RFC 8389

Definitions of Managed Objects for Mapping of Address and Port with Encapsulation (MAP-E)

📅 published December 2018, from ietf

RFC 8389: Definitions of Managed Objects for Mapping of Address and Port with Encapsulation (MAP-E) 🦋

okay bestie, let's get into it 💖 here's the title block tea:

  • RFC number: 8389
  • Written for: the Internet Engineering Task Force (IETF) 🌸
  • Category: Standards Track ✨
  • ISSN: 2070-1721
  • Date: December 2018
  • Authors: Y. Fu (CNNIC), S. Jiang (Huawei Technologies Co., Ltd), B. Liu (Huawei Technologies Co., Ltd), J. Dong (Tsinghua University), and Y. Chen (Tsinghua University) 👑
  • Obsoletes / Updates: the title block doesn't list any RFCs it obsoletes or updates 🙈

Abstract ✨

This memo defines a portion of the Management Information Base (MIB) for Mapping of Address and Port with Encapsulation (MAP-E) for use with network management protocols. 🫶

Status of This Memo 📜

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. 💅

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8389. 🌈

Copyright (c) 2018 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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 🎀

Table of Contents 🗂️

1. Introduction ....................................................2
2. The Internet-Standard Management Framework ......................2
3. Terminology .....................................................3
4. Structure of the MIB Module .....................................3
   4.1. The mapMIBObjects ..........................................3
        4.1.1. The mapRule Subtree .................................3
        4.1.2. The mapSecurityCheck Subtree ........................3
   4.2. The mapMIBConformance Subtree ..............................4
5. Definitions .....................................************4
6. IANA Considerations ............................................12
7. Security Considerations ........................................12
8. References .....................................................13
   8.1. Normative References ......................................13
   8.2. Informative References ....................................14
Acknowledgements ..................................................15
Authors' Addresses ................................................16

1. Introduction 🧚

Mapping of Address and Port with Encapsulation (MAP-E) [RFC7597] is a stateless, automatic tunneling mechanism for providing an IPv4 connectivity service to end users over a service provider's IPv6 network. So basically it's a way to give people IPv4 connectivity when the network underneath is IPv6, and it's giving clever engineering vibes 🔥

This document defines a portion of the Management Information Base (MIB) for use with monitoring MAP-E devices. 📊

2. The Internet-Standard Management Framework 🧠

For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 [RFC3410]. 📚

Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580 [RFC2580]. 💜

3. Terminology 🔑

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. These are the official capital-letter key words, so the capitals are doing real work here ⭐

4. Structure of the MIB Module 🏗️

The IF-MIB [RFC2863] defines generic managed objects for managing interfaces. Each logical interface (physical or virtual) has an ifEntry. Tunnels are handled by creating a logical interface (ifEntry) for each tunnel. Each MAP-E tunnel endpoint also acts as a virtual interface that has a corresponding entry in the IF-MIB. Those corresponding entries are indexed by ifIndex. The MAP-E MIB is configurable on a per-interface basis, so it depends on several parts (ifEntry) of the IF-MIB [RFC2863]. Think of it as the MAP-E MIB leaning on the IF-MIB like a bestie 🫶

4.1. The mapMIBObjects 🎀

4.1.1. The mapRule Subtree 💅

The mapRule subtree describes managed objects used for managing the multiple mapping rules in MAP-E.

According to [RFC7597], the mapping rules are divided into two categories: Basic Mapping Rule (BMR) and Forwarding Mapping Rule (FMR). According to Section 4.1 of [RFC7598], an F-flag specifies whether the rule is to be used for forwarding (FMR). If set, this rule is used as an FMR; if not set, this rule is BMR only and MUST NOT be used for forwarding. A BMR can also be used as an FMR for forwarding if the F-flag is set. So, the RuleType definition in the MAP-E MIB (see Section 5) defines bmrAndfmr to specify this scenario. The F-flag is the whole vibe here, so pay attention to it 👀

4.1.2. The mapSecurityCheck Subtree 🛡️

The mapSecurityCheck subtree provides statistics for the number of invalid packets that have been identified. [RFC7597] defines two kinds of invalid packets:

  • The Border Relay (BR) will validate the received packet's source IPv6 address against the configured MAP domain rule and the destination IPv6 address against the configured BR IPv6 address.
  • The MAP node (Customer Edge (CE) and BR) will check that the received packet's source IPv4 address and port are in the range derived from the matching MAP rule.

4.2. The mapMIBConformance Subtree 📋

The mapMIBConformance subtree provides conformance information of MIB objects.

5. Definitions 💖

The following MIB module imports definitions from [RFC2578], [RFC2579], [RFC2580], [RFC2863], and [RFC4001]. Here comes the actual MIB module, so grab your snacks 🍓

      MAP-E-MIB DEFINITIONS  ::=  BEGIN

      IMPORTS
         MODULE-IDENTITY, OBJECT-TYPE, mib-2,
         Unsigned32, Counter64
            FROM SNMPv2-SMI                 --RFC 2578
         TEXTUAL-CONVENTION
            FROM SNMPv2-TC                  --RFC 2579
         ifIndex
            FROM IF-MIB                     --RFC 2863
         InetAddressIPv6, InetAddressIPv4,
         InetAddressPrefixLength
            FROM INET-ADDRESS-MIB           --RFC 4001
         OBJECT-GROUP, MODULE-COMPLIANCE
            FROM SNMPv2-CONF;               --RFC 2580

      mapMIB MODULE-IDENTITY
      LAST-UPDATED "201811260000Z"
      ORGANIZATION
         "IETF Softwire Working Group"
      CONTACT-INFO
         "Yu Fu
          CNNIC
          No. 4 South 4th Street, Zhongguancun
          Beijing 100190
          China
          Email: eleven711711@foxmail.com

          Sheng Jiang
          Huawei Technologies Co., Ltd
          Q14, Huawei Campus, No. 156 Beiqing Road
          Hai-Dian District, Beijing 100095
          China
          Email: jiangsheng@huawei.com

          Bing Liu
          Huawei Technologies Co., Ltd
          Q14, Huawei Campus, No. 156 Beiqing Road
          Hai-Dian District, Beijing 100095
          China
          Email: leo.liubing@huawei.com

          Jiang Dong
          Tsinghua University
          Department of Computer Science, Tsinghua University
          Beijing 100084
          China
          Email: knight.dongjiang@gmail.com

          Yuchi Chen
          Tsinghua University
          Department of Computer Science, Tsinghua University
          Beijing 100084
          China
          Email: chenycmx@gmail.com"

      DESCRIPTION
         "This MIB module is defined for management of objects for
          MAP-E BRs or CEs.

          Copyright (c) 2018 IETF Trust and the persons identified as
          authors of the code.  All rights reserved.

          Redistribution and use in source and binary forms, with or
          without modification, is permitted pursuant to, and subject to
          the license terms contained in, the Simplified BSD License set
          forth in Section 4.c of the IETF Trust's Legal Provisions
          Relating to IETF Documents
          (https://trustee.ietf.org/license-info)."
      REVISION    "201811260000Z"
      DESCRIPTION
        "Initial version.  Published as RFC 8389."
       ::=  {  mib-2 242  }

      mapMIBObjects OBJECT IDENTIFIER ::= {mapMIB 1}

      mapRule   OBJECT IDENTIFIER
         ::=  { mapMIBObjects 1 }

      mapSecurityCheck   OBJECT IDENTIFIER
         ::=  { mapMIBObjects 2 }

      -- ==============================================================
      -- Textual Conventions Used in This MIB Module
      -- ==============================================================
      RulePSID ::= TEXTUAL-CONVENTION
         DISPLAY-HINT "0x:"
         STATUS       current
         DESCRIPTION
             "Indicates that the Port Set ID (PSID) is represented as
              hexadecimal for clarity."
         SYNTAX       OCTET STRING (SIZE (2))

      RuleType ::= TEXTUAL-CONVENTION
         STATUS       current
         DESCRIPTION
            "Enumerates the type of the mapping rule.  It
             defines three types of mapping rules here:
               bmr: Basic Mapping Rule (not Forwarding Mapping Rule)
               fmr: Forwarding Mapping Rule (not Basic Mapping Rule)
               bmrAndfmr: Basic and Forwarding Mapping Rule
             The Basic Mapping Rule may also be a Forwarding Mapping
             Rule for mesh mode."
         REFERENCE   "bmr, fmr: Section 5 of RFC 7597.
                      bmrAndfmr: Section 5 of RFC 7597, Section 4.1
                      of RFC 7598."
         SYNTAX       INTEGER {
             bmr(1),
             fmr(2),
             bmrAndfmr(3)
             }

      mapRuleTable OBJECT-TYPE
         SYNTAX     SEQUENCE OF MapRuleEntry
         MAX-ACCESS  not-accessible
         STATUS     current
         DESCRIPTION
            "The (conceptual) table containing rule information for
             a specific mapping rule.  It can also be used for row
             creation."
         ::=  { mapRule 1 }

      mapRuleEntry OBJECT-TYPE
         SYNTAX     MapRuleEntry
         MAX-ACCESS  not-accessible
         STATUS     current
         DESCRIPTION
            "Each entry in this table contains the information on a
             particular mapping rule."
             INDEX   {  ifIndex,
                        mapRuleID }
         ::=  { mapRuleTable 1 }

I'm picking up mid-table, so here's the MapRuleEntry structure and the mapping rule objects 💖

      MapRuleEntry  ::=
         SEQUENCE {
          mapRuleID                   Unsigned32,
          mapRuleIPv6Prefix           InetAddressIPv6,
          mapRuleIPv6PrefixLen        InetAddressPrefixLength,
          mapRuleIPv4Prefix           InetAddressIPv4,
          mapRuleIPv4PrefixLen        InetAddressPrefixLength,
          mapRuleBRIPv6Address        InetAddressIPv6,
          mapRulePSID                 RulePSID,
          mapRulePSIDLen              Unsigned32,
          mapRuleOffset               Unsigned32,
          mapRuleEALen                Unsigned32,
          mapRuleType                 RuleType
      }

      mapRuleID OBJECT-TYPE
          SYNTAX Unsigned32 (1..4294967295)
          MAX-ACCESS not-accessible
          STATUS current
          DESCRIPTION
             "A unique identifier used to distinguish mapping
              rules."
          ::= { mapRuleEntry 1 }

     -- The object mapRuleIPv6Prefix is IPv6 specific; hence, it does
     -- not use the version-agnostic InetAddress.

     mapRuleIPv6Prefix OBJECT-TYPE
          SYNTAX     InetAddressIPv6
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The IPv6 prefix defined in the mapping rule that will be
              assigned to CEs."
          ::= { mapRuleEntry 2 }

      mapRuleIPv6PrefixLen OBJECT-TYPE
          SYNTAX     InetAddressPrefixLength
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The length of the IPv6 prefix defined in the mapping rule
              that will be assigned to CEs."
          ::= { mapRuleEntry 3 }

     -- The object mapRuleIPv4Prefix is IPv4 specific; hence, it does
     -- not use the version-agnostic InetAddress.

      mapRuleIPv4Prefix OBJECT-TYPE
          SYNTAX     InetAddressIPv4
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The IPv4 prefix defined in the mapping rule that will be
              assigned to CEs."
          ::= { mapRuleEntry 4 }

      mapRuleIPv4PrefixLen OBJECT-TYPE
          SYNTAX     InetAddressPrefixLength
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The length of the IPv4 prefix defined in the mapping
              rule that will be assigned to CEs."
          ::= { mapRuleEntry 5 }

     -- The object mapRuleBRIPv6Address is IPv6 specific; hence, it does
     -- not use the version-agnostic InetAddress.

      mapRuleBRIPv6Address OBJECT-TYPE
          SYNTAX     InetAddressIPv6
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The IPv6 address of the BR that will be conveyed to CEs.
              If the BR IPv6 address is anycast, the relay must use
              this anycast IPv6 address as the source address in
              packets relayed to CEs."
          ::= { mapRuleEntry 6 }

       mapRulePSID  OBJECT-TYPE
          SYNTAX     RulePSID
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The PSID value algorithmically identifies a set of
              ports assigned to a CE."
          REFERENCE
               "PSID: Section 5.1 of RFC 7597."
          ::= { mapRuleEntry 7 }

      mapRulePSIDLen  OBJECT-TYPE
          SYNTAX     Unsigned32(0..16)
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The bit length value of the number of significant bits in
              the PSID field.  When it is set to 0, the PSID
              field is to be ignored."
          ::= { mapRuleEntry 8 }

      mapRuleOffset OBJECT-TYPE
          SYNTAX     Unsigned32(0..15)
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The number of the mapRuleOffset is 6 by default to
              exclude the system ports (0-1023).  It is provided via
              the Rule Port Mapping Parameters in the Basic Mapping
              Rule."
          DEFVAL {6}
          ::= { mapRuleEntry 9 }

      mapRuleEALen OBJECT-TYPE
          SYNTAX     Unsigned32(0..48)
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "The length of the Embedded Address (EA) defined in
              mapping rule that will be assigned to CEs."
         REFERENCE
               "EA: Section 3 of RFC 7597."
          ::= { mapRuleEntry 10 }

     mapRuleType OBJECT-TYPE
          SYNTAX     RuleType
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "Indicates the type of mapping rule.
              '1' represents a BMR.
              '2' represents an FMR.
              '3' represents a BMR that is also an FMR for mesh mode."
           REFERENCE
               "bmr, fmr: Section 5 of RFC 7597.
                bmrAndfmr: Section 5 of RFC 7597, Section 4.1 of
                RFC 7598."
          ::= { mapRuleEntry 11 }

      mapSecurityCheckTable OBJECT-TYPE
         SYNTAX     SEQUENCE OF MapSecurityCheckEntry
         MAX-ACCESS  not-accessible
         STATUS     current
         DESCRIPTION
            "The (conceptual) table containing information on
             MAP security checks.  This table can be used for
             statistics on the number of invalid packets that
             have been identified."
         ::=  { mapSecurityCheck 1 }

      mapSecurityCheckEntry OBJECT-TYPE
         SYNTAX     MapSecurityCheckEntry
         MAX-ACCESS  not-accessible
         STATUS     current
         DESCRIPTION
            "Each entry in this table contains information on a
             particular MAP security check."
             INDEX   { ifIndex }
         ::=  { mapSecurityCheckTable 1 }

      MapSecurityCheckEntry  ::=
         SEQUENCE {
          mapSecurityCheckInvalidv4       Counter64,
          mapSecurityCheckInvalidv6       Counter64
      }

      mapSecurityCheckInvalidv4 OBJECT-TYPE
          SYNTAX     Counter64
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "Indicates the number of received IPv4 packets
              that do not have a payload source IPv4 address or
              port within the range defined in the matching MAP
              rule.  It corresponds to the second kind of
              invalid packet described in Section 4.1.2."
          ::= { mapSecurityCheckEntry 1 }

      mapSecurityCheckInvalidv6 OBJECT-TYPE
          SYNTAX     Counter64
          MAX-ACCESS read-only
          STATUS     current
          DESCRIPTION
             "Indicates the number of received IPv6 packets that
              do not have a source or destination IPv6 address
              matching a Basic Mapping Rule.  It corresponds
              to the first kind of invalid packet described
              in Section 4.1.2."
          ::= { mapSecurityCheckEntry 2 }

      -- Conformance Information
      mapMIBConformance OBJECT IDENTIFIER ::= {mapMIB 2}
      mapMIBCompliances OBJECT IDENTIFIER ::= { mapMIBConformance 1 }
      mapMIBGroups OBJECT IDENTIFIER ::= { mapMIBConformance 2 }

      -- compliance statements
      mapMIBCompliance MODULE-COMPLIANCE
         STATUS current
         DESCRIPTION
            "Describes the minimal requirements for conformance
             to the MAP-E MIB."
         MODULE -- this module
             MANDATORY-GROUPS { mapMIBRuleGroup , mapMIBSecurityGroup }
        ::= { mapMIBCompliances 1 }

      -- Units of Conformance
      mapMIBRuleGroup OBJECT-GROUP
         OBJECTS {
                 mapRuleIPv6Prefix,
                 mapRuleIPv6PrefixLen,
                 mapRuleIPv4Prefix,
                 mapRuleIPv4PrefixLen,
                 mapRuleBRIPv6Address,
                 mapRulePSID,
                 mapRulePSIDLen,
                 mapRuleOffset,
                 mapRuleEALen,
                 mapRuleType  }
         STATUS current
         DESCRIPTION
            "The group of objects used to describe the MAP-E mapping
             rule."
         ::= { mapMIBGroups 1 }

     mapMIBSecurityGroup OBJECT-GROUP
        OBJECTS {
           mapSecurityCheckInvalidv4,
           mapSecurityCheckInvalidv6 }
       STATUS current
       DESCRIPTION
          "The group of objects used to provide information on the
           MAP-E security checks."
       ::= { mapMIBGroups 2 }

       END

6. IANA Considerations ✨

Okay, so the MIB module in this doc uses a couple of IANA-assigned OBJECT IDENTIFIER values, and they're recorded in the SMI Numbers registry 🦋 Here's the lineup:

      Descriptor        OBJECT IDENTIFIER value
      ----------        -----------------------
      MAP-E-MIB          { mib-2 242 }

7. Security Considerations 💀

Okay bestie, this section is SERIOUS, so read it slowly 🫶

There are no management objects defined in this MIB module with a MAX-ACCESS clause of read-write and/or read-create. So if this MIB module is implemented correctly, there's no risk that an intruder can alter or create any management objects here via direct SNMP SET operations. Iconic behaviour, honestly 🌸

Some objects in this MIB module can be considered sensitive or vulnerable in some network environments 🙈 That includes INDEX objects with a MAX-ACCESS of not-accessible, plus any indices from other modules exposed via AUGMENTS. So it's really important to control even GET and/or NOTIFY access to these objects, and possibly even encrypt their values when they're sent over the network via SNMP. These are the tables and objects, with their sensitivity and vulnerability:

  • mapRuleIPv6Prefix
  • mapRuleIPv6PrefixLen
  • mapRuleIPv4Prefix
  • mapRuleIPv4PrefixLen
  • mapRuleBRIPv6Address
  • mapRulePSID
  • mapRulePSIDLen
  • mapRuleOffset
  • mapRuleEALen
  • mapRuleType

Some of the MIB model's objects are vulnerable because the info they hold could be used to target an attack against a MAP node (CE or BR) 😭 For example, an intruder could use it to help deduce the customer IPv4 and IPv6 topologies and the address-sharing ratios the ISP is using. Not okay!

SNMP versions before SNMPv3 didn't include adequate security 💀 Even if the network itself is secure (for example by using IPsec), there's no control over who on that secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB module.

Implementations SHOULD provide the security features described by the SNMPv3 framework (see [RFC3410]). Implementations claiming compliance to the SNMPv3 standard MUST include full support for authentication and privacy via the User-based Security Model (USM) [RFC3414] with the AES cipher algorithm [RFC3826]. Implementations MAY also provide support for the Transport Security Model (TSM) [RFC5591] in combination with a secure transport such as SSH [RFC5592] or TLS/DTLS [RFC6353].

Further, deploying SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security 🔥 It's then a customer/operator responsibility to make sure the SNMP entity giving access to an instance of this MIB module is configured so that only principals (users) with legitimate rights can GET or SET (change/create/delete) the objects. Locking the door, bestie 🧚

8. References ✨

8.1. Normative References 📚

8.2. Informative References 🌈

Acknowledgements 🙏

okay bestie, the authors wanted to thank these legends for their valuable comments: David Harrington, Mark Townsley, Shishio Tsuchiya, Yong Cui, Suresh Krishnan, Bert Wijnen, Ian Farrer, and Juergen Schoenwaelder. 💖 they're literally the reason this spec is so solid, no cap. 🫶

Authors' Addresses 🎀

here are the squad members and where to find them, iykyk 💅

Yu Fu 🧚

Yu Fu
CNNIC
No. 4 South 4th Street, Zhongguancun
Beijing  100190
China

Email: eleven711711@foxmail.com

Sheng Jiang 🌈

Sheng Jiang
Huawei Technologies Co., Ltd
Q14, Huawei Campus, No. 156 Beiqing Road
Hai-Dian District, Beijing  100095
China

Email: jiangsheng@huawei.com

Bing Liu ✨

Bing Liu
Huawei Technologies Co., Ltd
Q14, Huawei Campus, No. 156 Beiqing Road
Hai-Dian District, Beijing  100095
China

Email: leo.liubing@huawei.com

Jiang Dong 🌸

Jiang Dong
Tsinghua University
Department of Computer Science, Tsinghua University
Beijing  100084
China

Email: knight.dongjiang@gmail.com

Yuchi Chen 👑

Yuchi Chen
Tsinghua University
Department of Computer Science, Tsinghua University
Beijing  100084
China

Email: flashfoxmx@gmail.com

that's the whole spec, bestie! 🌈💜🦋

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