Source Address Validation Improvements (savi)

Last Modified: 2008-11-05

Additional information is available at tools.ietf.org/wg/savi

Chair(s):

  • Christian Vogt <christian.vogt@ericsson.com>

  • Bill Fenner <fenner@fenron.com>

    Internet Area Director(s):

  • Ralph Droms <rdroms@cisco.com>
  • Jari Arkko <jari.arkko@piuha.net>

    Internet Area Advisor:

  • Jari Arkko <jari.arkko@piuha.net>

    Technical Advisor(s):

  • Jianping Wu <jianping@cernet.edu.cn>

    Secretary(ies):

  • Jun Bi <junbi@tsinghua.edu.cn>

    Mailing Lists:

    General Discussion: savi@ietf.org
    To Subscribe: https://www.ietf.org/mailman/listinfo/savi
    Archive: http://www.ietf.org/mail-archive/web/savi/current/maillist.html

    Description of Working Group:

    While ingress filtering [RFC 2827, BCP 38] provides a way to validate
    IP source addresses at an aggregated level, there is not yet a
    standardized mechanism for IP source address validation at a finer
    granularity. Having a finer granularity would be helpful in a number
    of situations, including filtering traffic from customer interfaces
    implemented as ports in a layer 3 aware bridge or a router, general
    improvements in filtering accuracy in enterprise networks, etc.
    Depending on the situation, there may be a requirement for blocking
    spoofed packets or merely logging packets that appear to be spoofed.

    Partial solutions exist to prevent nodes from spoofing the IP source
    address of another node in the same IP link (e.g., the "IP source
    guard"), but are proprietary. The purpose of the proposed "Source
    Address Validation Improvements" working group is to standardize
    mechanisms that prevent nodes attached to the same IP link from
    spoofing each other's IP addresses.

    The scope of the WG is as follows:

    - The working group considers only solutions implemented on systems
    located on the same IP link as a to-be-verified node. The goal of the
    working group is the LAN environment and solutions running in routers or
    layer 3 aware Ethernet bridges.

    - Both IPv4 and IPv6 need to be covered.

    - The first goal of the working group is on unicast traffic, but
    using the same mechanisms to police multicast traffic is also
    within the scope.

    - All address assignment mechanisms need to be supported, including
    stateless, stateful, and manual configuration; as well as privacy and
    cryptographically generated addresses.

    - Solutions are preferably based on observing user traffic, or on
    observing or using existing signaling protocols. Examples of
    protocols that can be useful to observe/use are ARP, Neighbor
    Discovery, DHCP, and DHCP Prefix Delegation protocols. Observing
    addresses in IP headers can also be useful. The gathered
    information is used to determine what IP source addresses in
    packets are appropriate. Where automatic operation is impossible
    or would lead to sub-optimal validation results, solutions may
    require manual configuration.

    - Interdomain scenarios (across Autonomous Systems) that require
    information from routing protocols like BGP are out of scope.
    Nevertheless, solution may observe routing protocol signaling
    to detect that a device is a router.

    - Tracking other protocols is not within the scope of the WG.

    - No changes to hosts are allowed.

    - The WG is prohibited from creating its own protocols
    or extensions/modifications of current protocols.

    These limitations in the scope may be relaxed through later
    rechartering. For instance, solutions tailored for PPP links
    and specific environments may be added later, or solutions
    involving co-operation of the nodes on the link may be
    developed once the baseline solutions have been completed.
    However, the WG is already chartered to work also on a
    solution for Ethernet-based broadband access networks that
    are used in DSL environments. This work is a specialization
    of the working group's primary LAN-based solution.

    In order to reach a result that is widely usable and unlikely to
    disturb existing network practices, the working group needs to
    take into account

    - nodes that use static addresses,
    - nodes with multiple IP addresses on the same interface,
    - nodes that use multiple link-layer addresses on the same interface,
    - nodes that have multiple interfaces to the same link,
    - attachment of another bridge at a bridge port,
    - presence of routers, NATs, and other similar devices on the same link,
    including their distinction from hosts with multiple interfaces or
    hosts with multiple IP addresses on a single interface,
    - use of SEcure Neighbor Discovery in some networks,
    - nodes that move to another port on the same link, and
    - hosts with anycast addresses.

    However, should such wide applicability turn out to be impossible,
    the working group will document the limitations of the solutions
    in due manner. In particular, it is likely that anycast addressing
    and nodes that employ multiple interfaces for load balancing at
    link layer are indistinguishable from an actual spoofing attack.
    There may also be a difference in the applicability between blocking
    and merely logging spoofed packets. In any case, the solutions
    may require to be explicitly turned on for each network or interface
    where they are applicable.

    For background information, the working group will also develop a
    threats analysis document that describes what threats the solutions
    from the WG protect against. This document also contrasts SAVI
    to existing solutions.

    Goals and Milestones:

    Jul 2008  WG approval
    Aug 2008  First WG draft on threats document
    Oct 2008  First WG draft on IPv4 solution
    Oct 2008  First WG draft on IPv6 solution
    Oct 2008  Submit document on threats to IESG for Informational RFC
    Dec 2008  First WG draft on SAVI solution rationale
    Dec 2008  First WG draft on SeND-based SAVI extension
    Feb 2009  First WG draft on solution for Ethernet-based broadband access network
    Mar 2009  Submit IPv4 solution to IESG for Proposed Standard
    May 2009  Submit IPv6 solution to IESG for Proposed Standard
    May 2009  Submit SAVI solution rationale to IESG for Informational RFC
    May 2009  Submit SeND-based SAVI extension to IESG for Informational RFC
    Oct 2009  Submit Ethernet-based broadband access network solution to IESG for Proposed Standard

    Internet-Drafts:

    SAVI Threat Scope (46123 bytes)
    A Solution Space Analysis for First-Hop IP Source Address Validation (11612 bytes)
    First-Come First-Serve Source-Address Validation Implementation (22375 bytes)
    SeND-based Source-Address Validation Implementation (19295 bytes)

    No Request For Comments

    IETF Secretariat - Please send questions, comments, and/or suggestions to ietf-web@ietf.org.

    Return to working group directory.

    Return to IETF home page.