saag G. Lebovitz Internet-Draft Juniper Intended status: Informational January 23, 2009 Expires: July 24, 2009 Roadmap for Cryptographic Authentication of Routing Protocol Packets on the Wire draft-lebovitz-kmart-roadmap-00 Status of this Memo Distribution of this memo is unlimited. This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 July 24, 2009. Abstract In the March of 2006 the IAB held a workshop on the topic of "Unwanted Internet Traffic". The report from that workshop is documented in RFC 4948 [RFC4948]. Section 8.2 of RFC 4948 calls for "[t]ightening the security of the core routing infrastructure." Four main steps were identified for improving the security of the routing infrastructure. One of those steps was "securing the routing protocols' packets on the wire." One mechanism for securing routing protocol packets on the wire is the use of per-packet cryptographic message authentication, providing both peer authentication and message integrity. Many different routing protocols exist and they employ a range of different transport subsystems. Therefore there Lebovitz & Expires July 24, 2009 [Page 1] Internet-Draft KMART Roadmap January 2009 must necessarily be various methods defined for applying cryptographic authentication to these varying protocols. Many routing protocols already have some method for accomplishing cryptographic message authentication. However, in many cases the existing methods are dated, vulnerable to attack, and/or employ cryptographic algorithms that have been depricated. This document creates a roadmap of protocol specification work for the use of modern cryptogrpahic mechanisms and algorithms for message authentication in routing protocols. It also defines the framework for a key management protocol that may be used to create and manage session keys for message authentication and integrity. This roadmap reflects the input of both the security area and routing area in order to form a jointly agreed upon and prioritized work list for the effort. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.4. Threats . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4.1. Threats In Scope . . . . . . . . . . . . . . . . . . . 5 1.4.2. Threats Out of Scope . . . . . . . . . . . . . . . . . 6 1.5. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.6. Non-Goals . . . . . . . . . . . . . . . . . . . . . . . . 9 1.7. Audience . . . . . . . . . . . . . . . . . . . . . . . . . 9 2. The Roadmap . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1. Categorizing Routing Protocols . . . . . . . . . . . . . . 9 2.2. Security Characterization Vectors . . . . . . . . . . . . 11 2.2.1. Internal vs. External Operation . . . . . . . . . . . 11 2.2.2. Unique versus Shared Keys . . . . . . . . . . . . . . 11 2.2.3. Out of Band vs. In-band Key Management . . . . . . . . 13 2.3. Common Framework . . . . . . . . . . . . . . . . . . . . . 13 2.4. Work Items Per Routing Protocol . . . . . . . . . . . . . 18 2.5. Protocols, Categories, and Priorities . . . . . . . . . . 19 3. Change History . . . . . . . . . . . . . . . . . . . . . . . . 21 4. Needs Work in Next Draft (RFC Editor: Delete Before Publishing) . . . . . . . . . . . . . . . . . . . . . . . . . 21 5. Security Considerations . . . . . . . . . . . . . . . . . . . 22 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 8.1. Normative References . . . . . . . . . . . . . . . . . . . 22 8.2. Informative References . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24 Intellectual Property and Copyright Statements . . . . . . . . . . 25 Lebovitz & Expires July 24, 2009 [Page 2] Internet-Draft KMART Roadmap January 2009 1. Introduction In March 2006 the Internet Architecture Board (IAB) held a workshop on the topic of "Unwanted Internet Traffic". The report from that workshop is documented in RFC 4948 [RFC4948]. Section 8.1 of that document states that "A simple risk analysis would suggest that an ideal attack target of minimal cost but maximal disruption is the core routing infrastructure." Section 8.2 calls for "[t]ightening the security of the core routing infrastructure." Four main steps were identified for that tightening: o More secure mechanisms and practices for operating routers. This work is being addressed in the OpSec Working Group. o Cleaning up the Internet Routing Registry repository [IRR], and securing both the database and the access, so that it can be used for routing verifications. This work is being conducted through liaisons with the RIR's globally. o Specifications for cryptographic validation of routing message content. This work is being done in the SIDR Working Group. o Securing the routing protocols' packets on the wire This document addresses the last bullet, securing the packets on the wire of the routing protocol exchanges. 1.1. Terminology [to be filled out later] Base RP key_store KMP session keys 1.2. Requirements Language 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 [RFC2119]. 1.3. Scope Four basic tactics may be employed in order to secure any piece of data as it is transmitted over the wire: privacy (or encryption), authentication, message integrity, non-repudiation. The focus for this effort, and the scope for this roadmap document, will be message Lebovitz & Expires July 24, 2009 [Page 3] Internet-Draft KMART Roadmap January 2009 authentication and packet integrity only. This work explicitly excludes, at this point in time, the other two tactics: privacy and non-repudiation. Since the objective of most routing protocols is to broadly advertise the routing topology, routing messages are commonly sent in the clear; confidentiality is not normally required for routing protocols. However, the two explicitly excluded tactics may be addressed in future work. This work will also include the definition of a key management protocol for creating and managing session keys for the message authentication and data integrity functions. It is possible for routing protocol packets to be transmitted employing all four security tactics mentioned above using existing standards. For example, one could run unicast, layer 3 or above routing protocol packets through IPsec ESP [RFC4303]. This would provide the added benefit of privacy, and non-repudiation. However, routing products have been fine tuned over the years for the specific processing necessary for these routing protocols non-encapsulated formats. Operators are, therefore, quite unwilling to explore new packet encapsulations for these tried and true protocols. In addition, at least in the case of BGP and LDP, these protocols already have existing mechanisms for cryptographically authenticating and integrity checking the packets on the wire. Implemented products have already been produced and code has already been written and, both have been optimized for the existing mechanisms. Therefore, the scope of this roadmap of work includes: o making use of existing routing protocol security protocols, where they exist, and enhancing or updating them as necessary for modern cryptographic best practices, o developing a framework for using automatic key management in order to ease deployment, lower cost of operation, and allow for rapid responses to security breaches, and o specifying the automated key management protocol that may be combined with the bits-on-the-wire mechanisms The work also serves as an agreement between the Routing Area and the Security Area about the priorities and work plan for incrementally delivering the above work. This point is important. There will be times when the best-security-possible will give way to vastly- improved-over-current-security-but-admittedly-not-yet-best-security- possible, in order that incremental progress toward a more secure Internet may be achieved. As such, the document will call out places where agreement has been reached on such trade offs. Lebovitz & Expires July 24, 2009 [Page 4] Internet-Draft KMART Roadmap January 2009 The document does not contain protocol specifications. Instead, it defines the areas where protocol specification work is needed and sets both a direction and a relative priority for addressing that specification work. 1.4. Threats In RFC2828[RFC2828], a threat is defined as a potential for violation of security, which exists when there is a circumstance, capability, action, or event that could breach security and cause harm. This section defines the threats that are in scope for this roadmap, and those that are explicitly out of scope. This document leverages the "Generic Threats to Routing Protocols" model, RFC 4593 [RFC4593] , capitalizes terms from that document, and offers a terse definition of those terms. (More thorough description of routing protocol threats sources, motivations, consequences and actions can be found in RFC 4593 [RFC4593] itself). The threat listings below expand upon these threat definitions. 1.4.1. Threats In Scope The threats that will be addressed in this roadmap are those from OUTSIDERS, attackers that may reside anywhere in the Internet, have the ability to send IP traffic to the router, may be able to observe the router's replies, and may even control the path for a legitimate peer's traffic. These are not legitimate participants in the routing protocol. Message authentication and integrity protection specifically aims to identify messages originating from OUTSIDERS. The concept of OUTSIDERS can be further refined to include attackers who are terminated employees, and those sitting on-path. o On-Path - attackers with control of a network resource or a tap along the path of packets between two routers. An on-path outsider can attempt a man-in-the-middle attack, in addition to several other attack actions. A man-in-the-middle (MitM) attack occurs when an attacker who has access to packets flowing between two peers tampers with those packets in such a way that both peers think they are talking to each other directly, when in fact they are actually talking to the attacker only. Protocols conforming to this roadmap will use cryptographic mechanisms to prevent a man-in-the-middle attacker from situating himself undetected. o Terminated Employees - in this context, those who had access router configuration that included keys or keying material like pre-shared keys used in securing the routing protocol. Using this material, the attacker could attempt to impersonate a legitimate router. The goal of addressing this source specifically is to call out the case where new keys or keying material becomes necessary very quickly, with little operational expense, upon the Lebovitz & Expires July 24, 2009 [Page 5] Internet-Draft KMART Roadmap January 2009 termination of such an employee. This grouping could also refer to any attacker who somehow managed to gain access to keying material, and said access had been detected by the operators such that the operators have an opportunity to move to new keys in order to prevent attack. These ATTACK ACTIONS are in scope for this roadmap: o SPOOFING - when an illegitimate device assumes the identity of a legitimate one. Spoofing can be used, for example, to inject unrealistic routing information that causes the disruption of network services. Spoofing can also be used to cause a neighbor relationship to form that subsequently denies the formation of the relationship with the legitimate router. o FALSIFICATION - an action whereby an attacker sends false routing information. To falsify the routing information, an attacker has to be either the originator or a forwarder of the routing information. Falsification may occur by an ORIGINATOR, or a FORWARDER, and may involve OVERCLAIMING, MISCLAIMING, or MISTATEMENT of network resource reachability. We must be careful to remember that in this work we are only targeting falsification from outsiders as may occur from tampering with packets in flight. Falsification from BYZANTINES (see the Threats Out of Scope section (Section 1.4.2) below) are not addressed by this roadmap, but by other work in the IETF. o INTERFERENCE - when an attacker inhibits the exchanges by legitimate routers. The types of interference addressed by this work include: * ADDING NOISE * REPLAYING OUT-DATED PACKETS * INSERTING MESSAGES * CORRUPTING MESSAGES * BREAKING SYNCHRONIZATION * Changing message content o DoS attacks on transport sub-systems - when an attacker sends packets aimed at halting or preventing the underlying protocol over which the routing protocol runs, for example halting a BGP session by sending a TCP FIN packet. Another example is sending packets which confuse or overwhelm a security mechanism itself, for example initiating an overwhelming load of keying protocol initiations from bogus sources. 1.4.2. Threats Out of Scope Threats from BYZANTINE sources -- faulty, misconfigured, or subverted routers, i.e., legitimate participants in the routing protocol -- are out of scope for this roadmap. Any of the attacks described in the above section (Section 1.4.1) that may be levied by a BYZANTINE Lebovitz & Expires July 24, 2009 [Page 6] Internet-Draft KMART Roadmap January 2009 source are therefore also out of scope. In addition, these other attack actions are out of scope for this work: o SNIFFING - passive observation of route message contents in flight o FALSIFICATION by BYZANTINE sources - unauthorized message content by a legitimate source. o INTERFERENCE due to: * NOT FORWARDING PACKETS - cannot be prevented with cryptographic authentication * DELAYING MESSAGES - cannot be prevented with cryptographic authentication * DENIAL OF RECEIPT - cannot be prevented with cryptographic authentication * UNAUTHORIZED MESSAGE CONTENT - the work of the IETF's SIDR working group grouphttp://www.ietf.org/html.charters/sidr-charter.html). 1.5. Goals The goals and general guidance for this work roadmap follow: o Provide authentication and integrity protection for packets on the wire of existing routing protocols o Deliver a path to incrementally improve security of the routing infrastructure. The principle of crawl, walk, run will be in place. Routing protocol authentication mechanisms may not go immediately from their current state to a state containing the best possible, most modern security practices. Incremental steps will need to be taken for a few very practical reasons. First, there is a great deal of deployed routing devices in operating networks that will not be able to run the most modern cryptographic mechanisms without significant and unacceptable performance penalties. The roadmap for any one routing protocol MUST allow for incremental improvements on existing operational devices. Second, current routing protocol performance on deployed devices has been achieved over the last 20 years through extensive tuning of software and hardware elements, and is a constant focus for improvement by vendors and operators alike. The introduction of new security mechanisms affects this performance balance. The performance impact of any incremental step of security improvement will need to be weighed by the community, and introduced in such a way that allows the vendor and operator community a path to adoption that upholds reasonable performance metrics. Therefore, certain specification elements may be introduced carrying the "SHOULD" guidance, with the intention that the same mechanism will carry a "MUST" in the next release of the specification. This Lebovitz & Expires July 24, 2009 [Page 7] Internet-Draft KMART Roadmap January 2009 gives the vendors and implementors the guidance they need to tune their software and hardware appropriately over time. Last, some security mechanisms require the build out of other operational support systems, and this will take time. An example where these three reasons are at play in an incremental improvement roadmap is seen in the improvement of BGP's [RFC4271] security via the update of the TCP Authentication Option (TCP-AO) [I-D.ietf-tcpm-tcp-auth-opt] effort. It would be ideal, and reflect best common security practice, to have a fully specified key management protocol for negotiating TCP-AO's authentication material, using certificates for peer authentication in the keying. However, in the spirit of incremental deployment, we will first address issues like cryptographic algorithm agility, replay attacks, TCP session resetting in the base TCP-AO protocol before we layer key management on top of it. o The deploy-ability of the improved security solutions on currently running routing infrastructure equipment. This begs the consideration of the current state of processing power available on routers in the network today. o Operational deploy-ability - A solutions acceptability will also be measured by how deployable the solution is by common operator teams using common deployment processes and infrastructures. I.e. We will try to make these solutions fit as well as possible into current operational practices or router deployment. This will be heavily influenced by operator input, to ensure that what we specify can -- and, more importantly, will -- be deployed once specified and implemented by vendors. Deployment of incrementally more secure routing infrastructure in the Internet is the final measure of success. o Address the threats enumerated above in the "Threats" section (Section 1.4) for each routing protocol, along a roadmap. Not all threats may be able to be addressed in the first specification update for any one protocol. Roadmaps will be defined so that both the security area and the routing area agree on how the threats will be addressed completely over time. o Reuse common mechanisms across routing protocols whenever possible - For example, designers should aim to re-use the key management protocol that will be defined for BGP's TCP-AO key establishment for as many other routing protocols as possible. This is but one example. o Bridge any gaps between routing and security engineers by recording agreements on work items, roadmaps, and guidance from the Area leads and Internet Architecture Board (IAB, www.iab.org). o Create a re-usable architecture and guidelines for various IETF working teams who will address these security improvements for various protocols Lebovitz & Expires July 24, 2009 [Page 8] Internet-Draft KMART Roadmap January 2009 1.6. Non-Goals The following two goals are considered out-of-scope for this effort. o privacy of the packets on the wire, at this point in time. Once this roadmap is realized, we may revisit work on privacy. o Message content security. This work is being deal with in other areas, like SIDR. 1.7. Audience The audience for this roadmap includes: o Routing Area working group chairs and members - These people are charged with updates to the routing protocol specifications. Any and all cryptographic authentication work on these specifications will occur in Routing Area working groups. o Security Area reviewers of routing area documents - These people are delegated by the Security Area Directors to perform reviews on routing protocol specifications as they pass through working group last call or IESG review. They will pay particular attention to the use of cryptographic authentication and corresponding security mechanisms for the routing protocols. They will ensure that incremental security improvements are being made, in line with this roadmap. o Security Area engineers partnering with routing area authors/ designers on the security mechanisms in routing protocol specifications - Some of these security area engineers will be assigned by the Security Area Directors, while others will be interested parties. 2. The Roadmap 2.1. Categorizing Routing Protocols For the purpose of this security roadmap definition, we will categorize the routing protocols into groups and have design teams focus on the specification work within those groupings. It is believed that the groupings will have like requirements for their authentication mechanisms, and that reuse of authentication mechanisms will be greatest within these grouping. The first categorization defines three types of messaging transactions used on the wire by the base routing protocol, the Base RP. They are: Lebovitz & Expires July 24, 2009 [Page 9] Internet-Draft KMART Roadmap January 2009 One-to-One One peer router directly and intentionally delivers a route update specifically to one other peer router. Examples are BGP and LDP. [question to reviewers: Should we list all protocols into these categories right here, or just give a few examples?] One-to-Many A router peers with multiple other routers on a single network segment such that it creates and sends one route update message which is intended for consumption by multiple peers. Examples would be OSPF and IS-IS. Client-Server A client-server routing protocol is one where one router initiates a request for route information from another router, who then formulates a response to that request, and replies with the requested data. Examples are ???? and ????. Multicast Multicast protocols have unique security properties because of the fact that they are inherently group-based protocols and thus have group keying requirements. In addition, they are called out here separately because much work has already been done by the Multicast Security working group (MSEC, http://www.ietf.org/html.charters/msec-charter.html), with much of the specification work already completed. [author's note: I think the above definitions need clean up. Routing area folks, especially ADs, PLEASE suggest new text.] The second axis of categorization groups protocols by the keying mechanism that will be necessary for distributing session keys to the actual routing protocol transports. They are: Peer keying One router sends the keying messages directly and only to one other router, such that a one-to-one, unique keying security association (SA) is established between the two routers Group Keying One router creates and distributes a single keying message to multiple peers. In this case an group SA will be established and used between multiple peers simultaneously. Group keying exists for protocols like OSPF [RFC2328] , and also for multicast protocols like PIM-SM [RFC4601]. Lebovitz & Expires July 24, 2009 [Page 10] Internet-Draft KMART Roadmap January 2009 There must also be given consideration The work items placed on the roadmap will be defined and assigned based on these categorizations. 2.2. Security Characterization Vectors A few more considerations must be made about the protocol and its use when initially categorizing the protocol and scoping the authentication work. 2.2.1. Internal vs. External Operation The designers must consider whether the protocol is an internal routing protocol or an external one, i.e. Does it primarily run between peers within a single domain of control or between two different domains of control? Some protocols may be used in both cases, internally and externally, and as such various modes of authentication operation may be required for the same protocol. While it is preferred that all routing exchanges run with the utmost security mechanisms enabled in all deployments, the exhortation is greater for those protocols running at a peering point between two domains of control, and greatest for those on public exchange point links, because the volume of attackers are greater from the outside. Note however that the consequences of internal attacks maybe no less severe -- in fact they may be quite a bit more sever -- than an external attack. An example of this internal versus external consideration is BGP which has both EBGP and IBGP modes. Another example is a multicast protocol where the neighbors are sometimes within a domain of control and sometimes external, like at an exchange link. It would be more acceptable to give up some security to get some convenience by using a group key on large broadcast networks within your domain, whereas operators may favor security over convenience and use unique keying on peering links. In this case again, designers must consider both modes of operation and ensure the authentication mechanisms fit both. Operators are encouraged to run cryptographic authentication on all their adjacencies, but to work from the outside in, i.e. The EBGP links are a higher priority than the IBGP links because they are externally facing. 2.2.2. Unique versus Shared Keys This section discusses security considerations of when it is appropriate to use the same authentication key inputs for multiple peers and when it is not. This is largely a debate of convenience Lebovitz & Expires July 24, 2009 [Page 11] Internet-Draft KMART Roadmap January 2009 versus security. It is often the case that the best secured mechanism is also the least convenient mechanism. For example, an air gap between a host and the network absolutely prevents remote attacks on the host, but having to copy and carry files using the "sneaker net" is quite inconvenient and unscalable. Operators have erred on the side of convenience when it comes to securing routing protocols with cryptographic authentication. Many do not use it at all. Some use it only on external links, but not on internal links. Those that do use it often use the same key for all peers across their entire network. It is common to see the same key in use for years, and that being the same key that was entered when authentication was originally configured. The goal for designers is to create authentication mechanisms that are easy for the operators to deploy, and still use unique keys. Operators have the impression that they NEED shared keys, when in fact they do not. What they need is the relative convenience they experience from deploying cryptographic authentication with shared keys, compared to the inconvenience they would experience if they deployed the same authentication mechanism using unique keys per pair. An example is BGP Route Reflectors. Here operators often use the same authentication key between each client and the route reflector. The roadmaps defined from this guidance document will allow for unique keys to be used between each client and the peer, without sacrificing much convenience. Designers should strive to deliver unique keying mechanisms with similar ease-of-deployment properties as today's shared keys. Operators must understand the consequences of using shared keys across many peers. Unique keys are more secure than shared keys because the reduce both the attack target size and the attack consequence size. In this context, the attack target size represents the number of unique routing exchanges across a network that an attacker may be able to observe in order to gain security association credentials, i.e. Crack the keys. If a shared key is used across the entire internal domain of control, then the attack target size is very large. The larger the attack target, the easier it is for the attacker to gain access to analysis data, and greater the volume of analysis data he can access, both of which make his job easier. In this context, the attack consequence size represents the amount of routing adjacencies that can be negatively affected once a breach has occurred, i.e. Once the keys have been acquired by the attacker. Again, if a shared key is used across the internal domain, then the consequence size is the whole network. Ideally, unique key pairs would be used for each adjacency. In some cases designers may need to use shared keys in order to solve Lebovitz & Expires July 24, 2009 [Page 12] Internet-Draft KMART Roadmap January 2009 the given problem space. For example, a multicast packet is sent once but then observed and consumed by several routing neighbors. If unique keys were used per neighbor, the benefit of multicast would be erased because the casting peer would have to create a different announcement packet/stream for each listening peer. Though this may be desired and acceptable in some small amount of use cases, it is not the norm. Shared group keys are an acceptable solution here, and much work has been done already in this area (see MSEC working group). 2.2.3. Out of Band vs. In-band Key Management [need to fill this out in next rev (ran out of time), outline points below] This section discussed the security and use case considerations for keys placed on devices through out-of-band configurations versus through in-band key management protocol exchanges with peers. Define in-band key management exchange as using crypto protected ID verification and session key negotiation. Drawbacks of oob - scale-ability, complexity and speed of changing if breech is suspected, i.e. terminated employee or compromised machine. Pros, set in OSS system and pushed to all devices. Operators have mechanisms in place for this already. Pros of in-line KMP - results in key that is not recorded anywhere and thus not steal-able if a server or other data store is stolen or compromised, fresh keys, regular rekeys w/o operator involvement or oversight, can leverage properties of assymetric keys vs shared keys. Cons - more crypto overhead, though only at start up and re-key, for the router device. The desired end goal is in-band KMPs. 2.3. Common Framework Each of the categories of routing protocols above will require unique designs for authenticating and integrity checking their protocols. However, a single underlying framework for delivering automatic keying to those solutions will be pursued. Providing such a single framework will significantly reduce the complexity of each step of the overall roadmap. For example, if each Base RP needed to define it's own key management protocol this would balloon the total amount of different sockets that needed to be opened and processes that needed to be simultaneously running on an implementation. It would also significantly increase the run-time complexity and memory Lebovitz & Expires July 24, 2009 [Page 13] Internet-Draft KMART Roadmap January 2009 requirements of such systems running multiple Base RPs, causing perhaps slower performance of such systems. However, if we can land on a very small set (perhaps one or two) of automatic key management protocols, KMPs, that the various Base RP's can use, then we can reduce this implementation and run-time complexity. We can also decrease the total amount of time implementers need to deliver the KMPs for the Base RPs that will provide better threat protection. The components for the framework are listed here, and described below: o BaseRP security mechanism o KMP o key_store o Base RP-to-KMP API o Base RP-to-key_store API o KMP-to-key_store API o Common Base RP mechanisms o Identifiers o Proof of identity o Profiles The framework is modularized for how keys and security association (SA) parameters generally get passed from a KMP to a transport protocol. It contains three main blocks and APIs. Lebovitz & Expires July 24, 2009 [Page 14] Internet-Draft KMART Roadmap January 2009 +-------------------+ | | | KMP Function | | | +---------+---------+ | | API | | +--------------------+ | | | Session | | Key Store | | | +---------+----------+ | | API | | +---------+----------+ | | | Transport Keys | | | +--------------------+ Figure 1: Automatic Key Management Framework Each element of the framework is described here. Base RP Base RP security mechanism - In each case, the Base RP will contain a mechanism for using session keys in their security option. KMP There will be an automated key management protocol, KMP. This KMP will run between the peers. The KMP serves as a protected channel between the peers, through which they can negotiate and pass important data required to exchange key identifiers, derive session keys, determine re-keying, synchronize their keying state, signal various keying events, notify with error messages, etc. As an analogy, in the IPsec protocol [RFC 4301, 4303 and 4306] IKEv2 is the KMP that runs between the two peers, while AH and ESP are two different base protocols that take session keys from IKEv2 and use them in their transmissions. In the analogy, the Base RP, say BGP and LDP are analogous to ESP and AH, while the KMP is analogous to IKEv2 itself. Lebovitz & Expires July 24, 2009 [Page 15] Internet-Draft KMART Roadmap January 2009 Key_store Each implementation will also contain a protocol independent mechanism for storing keys, called key_store. The key_store will have multiple different logical containers, one container for each session key that any given Base RP will need. RP-KMP API There will be an API for the Base RP to request a session key of the KMP, and be notified when the keys are available for it. The API will also contain a mechanism for the KMP to notify the Base RP that there are new keys that it must now use, even if it didn't request those keys. The API will also include a mechanism for the KMP to receive requests for session keys and other parameters from the routing protocol. The KMP will also be aware of the various Base RPs and each of their unique parameters that need to be negotiated and returned. RP-key_store API There will be an API for Base RP to retrieve the keys from the key_store. This will enable implementers to reuse the same API calls for all their Base RPs. The API will necessarily include facility to retrieve other parameters it may need to construct it's packets, like key IDs or key lifetimes, etc. KMP-key_store API There will be an API for the KMP to place keys and parameters into the key_store after their negotiation and derivation with the other peer. This will enable the implementers to reuse the same calls for multiple KMPs that may be needed to address the various categories of RPs as described in Section [Categorizing..link this later.]. [after writing this all up, I'm not sure we really need the key_store in the middle. As long as we standardize fully all the calls needed from any RP to any KMP, then there can be a generic hand-down function from the KMP to the RP when the key and parameters are ready. Let's sleep on it.] [will need state machines and function calls for these APIs, as one of the work items. In essence, there is a need for a core team to develop the APIs out completely in order for the RP teams to use them. Need to get this team going asap.] Lebovitz & Expires July 24, 2009 [Page 16] Internet-Draft KMART Roadmap January 2009 ldentitifiers A KMP is fed by identities. The identities are text strings used by the peers to indicate to each other that each are known to the other, and authorized to establish connections. Those identities must be represented in some standard string format, e.g. an IP address -- either v4 or v6, an FQDN, an RFC 822 email address, a Common Name [RFC PKI], etc. Note that even though routers do not normally have email addresses, one could use an RFC 822 email address string as a formatted identifier for a router. They would do so simply by putting the router's reference number or name-code as the "NAME" part of the address, left of the "@" symbol. They would then place some locational context in the "DOMAIN" part of the string, right of the "@" symbol. An example would be "rtr0210@sf.ca.us.company.com". This document does not suggest this string value at all. Instead, the concept is used only to clarify that the type of string employed does not matter. It only matters that the type of string must be agreed upon by the two endpoints. Further, the string can be used as an identifier in this context, even if the string is not actually provisioned in it's source domain. For example, the email address "rtr0210@sf.ca.us.company.com" may not actually exist, but that string may still be used as an identifier in the routing protocol security context. What is important is that the community decide on a small but flexible set of Identifiers they will all support, and that they decide on the exact format of those string. The formats that will be used must be standardized and must be sensible for the routing infrastructure. Identity Proof Once the form of identity is decided, then there must be a cryptographic proof of that identity, that the peer really is who they assert themselves to be. Proof of identity can be arranged between the peers in a few ways, for example pre-shared keys, raw assymetric keys, or a more user-friendly representation of assymetric keys, like a certificate. Certificates can used in a way requiring very little supporting systems, as is the case with self-signed certificates. Self-signed certificates will have somewhat lower security properties than Certificate Authority signed certificates [RFC Certs]. The use of these different identity proofs vary in ease of deployment, ease of ongoing management, startup effort, ongoing effort and management, security strength, and consequences from loss of secrets from one part of the system to the rest of the system, i.e. Resistance to a security breach, and the effort required to remediate the whole system in the event of such a breach. Lebovitz & Expires July 24, 2009 [Page 17] Internet-Draft KMART Roadmap January 2009 Profiles Once the KMP, Identifiers and Proofs mechanisms are converged upon, they must be clearly profiled for each Base RP, so that implementors and deployers alike understand the different pieces of the solution, and can have similar configurations and interoperability across multiple vendors' devices, so as to reduce management difficulty. The profiles SHOULD also provide guidance on when to use which various combinations of options. This will, again, simplify use and interoperability. Common Mechanisms - In as much as they exist, the framework will capture mechanisms that can be used commonly not only within a particular category of Base RP and Base RP to KMP, but also between Base RP categories. Again, the goal here is simplifying the implementations and runtime code and resource requirements. There is also a goal here of favoring well vetted, reviewed, operationally proven security mechanisms over newly brewed mechanisms that are less well tried in the wild. 2.4. Work Items Per Routing Protocol Each Base RP will have a team (the [RP]-KMART team) working on incrementally improving their Base RP's security, These teams will have the following main work items: Characterize the RP Assess the Base RP to see what authentication mechanisms it has today. Does it needs significant improvement to its existing mechanisms or not? This will include determining if modern, strong security algorithms and parameters are present. Define Optimal State List the requirements for the Base RP's session key usage and format to contain to modern, strong security algorithms and mechanisms [RFC?????]. This includes things like cipher agility, keyID, overlapping keys, rolling keys, IV, etc. The goal here is to determine what is needed for they Base RP alone to be used securely with at least manual keys. KMP Analysis Review requirements for KMPs [RFC????]. Identify any nuances for this particular protocol's needs and its use cases for KMP. List the requirements that this RP has for being able to be use in conjunctions with a KMP. Lebovitz & Expires July 24, 2009 [Page 18] Internet-Draft KMART Roadmap January 2009 Gap Analysis Enumerate the requirements for this protocol to move from its current security state, the first bullet, to its optimal state, bullet two above. Define the Roadmap Create a roadmap of the design work and release a document(s) Design Do the design and document work for a KMP to be able to generate the Base RP's session keys for the packets on the wire. These will be the arguments passed in the API to the KMP in order to bootstrap the session keys to the Base RP. There will also be a team formed to work on the base framework mechanisms for each of the main categories, i.e. the blocks and API's represented in figure 1 (Figure 1). 2.5. Protocols, Categories, and Priorities This section groups the Base RPs into like categories, according to attributes set forth in Categories Section (Section 2.1). Each group will have a design team tasked with improving the security of the Base RP mechanisms and defining the KMP requirements for their group, then rolling both into a roadmap document upon which they will execute. BGP, LDP and MSDP The Base RP's that fall into the category of the one-to-one peering messages, and will use peer keying protocols, AND are all transmitted over TCP include BGP RFC 4271 [RFC4271], LDP [RFC3036] and MSDP [RFC3618]. A team will work on one mechanism to cover these three protocols. The exception is the mode where LDP is used directly on the LAN [RFC????]. The work for this may go into the Group keying category (w/ OSPF) mentioned below PCE over TCP [my notes were unclear about what to do with this] OSPF, ISIS, and RIP The Base RPs that fall into the category Group keying with one-to- many peering messages includes OSPF [RFC2328], ISIS [RFC1195] and RIP [RFC2453]. Not surprisingly, all these routing protocols have two other things in common. First, they are run on a combination of the OSI datalink layer 2, and the OSI network layer 3. Second, they are all internal gateway protocols, or IGPs. The keying mechanisms and use will be much more complicated to define for these. Lebovitz & Expires July 24, 2009 [Page 19] Internet-Draft KMART Roadmap January 2009 BFD Because it is less of a routing protocol, per se, and more of a peer aliveness detection mechanism, Bidirectional Forwarding Detection (BFD) [RFC????] will have its own team. RSVP [RFC????], RSVP-TE [RFC????], and PCE These three protocols will be handled together. [what more characterisation should we give here? Routing AD's, provide text pls?] PIM-SM and PIM-DM Finally, the multicast protocols of PIM-SM [RFC4601] and PIM-DM [RFC3973] will be handled together. However, much work has been done in the MSEC working group on these, so it is highly likely that no additional work will need to be done for these. These protocols are deemed out-of-scope for this current iteration of the work roadmap. Once all of the protocols listed above have had their work completed, or are clearly within site of completion, then the community will revisit the need and interest for working on these: o MANET o FORCES [need text from routing ADs on why these are out of scope] Resources from both the routing area and the security area will be applied to work on these problem spaces as quickly as possible. Realizing that such resources are far from unlimited, a rank order priority for addressing the work of incrementally securing these groups of routing protocols is provided: o Priority 1 - BGP / LDP / MSDP o Priority 2 - BFD o Priority 3 - OSPF / ISIS / RIP o Priority 4 - RSVP and RSVP-TE By far the most important group is the Priority 1 group as these are the protocols used on the most public and exposed segments of the networks, at the peering points between operators and between operators and their customers. BFD, as a detection mechanism underlying the Priority 1 protocols is therefore second. Lebovitz & Expires July 24, 2009 [Page 20] Internet-Draft KMART Roadmap January 2009 3. Change History [NOTE TO RFC EDITOR: this section for use during I-D stage only. Please remove before publishing as RFC.] -00-00 original rough rough rough draft for review by routing and security AD's -00- original submission o adds new category = multicast protocols in category section and mentions mcast in group keying category description. o add a lot of references where they did not exist before, or where there were only place holders. Still more work needed on this. o abstract filled in o changed from standards track to informational (this was an oversight in last draft). o filled out threats section with detailed descriptions, and linked to RPsec threats RFC o made ascii art for the basic KMP framework o added section on internal versus external peering and the requirements decisions for them o added security characterization section in sect 2, added sections discussing internal vs external protocols, shared vs unique keys, oob vs in-band keying o incorporates all D Ward's feedback from his initial skim of the document. 4. Needs Work in Next Draft (RFC Editor: Delete Before Publishing) [NOTE TO RFC EDITOR: this section for use during I-D stage only. Please remove before publishing as RFC.] List of stuff that still needs work o expand the framework figure to include all the framework elements o move standard terminology section next to other terminology section o clean up the three definitions of route message type categories o a: ref each of the sections for internal hopping o More clarity on the work items for those defining and specifying the framework elements and API's themselves. o What category is PCEP over TCP? It's own, or grouped with BGP? o text justifying RSVP and RSVP-TE and what we thing solving that problem may look like o more justification for why MANET and FORCES are out of scope. Need ref for those RFCs. Lebovitz & Expires July 24, 2009 [Page 21] Internet-Draft KMART Roadmap January 2009 o Get RFC references and insert o security section? o 5. Security Considerations This entire document focuses on improving the security of routing protocols by improving or implementing cryptographic authentication for each routing protocol. Security considerations are largely contained within the body text of the document. [we can pull pieces out of body and place here, if people think it more appropriate]. 6. IANA Considerations This document has no actions for IANA. 7. Acknowledgements The outline for this draft was created from discussions and agreements with Routing AD's Ross Callon and Dave Ward, Security AD's Tim Polk and Pasi Eronen, and IAB members Danny McPherson and Gregory Lebovitz. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2828] Shirey, R., "Internet Security Glossary", RFC 2828, May 2000. [RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303, December 2005. [RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to Routing Protocols", RFC 4593, October 2006. Lebovitz & Expires July 24, 2009 [Page 22] Internet-Draft KMART Roadmap January 2009 [RFC4948] Andersson, L., Davies, E., and L. Zhang, "Report from the IAB workshop on Unwanted Traffic March 9-10, 2006", RFC 4948, August 2007. 8.2. Informative References [I-D.ietf-tcpm-tcp-auth-opt] Touch, J., Mankin, A., and R. Bonica, "The TCP Authentication Option", draft-ietf-tcpm-tcp-auth-opt-02 (work in progress), November 2008. [I-D.narten-iana-considerations-rfc2434bis] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", draft-narten-iana-considerations-rfc2434bis-09 (work in progress), March 2008. [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and dual environments", RFC 1195, December 1990. [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453, November 1998. [RFC3036] Andersson, L., Doolan, P., Feldman, N., Fredette, A., and B. Thomas, "LDP Specification", RFC 3036, January 2001. [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", BCP 72, RFC 3552, July 2003. [RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery Protocol (MSDP)", RFC 3618, October 2003. [RFC3973] Adams, A., Nicholas, J., and W. Siadak, "Protocol Independent Multicast - Dense Mode (PIM-DM): Protocol Specification (Revised)", RFC 3973, January 2005. [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, August 2006. Lebovitz & Expires July 24, 2009 [Page 23] Internet-Draft KMART Roadmap January 2009 Authors' Addresses Gregory Lebovitz Juniper Networks, Inc. 1194 North Mathilda Ave. Sunnyvale, CA 94089-1206 US Phone: Email: gregory.ietf@gmail.com Phone: Email: Lebovitz & Expires July 24, 2009 [Page 24] Internet-Draft KMART Roadmap January 2009 Copyright and License Notice Copyright (c) 2008 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. 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