--- 1/draft-ietf-hip-rfc5206-bis-13.txt 2016-10-10 17:15:54.086629352 -0700 +++ 2/draft-ietf-hip-rfc5206-bis-14.txt 2016-10-10 17:15:54.166631434 -0700 @@ -1,50 +1,50 @@ Network Working Group T. Henderson, Ed. Internet-Draft University of Washington Obsoletes: 5206 (if approved) C. Vogt Intended status: Standards Track Independent -Expires: March 13, 2017 J. Arkko +Expires: April 13, 2017 J. Arkko Ericsson - September 9, 2016 + October 10, 2016 Host Mobility with the Host Identity Protocol - draft-ietf-hip-rfc5206-bis-13 + draft-ietf-hip-rfc5206-bis-14 Abstract This document defines a mobility extension to the Host Identity Protocol (HIP). Specifically, this document defines a "LOCATOR_SET" parameter for HIP messages that allows for a HIP host to notify peers about alternate addresses at which it may be reached. This document also defines how the parameter can be used to preserve communications across a change to the IP address used by one or both peer hosts. The same LOCATOR_SET parameter can also be used to support end-host - multihoming, but the procedures are out of scope for this document - and are specified elsewhere. This document obsoletes RFC 5206. + multihoming (specified in RFC[Replace with the RFC number for draft- + ietf-hip-multihoming]). This document obsoletes RFC 5206. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." - This Internet-Draft will expire on March 13, 2017. + This Internet-Draft will expire on April 13, 2017. Copyright Notice Copyright (c) 2016 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 @@ -56,69 +56,71 @@ Table of Contents 1. Introduction and Scope . . . . . . . . . . . . . . . . . . . 3 2. Terminology and Conventions . . . . . . . . . . . . . . . . . 4 3. Protocol Model . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Operating Environment . . . . . . . . . . . . . . . . . . 5 3.1.1. Locator . . . . . . . . . . . . . . . . . . . . . . . 7 3.1.2. Mobility Overview . . . . . . . . . . . . . . . . . . 7 3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 8 - 3.2.1. Mobility with a Single SA Pair (No Rekeying) . . . . 8 + 3.2.1. Mobility with a Single SA Pair (No Rekeying) . . . . 9 3.2.2. Mobility with a Single SA Pair (Mobile-Initiated Rekey) . . . . . . . . . . . . . . . . . . . . . . . 10 - 3.2.3. Mobility messaging through rendezvous server . . . . 10 + 3.2.3. Mobility messaging through rendezvous server . . . . 11 3.2.4. Network Renumbering . . . . . . . . . . . . . . . . . 12 3.3. Other Considerations . . . . . . . . . . . . . . . . . . 12 3.3.1. Address Verification . . . . . . . . . . . . . . . . 12 - 3.3.2. Credit-Based Authorization . . . . . . . . . . . . . 12 + 3.3.2. Credit-Based Authorization . . . . . . . . . . . . . 13 3.3.3. Preferred Locator . . . . . . . . . . . . . . . . . . 14 - 4. LOCATOR_SET Parameter Format . . . . . . . . . . . . . . . . 14 + 4. LOCATOR_SET Parameter Format . . . . . . . . . . . . . . . . 15 4.1. Traffic Type and Preferred Locator . . . . . . . . . . . 16 - 4.2. Locator Type and Locator . . . . . . . . . . . . . . . . 16 + 4.2. Locator Type and Locator . . . . . . . . . . . . . . . . 17 4.3. UPDATE Packet with Included LOCATOR_SET . . . . . . . . . 17 5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 17 - 5.1. Locator Data Structure and Status . . . . . . . . . . . . 17 - 5.2. Sending LOCATOR_SETs . . . . . . . . . . . . . . . . . . 19 - 5.3. Handling Received LOCATOR_SETs . . . . . . . . . . . . . 19 + 5.1. Locator Data Structure and Status . . . . . . . . . . . . 18 + 5.2. Sending the LOCATOR_SET . . . . . . . . . . . . . . . . . 19 + 5.3. Handling Received LOCATOR_SETs . . . . . . . . . . . . . 20 5.4. Verifying Address Reachability . . . . . . . . . . . . . 22 5.5. Changing the Preferred Locator . . . . . . . . . . . . . 23 - 5.6. Credit-Based Authorization . . . . . . . . . . . . . . . 23 + 5.6. Credit-Based Authorization . . . . . . . . . . . . . . . 24 5.6.1. Handling Payload Packets . . . . . . . . . . . . . . 24 - 5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . 25 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 26 - 6.1. Impersonation Attacks . . . . . . . . . . . . . . . . . . 27 - 6.2. Denial-of-Service Attacks . . . . . . . . . . . . . . . . 28 - 6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . 28 - 6.2.2. Memory/Computational-Exhaustion DoS Attacks . . . . . 28 - 6.3. Mixed Deployment Environment . . . . . . . . . . . . . . 29 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 - 8. Authors and Acknowledgments . . . . . . . . . . . . . . . . . 30 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 - 9.1. Normative references . . . . . . . . . . . . . . . . . . 30 - 9.2. Informative references . . . . . . . . . . . . . . . . . 31 - Appendix A. Document Revision History . . . . . . . . . . . . . 32 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 + 5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . 26 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 27 + 6.1. Impersonation Attacks . . . . . . . . . . . . . . . . . . 28 + 6.2. Denial-of-Service Attacks . . . . . . . . . . . . . . . . 29 + 6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . 29 + 6.2.2. Memory/Computational-Exhaustion DoS Attacks . . . . . 29 + 6.3. Mixed Deployment Environment . . . . . . . . . . . . . . 30 + 6.4. Privacy Concerns . . . . . . . . . . . . . . . . . . . . 31 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31 + 8. Differences from RFC 5206 . . . . . . . . . . . . . . . . . . 31 + 9. Authors and Acknowledgments . . . . . . . . . . . . . . . . . 32 + 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 33 + 10.1. Normative references . . . . . . . . . . . . . . . . . . 33 + 10.2. Informative references . . . . . . . . . . . . . . . . . 34 + Appendix A. Document Revision History . . . . . . . . . . . . . 35 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 1. Introduction and Scope The Host Identity Protocol [RFC7401] (HIP) supports an architecture that decouples the transport layer (TCP, UDP, etc.) from the internetworking layer (IPv4 and IPv6) by using public/private key pairs, instead of IP addresses, as host identities. When a host uses HIP, the overlying protocol sublayers (e.g., transport layer sockets and Encapsulating Security Payload (ESP) Security Associations (SAs)) are instead bound to representations of these host identities, and the IP addresses are only used for packet forwarding. However, each - host must also know at least one IP address at which its peers are - reachable. Initially, these IP addresses are the ones used during - the HIP base exchange. + host needs to also know at least one IP address at which its peers + are reachable. Initially, these IP addresses are the ones used + during the HIP base exchange. One consequence of such a decoupling is that new solutions to network-layer mobility and host multihoming are possible. There are potentially many variations of mobility and multihoming possible. The scope of this document encompasses messaging and elements of procedure for basic network-level host mobility, leaving more complicated mobility scenarios, multihoming, and other variations for further study. More specifically, the following are in scope: This document defines a LOCATOR_SET parameter for use in HIP @@ -157,20 +159,26 @@ signaling the correspondent node); this document is concerned with end-to-end mobility. Finally, making underlying IP mobility transparent to the transport layer has implications on the proper response of transport congestion control, path MTU selection, and Quality of Service (QoS). Transport-layer mobility triggers, and the proper transport response to a HIP mobility or multihoming address change, are outside the scope of this document. + The main sections of this document are organized as follows. + Section 3 provides a summary overview of operations, scenarios, and + other considerations. Section 4 specifies the messaging parameter + syntax. Section 5 specifies the processing rules for messages. + Section 6 describes security considerations for this specification. + 2. Terminology and Conventions 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]. LOCATOR_SET. A HIP parameter containing zero or more Locator fields. Locator. A name that controls how the packet is routed through the network and demultiplexed by the end host. It may include a @@ -275,32 +283,33 @@ to use for ESP, and the IP addresses (used in both the HIP signaling packets and ESP data packets). Note that there can only be one such set of bindings in the outbound direction for any given packet, and the only fields used for the binding at the HIP layer are the fields exposed by ESP (the SPI and HITs). For the inbound direction, the SPI is all that is required to find the right host context. ESP rekeying events change the mapping between the HIT pair and SPI, but do not change the IP addresses. Consider next a mobility event, in which a host moves to another IP - address. Two things must occur in this case. First, the peer must - be notified of the address change using a HIP UPDATE message. - Second, each host must change its local bindings at the HIP sublayer - (new IP addresses). It may be that both the SPIs and IP addresses - are changed simultaneously in a single UPDATE; the protocol described - herein supports this. Although internal notification of transport - layer protocols regarding the path change (e.g. to reset congestion - control variables) may be desired, this specification does not - address such internal notification. In addition, elements of - procedure for traversing middleboxes, including network address - translators, may complicate the above basic scenario and are not - covered by this document. + address. Two things need to occur in this case. First, the peer + needs to be notified of the address change using a HIP UPDATE + message. Second, each host needs to change its local bindings at the + HIP sublayer (new IP addresses). It may be that both the SPIs and IP + addresses are changed simultaneously in a single UPDATE; the protocol + described herein supports this. Although internal notification of + transport layer protocols regarding the path change (e.g. to reset + congestion control variables) may be desired, this specification does + not address such internal notification. In addition, elements of + procedure for traversing network address translators (NATs) and + firewalls, including NATs and firewalls that may understand the HIP + protocol, may complicate the above basic scenario and are not covered + by this document. 3.1.1. Locator This document defines a generalization of an address called a "locator". A locator specifies a point-of-attachment to the network but may also include additional end-to-end tunneling or per-host demultiplexing context that affects how packets are handled below the logical HIP sublayer of the stack. This generalization is useful because IP addresses alone may not be sufficient to describe how packets should be handled below HIP. For example, in a host @@ -359,45 +368,47 @@ pair of IP addresses, which are the ones used in the base exchange. The readdressing protocol is an asymmetric protocol where a mobile host informs a peer host about changes of IP addresses on affected SPIs. The readdressing exchange is designed to be piggybacked on existing HIP exchanges. In support of mobility, the LOCATOR_SET parameter is carried in UPDATE packets. The scenarios below at times describe addresses as being in either an ACTIVE, UNVERIFIED, or DEPRECATED state. From the perspective of a - host, newly-learned addresses of the peer must be verified before put - into active service, and addresses removed by the peer are put into a - deprecated state. Under limited conditions described below + host, newly-learned addresses of the peer needs to be verified before + put into active service, and addresses removed by the peer are put + into a deprecated state. Under limited conditions described below (Section 5.6), an UNVERIFIED address may be used. The addressing states are defined more formally in Section 5.1. Hosts that use link-local addresses as source addresses in their HIP handshakes may not be reachable by a mobile peer. Such hosts SHOULD provide a globally routable address either in the initial handshake or via the LOCATOR_SET parameter. 3.2.1. Mobility with a Single SA Pair (No Rekeying) - A mobile host must sometimes change an IP address bound to an + A mobile host sometimes needs to change an IP address bound to an interface. The change of an IP address might be needed due to a change in the advertised IPv6 prefixes on the link, a reconnected PPP link, a new DHCP lease, or an actual movement to another subnet. In - order to maintain its communication context, the host must inform its - peers about the new IP address. This first example considers the + order to maintain its communication context, the host needs to inform + its peers about the new IP address. This first example considers the case in which the mobile host has only one interface, one IP address in use within the HIP session, a single pair of SAs (one inbound, one outbound), and no rekeying occurs on the SAs. We also assume that the new IP addresses are within the same address family (IPv4 or IPv6) as the previous address. This is the simplest scenario, - depicted in Figure 3. + depicted in Figure 3. Note that the conventions for message + parameter notations in figures (use of parentheses and brackets) is + defined in Section 2.2 of [RFC7401]. Mobile Host Peer Host UPDATE(ESP_INFO, LOCATOR_SET, SEQ) -----------------------------------> UPDATE(ESP_INFO, SEQ, ACK, ECHO_REQUEST) <----------------------------------- UPDATE(ACK, ECHO_RESPONSE) -----------------------------------> @@ -410,43 +421,52 @@ another; this case is sometimes referred to in the literature as a "break-before-make" case. The host may also obtain its new IP address before loosing the old one ("make-before-break" case). In either case, upon obtaining a new IP address, the mobile host sends a LOCATOR_SET parameter to the peer host in an UPDATE message. The UPDATE message also contains an ESP_INFO parameter containing the values of the old and new SPIs for a security association. In this case, the OLD SPI and NEW SPI parameters both are set to the value of the preexisting incoming SPI; this ESP_INFO does not trigger a rekeying event but is instead - included for possible parameter-inspecting middleboxes on the - path. The LOCATOR_SET parameter contains the new IP address - (Locator Type of "1", defined below) and a locator lifetime. The - mobile host waits for this UPDATE to be acknowledged, and - retransmits if necessary, as specified in the base specification - [RFC7401]. + included for possible parameter-inspecting firewalls on the path + ([RFC5207] specifies some such firewall scenarios in which the + HIP-aware firewall may want to associate ESP flows to host + identities). The LOCATOR_SET parameter contains the new IP + address (Locator Type of "1", defined below) and a locator + lifetime. The mobile host waits for this UPDATE to be + acknowledged, and retransmits if necessary, as specified in the + base specification [RFC7401]. 2. The peer host receives the UPDATE, validates it, and updates any local bindings between the HIP association and the mobile host's destination address. The peer host MUST perform an address verification by placing a nonce in the ECHO_REQUEST parameter of the UPDATE message sent back to the mobile host. It also includes an ESP_INFO parameter with the OLD SPI and NEW SPI parameters both set to the value of the preexisting incoming SPI, and sends this UPDATE (with piggybacked acknowledgment) to the - mobile host at its new address. The peer MAY use the new address - immediately, but it MUST limit the amount of data it sends to the - address until address verification completes. + mobile host at its new address. This UPDATE also acknowledges + the mobile host's UPDATE that triggered the exchange. The peer + host waits for its UPDATE to be acknowledged, and retransmits if + necessary, as specified in the base specification [RFC7401]. The + peer MAY use the new address immediately, but it MUST limit the + amount of data it sends to the address until address verification + completes. 3. The mobile host completes the readdress by processing the UPDATE - ACK and echoing the nonce in an ECHO_RESPONSE. Once the peer - host receives this ECHO_RESPONSE, it considers the new address to - be verified and can put the address into full use. + ACK and echoing the nonce in an ECHO_RESPONSE, containing the ACK + of the peer's UPDATE. This UPDATE is not protected by a + retransmission timer because it does not contain a SEQ parameter + requesting acknowledgment. Once the peer host receives this + ECHO_RESPONSE, it considers the new address to be verified and + can put the address into full use. While the peer host is verifying the new address, the new address is marked as UNVERIFIED in the interim, and the old address is DEPRECATED. Once the peer host has received a correct reply to its UPDATE challenge, it marks the new address as ACTIVE and removes the old address. 3.2.2. Mobility with a Single SA Pair (Mobile-Initiated Rekey) The mobile host may decide to rekey the SAs at the same time that it @@ -487,26 +507,28 @@ The HIP Rendezvous Extension [I-D.ietf-hip-rfc5204-bis] specifies a rendezvous service that permits the I1 packet from the base exchange to be relayed from a stable or well-known public IP address location to the current IP address of the host. It is possible to support double-jump mobility with this rendezvous service if the following extensions to the specifications of [I-D.ietf-hip-rfc5204-bis] and [RFC7401] are followed. 1. The mobile host sending an UPDATE to the peer, and not receiving an ACK, MAY resend the UPDATE to a rendezvous server (RVS) of the - peer, if such a server is known. The host may try the RVS of the + peer, if such a server is known. The host MAY try the RVS of the peer up to UPDATE_RETRY_MAX times as specified in [RFC7401]. The - host may try to use the peer's RVS before it has tried + host MAY try to use the peer's RVS before it has tried UPDATE_RETRY_MAX times to the last working address (i.e. the RVS - may be tried in parallel with retries to the last working - address). + MAY be tried in parallel with retries to the last working + address). The aggressiveness of a host replicating its UPDATEs + to multiple destinations, to try candidates in parallel instead + of serially, is a policy choice outside of this specification. 2. A rendezvous server supporting the UPDATE forwarding extensions specified herein MUST modify the UPDATE in the same manner as it modifies the I1 packet before forwarding. Specifically, it MUST rewrite the IP header source and destination addresses, recompute the IP header checksum, and include the FROM and RVS_HMAC parameters. 3. A host receiving an UPDATE packet MUST be prepared to process the FROM and RVS_HMAC parameters, and MUST include a VIA_RVS @@ -539,33 +561,34 @@ 3.3. Other Considerations 3.3.1. Address Verification When a HIP host receives a set of locators from another HIP host in a LOCATOR_SET, it does not necessarily know whether the other host is actually reachable at the claimed addresses. In fact, a malicious peer host may be intentionally giving bogus addresses in order to cause a packet flood towards the target addresses [RFC4225]. - Therefore, the HIP host must first check that the peer is reachable - at the new address. + Therefore, the HIP host needs to first check that the peer is + reachable at the new address. Address verification is implemented by the challenger sending some piece of unguessable information to the new address, and waiting for some acknowledgment from the Responder that indicates reception of the information at the new address. This may include the exchange of a nonce, or the generation of a new SPI and observation of data - arriving on the new SPI. + arriving on the new SPI. More details are found in Section 5.4 of + this document. An additional potential benefit of performing address verification is - to allow middleboxes in the network along the new path to obtain the - peer host's inbound SPI. + to allow NATs and firewalls in the network along the new path to + obtain the peer host's inbound SPI. 3.3.2. Credit-Based Authorization Credit-Based Authorization (CBA) allows a host to securely use a new locator even though the peer's reachability at the address embedded in the locator has not yet been verified. This is accomplished based on the following three hypotheses: 1. A flooding attacker typically seeks to somehow multiply the packets it generates for the purpose of its attack because @@ -618,32 +641,42 @@ |<-------------------------------| credit -= size(packet) | X credit < size(packet) | | => do not send packet! + address verification concludes | address | | ACTIVE |<-------------------------------| do not change credit | | Figure 5: Readdressing Scenario + This document does not specify how to set the credit limit value, but + the goal is to allow data transfers to proceed without much + interruption while the new address is verified. A simple heuristic + to accomplish this, if the sender knows roughly its round-trip time + (RTT) and current sending rate to the host, is to allow enough credit + to support maintaining the sending rate for a duration corresponding + to two or three RTTs. + 3.3.3. Preferred Locator - When a host has multiple locators, the peer host must decide which to - use for outbound packets. It may be that a host would prefer to - receive data on a particular inbound interface. HIP allows a - particular locator to be designated as a Preferred locator and + When a host has multiple locators, the peer host needs to decide + which to use for outbound packets. It may be that a host would + prefer to receive data on a particular inbound interface. HIP allows + a particular locator to be designated as a Preferred locator and communicated to the peer (see Section 4). 4. LOCATOR_SET Parameter Format - The LOCATOR_SET parameter is a critical parameter as defined by - [RFC7401]. It consists of the standard HIP parameter Type and Length + The LOCATOR_SET parameter has a type number value that is considered + to be a 'critical parameter' as per the definition in [RFC7401]; such + parameter types MUST be recognized and processed by the recipient. + The parameter consists of the standard HIP parameter Type and Length fields, plus zero or more Locator sub-parameters. Each Locator sub- parameter contains a Traffic Type, Locator Type, Locator Length, Preferred locator bit, Locator Lifetime, and a Locator encoding. A LOCATOR_SET containing zero Locator fields is permitted but has the effect of deprecating all addresses. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | @@ -696,21 +729,21 @@ Locator: The locator whose semantics and encoding are indicated by the Locator Type field. All Locator sub-fields are integral multiples of four octets in length. The Locator Lifetime indicates how long the following locator is expected to be valid. The lifetime is expressed in seconds. Each locator MUST have a non-zero lifetime. The address is expected to become deprecated when the specified number of seconds has passed since the reception of the message. A deprecated address SHOULD NOT be used as a destination address if an alternate (non-deprecated) is - available and has sufficient scope. + available and has sufficient address scope. 4.1. Traffic Type and Preferred Locator The following Traffic Type values are defined: 0: Both signaling (HIP control packets) and user data. 1: Signaling packets only. 2: Data packets only. @@ -744,42 +777,41 @@ 4.3. UPDATE Packet with Included LOCATOR_SET A number of combinations of parameters in an UPDATE packet are possible (e.g., see Section 3.2). In this document, procedures are defined only for the case in which one LOCATOR_SET and one ESP_INFO parameter is used in any HIP packet. Any UPDATE packet that includes a LOCATOR_SET parameter SHOULD include both an HMAC and a HIP_SIGNATURE parameter. The UPDATE MAY also include a HOST_ID parameter (which may be useful - for middleboxes inspecting the HIP messages for the first time). If - the UPDATE includes the HOST_ID parameter, the receiving host MUST - verify that the HOST_ID corresponds to the HOST_ID that was used to - establish the HIP association, and the HIP_SIGNATURE must verify with - the public key associated with this HOST_ID parameter. + for HIP-aware firewalls inspecting the HIP messages for the first + time). If the UPDATE includes the HOST_ID parameter, the receiving + host MUST verify that the HOST_ID corresponds to the HOST_ID that was + used to establish the HIP association, and the HIP_SIGNATURE MUST + verify with the public key associated with this HOST_ID parameter. The relationship between the announced Locators and any ESP_INFO parameters present in the packet is defined in Section 5.2. This document does not support any elements of procedure for sending more than one LOCATOR_SET or ESP_INFO parameter in a single UPDATE. 5. Processing Rules This section describes rules for sending and receiving the LOCATOR_SET parameter, testing address reachability, and using Credit-Based Authorization (CBA) on UNVERIFIED locators. 5.1. Locator Data Structure and Status - In a typical implementation, each locator announced in a LOCATOR_SET - parameter is represented by a piece of state that contains the - following data: + Each locator announced in a LOCATOR_SET parameter is represented by a + piece of state that contains the following data: o the actual bit pattern representing the locator, o the lifetime (seconds), o the status (UNVERIFIED, ACTIVE, DEPRECATED), o the Traffic Type scope of the locator, and o whether the locator is preferred for any particular scope. @@ -801,68 +833,78 @@ successfully. UNVERIFIED to DEPRECATED The locator lifetime expires while the locator is UNVERIFIED. ACTIVE to DEPRECATED The locator lifetime expires while the locator is ACTIVE. ACTIVE to UNVERIFIED There has been no traffic on the address for some time, and the local policy mandates that the address - reachability must be verified again before starting to use it + reachability needs to be verified again before starting to use it again. DEPRECATED to UNVERIFIED The host receives a new lifetime for the locator. A DEPRECATED address MUST NOT be changed to ACTIVE without first verifying its reachability. Note that the state of whether or not a locator is preferred is not necessarily the same as the value of the Preferred bit in the Locator sub-parameter received from the peer. Peers may recommend certain locators to be preferred, but the decision on whether to actually use a locator as a preferred locator is a local decision, possibly influenced by local policy. In addition to state maintained about status and remaining lifetime for each locator learned from the peer, an implementation would typically maintain similar state about its own locators that have been offered to the peer. + An unbounded locator lifetime can be signified by setting the value + of the lifetime field to the maximum (unsigned) value. + Finally, the locators used to establish the HIP association are by default assumed to be the initial preferred locators in ACTIVE state, with an unbounded lifetime. -5.2. Sending LOCATOR_SETs +5.2. Sending the LOCATOR_SET - The decision of when to send LOCATOR_SETs is basically a local policy - issue. However, it is RECOMMENDED that a host send a LOCATOR_SET - whenever it recognizes a change of its IP addresses in use on an - active HIP association, and assumes that the change is going to last - at least for a few seconds. Rapidly sending LOCATOR_SETs that force - the peer to change the preferred address SHOULD be avoided. + The decision of when to send the LOCATOR_SET is a local policy issue. + However, it is RECOMMENDED that a host send a LOCATOR_SET whenever it + recognizes a change of its IP addresses in use on an active HIP + association, and assumes that the change is going to last at least + for a few seconds. Rapidly sending LOCATOR_SETs that force the peer + to change the preferred address SHOULD be avoided. + + The sending of a new LOCATOR_SET parameter replaces the locator + information from any previously sent LOCATOR_SET parameter, and + therefore if a host sends a new LOCATOR_SET parameter, it needs to + continue to include all active locators. Hosts MUST NOT announce + broadcast or multicast addresses in LOCATOR_SETs. We now describe a few cases introduced in Section 3.2. We assume that the Traffic Type for each locator is set to "0" (other values for Traffic Type may be specified in documents that separate the HIP control plane from data plane traffic). Other mobility cases are possible but are left for further study. 1. Host mobility with no multihoming and no rekeying. The mobile host creates a single UPDATE containing a single ESP_INFO with a single LOCATOR_SET parameter. The ESP_INFO contains the current value of the SPI in both the OLD SPI and NEW SPI fields. The LOCATOR_SET contains a single Locator with a "Locator Type" of - "1"; the SPI must match that of the ESP_INFO. The Preferred bit + "1"; the SPI MUST match that of the ESP_INFO. The Preferred bit SHOULD be set and the "Locator Lifetime" is set according to local policy. The UPDATE also contains a SEQ parameter as usual. + This packet is retransmitted as defined in the HIP protocol specification [RFC7401]. The UPDATE should be sent to the peer's preferred IP address with an IP source address corresponding to the address in the LOCATOR_SET parameter. 2. Host mobility with no multihoming but with rekeying. The mobile host creates a single UPDATE containing a single ESP_INFO with a single LOCATOR_SET parameter (with a single address). The ESP_INFO contains the current value of the SPI in the OLD SPI and the new value of the SPI in the NEW SPI, and a KEYMAT Index as @@ -862,74 +904,84 @@ the address in the LOCATOR_SET parameter. 2. Host mobility with no multihoming but with rekeying. The mobile host creates a single UPDATE containing a single ESP_INFO with a single LOCATOR_SET parameter (with a single address). The ESP_INFO contains the current value of the SPI in the OLD SPI and the new value of the SPI in the NEW SPI, and a KEYMAT Index as selected by local policy. Optionally, the host may choose to initiate a Diffie Hellman rekey by including a DIFFIE_HELLMAN parameter. The LOCATOR_SET contains a single Locator with - "Locator Type" of "1"; the SPI must match that of the NEW SPI in + "Locator Type" of "1"; the SPI MUST match that of the NEW SPI in the ESP_INFO. Otherwise, the steps are identical to the case in which no rekeying is initiated. 5.3. Handling Received LOCATOR_SETs A host SHOULD be prepared to receive a single LOCATOR_SET parameter in a HIP UPDATE packet. Reception of multiple LOCATOR_SET parameters in a single packet, or in HIP packets other than UPDATE, is outside of the scope of this specification. + Because a host sending the LOCATOR_SET may send the same parameter in + different UPDATE messages to different destination addresses, + including possibly the rendezvous server of the host, the host + receiving the LOCATOR_SET MUST be prepared to handle the possibility + of duplicate LOCATOR_SETs sent to more than one of the host's + addresses. As a result, the host MUST detect and avoid reprocessing + a LOCATOR_SET parameter that is redundant with a LOCATOR_SET + parameter that has been recently received and processed. + This document describes sending both ESP_INFO and LOCATOR_SET parameters in an UPDATE. The ESP_INFO parameter is included when there is a need to rekey or key a new SPI, and is otherwise included - for the possible benefit of HIP-aware middleboxes. The LOCATOR_SET - parameter contains a complete listing of the locators that the host - wishes to make or keep active for the HIP association. + for the possible benefit of HIP-aware NATs and firewalls. The + LOCATOR_SET parameter contains a complete listing of the locators + that the host wishes to make or keep active for the HIP association. In general, the processing of a LOCATOR_SET depends upon the packet type in which it is included. Here, we describe only the case in which ESP_INFO is present and a single LOCATOR_SET and ESP_INFO are sent in an UPDATE message; other cases are for further study. The steps below cover each of the cases described in Section 5.2. The processing of ESP_INFO and LOCATOR_SET parameters is intended to be modular and support future generalization to the inclusion of multiple ESP_INFO and/or multiple LOCATOR_SET parameters. A host SHOULD first process the ESP_INFO before the LOCATOR_SET, since the ESP_INFO may contain a new SPI value mapped to an existing SPI, while a Type "1" locator will only contain a reference to the new SPI. When a host receives a validated HIP UPDATE with a LOCATOR_SET and ESP_INFO parameter, it processes the ESP_INFO as follows. The ESP_INFO parameter indicates whether an SA is being rekeyed, created, - deprecated, or just identified for the benefit of middleboxes. The - host examines the OLD SPI and NEW SPI values in the ESP_INFO - parameter: + deprecated, or just identified for the benefit of HIP-aware NATs and + firewalls. The host examines the OLD SPI and NEW SPI values in the + ESP_INFO parameter: 1. (no rekeying) If the OLD SPI is equal to the NEW SPI and both correspond to an existing SPI, the ESP_INFO is gratuitous - (provided for middleboxes) and no rekeying is necessary. + (provided for HIP-aware NATs and firewalls) and no rekeying is + necessary. 2. (rekeying) If the OLD SPI indicates an existing SPI and the NEW SPI is a different non-zero value, the existing SA is being rekeyed and the host follows HIP ESP rekeying procedures by creating a new outbound SA with an SPI corresponding to the NEW SPI, with no addresses bound to this SPI. Note that locators in the LOCATOR_SET parameter will reference this new SPI instead of the old SPI. 3. (new SA) If the OLD SPI value is zero and the NEW SPI is a new non-zero value, then a new SA is being requested by the peer. This case is also treated like a rekeying event; the receiving - host must create a new SA and respond with an UPDATE ACK. + host MUST create a new SA and respond with an UPDATE ACK. 4. (deprecating the SA) If the OLD SPI indicates an existing SPI and the NEW SPI is zero, the SA is being deprecated and all locators uniquely bound to the SPI are put into the DEPRECATED state. If none of the above cases apply, a protocol error has occurred and the processing of the UPDATE is stopped. Next, the locators in the LOCATOR_SET parameter are processed. For each locator listed in the LOCATOR_SET parameter, check that the @@ -976,21 +1028,23 @@ LOCATOR_SET. 5.4. Verifying Address Reachability A host MUST verify the reachability of an UNVERIFIED address. The status of a newly learned address MUST initially be set to UNVERIFIED unless the new address is advertised in a R1 packet as a new Preferred locator. A host MAY also want to verify the reachability of an ACTIVE address again after some time, in which case it would set the status of the address to UNVERIFIED and reinitiate address - verification. + verification. A typical verification that is protected by + retransmission timers is to include an ECHO REQUEST within an UPDATE + sent to the new address. A host typically starts the address-verification procedure by sending a nonce to the new address. A host MAY choose from different message exchanges or different nonce values so long as it establishes that the peer has received and replied to the nonce at the new address. For example, when the host is changing its SPI and sending an ESP_INFO to the peer, the NEW SPI value SHOULD be random and the random value MAY be copied into an ECHO_REQUEST sent in the rekeying UPDATE. However, if the host is not changing its SPI, it MAY still use the ECHO_REQUEST parameter for verification but with some other @@ -999,27 +1053,32 @@ In some cases, it MAY be sufficient to use the arrival of data on a newly advertised SA as implicit address reachability verification as depicted in Figure 7, instead of waiting for the confirmation via a HIP packet. In this case, a host advertising a new SPI as part of its address reachability check SHOULD be prepared to receive traffic on the new SA. Mobile host Peer host + UPDATE(ESP_INFO, LOCATOR_SET, ...) + ----------------------------------> + prepare incoming SA - NEW SPI in ESP_INFO (UPDATE) + UPDATE(ESP_INFO, ...) with new SPI <----------------------------------- switch to new outgoing SA data on new SA -----------------------------------> mark address ACTIVE + UPDATE(ACK, ECHO_RESPONSE) later arrives + -----------------------------------> Figure 7: Address Activation Via Use of a New SA When address verification is in progress for a new Preferred locator, the host SHOULD select a different locator listed as ACTIVE, if one such locator is available, to continue communications until address verification completes. Alternatively, the host MAY use the new Preferred locator while in UNVERIFIED status to the extent Credit- Based Authorization permits. Credit-Based Authorization is explained in Section 5.6. Once address verification succeeds, the status of @@ -1059,21 +1118,21 @@ 4. If the new Preferred locator has DEPRECATED status and there is at least one non-deprecated address, the host selects one of the non-deprecated addresses as a new Preferred locator and continues. If the selected address is UNVERIFIED, the address verification procedure described above will apply. 5.6. Credit-Based Authorization To prevent redirection-based flooding attacks, the use of a Credit- Based Authorization (CBA) approach MUST be used when a host sends - data to an UNVERIFIED locator. The following algorithm meets the + data to an UNVERIFIED locator. The following algorithm addresses the security considerations for prevention of amplification and time- shifting attacks. Other forms of credit aging, and other values for the CreditAgingFactor and CreditAgingInterval parameters in particular, are for further study, and so are the advanced CBA techniques specified in [CBA-MIPv6]. 5.6.1. Handling Payload Packets A host maintains a "credit counter" for each of its peers. Whenever a packet arrives from a peer, the host SHOULD increase that peer's @@ -1177,40 +1236,42 @@ The HIP mobility mechanism provides a secure means of updating a host's IP address via HIP UPDATE packets. Upon receipt, a HIP host cryptographically verifies the sender of an UPDATE, so forging or replaying a HIP UPDATE packet is very difficult (see [RFC7401]). Therefore, security issues reside in other attack domains. The two we consider are malicious redirection of legitimate connections as well as redirection-based flooding attacks using this protocol. This can be broken down into the following: - Impersonation attacks + 1) Impersonation attacks - direct conversation with the misled victim - man-in-the-middle attack - DoS attacks + 2) DoS attacks - flooding attacks (== bandwidth-exhaustion attacks) * tool 1: direct flooding * tool 2: flooding by botnets * tool 3: redirection-based flooding - memory-exhaustion attacks - computational-exhaustion attacks + 3) Privacy concerns + We consider these in more detail in the following sections. In Section 6.1 and Section 6.2, we assume that all users are using HIP. In Section 6.3 we consider the security ramifications when we have both HIP and non-HIP hosts. 6.1. Impersonation Attacks An attacker wishing to impersonate another host will try to mislead its victim into directly communicating with them, or carry out a man- @@ -1251,22 +1312,22 @@ 6.2.1. Flooding Attacks The purpose of a denial-of-service attack is to exhaust some resource of the victim such that the victim ceases to operate correctly. A denial-of-service attack can aim at the victim's network attachment (flooding attack), its memory, or its processing capacity. In a flooding attack, the attacker causes an excessive number of bogus or unwanted packets to be sent to the victim, which fills their available bandwidth. Note that the victim does not necessarily need - to be a node; it can also be an entire network. The attack basically - functions the same way in either case. + to be a node; it can also be an entire network. The attack functions + the same way in either case. An effective DoS strategy is distributed denial of service (DDoS). Here, the attacker conventionally distributes some viral software to as many nodes as possible. Under the control of the attacker, the infected nodes (e.g. nodes in a botnet), jointly send packets to the victim. With such an 'army', an attacker can take down even very high bandwidth networks/victims. With the ability to redirect connections, an attacker could realize a DDoS attack without having to distribute viral code. Here, the @@ -1332,50 +1393,129 @@ 4. A HIP host attempts to steal a non-HIP host's session. A HIP host could spoof the non-HIP host's IP address during the base exchange or set the non-HIP host's IP address as its preferred address via an UPDATE. Other possibilities exist, but a solution is to prevent the local redirection of sessions that were previously using an unverified address, but outside of the existing HIP context, into the HIP SAs until the address change can be verified. +6.4. Privacy Concerns + + The exposure of a host's IP addresses through HIP mobility extensions + may raise privacy concerns. The administrator of a host may be + trying to hide its location in some context through the use of a VPN + or other virtual interfaces. Similar privacy issues also arise in + other frameworks such as WebRTC and are not specific to HIP. + Implementations SHOULD provide a mechanism to allow the host + administrator to block the exposure of selected addresses or address + ranges. While this issue may be more relevant in a host multihoming + scenario in which multiple IP addresses might be exposed + ([I-D.ietf-hip-multihoming]), it is worth noting also here that + mobility events might cause an implementation to try to inadvertently + use a locator that the adminstrator would rather avoid exposing to + the peer host. + 7. IANA Considerations - RFC5206, obsoleted by this document, specified an allocation for a - LOCATOR parameter in the HIP Parameters registry. This document - requests IANA to rename the parameter to 'LOCATOR_SET' and to update - the reference from RFC5206 to this specification. + [RFC5206], obsoleted by this document, specified an allocation for a + LOCATOR parameter in the HIP Parameters registry, with a type value + of 193. This document requests IANA to rename the parameter to + 'LOCATOR_SET' and to update the reference from [RFC5206] to this + specification. - RFC5206, obsoleted by this document, specified an allocation a - LOCATOR_TYPE_UNSUPPORTED type in the Notify Message Type registry. - This document requests IANA to update the reference from RFC5206 to - this specification. + [RFC5206], obsoleted by this document, specified an allocation a + LOCATOR_TYPE_UNSUPPORTED type in the Notify Message Type registry, + with a type value of 46. This document requests IANA to update the + reference from [RFC5206] to this specification. -8. Authors and Acknowledgments +8. Differences from RFC 5206 + + This section summarizes the technical changes made from [RFC5206]. + This section is informational, intended to help implementors of the + previous protocol version. If any text in this section contradicts + text in other portions of this specification, the text found outside + of this section should be considered normative. + + This document specifies extensions to the HIP Version 2 protocol, + while [RFC5206] specifies extensions to the HIP Version 1 protocol. + [RFC7401] documents the differences between these two protocol + versions. + + [RFC5206] included procedures for both HIP host mobility and basic + host multihoming. In this document, only host mobility procedures + are included; host multihoming procedures are now specified in + [I-D.ietf-hip-multihoming]. In particular, multihoming-related + procedures related to the exposure of multiple locators in the base + exchange packets, the transmission, reception, and processing of + multiple locators in a single UPDATE packet, handovers across IP + address families, and other multihoming-related specification has + been removed. + + The following additional changes have been made: + + o The LOCATOR parameter in [RFC5206] has been renamed to + LOCATOR_SET. + + o Specification text regarding the handling of mobility when both + hosts change IP addresses at nearly the same time (a 'double-jump' + mobility scenario) has been added. + + o Specification text regarding the mobility event in which the host + briefly has an active new locator and old locator at the same time + (a 'make-before-break' mobility scenario) has been added. + + o Specification text has been added to note that a host may add the + source IP address of a received HIP packet as a candidate locator + for the peer even if it is not listed in the peer's LOCATOR_SET, + but that it should prefer locators explicitly listed in the + LOCATOR_SET. + + o This document clarifies that the HOST_ID parameter may be included + in UPDATE messages containing LOCATOR_SET parameters, for the + possible benefit of HIP-aware firewalls. + + o The previous specification mentioned that it may be possible to + include multiple LOCATOR_SET and ESP_INFO parameters in an UPDATE. + This document only specifies the case of a single LOCATOR_SET and + ESP_INFO parameter in an UPDATE. + + o The previous specification mentioned that it may be possible to + send LOCATOR_SET parameters in packets other than the UPDATE. + This document only specifies the use of the UPDATE packet. + + o This document describes a simple heuristic for setting the credit + value for Credit-Based Authorization. + + o This specification mandates that a host must be able to receive + and avoid reprocessing redundant LOCATOR_SET parameters that may + have been sent in parallel to multiple addresses of the host. + +9. Authors and Acknowledgments Pekka Nikander and Jari Arkko originated this document, and Christian Vogt and Thomas Henderson (editor) later joined as co-authors. Greg Perkins contributed the initial draft of the security section. Petri Jokela was a co-author of the initial individual submission. Credit-Based Authorization was originally introduced in [SIMPLE-CBA], and portions of this document have been adopted from that earlier draft. The authors thank Jeff Ahrenholz, Baris Boyvat, Rene Hummen, Miika Komu, Mika Kousa, Jan Melen, and Samu Varjonen for improvements to the document. -9. References +10. References -9.1. Normative references +10.1. Normative references [I-D.ietf-hip-rfc5203-bis] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Registration Extension", draft-ietf-hip-rfc5203-bis-11 (work in progress), August 2016. [I-D.ietf-hip-rfc5204-bis] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Rendezvous Extension", draft-ietf-hip-rfc5204-bis-08 (work in progress), August 2016. @@ -1393,36 +1533,46 @@ Henderson, "Host Identity Protocol Version 2 (HIPv2)", RFC 7401, DOI 10.17487/RFC7401, April 2015, . [RFC7402] Jokela, P., Moskowitz, R., and J. Melen, "Using the Encapsulating Security Payload (ESP) Transport Format with the Host Identity Protocol (HIP)", RFC 7402, DOI 10.17487/RFC7402, April 2015, . -9.2. Informative references +10.2. Informative references [CBA-MIPv6] Vogt, C. and J. Arkko, "Credit-Based Authorization for Mobile IPv6 Early Binding Updates", February 2005. [I-D.ietf-hip-multihoming] Henderson, T., Vogt, C., and J. Arkko, "Host Multihoming with the Host Identity Protocol", draft-ietf-hip- - multihoming-10 (work in progress), July 2016. + multihoming-11 (work in progress), September 2016. [RFC4225] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E. Nordmark, "Mobile IP Version 6 Route Optimization Security Design Background", RFC 4225, DOI 10.17487/RFC4225, December 2005, . + [RFC5206] Nikander, P., Henderson, T., Ed., Vogt, C., and J. Arkko, + "End-Host Mobility and Multihoming with the Host Identity + Protocol", RFC 5206, DOI 10.17487/RFC5206, April 2008, + . + + [RFC5207] Stiemerling, M., Quittek, J., and L. Eggert, "NAT and + Firewall Traversal Issues of Host Identity Protocol (HIP) + Communication", RFC 5207, DOI 10.17487/RFC5207, April + 2008, . + [SIMPLE-CBA] Vogt, C. and J. Arkko, "Credit-Based Authorization for Concurrent Reachability Verification", February 2006. Appendix A. Document Revision History To be removed upon publication +----------+--------------------------------------------------------+ | Revision | Comments | @@ -1476,29 +1626,49 @@ | | parameters in packets other than UPDATE (per previous | | | mailing list discussion) | | | | | draft-11 | Editorial improvements from WGLC | | | | | draft-12 | Update author affiliations and IPR boilerplate to | | | trust200902 | | | | | draft-13 | Editorial improvements to IANA considerations section. | | | | - | | Moved citation of [SIMPLE-CBA] to Section 8 and | + | | Moved citation of [SIMPLE-CBA] to Section 9 and | | | slightly updated text for redirection-based flooding | | | attacks in the Security Considerations section. | | | | | | Editorial improvements based on last call comments. | + | | | + | draft-14 | Added section to summarize changes from RFC5206. | + | | | + | | Replace references to 'middleboxes' with more specific | + | | 'NATs and firewalls'. | + | | | + | | Describe a simple heuristic for setting the credit | + | | value based on sending rate and RTT. | + | | | + | | Add subsection about privacy concerns of locator | + | | exposure to the Security Considerations section. | + | | | + | | Clarify that a host must be able to receive and avoid | + | | reprocessing redundant LOCATOR_SET parameters that may | + | | have been sent in parallel to multiple addresses of | + | | the host. | + | | | + | | Clarify that multicast or broadcast addresses must not | + | | be announced in a LOCATOR_SET. | + | | | + | | Editorial improvements based on last call comments. | +----------+--------------------------------------------------------+ Authors' Addresses - Thomas R. Henderson (editor) University of Washington Campus Box 352500 Seattle, WA USA EMail: tomhend@u.washington.edu Christian Vogt Independent