RFC 2667

IP Tunnel MIB

๐Ÿ“… published August 1999, from ietf

IP Tunnel MIB ๐Ÿ’–

  • Network Working Group, Request for Comments: 2667 ๐ŸŽ€
  • Author: D. Thaler, Microsoft ๐Ÿง‘โ€๐Ÿ’ป
  • Category: Standards Track ๐Ÿ‘‘
  • Date: August 1999 ๐Ÿ“…
  • Obsoletes/Updates: the title block doesn't list anything it obsoletes or updates ๐ŸŒธ

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. ๐Ÿ“ฎ

Copyright (C) The Internet Society (1999). All Rights Reserved. ยฉ๏ธโœจ

1. Abstract ๐Ÿฆ‹

okay so this memo defines a Management Information Base (MIB) for network management protocols in the Internet community ๐Ÿ“Š. The main point is managing tunnels of any type over IPv4 networks ๐Ÿš‡. Extension MIBs can be designed for protocol-specific objects, and they can also be designed for security-specific objects ๐Ÿ”. This MIB doesn't cover tunnels over non-IPv4 networks (IPv6 included) ๐Ÿ™…โ€โ™€๏ธ. Managing those tunnels might be handled by other MIBs, so bestie, go look there if you need it ๐Ÿงš.

Table of Contents ๐Ÿ“š

    1 Abstract ...................................................... 1
    2 Introduction .................................................. 2
    3 The SNMP Network Management Framework ......................... 2
    4 Overview ...................................................... 3
    4.1 Relationship to the Interfaces MIB .......................... 3
    4.1.1 Layering Model ............................................ 3
    4.1.2 ifRcvAddressTable ......................................... 4
    4.1.3 ifEntry ................................................... 4
    5 Definitions ................................................... 4
    6 Security Considerations ...................................... 12
    7 Acknowledgements ............................................. 12
    8 Author's Address ............................................. 12
    9 References ................................................... 13
   10 Intellectual Property Notice ................................. 15
   11 Full Copyright Statement ..................................... 16

2. Introduction ๐ŸŒˆ

Over the past several years, the IETF has specified a bunch of "tunneling" protocols ๐Ÿš‡โœจ. If you want the early history and examples of the model, check out [28] ๐Ÿ“–. This document describes a MIB used for managing tunnels of any type over IPv4 networks, and that includes GRE [16,17], IP-in-IP [18], Minimal Encapsulation [19], L2TP [20], PPTP [21], L2F [25], UDP (e.g., [26]), ATMP [22], and IPv6-in-IPv4 [27] tunnels ๐Ÿ’….

Extension MIBs can be designed for protocol-specific objects ๐Ÿงฉ. Extension MIBs can also be designed for security-specific objects (e.g., IPSEC [24]) and traffic conditioner [29] objects ๐Ÿ”. Finally, this MIB doesn't support tunnels over non-IPv4 networks (IPv6 included), and other MIBs might handle those ๐Ÿ™ˆ.

3. The SNMP Network Management Framework ๐Ÿ›ฐ๏ธ

The SNMP Management Framework is made up of five major components, so let's go through them ๐Ÿซถ:

  • An overall architecture, described in RFC 2571 [1].
  • Mechanisms for describing and naming objects and events for the purpose of management. The first version of this Structure of Management Information (SMI) is called SMIv1 and described in STD 16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The second version, called SMIv2, is described in STD 58, RFC 2578 [5], STD 58, RFC 2579 [6] and STD 58, RFC 2580 [7].
  • Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and described in STD 15, RFC 1157 [8]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [9] and RFC 1906 [10]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12].
  • Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15, RFC 1157 [8]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [13].
  • A set of fundamental applications described in RFC 2573 [14] and the view-based access control mechanism described in RFC 2575 [15].

Managed objects are accessed through a virtual information store, called the Management Information Base or MIB ๐Ÿ—„๏ธ. Objects in the MIB are defined using the mechanisms in the SMI โœจ.

This memo specifies a MIB module that is compliant to the SMIv2 ๐Ÿ’ซ. A MIB conforming to the SMIv1 can be produced through the appropriate translations. The resulting translated MIB must be semantically equivalent, except where objects or events are omitted because no translation is possible (use of Counter64). Some machine readable information in SMIv2 will be turned into textual descriptions in SMIv1 during the translation process. However, losing that machine readable information isn't considered to change the semantics of the MIB ๐Ÿค“.

4. Overview ๐Ÿ”

This MIB module has two tables ๐Ÿช„:

  • the Tunnel Interface Table, which holds info on the tunnels known to a router; and
  • the Tunnel Config Table, which can be used to dynamically create tunnels, and also maps endpoint addresses to the current interface index value ๐Ÿ—บ๏ธ.

4.1. Relationship to the Interfaces MIB ๐Ÿ”—

This section explains how this MIB relates to the Interfaces MIB [23] ๐Ÿ’•. Several areas of correlation are covered in the subsections below. Implementors should check the Interfaces MIB document to get the general intent of these areas ๐Ÿ“š.

4.1.1. Layering Model ๐Ÿฐ

Each logical interface (physical or virtual) has an ifEntry in the Interfaces MIB [23] ๐Ÿซง. Tunnels are handled by creating a logical interface (ifEntry) for each tunnel. Those are then correlated, using the ifStack table of the Interfaces MIB, to the interfaces where the local IPv4 addresses of the tunnels are configured ๐Ÿชข. The basic model looks something like this, for example:

         | |         | |          | |
      +--+ +---+  +--+ +---+      | |
      |IP-in-IP|  |  GRE   |      | |
      | tunnel |  | tunnel |      | |
      +--+ +---+  +--+ +---+      | |
         | |         | |          | |    <== attachment to underlying
      +--+ +---------+ +----------+ +--+     interfaces, to be provided
      |       Physical interface       |     by ifStack table
      +--------------------------------+

4.1.2. ifRcvAddressTable ๐Ÿ“ฌ

The ifRcvAddressTable usage is defined in the MIBs that define the encapsulation below the network layer ๐Ÿง…. For example, if IP-in-IP encapsulation is being used, the ifRcvAddressTable is defined by IP-in-IP ๐Ÿ™Œ.

4.1.3. ifEntry ๐Ÿงพ

IfEntries are defined in the MIBs that define the encapsulation below the network layer ๐Ÿงฑ. For example, if IP-in-IP encapsulation [20] is being used, the ifEntry is defined by IP-in-IP ๐ŸŽฏ.

The ifType of a tunnel should be set to "tunnel" (131). An entry in the IP Tunnel MIB will exist for every ifEntry with this ifType ๐Ÿซถ. An implementation of the IP Tunnel MIB may allow ifEntries to be created via the tunnelConfigTable ๐Ÿ› ๏ธ. Creating a tunnel will also add an entry in the ifTable and in the tunnelIfTable, and deleting a tunnel will likewise delete the entry in the ifTable and the tunnelIfTable ๐Ÿ’ฅ.

Using two different tables in this MIB was an important design decision ๐Ÿง โœจ. Traditionally, ifIndex values are chosen by agents, and they're allowed to change across restarts ๐Ÿ”„. Letting row creation happen directly in the Tunnel Interface Table, indexed by ifIndex, would complicate row creation and/or cause interoperability problems (if each agent had special restrictions on ifIndex) ๐Ÿ˜ญ. So instead, a separate table is used, indexed only by objects the manager controls. Namely, these are the addresses of the tunnel endpoints and the encapsulation protocol ๐Ÿซถ. Finally, an additional manager-chosen ID is used in the index to support protocols like L2F that allow multiple tunnels between the same endpoints ๐Ÿ‘ฏ.

5. Definitions ๐Ÿ’œ

TUNNEL-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE, transmission,
    Integer32, IpAddress             FROM SNMPv2-SMI
    RowStatus                        FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP  FROM SNMPv2-CONF
    ifIndex, InterfaceIndexOrZero    FROM IF-MIB;

tunnelMIB MODULE-IDENTITY
    LAST-UPDATED "9908241200Z" -- August 24, 1999
    ORGANIZATION "IETF Interfaces MIB Working Group"
    CONTACT-INFO
            " Dave Thaler
              Microsoft Corporation
              One Microsoft Way
              Redmond, WA  98052-6399
              EMail: dthaler@dthaler.microsoft.com"
    DESCRIPTION
            "The MIB module for management of IP Tunnels, independent of
            the specific encapsulation scheme in use."
    REVISION     "9908241200Z" -- August 24, 1999
    DESCRIPTION
            "Initial version, published as RFC 2667."
    ::= { transmission 131 }

tunnelMIBObjects OBJECT IDENTIFIER ::= { tunnelMIB 1 }

tunnel      OBJECT IDENTIFIER ::= { tunnelMIBObjects 1 }

-- the IP Tunnel MIB-Group
--
-- a collection of objects providing information about
-- IP Tunnels

tunnelIfTable OBJECT-TYPE
    SYNTAX     SEQUENCE OF TunnelIfEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The (conceptual) table containing information on configured
            tunnels."
    ::= { tunnel 1 }

tunnelIfEntry OBJECT-TYPE
    SYNTAX     TunnelIfEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "An entry (conceptual row) containing the information on a
            particular configured tunnel."
    INDEX      { ifIndex }
    ::= { tunnelIfTable 1 }

TunnelIfEntry ::= SEQUENCE {
    tunnelIfLocalAddress            IpAddress,
    tunnelIfRemoteAddress           IpAddress,
    tunnelIfEncapsMethod            INTEGER,
    tunnelIfHopLimit                Integer32,
    tunnelIfSecurity                INTEGER,
    tunnelIfTOS                     Integer32
}

tunnelIfLocalAddress OBJECT-TYPE
    SYNTAX     IpAddress
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The address of the local endpoint of the tunnel (i.e., the
            source address used in the outer IP header), or 0.0.0.0 if
            unknown."
    ::= { tunnelIfEntry 1 }

tunnelIfRemoteAddress OBJECT-TYPE
    SYNTAX     IpAddress
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The address of the remote endpoint of the tunnel (i.e., the
            destination address used in the outer IP header), or 0.0.0.0
            if unknown."
    ::= { tunnelIfEntry 2 }

okay the encapsulation stuff is literally the best part ๐ŸŽ€ here's the rest of the module

tunnelIfEncapsMethod OBJECT-TYPE
    SYNTAX     INTEGER {
                   other(1),   -- none of the following
                   direct(2),  -- no intermediate header
                   gre(3),     -- GRE encapsulation
                   minimal(4), -- Minimal encapsulation
                   l2tp(5),    -- L2TP encapsulation
                   pptp(6),    -- PPTP encapsulation
                   l2f(7),     -- L2F encapsulation
                   udp(8),     -- UDP encapsulation
                   atmp(9)     -- ATMP encapsulation

               }
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The encapsulation method used by the tunnel. The value
            direct indicates that the packet is encapsulated directly
            within a normal IPv4 header, with no intermediate header,
            and unicast to the remote tunnel endpoint (e.g., an RFC 2003
            IP-in-IP tunnel, or an RFC 1933 IPv6-in-IPv4 tunnel). The
            value minimal indicates that a Minimal Forwarding Header
            (RFC 2004) is inserted between the outer header and the
            payload packet. The value UDP indicates that the payload
            packet is encapsulated within a normal UDP packet (e.g., RFC
            1234).  The remaining protocol-specific values indicate that
            a header of the protocol of that name is inserted between
            the outer header and the payload header."
    ::= { tunnelIfEntry 3 }

tunnelIfHopLimit OBJECT-TYPE
    SYNTAX     Integer32 (0..255)
    MAX-ACCESS read-write
    STATUS     current
    DESCRIPTION
            "The TTL to use in the outer IP header. A value of 0
            indicates that the value is copied from the payload's
            header."
    ::= { tunnelIfEntry 4 }

tunnelIfSecurity OBJECT-TYPE
    SYNTAX     INTEGER {
                   none(1),   -- no security
                   ipsec(2),  -- IPSEC security
                   other(3)
               }
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The method used by the tunnel to secure the outer IP
            header.  The value ipsec indicates that IPsec is used
            between the tunnel endpoints for authentication or
            encryption or both.  More specific security-related
            information may be available in a MIB for the security
            protocol in use."
    ::= { tunnelIfEntry 5 }

tunnelIfTOS OBJECT-TYPE
    SYNTAX     Integer32 (-2..63)
    MAX-ACCESS read-write
    STATUS     current
    DESCRIPTION
            "The method used to set the high 6 bits of the TOS in the
            outer IP header.  A value of -1 indicates that the bits are
            copied from the payload's header. A value of -2 indicates
            that a traffic conditioner is invoked and more information
            may be available in a traffic conditioner MIB.  A value
            between 0 and 63 inclusive indicates that the bit field is
            set to the indicated value."
    ::= { tunnelIfEntry 6 }

tunnelConfigTable OBJECT-TYPE
    SYNTAX     SEQUENCE OF TunnelConfigEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The (conceptual) table containing information on configured
            tunnels.  This table can be used to map a set of tunnel
            endpoints to the associated ifIndex value.  It can also be
            used for row creation.  Note that every row in the
            tunnelIfTable with a fixed destination address should have a
            corresponding row in the tunnelConfigTable, regardless of
            whether it was created via SNMP."
    ::= { tunnel 2 }

tunnelConfigEntry OBJECT-TYPE
    SYNTAX     TunnelConfigEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "An entry (conceptual row) containing the information on a
            particular configured tunnel."
    INDEX      { tunnelConfigLocalAddress,
                 tunnelConfigRemoteAddress,
                 tunnelConfigEncapsMethod,
                 tunnelConfigID }
    ::= { tunnelConfigTable 1 }

TunnelConfigEntry ::= SEQUENCE {
    tunnelConfigLocalAddress            IpAddress,
    tunnelConfigRemoteAddress           IpAddress,
    tunnelConfigEncapsMethod            INTEGER,
    tunnelConfigID                      Integer32,
    tunnelConfigIfIndex                 InterfaceIndexOrZero,
    tunnelConfigStatus                  RowStatus
}

tunnelConfigLocalAddress OBJECT-TYPE

    SYNTAX     IpAddress
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The address of the local endpoint of the tunnel, or 0.0.0.0
            if the device is free to choose any of its addresses at
            tunnel establishment time."
    ::= { tunnelConfigEntry 1 }

tunnelConfigRemoteAddress OBJECT-TYPE
    SYNTAX     IpAddress
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The address of the remote endpoint of the tunnel."
    ::= { tunnelConfigEntry 2 }

tunnelConfigEncapsMethod OBJECT-TYPE
    SYNTAX     INTEGER {
                   other(1),   -- none of the following
                   direct(2),  -- no intermediate header
                   gre(3),     -- GRE encapsulation
                   minimal(4), -- Minimal encapsulation
                   l2tp(5),    -- L2TP encapsulation
                   pptp(6),    -- PPTP encapsulation
                   l2f(7),     -- L2F encapsulation
                   udp(8),     -- UDP encapsulation
                   atmp(9)
               }
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The encapsulation method used by the tunnel."
    ::= { tunnelConfigEntry 3 }

tunnelConfigID OBJECT-TYPE
    SYNTAX     Integer32 (1..2147483647)
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "An identifier used to distinguish between multiple tunnels
            of the same encapsulation method, with the same endpoints.
            If the encapsulation protocol only allows one tunnel per set
            of endpoint addresses (such as for GRE or IP-in-IP), the
            value of this object is 1.  For encapsulation methods (such
            as L2F) which allow multiple parallel tunnels, the manager
            is responsible for choosing any ID which does not conflict
            with an existing row, such as choosing a random number."

    ::= { tunnelConfigEntry 4 }

tunnelConfigIfIndex OBJECT-TYPE
    SYNTAX     InterfaceIndexOrZero
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "If the value of tunnelConfigStatus for this row is active,
            then this object contains the value of ifIndex corresponding
            to the tunnel interface.  A value of 0 is not legal in the
            active state, and means that the interface index has not yet
            been assigned."
    ::= { tunnelConfigEntry 5 }

tunnelConfigStatus OBJECT-TYPE
    SYNTAX     RowStatus
    MAX-ACCESS read-create
    STATUS     current
    DESCRIPTION
            "The status of this row, by which new entries may be
            created, or old entries deleted from this table. The agent
            need not support setting this object to createAndWait or
            notInService since there are no other writable objects in
            this table, and writable objects in rows of corresponding
            tables such as the tunnelIfTable may be modified while this
            row is active.

            To create a row in this table for an encapsulation method
            which does not support multiple parallel tunnels with the
            same endpoints, the management station should simply use a
            tunnelConfigID of 1, and set tunnelConfigStatus to
            createAndGo.  For encapsulation methods such as L2F which
            allow multiple parallel tunnels, the management station may
            select a pseudo-random number to use as the tunnelConfigID
            and set tunnelConfigStatus to createAndGo.  In the event
            that this ID is already in use and an inconsistentValue is
            returned in response to the set operation, the management
            station should simply select a new pseudo-random number and
            retry the operation.

            Creating a row in this table will cause an interface index
            to be assigned by the agent in an implementation-dependent
            manner, and corresponding rows will be instantiated in the
            ifTable and the tunnelIfTable.  The status of this row will
            become active as soon as the agent assigns the interface
            index, regardless of whether the interface is operationally
            up.

            Deleting a row in this table will likewise delete the
            corresponding row in the ifTable and in the tunnelIfTable."
    ::= { tunnelConfigEntry 6 }

-- conformance information

tunnelMIBConformance
                  OBJECT IDENTIFIER ::= { tunnelMIB 2 }
tunnelMIBCompliances
                  OBJECT IDENTIFIER ::= { tunnelMIBConformance 1 }
tunnelMIBGroups  OBJECT IDENTIFIER ::= { tunnelMIBConformance 2 }

-- compliance statements

tunnelMIBCompliance MODULE-COMPLIANCE
    STATUS  current
    DESCRIPTION
            "The compliance statement for the IP Tunnel MIB."
    MODULE  -- this module
    MANDATORY-GROUPS { tunnelMIBBasicGroup }

        OBJECT      tunnelIfHopLimit
        MIN-ACCESS  read-only
        DESCRIPTION
            "Write access is not required."

        OBJECT      tunnelIfTOS
        MIN-ACCESS  read-only
        DESCRIPTION
            "Write access is not required."

        OBJECT      tunnelConfigStatus
        MIN-ACCESS  read-only
        DESCRIPTION
            "Write access is not required."
   ::= { tunnelMIBCompliances 1 }

-- units of conformance

tunnelMIBBasicGroup OBJECT-GROUP
    OBJECTS { tunnelIfLocalAddress, tunnelIfRemoteAddress,
       tunnelIfEncapsMethod, tunnelIfHopLimit, tunnelIfTOS,
       tunnelIfSecurity, tunnelConfigIfIndex, tunnelConfigStatus }
    STATUS  current
    DESCRIPTION
            "A collection of objects to support basic management of IP
            Tunnels."
    ::= { tunnelMIBGroups 1 }

END

6. Security Considerations ๐Ÿ”

okay this section is serious, so buckle up ๐Ÿ˜ญ this MIB has readable objects that tell you stuff about IP tunnel interfaces ๐Ÿ‘€ and it also has a bunch of objects with a MAX-ACCESS of read-write and/or read-create, like the ones an admin uses to set up tunnels dynamically ๐Ÿ› ๏ธ

reading the readable stuff without permission is relatively innocuous, lowkey not a big deal ๐Ÿ™ˆ but messing with the writable objects without permission could cause a denial of service, or let someone create or change tunnels they have no business touching ๐Ÿ’€ so supporting SET operations in a non-secure environment, without proper protection, can seriously mess with network operations โ€ผ๏ธ

SNMPv1 by itself is that insecure environment, no cap ๐Ÿ˜ค and even if the network itself is secure (for example by using IPSec [24]), there's still no control over who on that secure network gets to access and SET (change/create/delete) the objects in this MIB ๐Ÿซ 

it is recommended that implementers look at the security features provided by the SNMPv3 framework ๐Ÿ”โœจ specifically, the User-based Security Model RFC 2574 [12] and the View-based Access Control Model RFC 2575 [15] are recommended ๐Ÿ’œ

and then it becomes a customer/user responsibility to make sure the SNMP entity giving access to this MIB is properly configured, so that only the principals (users) with legitimate rights get access to those objects ๐Ÿซถ this part is so important bestie ๐Ÿ’…

7. Acknowledgements ๐ŸŒˆ

this MIB module got updated based on feedback from the IETF's Interfaces MIB (IF-MIB) and Point-to-Point Protocol Extensions (PPPEXT) Working Groups ๐Ÿฆ‹ big thanks to them ๐ŸŽ€

8. Author's Address ๐Ÿง‘โ€๐Ÿ’ป

Dave Thaler is our author, and he's at Microsoft Corporation, so you can reach him here:

Dave Thaler
Microsoft Corporation
One Microsoft Way
Redmond, WA  98052-6399

Phone: +1 425 703 8835
EMail: dthaler@microsoft.com

9. References ๐Ÿ“š

Here's the full reading list, bestie. Every single source that the spec leans on is in here ๐Ÿค“

  • [1] Wijnen, B., Harrington, D. and R. Presuhn, "An Architecture for Describing SNMP Management Frameworks", RFC 2571, April 1999.
  • [2] Rose, M. and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based Internets", STD 16, RFC 1155, May 1990.
  • [3] Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC 1212, March 1991.
  • [4] Rose, M., "A Convention for Defining Traps for use with the SNMP", RFC 1215, March 1991.
  • [5] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
  • [6] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999.
  • [7] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.
  • [8] Case, J., Fedor, M., Schoffstall, M. and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, May 1990.
  • [9] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901, January 1996.
  • [10] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, January 1996.
  • [11] Case, J., Harrington D., Presuhn R. and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2572, April 1999.
  • [12] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2574, April 1999.
  • [13] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, January 1996.
  • [14] Levi, D., Meyer, P. and B. Stewart, "SNMPv3 Applications", RFC 2573, April 1999.
  • [15] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", RFC 2575, April 1999.
  • [16] Hanks, S., Li, T., Farinacci, D. and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 1701, October 1994.
  • [17] Hanks, S., Li, T., Farinacci, D. and P. Traina, "Generic Routing Encapsulation over IPv4 networks", RFC 1702, October 1994.
  • [18] Perkins, C., "IP Encapsulation within IP", RFC 2003, October 1996.
  • [19] Perkins, C., "Minimal Encapsulation within IP", RFC 2004, October 1996.
  • [20] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn, G. and B. Palter, "Layer Two Tunneling Protocol "L2TP"", RFC 2661, August 1999.
  • [21] Hamzeh, K., Pall, G., Verthein, W. Taarud, J., Little, W. and G. Zorn, "Point-to-Point Tunneling Protocol", RFC 2637, July 1999.
  • [22] Hamzeh, K., "Ascend Tunnel Management Protocol - ATMP", RFC 2107, February 1997.
  • [23] McCloghrie, K. and F. Kastenholz. "The Interfaces Group MIB using SMIv2", RFC 2233, November 1997.
  • [24] R. Atkinson, "Security architecture for the internet protocol", RFC 2401, November 1998.
  • [25] Valencia, A., Littlewood, M. and T. Kolar. "Cisco Layer Two Forwarding (Protocol) "L2F"", RFC 2341, May 1998.
  • [26] D. Provan, "Tunneling IPX Traffic through IP Networks", RFC 1234, June 1991.
  • [27] Gilligan, R. and E. Nordmark. "Transition Mechanisms for IPv6 Hosts and Routers", RFC 1933, April 1996.
  • [28] Woodburn, R. and D. Mills, "A Scheme for an Internet Encapsulation Protocol: Version 1", RFC 1241, July 1991.
  • [29] Nichols, K., Blake, S., Baker, F. and D. Black. "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December 1998.

10. Intellectual Property Notice ๐ŸŽ€

Okay, so the IETF doesn't take a position on whether any intellectual property or other rights might apply to the technology in this document, or whether any license under those rights is or isn't available. It also doesn't claim it has tried to find any of those rights. If you want the IETF's procedures for rights in standards-track and standards-related documents, look at BCP-11. Copies of claimed rights that were made available for publication, plus any assurances of licenses that are going to be made available, or the outcome of an attempt to get a general license or permission for implementers or users of this specification, can all be obtained from the IETF Secretariat. ๐Ÿ“

The IETF also invites anyone to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that might cover technology required to practise this standard. Send that information to the IETF Executive Director. ๐Ÿ’Œ

Copyright (C) The Internet Society (1999). All Rights Reserved. ๐ŸŒธ

So this document and its translations can be copied and handed out to others. Derivative works that comment on or explain it, or help with implementing it, can be written, copied, published and distributed, in whole or in part, with no restrictions of any kind. The catch is that the above copyright notice and this paragraph have to be included on all those copies and derivative works. This document itself can't be modified in any way, like removing the copyright notice or references to the Internet Society or other Internet organizations. The one exception is when it's needed for developing Internet standards, in which case the Internet Standards process copyright procedures must be followed, or when it's required to translate it into languages other than English. ๐ŸŒ

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