--- 1/draft-ietf-ipngwg-icmp-v3-03.txt 2006-02-04 23:38:59.000000000 +0100 +++ 2/draft-ietf-ipngwg-icmp-v3-04.txt 2006-02-04 23:38:59.000000000 +0100 @@ -1,75 +1,81 @@ Internet Draft A. Conta, Transwitch IPv6 Working Group S. Deering, Cisco Systems -February 15, 2004 +1 June 2004 Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification - + Status of this Memo - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. + By submitting this Internet-Draft, I certify that any applicable + patent or other IPR claims of which I am aware have been disclosed, + and any of which I become aware will be disclosed, in accordance with + RFC 3668. 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 August 20, 2004. + This internet draft will expire on December 4, 2004. Abstract This document describes the format of a set of control messages used in ICMPv6 (Internet Control Message Protocol). ICMPv6 is the Internet Control Message Protocol for Internet Protocol version 6 (IPv6). Table of Contents - 1. Introduction........................................3 - 2. ICMPv6 (ICMP for IPv6)..............................3 - 2.1 Message General Format.......................3 - 2.2 Message Source Address Determination.........5 - 2.3 Message Checksum Calculation.................6 - 2.4 Message Processing Rules.....................6 - 3. ICMPv6 Error Messages...............................9 - 3.1 Destination Unreachable Message..............9 - 3.2 Packet Too Big Message......................11 - 3.3 Time Exceeded Message.......................12 - 3.4 Parameter Problem Message...................14 - 4. ICMPv6 Informational Messages......................16 - 4.1 Echo Request Message........................16 - 4.2 Echo Reply Message..........................17 - 5. Security Considerations............................19 - 6. IANA Considerations................................21 - 7. References.........................................21 - 7.1 Normative...................................21 - 7.2 Informative.................................22 - 8. Acknowledgments....................................22 - 9. Authors' Addresses.................................22 - Appendix A - Changes since RFC 2463...................22 + 1. Introduction.....................................................3 + 2. ICMPv6 (ICMP for IPv6)...........................................3 + 2.1 Message General Format....................................3 + 2.2 Message Source Address Determination......................5 + 2.3 Message Checksum Calculation..............................6 + 2.4 Message Processing Rules..................................6 + 3. ICMPv6 Error Messages............................................9 + 3.1 Destination Unreachable Message...........................9 + 3.2 Packet Too Big Message...................................12 + 3.3 Time Exceeded Message....................................13 + 3.4 Parameter Problem Message................................15 + 4. ICMPv6 Informational Messages...................................17 + 4.1 Echo Request Message.....................................17 + 4.2 Echo Reply Message.......................................18 + 5. Security Considerations.........................................20 + 5.1 Authentication and Confidentiality of ICMP messages......20 + 5.2 ICMP Attacks.............................................20 + 6. IANA Considerations.............................................21 + 6.1 Procedure for new ICMPV6 Type and Code value assignments.22 + 6.2 Assignments for this document............................22 + 7. References......................................................23 + 7.1 Normative................................................23 + 7.2 Informative..............................................24 + 8. Acknowledgments.................................................24 + 9. Authors' Addresses..............................................24 + Appendix A - Changes since RFC 2463................................24 1. Introduction The Internet Protocol, version 6 (IPv6) is a new version of IP. IPv6 uses the Internet Control Message Protocol (ICMP) as defined for IPv4 [RFC-792], with a number of changes. The resulting protocol is called ICMPv6, and has an IPv6 Next Header value of 58. This document describes the format of a set of control messages used in ICMPv6. It does not describe the procedures for using these @@ -107,30 +113,52 @@ This document defines the message formats for the following ICMPv6 messages: ICMPv6 error messages: 1 Destination Unreachable (see section 3.1) 2 Packet Too Big (see section 3.2) 3 Time Exceeded (see section 3.3) 4 Parameter Problem (see section 3.4) + 100 Private experimentation + 101 Private experimentation + ICMPv6 informational messages: 128 Echo Request (see section 4.1) 129 Echo Reply (see section 4.2) + 200 Private experimentation + 201 Private experimentation + + 255 Reserved for expansion + + Type values 100, 101, 200, and 201 are reserved for private + experimentation. These are not intended for general use. It is + expected that multiple concurrent experiments will be done with the + same type values. Any wide scale and/or uncontrolled usage should + obtain real allocations as defined in section 6. + + Type value 255 is reserved for future expansion of the type value + range if there should be a shortage in the future. The details of + this are left for future work. One possible way of doing this that + would not cause any problems with current implementations is if the + type equals 255, use the code field for the new assignment. Existing + implementations would ignore the new assignments as specified in + section 2.4, section (b). The new messages using these expanded type + values, could assign fields in the message body for it's code values. + Every ICMPv6 message is preceded by an IPv6 header and zero or more IPv6 extension headers. The ICMPv6 header is identified by a Next Header value of 58 in the immediately preceding header. (NOTE: this is different than the value used to identify ICMP for IPv4.) - The ICMPv6 messages have the following general format: 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 | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + Message Body + | | @@ -156,45 +184,45 @@ | type-specific data (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | As much of invoking packet | + as will fit without the ICMPv6 packet + | exceeding the minimum IPv6 MTU [IPv6] | 2.2 Message Source Address Determination A node that sends an ICMPv6 message has to determine both the Source and Destination IPv6 Addresses in the IPv6 header before calculating - the checksum. If the node has more than one unicast address, it must + the checksum. If the node has more than one unicast address, it MUST choose the Source Address of the message as follows: (a) If the message is a response to a message sent to one of the - node's unicast addresses, the Source Address of the reply must + node's unicast addresses, the Source Address of the reply MUST be that same address. (b) If the message is a response to a message sent to a multicast or anycast group in which the node is a member, the Source Address - of the reply must be a unicast address belonging to the + of the reply MUST be a unicast address belonging to the interface on which the multicast or anycast packet was received. (c) If the message is a response to a message sent to an address - that does not belong to the node, the Source Address should be + that does not belong to the node, the Source Address SHOULD be that unicast address belonging to the node that will be most helpful in diagnosing the error. For example, if the message is a response to a packet forwarding action that cannot complete - successfully, the Source Address should be a unicast address + successfully, the Source Address SHOULD be a unicast address belonging to the interface on which the packet forwarding failed. (d) Otherwise, the node's routing table must be examined to determine which interface will be used to transmit the message to its destination, and a unicast address belonging to that - interface must be used as the Source Address of the message. + interface MUST be used as the Source Address of the message. 2.3 Message Checksum Calculation The checksum is the 16-bit one's complement of the one's complement sum of the entire ICMPv6 message starting with the ICMPv6 message type field, prepended with a "pseudo-header" of IPv6 header fields, as specified in [IPv6, section 8.1]. The Next Header value used in the pseudo-header is 58. (NOTE: the inclusion of a pseudo-header in the ICMPv6 checksum is a change from IPv4; see [IPv6] for the rationale for this change.) @@ -205,22 +233,22 @@ Implementations MUST observe the following rules when processing ICMPv6 messages (from [RFC-1122]): (a) If an ICMPv6 error message of unknown type is received, it MUST be passed to the upper layer. (b) If an ICMPv6 informational message of unknown type is received, it MUST be silently discarded. - (c) Every ICMPv6 error message (type < 128) includes as much of the - IPv6 offending (invoking) packet (the packet that caused the + (c) Every ICMPv6 error message (type < 128) MUST include as much of + the IPv6 offending (invoking) packet (the packet that caused the error) as will fit without making the error message packet exceed the minimum IPv6 MTU [IPv6]. (d) In those cases where the internet-layer protocol is required to pass an ICMPv6 error message to the upper-layer process, the upper-layer protocol type is extracted from the original packet (contained in the body of the ICMPv6 error message) and used to select the appropriate upper-layer process to handle the error. If the original packet had an unusually large amount of @@ -250,24 +278,24 @@ (e.5) a packet sent as a link-layer broadcast, (the exception from e.3 applies to this case too), or (e.6) a packet whose source address does not uniquely identify a single node -- e.g., the IPv6 Unspecified Address, an IPv6 multicast address, or an address known by the ICMP message sender to be an IPv6 anycast address. (f) Finally, in order to limit the bandwidth and forwarding costs - incurred sending ICMPv6 error messages, an IPv6 node MUST limit - the rate of ICMPv6 error messages it sends. This situation may - occur when a source sending a stream of erroneous packets fails - to heed the resulting ICMPv6 error messages. + incurred by sending ICMPv6 error messages, an IPv6 node MUST + limit the rate of ICMPv6 error messages it sends. This + situation may occur when a source sending a stream of erroneous + packets fails to heed the resulting ICMPv6 error messages. A recommended method for implementing the rate-limiting function is a token bucket, limiting the average rate of transmission to N, where N can either be packets/second or a fraction of the attached link's bandwidth, but allowing up to B error messages to be transmitted in a burst, as long as the long-term average is not exceeded. Rate-limiting mechanisms which cannot cope with bursty traffic (e.g., traceroute) are not recommended; for example a simple @@ -344,24 +372,23 @@ If the reason for the failure to deliver is that the destination is beyond the scope of the source address, the Code field is set to 2. This condition can occur only when the scope of the source address is smaller than the scope of the destination address (e.g., when a packet has a link-local source address and a global-scope destination address) and the packet cannot be delivered to the destination without leaving the scope of the source address. If the reason for the failure to deliver can not be mapped to any of - the specific codes listed above, the Code field is set to 3. The - example of such cases are inability to resolve the IPv6 destination - address into a corresponding link address, or a link-specific problem - of some sort. + other codes, the Code field is set to 3. The example of such cases + are inability to resolve the IPv6 destination address into a + corresponding link address, or a link-specific problem of some sort. One specific case in which a Destination Unreachable message with a code 3 is sent is in response to a packet received by a router from a point-to-point link, destined to an address within a subnet assigned to that same link (other than one of the receiving router's own addresses). In such a case, the packet MUST NOT be forwarded back onto the arrival link. A destination node SHOULD send a Destination Unreachable message with Code 4 in response to a packet for which the transport protocol @@ -370,20 +397,22 @@ If the reason for the failure to deliver is that packet with this source address is not allowed due to ingress or egress filtering policies, the Code field is set to 5. If the reason for the failure to deliver is that the route to the destination is a reject route, the Code field is set to 6. This may occur if the router has been configured to reject all the traffic for a specific prefix. + Codes 5 and 6 are more informative subsets of code 1. + Upper layer notification A node receiving the ICMPv6 Destination Unreachable message MUST notify the upper-layer process. 3.2 Packet Too Big Message 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @@ -654,24 +683,29 @@ Header or IP Encapsulating Security Payload Header exists for the destination address. The security associations may have been created through manual configuration or through the operation of some key management protocol. Received ICMP packets that have Authentication Header or Encapsulating Security Payload Header must be processed as specified in [IPv6-AUTH] and [IPv6-ESP]. The ICMP packets that fail the security processing MUST be ignored and discarded. - It SHOULD be possible for the system administrator to configure a - node to ignore any ICMP messages that are not authenticated using - either the Authentication Header or Encapsulating Security Payload. - Such a switch SHOULD default to allowing unauthenticated messages. + The system administrator MAY be allowed to configure a node to ignore + any ICMP messages that are not authenticated using either the + Authentication Header or Encapsulating Security Payload. If + provided, such a switch SHOULD default to allowing unauthenticated + messages. Note that setting up Security Associations to deal with + all the required ICMP packets is a very difficult task (e.g., + consider the Path MTU Discovery packets). So Path MTU Discovery (and + possibly some others) may not work if the node only allows + authenticated ICMP packets. 5.2 ICMP Attacks ICMP messages may be subject to various attacks. A complete discussion can be found in the IP Security Architecture [IPv6-SA]. A brief discussion of such attacks and their prevention is as follows: 1. ICMP messages may be subject to actions intended to cause the receiver to believe the message came from a different source than the message originator. The protection against this attack can be @@ -716,77 +750,129 @@ multicast routers does require the malicious node to be part of the correct multicast path i.e. near to the multicast source. This attack can only be avoided by securing the multicast traffic. The multicast source should be careful while sending multicast traffic with the destination options marked as mandatory because they can cause a denial of service attack to themselves if the destination option is unknown to a large number of destinations. 6. IANA Considerations - IANA considerations for the values of ICMPv6 type and code are given - in [RFC-2780]. +6.1 Procedure for new ICMPV6 Type and Code value assignments - ICMPv6 type 1 "Destination Unreachable" code 2 that was unassigned in - [RFC-2463], has been assigned to "beyond scope of source address" - message. + The IPv6 ICMP header [ICMPV6] contains the following fields that + carry values assigned from IANA-managed name spaces: Type and Code. + Code field values are defined relative to a specific Type value. - IANA is requested to assign the following two new codes for ICMPv6 - type 1 "Destination Unreachable". + Values for the IPv6 ICMP Type fields are allocated using the + following procedure: + + 1. The IANA should allocate and permanently register new ICMPv6 type + codes from IETF RFC publication. This is for all RFC types + including standards track, informational, experimental status, + etc. + + 2. IETF working groups with working group consensus and area director + approval can request reclaimable ICMPV6 type code assignments from + the IANA. The IANA will tag the values as "reclaimable in + future". + + The "reclaimable in the future" tag will be removed when an is + published documenting the protocol as defined in 1). This will + make the assignment permanent. + + At the point where the type values are 85% assigned, the IANA will + request that the IETF review the assignments tagged "reclaimable + in the future" and make a recommendation to the IANA which ones + can be reclaimed and reassigned. + + 3. Requests for type value assignments from outside of the IETF + should be sent to the IETF for review. The general guideline for + this review is that the assignment should be made if there is + public and open documentation of the protocol and if the + assignment is not being used to circumvent an existing IETF + protocol or work in progress. + + The policy for assigning Code values for new IPv6 ICMP Types should + be defined in the document defining the new Type values. + +6.2 Assignments for this document + + The following should update the assignments located at: + + http://www.iana.org/assignments/icmpv6-parameters + + The IANA is requested to reassign ICMPv6 type 1 "Destination + Unreachable" code 2, that was unassigned in [RFC-2463], to: + + 2 - beyond scope of source address + + The IANA is requested to assign the following two new codes values + for ICMPv6 type 1 "Destination Unreachable": 5 - source address failed ingress/egress policy 6 - reject route to destination + The IANA is requested to assign the following new type values: + + 100 Private experimentation + 101 Private experimentation + + 200 Private experimentation + 201 Private experimentation + + 255 Reserved for expansion + 7. References 7.1 Normative [IPv6] Deering, S., R. Hinden, "Internet Protocol, Version 6, Specification", RFC2460, December 1998. - [IPv6-ADDR] Hinden, R., S. Deering, "IP Version 6 Addressing - Architecture", RFC2373, July 1998. - [IPv6-DISC] Narten, T., E. Nordmark, W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC2461, December, 1998. [RFC-792] Postel, J., "Internet Control Message Protocol", STD 5, RFC792, September 1981. [RFC-2463] Conta, A., S. Deering, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC2463, December, 1998. [RFC-1122] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 5, RFC1122, August 1989. - [PMTU] McCann, J., S. Deering, J. Mogul, "Path MTU Discovery - for IP version 6", RFC1981, August 1996. - [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP14, RFC2119, March 1997. +7.2 Informative + + [RFC-2780] Bradner, S., V. Paxson, "IANA Allocation Guidelines For + Values In the Internet Protocol and Related Headers", + RFC 2780, March 2000. + + [IPv6-ADDR] Hinden, R., S. Deering, "IP Version 6 Addressing + Architecture", RFC2373, July 1998. + + [PMTU] McCann, J., S. Deering, J. Mogul, "Path MTU Discovery + for IP version 6", RFC1981, August 1996. + [IPv6-SA] Kent, S., R. Atkinson, "Security Architecture for the Internet Protocol", RFC1825, November 1998. [IPv6-AUTH] Kent, S., R. Atkinson, "IP Authentication Header", RFC 2402, November 1998. [IPv6-ESP] Kent, S., R. Atkinson, "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998. -7.2 Informative - - [RFC-2780] Bradner, S., V. Paxson, "IANA Allocation Guidelines For - Values In the Internet Protocol and Related Headers", - RFC 2780, March 2000. - 8. Acknowledgments The document is derived from previous ICMP drafts of the SIPP and IPng working group. The IPng working group and particularly Robert Elz, Jim Bound, Bill Simpson, Thomas Narten, Charlie Lynn, Bill Fink, Scott Bradner, Dimitri Haskin, Bob Hinden, Jun-ichiro Itojun Hagino, Tatuya Jinmei, Brian Zill, Pekka Savola, and Fred Templin (in chronological order) provided extensive review information and feedback. @@ -828,33 +914,80 @@ addresses belong to the link itself ("anti-ping-ponging" rule). - Added description of Time Exceeded Code 1 (fragment reassembly timeout). - Added "beyond scope of source address", "source address failed ingress/egress policy", and "reject route to destination" messages to the family of "unreachable destination" type ICMP error messages (section 3.1). + - Reserved some ICMP type values for experimentation. + - Added a NOTE in section 2.4, that specifies ICMP message processing rules precedence. - Added ICMP REDIRECT to the list in Section 2.4 e) of cases in which ICMP error messages are not to be generated. - Made minor editorial changes in Section 2.3 on checksum calculation, and in Section 5.2. - Clarified in section 4.2, regarding the Echo Reply Message, that the source address of an Echo Reply to an anycast Echo Request should be a unicast address, as in the case of multicast. - Revised the Security Considerations section. Added the use of - Encapsulating Security Payload Header for authentication. + Encapsulating Security Payload Header for authentication. Changed + the requirement of an option of "not allowing unauthenticated ICMP + messages" to MAY from SHOULD. - Added a new attack in the list of possible ICMP attacks in section 5.2. - Separated References into Normative and Informative. - Added reference to RFC-2780 "IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers" + +Full Copyright Statement + + Copyright (C) The Internet Society (2004). 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