DHC J. Brzozowski Internet-Draft Comcast Cable Intended status: Standards Track K. Kinnear Expires:
September 3,June 21, 2007 B. Volz S. Zeng Cisco Systems, Inc. March 2, 2007December 18, 2006 DHCPv6 Leasequery <draft-ietf-dhc-dhcpv6-leasequery-00.txt><draft-ietf-dhc-dhcvp6-leasequery-01.txt> Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 3,June 21, 2007. Copyright Notice Copyright (C) The IETF Trust (2007).Internet Society (2006). Abstract This document specifies leasequery for the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) which can be used as a means to obtain lease information about DHCPv6 clients from a DHCPv6 server. This document specifies the scope of data that can be retrieved as well as both DHCPv6 leasequery requestor and server behavior. This document extends DHCPv6. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4 3.1. On-Demand Query . . . . . . . . . . . . . . . . . . . . . 4 3.2. Anticipatory Query . . . . . . . . . . . . . . . . . . . . 4 3.3. Query Types . . . . . . . . . . . . . . . . . . . . . . . 5 4. Protocol Details . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Message and Option Definitions . . . . . . . . . . . . . . 5 4.1.1. Messages . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.2. Options . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.3. Status Codes . . . . . . . . . . . . . . . . . . . . . 10 4.1.4. Transmission and Retransmission Parameters . . . . . . 11 4.2. Message Validation . . . . . . . . . . . . . . . . . . . . 11 4.2.1. LEASEQUERY . . . . . . . . . . . . . . . . . . . . . . 11 4.2.2. LEASEQUERY-REPLY . . . . . . . . . . . . . . . . . . . 11 4.3. DHCPv6 Leasequery Requestor Behavior . . . . . . . . . . . 12 4.3.1. Creation of LEASEQUERY . . . . . . . . . . . . . . . . 12 4.3.2. Transmission of LEASEQUERY . . . . . . . . . . . . . . 12 4.3.3. Receipt of LEASEQUERY-REPLY . . . . . . . . . . . . . 13 4.3.4. Handling DHCPv6 Client Data from Multiple Sources . . 13 4.4. DHCPv6 Leasequery Server Behavior . . . . . . . . . . . . 14 4.4.1. Receipt of LEASEQUERY Messages . . . . . . . . . . . . 14 4.4.2. Constructing the Client's OPTION_CLIENT_DATA . . . . . 15 4.4.3. Transmission of LEASEQUERY-REPLY Messages . . . . . . 16 5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 8. Modification History . . . . . . . . . . . . . . . . . . . . . 18 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 9.1. Normative References . . . . . . . . . . . . . . . . . . . 19 9.2. Informative References . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 2019 Intellectual Property and Copyright Statements . . . . . . . . . . 21 1. Introduction The DHCPv6  protocol specifies a mechanism for the assignment of both IPv6 address and configuration information to IPv6 nodes. IPv6 Prefix Options for DHCPv6  specifies a mechanism for the automated delegation of IPv6 prefixes and related options. Similar to DHCPv4 ,, DHCPv6 servers maintain authoritative information related to its operations including but not limited to lease information for IPv6 addresses and delegated prefixes. The requirement exists in various types of IPv6 deployments, particularly those of a broadband variety, to leverage DHCPv6  for retrieving data related to the operation of DHCPv6 servers programmatically. In particular it is desirable to be able to extract lease information about IPv6 addresses and delegated prefixes assigned using DHCPv6  . Specific examples where this information has illustrated value are in broadband networks to facilitate access control by edge devices. This capability to programitcally extract lease data from the DHCPv6 server is called leasequery. Existing specifications, such as  are leveraged as a basis for extending the DHCPv6 protocol to support leasequery. The motivations and justifications identified in  also generally apply to this specification. Furthermore, advancements in DHCPv6  are expanded upon to specify additional means by which IPv6 address and delegated prefix lease data can be retrieved through DHCPv6 leasequery. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in . DHCPv6 terminology is defined in . Terminology specific to DHCPv6 leasequery can be found below: client(s) The nodes that have one or more bindings with a DHCPv6 server. This does not refer to the node issuing the LEASEQUERY unless it itself has one or more bindings with a DHCPv6 server. requestor The node that sends LEASEQUERY messages to one or more servers to retrieve information on the bindings for a client. 3. Protocol Overview The focus of this document is to extend the DHCPv6 protocol to allow processes and devices that wish to access information from a DHCPv6 server to do so in a lightweight and convenient manner. It is especially appropriate for processes and devices that already interpret DHCPv6 messages. The LEASEQUERY message is a query message only and does not affect the state of the IPv6 address or prefix, or the binding information associated with it. One important motivating example is that the LEASEQUERY message allows access concentrators to query DHCP servers to obtain location information of broadband access network devices. The leasequery capability described in this document parallels the DHCPv4 leasequery capability documented in . As such, it shares many of the basic motivations, design goals and constraints as the capability described in Section 4 of . 3.1. On-Demand Query The on-demand leasequery capability allows requesting just the information necessary to satisfy an immediate need. If the requestor is an access concentrator, then the immediate need will typically be that it has received an IPv6 packet and it needs to refresh its information concerning the DHCPv6 client to which that an IPv6 address is currently leased. In this case, the request will be by Address. This fits clearly into the single request/response cycle common to other DHCPv6 message exchanges. However, this approach has limitations when used with prefix delegation  as no traffic may arrive because the access concentrator is unable to inject the appropriate routing information into the routing infrastructure, such as after a reboot. This approach does work if the access concentrator is configured to inject routing information for a prefix which aggregates potentially delegated prefixes. Or, if the access concentrator and requesting router use a routing protocol; as then the requesting router can trigger the access concentrator to request information from a DHCPv6 server and inject appropriate routing information into the routing infrastructure. 3.2. Anticipatory Query A second approach for requesting information from a DHCPv6 server would be to use a leasequery-like capability to rebuild an internal data store containing information available from a DHCPv6 server. The rebuilding of the data store in this approach can take place as soon as possible after the need to rebuild it is discovered (such as on booting), and doesn't wait on the receipt of specific packets to trigger a piecemeal database update (as is the case for on-demand leasequery). This approach would also remove the limitation discussed above for prefix delegation. This anticipatory query is not specified in this document and is an area of future work. 3.3. Query Types Leasquery provides for the following queries: Query by IPv6 address - This query allows a requestor to request from a server the bindings for a client that either is bound to the address or has been delegated the prefix that contains the address. Query by Client Identifier (DUID) - This query allows a requestor to request from a server the bindings for a specific client on a specific link or a list of the links on which the client has one or more bindings. 4. Protocol Details 4.1. Message and Option Definitions 4.1.1. Messages The LEASEQUERY and LEASEQUERY-REPLY messages use the Client/Server message formats described in , section 6. Two new message codes are defined: LEASEQUERY (TBD) - A requestor sends a LEASEQUERY message to any available server to obtain information on a client's or clients' leases. The options in an OPTION_LQ_QUERY determine the query. LEASEQUERY-REPLY (TBD) - A server sends a LEASEQUERY-REPLY message containing client data in response to a LEASEQUERY message. 4.1.2. Options 22.214.171.124. Query Option The Leasequery Query option is used only in a LEASEQUERY message and identifies the query being performed. The option includes the query type, link-address (or 0::0), and option(s) to provide data needed for the query. The format of the Query option is shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_LQ_QUERY | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | query-type | | +-+-+-+-+-+-+-+-+ | | | | link-address | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . +-+-+-+-+-+-+-+-+ . . query-options . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_LQ_QUERY (TBD) option-len 17 + length of query-options field. link-address A global address that will be used by the server to identify the link to which the query applies, or 0::0 if unspecified. query-type the query requested (see below). query-options the options related to the query. The query-type and required query-options are: QUERY_BY_ADDRESS (1) - The query-options MUST contain an OPTION_IAADDR option . The link-address field, if not 0::0, specifies an address for the link on which the client is located if the address in the OPTION_IAADDR option is of insufficient scope. Only the information for the client that has a lease for the specified address or was delegated a prefix that contains the specified address is returned (if available). QUERY_BY_CLIENTID (2) - The query-options MUST contain an OPTION_CLIENTID option . The link-address field, if not 0::0, specifies an address for the link on which the client is located. If the link-address field is 0::0, the server SHOULD search all of its links of the client. The query-options MAY also include an OPTION_ORO option  to indicate the options for each client that the requestor would like the server to return. Note that this OPTION_ORO is distinct and separate from an OPTION_ORO that may be in the requestor's LEASEQUERY message. If a server receives an OPTION_LQ_QUERY with a query-type it does not support, the server SHOULD return an UnknownQueryType status-code. If a server receives a supported query-type but the query-options is missing a required option, the server SHOULD return a MalformedQuery status-code. 126.96.36.199. Client Data Option The Client Data option is used to encapsulate the data for a single client on a single link in a LEASEQUERY-REPLY message. The format of the Client Data option is shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_CLIENT_DATA | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . client-options . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_CLIENT_DATA (TBD) option-len length, in octets, of the encapsulated client- options field. client-options the options associated with this client. The encapsulated client-options include the OPTION_CLIENTID, OPTION_IAADDR, OPTION_IAPREFIX, and OPTION_CLT_TIME options and other options specific to the client and requested by the requestor in the OPTION_ORO in the OPTION_LQ_QUERY's query-options. The server MUST return all of the client's statefully assigned addresses and delegated prefixes, with a non-zero valid lifetime, on the link. 188.8.131.52. Client Last Transaction Time Option The Client Last Transaction Time option is encapsulated in an OPTION_CLIENT_DATA and identifies how long ago the server last communicated with the client, in seconds. The format of the Client Last Transaction Time option is shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_CLT_TIME | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | client-last-transaction-time | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_CLT_TIME (TBD) option-len 4 client-last-transaction-time the number of seconds since the server last communicated with the client (on that link). The client-last-transaction-time is a positive value and reflects the number of seconds since the server last communicated with the client (on that link). 184.108.40.206. Relay Data The Relay Data option is used only in a LEASEQUERY-REPLY message and provides the relay agent information used when the client last communicated with the server. The format of the Client Links option is shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_LQ_RELAY_DATA | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | peer-address (IPv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | DHCP-relay-message | . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_LQ_RELAY_DATA (TBD) option-len 16 + length of DHCP-relay-message. peer-address The address of the relay agent from which the relayed message was received by the server. DHCP-relay-message The last complete relayed message excluding the client's message OPTION_RELAY_MSG received by the server. This option is used by the server to return full relay agent information for a client. It MUST NOT be returned if the server does not have such information, either because the client last communicated directly (without relay agent) with the server or if the server does not retained such information. If returned, the DHCP-relay-message MUST contain a valid (perhaps multi-hop) RELAY-FORW message as most recently received by the server for the client. However, the (inner most) OPTION_RELAY_MSG option containing the client's message MUST have been removed. This option SHOULD only be returned if requested by the OPTION_ORO of the OPTION_LQ_QUERY. 220.127.116.11. Client Link Option The Client Link option is used only in a LEASEQUERY-REPLY message and identifies the links on which the client has one or more bindings. It is used in reply to a query when no link-address was specified and the client is found to be on more than one link. The format of the Client Link option is shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_LQ_CLIENT_LINK | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | link-address (IPv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | link-address (IPv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_LQ_CLIENT_LINKS (TBD) option-len Length of the list of links in octets; must be a multiple of 16. link-address A global address used by the server to identify the link on which the client is located. A server may respond to a query by client-id, where the 0::0 link- address was specified, with this option if the client is found to be on multiple links. The requestor may then repeat the query once for each link-address returned in the list, specifying the returned link- address. If the client is on a single link, the server SHOULD return the client's data in an OPTION_CLIENT_DATA option. 4.1.3. Status Codes The following new status codes are defined: UnknownQueryType (TBD) - The query-type is unknown to or not supported by the server. MalformedQuery (TBD) - The query is not valid, for example a required query-option is missing from the OPTION_LQ_QUERY. NotConfigured (TBD) - The server does not have the target address or link in its configuration. NotAllowed (TBD) - The server does not allow the requestor to issue this LEASEQUERY. 4.1.4. Transmission and Retransmission Parameters This section presents a table of values used to describe the message transmission behavior for leasequery. Parameter Default Description ---------------------------------- LQ_TIMEOUT 1 sec Initial LEASEQUERY timeout LQ_MAX_RT 10 secs Max LEASEQUERY timeout value LQ_MAX_RC 5 Max LEASEQUERY retry attempts 4.2. Message Validation 4.2.1. LEASEQUERY Requestors and clients MUST discard any received LEASEQUERY messages. Servers MUST discard any received LEASEQUERY messages that meet any of the following conditions: o the message does not include an OPTION_CLIENTID option. o the message includes an OPTION_SERVERID option but the contents of the OPTION_SERVERID option does not match the server's identifier. o the message does not include an OPTION_LQ_QUERY option. 4.2.2. LEASEQUERY-REPLY Requestors MUST discard any received LEASEQUERY-REPLY messages that meet any of the following conditions: o the message does not include an OPTION_SERVERID option. o the message does not include an OPTION_CLIENTID option or the contents of the OPTION_CLIENTID option do not match the DUID of the requestor. o the "transaction-id" field in the message does not match the value used in the original message. Servers and Relay Agents (on the server port, 547 ) MUST discard any received LEASEQUERY-REPLY messages. 4.3. DHCPv6 Leasequery Requestor Behavior This section describes how a requestor initiates lease data retrieval from DHCPv6 servers. 4.3.1. Creation of LEASEQUERY The requestor sets the "msg-type" field to LEASEQUERY. The requestor generates a transaction ID and inserts this value in the "transaction-id" field. The requestor MUST include an OPTION_CLIENTID option to identify itself to the server. The requestor MUST include an OPTION_LQ_QUERY option and set the query-type, link-address, and query-options as appropriate to the query-type (Section 18.104.22.168). The requestor SHOULD include an OPTION_SERVERID if it is not unicasting the LEASEQUERY yet only wants a response from a specific server. 4.3.2. Transmission of LEASEQUERY The requestor MAY be configured to use a list of destination addresses, which MAY include unicast addresses, the All_DHCP_Servers multicast address, or other addresses selected by the network administrator. If the requestor has not been explicitly configured, it MAY use the All_DHCP_Servers multicast address as the default. The requestor SHOULD send LEASEQUERY to one or more DHCPv6 servers which are known to possess authoritative information concerning the query target. In the absence of information concerning which DHCPv6 servers might possess authoritative information on the query target, the requestor SHOULD send LEASEQUERY to all DHCPv6 servers that the requestor knows about or is configured with. For example, the requestor MAY send LEASEQUERY to the All_DHCP_Servers multicast address. The requestor transmits LEASEQUERY messages according to section 14 of , using the following parameters: IRT LQ_TIMEOUT MRT LQ_MAX_RT MRC LQ_MAX_RC MRD 0 If the message exchange fails, the requestor takes an action based on the requestor's local policy. Examples of actions the requestor might take include: o Select another server from a list of servers known to the requestor. o Send to multiple servers by multicasting to the All_DHCP_Servers address. o Terminate the leasequery. 4.3.3. Receipt of LEASEQUERY-REPLY A successful LEASEQUERY-REPLY is one without an OPTION_STATUS_CODE option (or an OPTION_STATUS_CODE option with a success code). There are three varients: 1. If the server has bindings for the requested client, the message includes an OPTION_CLIENT_DATA option and the requestor extracts the client data for the LEASEQUERY-REPLY and updates its binding information database. If the OPTION_CLIENT_DATA contains no OPTION_CLT_TIME, the requestor SHOULD silently discard the OPTION_CLIENT_DATA option. The LEASEQUERY-REPLY SHOULD contain an OPTION_SERVER_RSN option  and the requestor SHOULD only update its binding information database as described in . 2. If the server found bindings for the client on multiple links, the message includes an OPTION_CLIENT_LINK option. The requestor will need to reissue LEASEQUERY messages using each of the returned link-addresses to obtain the client's bindings. 3. If the server has no bindings for the client, neither the OPTION_CLIENT_DATA nor OPTION_CLIENT_LINK option will be present. An unsuccessful LEASEQUERY-REPLY is one that has an OPTION_STATUS_CODE with an error code. Depending on the status code, the requestor may try a different server (such as for NotAllowed, NotConfigured, and UnknownQueryType), try a different or corrected query (such as for UnknownQueryType and MalformedQuery), or terminate the query. 4.3.4. Handling DHCPv6 Client Data from Multiple Sources A requestor may receive lease data on the same client from the same DHCPv6 server in response to different types of LEASEQUERY. If a LEASEQUERY is sent to multiple servers, the requestor may receive from several servers lease data on the same DHCPv6 client. Additionally, if a requestor is an access concentrator, it may receive lease data from other than leasequery exchanges, e.g., . This section describes how the requestor handles multiple lease data sources on the same DHCPv6 client from the same server or different servers. The client data from the different sources may be disjoint or overlapping. The disjoint and overlapping relationship can happen between data from the same server or different servers. If client data from two sources on the same client are of different types or values, then the data are disjoint. An example of data of different types is when a requestor receives an IPv6 address lease from one server and a prefix lease from another server, both assigned to the same client. An example of different values (but the same type) is when a requestor receives two IPv6 address leases from two different servers, both assigned to the same client, but the leases are on two different IPv6 addresses. If the requestor receives disjoint client data from different sources, it SHOULD merge them. If client data from two sources on the same client are of the same type and value, then the data are overlapping. An example of overlapping data is when a requestor receives a lease on the same IPv6 address from two different servers. Overlapping client data are also called conflicting data. The requestor SHOULD use the OPTION_SERVER_RSN  to resolve data conflicts originated from the same server, and SHOULD accept data with the higher server-sequence-number. The requestor SHOULD use the OPTION_CLT_TIME to resolve data conflicts originated from different servers, and SHOULD accept data with most recent OPTION_CLT_TIME. 4.4. DHCPv6 Leasequery Server Behavior A DHCPv6 server sends LEASEQUERY-REPLY messages in response to valid LEASEQUERY messages it receives to return the statefully assigned addresses, delegated prefixes, and other information about that match the query. 4.4.1. Receipt of LEASEQUERY Messages Upon receipt of a valid LEASEQUERY message, the DHCPv6 server locates the requested client, collects data on the client, and constructs and returns a LEASEQUERY-REPLY. A LEASEQUERY message can not be used to assign, release, or otherwise modify bindings or other configuration information. The server constructs a LEASEQUERY-REPLY message by setting the "msg- type" field to LEASEQUERY-REPLY, and copying the transaction ID from the LEASEQUERY message into the transaction-id field. If the query-type in the OPTION_LQ_QUERY option is not a known or supported value, the server adds an OPTION_STATUS_CODE option with the UnknownQueryType status code and sends the LEASEQUERY-REPLY to the requestor. If the query-options do not contain the required options for the query-type, the server adds an OPTION_STATUS_CODE option with the MalformedQuery status code and sends the LEASEQUERY- REPLY to the client. A server may also restrict LEASEQUERY messages, or query-types, to certain requestors. In this case, the server MAY discard the LEASEQUERY message or MAY add an OPTION_STATUS_CODE option with the NotAllowed status code and send the LEASEQUERY-REPLY to the requestor. If the OPTION_LQ_QUERY specified a non-zero link-address, the server MUST use the link-address to find the appropriate link for the client. For a QUERY_BY_ADDRESS, if the 0::0 link-address was specified, the server uses the address from the OPTION_IAADDR option to find the appropriate link for the client. In either of these cases, if the server is unable to find the link, it SHOULD return an OPTION_STATUS_CODE option with the NotConfigured status and send the LEASEQUERY-REPLY to the requestor. For a QUERY_BY_CLIENTID, if a 0::0 link-address was specified, the server MUST search all of its links for the client. If the client is only found on a single link, the server SHOULD return that client's data in an OPTION_CLIENT_DATA option. If the client is found on more than a single link, the server MUST return the list of links in the OPTION_CLIENT_LINK option; the server MUST NOT return any client data. Otherwise, the server uses the data in the OPTION_LQ_QUERY to initiate the query. The result of the query will be zero or one client. This will result in zero or one OPTION_CLIENT_DATA option being added to the LEASEQUERY-REPLY. 4.4.2. Constructing the Client's OPTION_CLIENT_DATA An OPTION_CLIENT_DATA option in a LEASEQUERY-REPLY message MUST minimally contain the following data. 1. OPTION_CLIENTID 2. OPTION_IAADDR 3. OPTION_IAPREFIX 4. OPTION_CLT_TIME Depending on the bindings the client has on a link, either OPTION_IAADDR options, OPTION_IAPREFIX options, or both may be present. The OPTION_CLIENT_DATA SHOULD include options requested in the OPTION_ORO of the OPTION_LQ_QUERY option in the LEASEQUERY message and that are acceptable to return based on the list of "sensitive options", discussed below. DHCPv6 servers SHOULD be configurable with a list of "sensitive options" that must not be returned to the requestor when specified in the OPTION_ORO of the OPTION_LQ_QUERY option in the LEASEQUERY message. Any option on this list MUST NOT be returned to a requestor, even if requested by that requestor. 4.4.3. Transmission of LEASEQUERY-REPLY Messages The server sends the LEASEQUERY-REPLY message as described in the "Transmission of Reply Messages" section of . 5. Security Considerations The senders of LEASEQUERY messages are expected to be within the same security domain as the DHCPv6 server. As such, the security threat to DHCPv6 leasequery is inherently an insider threat. However, this document doesn't prohibit entities in external security domains from sending LEASEQUERY messages to DHCPv6 servers. Regardless of the network configuration, however, the potential attacks by insiders and outsiders are the same. If the requestor is an access concentrator, DHCPv6 leasequery security SHOULD follow security between the relay agent and the DHCPv6 server as described in  Sections 21.1 and 22.11. Requestors are essentially a DHCPv6 client for the purposes of the LEASEQUERY message. Thus, DHCPv6 authentication  is also an appropriate mechanism for securing LEASEQUERY and LEASEQUERY-REPLY messages. Access concentrators are expected to be common leasequery requestors. Access concentrators that use DHCPv6 gleaning (i.e., ),), refreshed with LEASEQUERY messages, will maintain accurate client/binding information. This ensures that the access concentrator can forward data traffic to the intended destination in the broadband access network, can perform IPv6 source address verification of datagrams from the access network, and can encrypt traffic that can only be decrypted by the intended access modem (e.g., [BPI] and ).[BPI+]). Thus, the LEASEQUERY message allows an access concentrator to provide considerably enhanced security. DHCPv6 servers SHOULD prevent exposure of their information (particularly the mapping of hardware address to IPv6 address, which can be an invasion of broadband subscriber privacy) by employing the techniques detailed in , Section 21, "Authentication of DHCP Messages". DHCPv6 servers SHOULD also provide for the ability to restrict the information that they make via leasequery, as described in Section 4.4.2. DHCPv6 servers supporting LEASEQUERY SHOULD ensure that they cannot be successfully attacked by being flooded with large quantities of LEASEQUERY messages in a short time. In some environments, it may be appropriate to configure a DHCPv6 server with the IPv6 source addresses of the relay agents for which it may respond to LEASEQUERY messages, thereby allowing it to respond only to requests from only a handful of relay agents. This does not provide any true security, but may be useful to thwart unsophisticated attacks of various sorts. Replayed messages can represent a DOS attack through exhaustion of processing resources, bogus leasequery requestors can send a lot of LEASEQUERY messages to overwhelm a DHCPv6 server, thus preventing the server from serving legitimate and regular DHCPv6 clients as well as legitimate DHCPv6 leasequery requestors, denying configurations to legitimate DHCPv6 clients as well lease information to legitimate DHCPv6 leasequery requestors. One attack specific to an access concentrator as a requestor is the establishment of a malicious server with the intent of providing incorrect lease or route information to the access concentrator, thwarting source IPv6 address verification and preventing correct routing. The use of the OPTION_SERVER_RSN option  does provide an attacker that also knows the server's DUID the ability to effectively lock out future updates from the real server by supply a large sequence number. 6. IANA Considerations IANA is requested to assign the following new DHCPv6 Message types in the registry maintained in http://www.iana.org/assignments/dhcpv6-parameters: LEASEQUERY LEASEQUERY-REPLY IANA is requested to assign the following new DHCPv6 Option Codes in the registry maintained in http://www.iana.org/assignments/dhcpv6-parameters: OPTION_LQ_QUERY OPTION_CLIENT_DATA OPTION_CLT_TIME OPTION_LQ_RELAY_DATA OPTION_LQ_CLIENT_LINK IANA is requested to assign the following new DHCPv6 Status Codes in the registry maintained in http://www.iana.org/assignments/dhcpv6-parameters: UnknownQueryType MalformedQuery NotConfigured NotAllowed IANA is requested to create a new registry for the OPTION_LQ_QUERY option query-type codes in the registry maintained in http://www.iana.org/assignments/dhcpv6-parameters with the following initial assignments: QUERY_BY_ADDRESS 1 QUERY_BY_CLIENTID 2 7. Acknowledgements Thanks to Ralph Droms, Richard Johnson, Josh Littlefield, Hemant Singh, Pak Siripunkaw, Markus Stenberg, and Ole Troan for their input, ideas, and review during the production of this document. 8. Modification History If this section is present in the document when it is submitted for publication, the RFC Editor is requested to remove it. This document was previously accidentally published under an incorrect name, draft-ietf-dhc-dhcvp6-leasequery-00 and draft-ietf-dhc-dhcvp6-leasequery-01. The changes between the -00 and -01 version were:Changes in rev -01: o Added the ability to query by client identifier (DUID), QUERY_BY_CLIENTID. To avoid potentially large messages for clients that are multihomed or mobile, a new option, OPTION_LQ_CLIENT_LINK, to return the list of the links the client is on was added. The requestor then needs to re-query for each link, specifying the link-address in the query to get the client's data. o Added the ability to return full relay agent details via the OPTION_LQ_RELAY_DATA option. o And, other minor changes to accommodate the above. The changes between draft-ietf-dhc-dhcvp6-leasequery-01 and this version with the corrected document name were: o Fixed draft name (had dhcvp6 instead of dhcpv6). o Removed reference to SRSN I-D and associated text. SRSN is only needed if and when RAAN moves forward (in or close to its current form). o Added  and  references that were missing (referenced in Security Considerations section). o Updated RAAN I-D reference to current version. o Updated boilerplate and copyright year.9. References 9.1. Normative References  Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003.  Woundy, R. and K. Kinnear, "Dynamic Host Configuration Protocol (DHCP) Leasequery", RFC 4388, February 2006.  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003.  Volz, B. and R. Droms, "DHCPv6 Server Reply Sequence Number Option (draft-volz-dhc-dhcpv6-srsn-option-*)", August 2006. 9.2. Informative References  Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997.  Droms, R., "DHCPv6Volz, B., and O. Troan, "DHCP Relay Agent Assignment Notification (RAAN) Option", draft-ietf-dhc-dhcpv6-agentopt-delegate-02 (work in progress), November 2006.  SCTE Data Standards Subcommittee, "Data-Over-Cable Service Interface Specifications: DOCSIS 1.0 Baseline Privacy Interface Specification SCTE 22-2 2002", 2002, available at http://www.scte.org/standards/.  CableLab, "Data-Over-Cable Service Interface Specifications: Baseline Privacy Plus Interface Specification CM-SP-BPI+_I12- 050812",Option (draft-ietf-dhc-dhcpv6-agentopt-delegate-*)", August 2005, available at http://www.cablemodem.com/.2006. Authors' Addresses John Jason Brzozowski Comcast Cable 1800 Bishops Gate Boulevard Mt. Laurel, NJ 08054 USA Phone: +1 856 324 2671 Email: email@example.com Kim Kinnear Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0000 Email: firstname.lastname@example.org Bernard Volz Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0000 Email: email@example.com Shengyou Zeng Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0000 Email: firstname.lastname@example.org Full Copyright Statement Copyright (C) The IETF Trust (2007).Internet Society (2006). 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