greeting" element MAY contain one or more "Option" sub-elements. Each "Option" element within an "IDXP-Greeting" element represents a request to enable an IDXP option on the channel being negotiated. See Section 4 for a complete description of IDXP options and the "Option" element. 3.4.3 The IDMEF-MESSAGE Element The "IDMEF-Message" element carries the information to be exchanged between the peers. See Section 5 of [4] for the definition of this element. Feinstein, et al. Expires December 16, 2002 [Page 14] Internet-Draft The IDXP June 2002 4. IDXP Options IDXP provides a service for the reliable exchange of data between intrusion detection entities. Options are used to alter the semantics of the service. The specification of an IDXP option MUST define: o the identity of the option; o what content, if any, is contained within the option; and, o the processing rules for the option. An option registration template (c.f. Section 6) organizes this information. An "Option" element is contained within an "IDXP-Greeting" element. The "IDXP-Greeting" element itself MAY contain one or more "Option" elements. The "Option" element has several attributes and contains arbitrary content: o the "internal" and the "external" attributes, exactly one of which MUST be present, uniquely identify the option; o the "mustUnderstand" attribute, whose presence is OPTIONAL and whose default value is "false", specifies whether the option, if unrecognized, MUST cause an error in processing to occur; and, o the "localize" attribute, whose presence is OPTIONAL, specifies one or more language tokens, each identifying a desirable language tag to be used if textual diagnostics are returned to the originator. The value of the "internal" attribute is the IANA-registered name for the option. If the "internal" attribute is not present, then the value of the "external" attribute is a URI or URI with a fragment- identifier. Note that a relative-URI value is not allowed. The "mustUnderstand" attribute specifies whether the peer may ignore the option if it is unrecognized. If the value of the "mustUnderstand" attribute is "true", and if the peer does not recognize the option, then an error in processing has occurred. When absent, the value of the "mustUnderstand" attribute is defined to be "false". Feinstein, et al. Expires December 16, 2002 [Page 15] Internet-Draft The IDXP June 2002 4.1 The channelPriority Option Section 7.3 contains the IDXP option registration for the "channelPriority" option. This option contains a "channelPriority" element (c.f., Section 8.2). By default, IDXP does not place any requirements on how peers should manage multiple IDXP channels. The "channelPriority" option provides a way for peers using multiple IDXP channels to request relative priorities for each channel. When sending an "IDXP-Greeting" element during the provisioning of an IDXP channel, the originating peer MAY request that the remote peer assign a priority to the channel by including an "Option" element containing a "channelPriority" element. The "channelPriority" element has one attribute named "priority", of range 0..2147483647. This attribute is REQUIRED. Not coincidentally, this is the maximum range of possible BEEP channel numbers. 0 is defined to represent the highest priority, with relative priority decreasing as the "priority" value ascends. For example, during the exchange of "IDXP-Greeting" elements during channel provisioning, an analyzer successfully requests that a manager assign a priority to the channel: analyzer manager --------------- greeting w/ option -----------------> <---------------------- ------------------------ C: MSG 1 17 . 1984 165 C: Content-Type: text/xml C: C: C: C: C: END S: RPY 1 17 . 2001 7 S: Content-Type: text/xml S: S: S: END Feinstein, et al. Expires December 16, 2002 [Page 16] Internet-Draft The IDXP June 2002 For example, during the exchange of "IDXP-Greeting" elements during channel provisioning, a manager unsuccessfully requests that an analyzer assign a priority to the channel: analyzer manager <---------------- greeting w/ option ---------------- --------------------- ----------------------> S: MSG 1 17 . 1312 194 S: Content-Type: text/xml S: S: S: S: S: END C: ERR 1 17 . 451 68 C: Content-Type: text/xml C: C: 'channelPriority' option was unrecognized C: END 4.2 The streamType Option Section 7.4 contains the IDXP option registration for the "streamType" option. This option contains a "streamType" element (c.f., Section 8.3). By default, IDXP provides no explicit method for categorizing channels. The "streamType" option provides a way for peers to request that a channel be categorized as a particular stream type. When sending an "IDXP-Greeting" element during the provisioning of an IDXP channel, the originating peer MAY request that the remote peer assign a stream type to the channel by including an "Option" element containing a "streamType" element. The "streamType" element has one attribute named "type", with the possible values of "alert", "heartbeat", or "config". This attribute is REQUIRED. A value of "alert" indicates that the channel should be categorized as being used for the exchange of ID alerts. A value of "heartbeat" indicates that the channel should be categorized as being used for the exchange of heartbeat messages such as the "Heartbeat" element (c.f., Section 5 of [4]). A value of "config" indicates that the channel should be categorized as being used for the exchange of configuration messages. Feinstein, et al. Expires December 16, 2002 [Page 17] Internet-Draft The IDXP June 2002 For example, during the exchange of "IDXP-Greeting" elements during channel provisioning, an analyzer successfully requests that a manager assign a stream type to the channel: analyzer manager --------------- greeting w/ option -----------------> <---------------------- ------------------------ C: MSG 1 21 . 1963 155 C: Content-Type: text/xml C: C: C: C: C: END S: RPY 1 21 . 1117 7 S: Content-Type: text/xml S: S: S: END Feinstein, et al. Expires December 16, 2002 [Page 18] Internet-Draft The IDXP June 2002 For example, during the exchange of "IDXP-Greeting" elements during channel provisioning, a manager unsuccessfully requests that an analyzer assign a stream type to the channel: analyzer manager <---------------- greeting w/ option ---------------- --------------------- ----------------------> S: MSG 1 21 . 1969 176 S: Content-Type: text/xml S: S: S: S: S: END C: ERR 1 21 . 1292 63 C: Content-Type: text/xml C: C: 'streamType' option was unrecognized C: END Feinstein, et al. Expires December 16, 2002 [Page 19] Internet-Draft The IDXP June 2002 5. Fulfillment of IDWG Communications Protocol Requirements The following lists the communications protocol requirements established in Section 5 of [9] and, for each requirement, describes the manner in which it is fulfilled by IDXP. The [protocol] MUST support reliable transmission of messages. IDXP operates over BEEP, which operates only over reliable connection-oriented transport protocols (e.g., TCP). In addition, BEEP peers communicate using a simple request-response protocol, which provides end-to-end reliability between peers. The [protocol] MUST support transmission of messages between ID components across firewall boundaries without compromising security. The TUNNEL profile [7] MUST be offered as an option for creation of application-layer tunnels to allow operation across firewalls. The TUNNEL profile SHOULD be used to provide an application-layer tunnel. The ability to authenticate hosts during the creation of an application-layer tunnel MUST be provided by the mechanism chosen to create such tunnels. A firewall may therefore be configured to authenticate all hosts attempting to tunnel into the protected network. If the TUNNEL profile is used, SASL (c.f., Section 4.1 of [8]) MUST be offered as a mechanism by which hosts can be authenticated. The [protocol] MUST support mutual authentication of the analyzer and the manager to each other. IDXP supports mutual authentication of the peers through the use of an appropriate underlying BEEP security profile. The TLS profile and members of the SASL family of profiles (c.f., Section 4.1 of [8]) are examples of security profiles that may be used to authenticate the identity of communicating ID components. TLS MUST be offered as a mechanism to provide mutual authentication, and TLS SHOULD be used to provide mutual authentication. The [protocol] MUST support confidentiality of the message content during message exchange. The selected design MUST be capable of supporting a variety of encryption algorithms and MUST be adaptable to a wide variety of environments. IDXP supports confidentiality through the use of an appropriate underlying BEEP security profile. The TLS profile is an example a security profile that offers confidentiality. The TLS profile with the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite MUST be offered as a mechanism to provide confidentiality, and TLS with Feinstein, et al. Expires December 16, 2002 [Page 20] Internet-Draft The IDXP June 2002 this cipher suite SHOULD be used to provide confidentiality. The TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite uses ephemeral Diffie-Hellman (DHE) with DSS signatures for key exchange and triple DES (3DES) and cipher-block chaining (CBC) for encryption. Stronger cipher suites are optional. The [protocol] MUST ensure the integrity of the message content. The selected design MUST be capable of supporting a variety of integrity mechanisms and MUST be adaptable to a wide variety of environments. IDXP supports message integrity through the use of an appropriate underlying BEEP security profile. The TLS profile and members of the SASL family of profiles (c.f., Section 4.1 of [8]) are examples of security profiles that offer message integrity. The TLS profile with the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite MUST be offered as a mechanism to provide integrity, and TLS with this cipher suite SHOULD be used to provide integrity. The TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite uses the Secure Hash Algorithm (SHA) for integrity protection using a keyed message authentication code. Stronger cipher suites are optional. The [protocol] SHOULD be able to ensure non-repudiation of the origin of IDMEF messages. IDXP supports non-repudiation of session origin through the use of an appropriate underlying BEEP security profile. An IDXP peer application MAY use IDMEF content and/or BEEP session credentials to provide for non-repudiation of message origin. The TLS profile is an example of a security profile that offers non-repudiation of session origin through the authentication of public-key certificates. TLS MUST be offered as a mechanism to provide non- repudiation of session origin, and TLS SHOULD be used to provide non-repudiation of session origin. The [protocol] SHOULD resist protocol denial of service attacks. IDXP supports resistance to denial of service (DoS) attacks through the use of an appropriate underlying BEEP security profile. BEEP peers offering the IDXP profile MUST offer the use of TLS with the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite, and SHOULD use TLS with that cipher suite. To resist DoS attacks it is helpful to discard traffic arising from a non-authenticated source. BEEP peers MUST support the use of authentication in conjunction with any mechanism used to create application-layer tunnels. In particular, the use of some form of SASL authentication (c.f., Section 4.1 of [8]) MUST be offered to provide authentication in the use of the TUNNEL profile. See Section 7 of [7] for a discussion of security considerations in Feinstein, et al. Expires December 16, 2002 [Page 21] Internet-Draft The IDXP June 2002 the use of the TUNNEL profile. The [protocol] SHOULD resist malicious duplication of messages. IDXP supports resistance to malicious duplication of messages (i.e., replay attacks) through the use of an appropriate underlying BEEP security profile. The TLS profile is an example of a security profile offering resistance to replay attacks. The TLS profile with the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite MUST be offered as a mechanism to provide resistance against replay attacks, and TLS with this cipher suite SHOULD be used to provide resistance against replay attacks. The TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite uses cipher-block chaining (CBC) to ensure that even if a message is duplicated the cipher-text duplicate will produce a very different plain-text result. Stronger cipher suites are optional. Feinstein, et al. Expires December 16, 2002 [Page 22] Internet-Draft The IDXP June 2002 6. IDXP Option Registration Template When an IDXP option is registered, the following information is supplied: Option Identification: specify the NMTOKEN or the URI that authoritatively identifies this option. Contains: specify the XML content that is contained within the "Option" element. Processing Rules: specify the processing rules associated with the option. Contact Information: specify the postal and electronic contact information for the author(s) of the option. Feinstein, et al. Expires December 16, 2002 [Page 23] Internet-Draft The IDXP June 2002 7. Initial Registrations 7.1 Registration: The IDXP Profile Profile identification: http://iana.org/beep/transient/idwg/idxp Messages exchanged during channel creation: "IDXP-Greeting" Messages starting one-to-one exchanges: "IDXP-Greeting", "IDMEF- Message" Messages in positive replies: "ok" Messages in negative replies: "error" Messages in one-to-many exchanges: none Message syntax: c.f., Section 3.3 Message semantics: c.f., Section 3.4 Contact information: c.f., the "Authors' Addresses" section of this memo 7.2 Registration: The System (Well-Known) TCP port number for IDXP Protocol Number: TCP Message Formats, Types, Opcodes, and Sequences: c.f., Section 3.3 Functions: c.f., Section 3.4 Use of Broadcast/Multicast: none Proposed Name: Intrusion Detection Exchange Protocol Short name: idxp Contact Information: c.f., the "Authors' Addresses" section of this memo 7.3 Registration: The channelPriority Option Option Identification: channelPriority Contains: channelPriority (c.f., Section 8.2) Processing Rules: c.f., Section 4.1 Feinstein, et al. Expires December 16, 2002 [Page 24] Internet-Draft The IDXP June 2002 Contact Information: c.f., the "Authors' Addresses" section of this memo 7.4 Registration: The streamType Option Option Identification: streamType Contains: streamType (c.f., Section 8.3) Processing Rules: c.f., Section 4.2 Contact Information: c.f., the "Authors' Addresses" section of this memo Feinstein, et al. Expires December 16, 2002 [Page 25] Internet-Draft The IDXP June 2002 8. The DTDs 8.1 The IDXP DTD The following is the DTD defining the valid elements for the IDXP profile %BEEP; %IDMEF; 8.2 The channelPriority Option DTD The following is the DTD defining the valid elements for the channelPriority option Feinstein, et al. Expires December 16, 2002 [Page 27] Internet-Draft The IDXP June 2002 8.3 The streamType DTD The following is the DTD defining the valid elements for the streamType option Feinstein, et al. Expires December 16, 2002 [Page 28] Internet-Draft The IDXP June 2002 Feinstein, et al. Expires December 16, 2002 [Page 29] Internet-Draft The IDXP June 2002 9. Reply Codes This section lists the three-digit error codes the IDXP profile may generate. code meaning ==== ======= 421 Service not available (E.g., the peer does not have sufficient resources.) 450 Requested action not taken (E.g., DNS lookup failed or connection could not be established. See also 550.) 454 Temporary authentication failure 500 General syntax error (E.g., poorly-formed XML) 501 Syntax error in parameters (E.g., non-valid XML) 504 Parameter not implemented 530 Authentication required 534 Authentication mechanism insufficient (E.g., cipher suite too weak, sequence exhausted, etc.) 535 Authentication failure 537 Action not authorized for user 550 Requested action not taken (E.g., peer could be contacted, but malformed greeting or no IDXP profile advertised.) 553 Parameter invalid 554 Transaction failed (E.g., policy violation) Feinstein, et al. Expires December 16, 2002 [Page 30] Internet-Draft The IDXP June 2002 10. Security Considerations The IDXP profile is a profile of BEEP. In BEEP, transport security, user authentication, and data exchange are orthogonal. Refer to Section 8 of [8] for a discussion of this. It is strongly recommended that those wanting to use the IDXP profile initially negotiate a BEEP security profile between the peers that offers the required security properties. The TLS profile SHOULD be used to provide for transport security. See Section 5 for a discussion of how IDXP fulfills the IDWG communications protocol requirements. See Section 2.4 for a discussion of the trust model. 10.1 Use of the TUNNEL Profile See Section 5 for IDXP's requirements on application-layer tunneling and the TUNNEL profile specifically. See Section 7 of [7] for a discussion of the security considerations inherent in the use of the TUNNEL profile. 10.2 Use of Underlying Security Profiles At present, the TLS profile is the only BEEP security profile known to meet all of the requirements set forth in Section 5 of [9]. When securing a BEEP session with the TLS profile, the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite offers an acceptable level of security. See Section 5 for a discussion of how IDXP fulfills the IDWG communications requirements through the use of an underlying security profile. Feinstein, et al. Expires December 16, 2002 [Page 31] Internet-Draft The IDXP June 2002 References [1] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler, "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC-xml, October 2000, . [4] Curry, D. and H. Debar, "Intrusion Detection Message Exchange Format Data Model and Extensible Markup Language (XML) Document Type Definition", RFC XXXX, Month YYYY. [5] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, November 1996. [6] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987. [7] New, D., "The TUNNEL Profile Registration", RFC XXXX, Month YYYY. [8] Rose, M., "The Blocks Extensible Exchange Protocol Core", RFC 3080, March 2001. [9] Wood, M. and M. Erlinger, "Intrusion Detection Message Exchange Requirements", RFC XXXX, Month YYYY. Authors' Addresses Benjamin S. Feinstein Guardent, Inc. EMail: Ben.Feinstein@guardent.com URI: http://www.guardent.com/ Gregory A. Matthews CSC/NASA Ames Research Center EMail: gmatthew@nas.nasa.gov URI: http://www.nas.nasa.gov/ Feinstein, et al. Expires December 16, 2002 [Page 32] Internet-Draft The IDXP June 2002 John C. C. White MITRE Corporation EMail: jccw@mitre.org URI: http://www.mitre.org/ Feinstein, et al. Expires December 16, 2002 [Page 33] Internet-Draft The IDXP June 2002 Appendix A. IANA Considerations The IANA registers "IDXP" as a standards-track BEEP profile, as specified in Section 7.1. The IANA changes the IDXP profile identification to "http://iana.org/beep/IDXP". The IANA registers "idxp" as a TCP port number, as specified in Section 7.2 The IANA maintains a list of: IDXP options, c.f., Section 6. For this list, the IESG is responsible for assigning a designated expert to review the specification prior to the IANA making the assignment. As a courtesy to developers of non-standards track IDXP options, the mailing list idxp-java-users@lists.sourceforge.net may be used to solicit commentary. The IANA makes the registrations specified in Section 7.3 and Section 7.4. Feinstein, et al. Expires December 16, 2002 [Page 34] Internet-Draft The IDXP June 2002 Appendix B. History of Significant Changes The RFC Editor should remove this section and its corresponding TOC references prior to publication. B.1 Significant Changes Since beep-idxp-04 Added sentence to Section 3.4 explaining the situation in which an "error" element may be issued within an "RPY" message. Modified examples in Section 4.1 and 4.2, changing the message types from "RPY" to "ERR" for the negative response sent by the client. Fixed two locations where we were referencing the wrong section of the requirements document. Removed references to IP and the %IP attribute. Modified part of Section 5 dealing with non-repudiation of message origin. Modified Section 1.3 to further refine terminology. Replaced all remaining references to "entities" with references to "peers". B.2 Significant Changes Since beep-idxp-03 Modified references to Internet-Drafts to contain placeholders for their forthcoming RFC numbers. Modified IDMEF formal public identifier (FPI) in the IDXP DTD to reflect the changes in draft-ietf-idwg-idmef-xml-06. Modified IDXP FPI for the IDXP DTD to be more in line with the IDMEF FPI. B.3 Significant Changes Since beep-idxp-02 Added IDXP option registration template and registered two initial options. Indicated that the IANA should change the profile identification to "http://iana.org/beep/IDXP" upon adoption of IDXP as a standards- track BEEP profile. Renamed the "Options" element to "Option" and allowed multiple "Option" sub-elements within an "IDXP-Greeting" element. Also added Feinstein, et al. Expires December 16, 2002 [Page 35] Internet-Draft The IDXP June 2002 attributes to "Option" element. Modified IANA profile registration and added TCP port number IANA registration. Reordered some sections to improve the flow of the document. Changed IDXP DTD identifier to be more IETF-like and removed URLs from ENTITY declarations. Changed IDXP profile URI to fall under the "http://iana.org/beep/ transient" namespace. Modified Section 1.3 to reference the requirements language specified by [2]. Eliminated the use of the "endpoint" terminology, in favor of "peer". Modified figures to make them more understandable. Modified Sections 2, 3, and 4 to use the requirements language specified by [2]. Indicated that the RFC Editor should remove Appendix B and its corresponding TOC reference prior to publication. Fixed several typos. B.4 Significant Changes Since beep-idxp-01 Added new MUST and SHOULD language for use of TLS and TUNNEL profiles. Modified the "IDXP-Greeting" element to include an "Options" sub- element. Changed IDXP profile URI. B.5 Significant Changes Since beep-idxp-00 Added Section 5, describing how IDXP fulfills the communication protocol requirements of the IDWG. Moved IDXP profile registration to Appendix A. Clarified the role that underlying BEEP security profiles must play. Clarified how IDMEF messages fit into IDXP. Feinstein, et al. Expires December 16, 2002 [Page 36] Internet-Draft The IDXP June 2002 Clarified how the IDXP profile channels and BEEP sessions interact. Made terminology clarifications and changes for overall consistency. Feinstein, et al. Expires December 16, 2002 [Page 37] Internet-Draft The IDXP June 2002 Appendix C. Acknowledgements The authors gratefully acknowledge the contributions of Darren New, Marshall T. Rose, Roy Pollock, Tim Buchheim, Mike Erlinger, and Paul Osterwald. Feinstein, et al. Expires December 16, 2002 [Page 38] Internet-Draft The IDXP June 2002 Full Copyright Statement Copyright (C) The Internet Society (2002). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Feinstein, et al. Expires December 16, 2002 [Page 39]