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Versions: (draft-hartman-nvo3-security-requirements) 00 01 02 03 04 05 06 07

Network Working Group                                         S. Hartman
Internet-Draft                                         Painless Security
Intended status: Experimental                                   D. Zhang
Expires: April 25, 2014                                           Huawei
                                                            M. Wasserman
                                                       Painless Security
                                                        October 22, 2013


                     Security Requirements of NVO3
                draft-ietf-nvo3-security-requirements-01

Abstract

   The draft provides a list of security requirements to benefit the
   design of NOV3 security mechanisms.  In addition, this draft
   introduces the candidate techniques which could be used to fulfill
   such security requirements.

Requirements Language

   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 RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on April 25, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  NVO3 Overlay Architecture . . . . . . . . . . . . . . . . . .   3
   4.  Threat Model  . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Outsider Capabilities . . . . . . . . . . . . . . . . . .   4
     4.2.  Insider Capabilities  . . . . . . . . . . . . . . . . . .   5
     4.3.  Security Issues In Scope and Out of Scope . . . . . . . .   5
   5.  Security Requirements and Candidate Approaches  . . . . . . .   6
     5.1.  Control/Data Traffic within Overlay . . . . . . . . . . .   6
       5.1.1.  Control Plane Security  . . . . . . . . . . . . . . .   6
       5.1.2.  Data Plane  . . . . . . . . . . . . . . . . . . . . .   9
     5.2.  Control/Data Traffic between NVEs and Hypervisors . . . .  10
       5.2.1.  Distributed Deployment of NVE and Hypervisor  . . . .  11
     5.3.  Key Management  . . . . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Security is a key issue which needs to be considered in the design of
   a data center network.  This document discusses the security risks
   that a NVO3 network may encounter and the security requirements that
   a NVO3 network needs to fulfill.  In addition, this draft attempts to
   discuss the security techniques which could be applied to fulfill
   such requirements.









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   The remainder of this document is organized as follows.  Section 2
   introduces the terms used in this memo.  Section 3 gives a briefly
   introduction of the NVO3 network architecture.  Section 4 discusses
   the attack model of this work.  Section 5 describes the essential
   security requirements which should be fulfilled in the generation of
   a NVO3 network.

2.  Terminology

   This document uses the same terminology as found in the NVO3
   Framework document [I-D.ietf-nvo3-framework] and
   [I-D.kreeger-nvo3-hypervisor-nve-cp].  Some of the terms defined in
   the framework document have been repeated in this section for the
   convenience of the reader, along with additional terminology that is
   used by this document.

   Tenant System (TS): A physical or virtual system that can play the
   role of a host, or a forwarding element such as a router, switch,
   firewall, etc.  It belongs to a single tenant and connects to one or
   more VNs of that tenant.

   End System (ES): An end system of a tenant, which can be, e.g., a
   virtual machine(VM), a non-virtualized server, or a physical
   appliance.  A TS is attached to a Network Virtualization Edge(NVE)
   node.

   Network Virtualization Edge (NVE): An NVE implements network
   virtualization functions that allow for L2/L3 tenant separation and
   tenant-related control plane activity.  An NVE contains one or more
   tenant service instances whereby a TS interfaces with its associated
   instance.  The NVE also provides tunneling overlay functions.

   Virtual Network (VN): This is a virtual L2 or L3 domain that belongs
   to a tenant.

   Network Virtualization Authority (NVA).  A back-end system that is
   responsible for distributing and maintaining the mapping information
   for the entire overlay system.  Note that the WG never reached
   consensus on what to call this architectural entity within the
   overlay system, so this term is subject to change.

   NVO3 device: In this memo, the devices (e.g., NVE and NVA) work
   cooperatively to provide NVO3 overlay functionalities are called as
   NOV3 devices.

3.  NVO3 Overlay Architecture





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                      ..................................
                      .                                .
                      .                                .
                      .                                .
                    +-+--+                          +--+-++--------+
    +--------+      | NV |                          | NV || Tenant |
    | Tenant +------+Edge|       L3 Overlay         |Edge|| System |
    | System |      +-+--+        Network           +--+-++--------+
    +--------+        .                                .
                      .                                .
                      .                                .
                      ..................................



   This figure illustrates a simple nov3 overlay example where NVEs
   provide a logical L2/L3 interconnect for the TSes that belong to a
   specific tenant network over L3 networks.  A packet from a tenant
   system is encapsulated when they reach the egress NVE.  Then
   encapsulated packet is then sent to the remote NVE through a proper
   tunnel.  When reaching the ingress NVE, the packet is decapsulated
   and forwarded to the target tenant system.  The address
   advertisements and tunnel mappings are distributed among the NVEs
   through either distributed control protocols or by certain
   centralized servers (called NVAs).

4.  Threat Model

   To benefit the discussion, in this analysis work, attacks are
   classified into two categories: inside attacks and outside attacks.
   An attack is considered as an inside attack if the adversary
   performing the attack (inside attacker or insider) has got certain
   privileges in changing the configuration or software of a NVO3 device
   and initiates the attack within the overlay security perimeter.  In
   contrast, an attack is referred to as an outside attack if the
   adversary performing the attack (outside attacker or outsider) has no
   such privilege and can only initiate the attacks from compromised
   TSes (or the network devices of the underlying network which the
   overlay is located upon).  Note that in a complex attack inside and
   outside attacking operations may be performed in a well organized way
   to expand the damages caused by the attack.

4.1.  Outsider Capabilities

   The following capabilities of outside attackers MUST be considered in
   the design of a NOV3 security mechanism:

   1.  Eavesdropping on the packets,



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   2.  Replaying the intercepted packets, and

   3.  Generating illegal packets and injecting them into the network.

   With a successful outside attack, an attacker may be able to:

   1.  Analyze the traffic pattern within the network,

   2.  Disrupt the network connectivity or degrade the network service
       quality, or

   3.  Access the contents of the data/control packets if they are not
       properly encrypted.

4.2.  Insider Capabilities

   It is assumed that an inside attacker can perform any types of
   outside attacks from the inside or outside of the overlay perimeter.
   In addition, in an inside attack, an attacker may use already
   obtained privilege to, for instance,

   1.  Interfere with the normal operations of the overlay as a legal
       entity, by sending packets containing invalid information or with
       improper frequencies,

   2.  Perform spoofing attacks and impersonate another legal device to
       communicate with victims using the cryptographic information it
       obtained, and

   3.  Access the contents of the data/control packets if they are
       encrypted with the keys held by the attacker.

4.3.  Security Issues In Scope and Out of Scope

   During the specification of security requirements, the following
   security issues needs to be considered:

   1.  Insecure underlying network.  It is normally assumed that a
       underlying network connecting NOV3 devices (NVEs and NVAs) is
       secure if it is located within a data center and cannot be
       directly accessed by tenants.  However, in a virtual data center
       scenario, a NVO3 overlay scatters across different sites which
       are connected through the public network.  Outside attacks may be
       raised from the underlying network.

   2.  Insider attacker.  During the design of a security solution for a
       NVO3 network, the inside attacks raised from compromised NVO3
       devices (NVEs and NVAs) needs to be considered.



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   3.  Insecure tenant network.  It is reasonable to consider the
       conditions where the network connecting TSes and NVEs is
       accessible to outside attackers.

   The following issues are out of scope of cosideration in this
   document:

   1.  In this memo it is assumed that security protocols, algorithms,
       and implementations provide the security properties for which
       they are designed; attacks depending on a failure of this
       assumption are out of scope.  As an example, an attack caused by
       a weakness in a cryptographic algorithm is out of scope, while an
       attack caused by failure to use confidentiality when
       confidentiality is a security requirement is in scope.

   2.  In practice an attacker controlling an underlying network device
       may break the communication of the overlays by discarding or
       delaying the delivery of the packets passing through it.
       However, this type of attack is out of scope.

5.  Security Requirements and Candidate Approaches

   This section introduces the security requirements and candidate
   solutions.

5.1.  Control/Data Traffic within Overlay

   This section analyzes the security issues in the control and data
   plans of a NVO3 overlay.

5.1.1.  Control Plane Security

   REQ1:  A NVO3 security solution MUST enable two NOV3 devices (NVE or
      NVA) to perform mutual authentication before exchanging control
      packets.

      This requirement is used to prevent an attacker from impersonating
      a legal NVO3 device and sending out bogus control packets without
      being detected.

      The authentication between devices can be performed as a part of
      automated key management protocols (e.g., IKEv2[RFC5996],
      EAP[RFC4137], etc.).  After such an authentication procedure, an
      device can find out whether its peer holds valid security
      credentials and is the one who it has claimed.  Additionally, the
      keys shared between the devices can be also used for the
      authentication purpose.  For instance, assumed a NVE and a NVA
      have shared a secret key without known by any other third parties.



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      The NVE can ensure that a device that it is communicating with is
      the NVA if the device can prove that it possesses the shared key.

      a: The identity of the network devices SHOULD be verified during
      authentication.

      In some authentication mechanisms, instead of verifying the peers'
      identities, the authentication result can only prove that a device
      joining the authentication is a legal member of a group.  However,
      for a better damage confining capability to insider attacker, it
      is recommended to verify the devices' identities during
      authentication.  Therefore, an insider attacker cannot impersonate
      others, even when it holds legal credentials or keys.

   REQ2:  Before accepting a control packet, the device receiving the
      packet MUST verify whether the packet comes from one which has the
      privilege to send that packet.

      This is an authorization requirement.  A device needs to clarify
      the roles (e.g., a NVE or a NVA) that its authentication peer acts
      as in the overlay.  Therefore, if a compromised NVE uses it
      credentials to impersonate a NVA to communicate with other NVEs,
      it will be detected.  In addition, authorization is important for
      enforcing the VN isolation, a device only can distribute control
      packets within the VNs it is involved within.  If a control packet
      about a VN is sent from a NVE which is not authorized to support
      the VN, the packet will not be accepted

      Normally, it is assumed that the access control operations are
      based on the authentication results.  The simple authorization
      mechanisms (such as ACLs which filters packets based on the packet
      addresses) can be used as auxiliary approaches since they are
      relatively easy to bypass if attackers can access to the network
      and modify packets.

   REQ3:  Integrity, confidentiality, and origin Authentication
      protection for Control traffics

      It is the responsibility of a NVO3 overlay to protect the control
      packets transported over the overlay against the attacks raised
      from the underlying network.

      a: The integrity and origin authentication of the packets MUST be
      guaranteed.

      With this requirement, the receiver can ensure that the packets
      are from the legitimate sender, not replayed, and not modified
      during the transportation.



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      b: The signaling packets SHOULD be encrypted.

      On many occasions, the signaling packets can be transported in
      plaintext.  However, In the cases where the information contained
      within the signaling packets are sensitive or valuable to
      attackers , the signaling packets related with that tenant need be
      encrypted.

      To achieve such objectives, when the network devices exchange
      control plane packets, integrated security mechanisms or
      underlying security protocols need to provided.  In addition,
      cryptographic keys need to be deployed manually in advance or
      dynamically generated by using certain automatic key management
      protocols (e.g., TLS [RFC5246]).  The keys are used to generate
      digests for or encrypt control packets.

   REQ4:  The toleration of DOS attacks

      a: Frequency in distributing control packets within in the overlay
      MUST be limited.

      The issues within DOS attacks also need to be considered in
      designing the overlay control plane.  For instance, in the VXLAN
      solution[I-D.mahalingam-dutt-dcops-vxlan], an attacker attached to
      a NVE can try to manipulate the NVE to keep multicasting control
      packets by sending a large amount of ARP packets to query the
      inexistent VMs.  In order to mitigate this type of attack, the
      NVEs SHOULD be only allowed to send signaling packet in the
      overlay with a limited frequency.  When there are centralized
      servers (e.g., the backend oracles providing mapping information
      for NVEs[I-D.ietf-nvo3-overlay-problem-statement], or the SDN
      controllers) are located within the overlay, the potential
      security risks caused by DDOS attack on such servers can be more
      serious.

      b: Mitigation of amplification attacks SHOULD be provided.

      During the design of the control plane, it is important to
      consider the amplification effects.  For instance, if NVEs may
      generate a large response to a short request, an attacker may send
      spoofed requests to the NVEs with the source address of a victim.
      Then the NVEs will send the response to the victim and result in
      DDOS attacks.

      If the amplification effect cannot be avoided in the control
      protocol, the requirements 1,2,3, and 4a can all be used to
      benefit the mitigation of this type of attacks.




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   REQ5:  The key management solution MUST be able to confine the scope
      of key distribution and provide different keys to isolate the
      control traffic according to different security requirements.

      a: It SHOULD be guaranteed that different keys are used to secure
      the control packets exchanged within different tenant networks.

      This requirement can be used to provide a basic attack confinement
      capability.  The compromise of a NVE working within a tenant will
      not result in the key leakage of other tenant networks.

      b: It SHOULD be guaranteed that different keys are used to secure
      the control packets exchanges with different VNs.

      This requirement can be used to provide a better attack
      confinement capability for the control plane.  The compromise of a
      NVE working within a VN will not result in the key leakage of
      other VNs.  However, since there is only a single key used for
      securing the data traffic within a VN, an attacker which has
      compromised a NVE within the VN may be able to impersonate any
      other NVEs within the VN to send out bogus control packets.  In
      addition, the key management overheads introduced by key
      revocation also need to be considered[RFC4046].  When a NVE stops
      severing a VN, the key used for the VN needs to be revoked, and a
      new key needs to be distributed for the NVO3 devices still within
      the VN.

      If we expect to provide a even stronger confinement capability and
      prevent a compromised NVE from impersonating other NVEs even when
      they are in the same VN, different NVEs working inside a VN need
      to secure their signaling packets with different keys.

      If there is automated key management deployed, the authentication
      and authorization can be used to largely mitigate the isolation
      issues.  When a NVE attempts to join a VN, the NVE needs to be
      authenticated and prove that it have sufficient privileges.  Then,
      a new key (or a set of keys) will be generated to secure its
      control packet exchanged with this VN.

5.1.2.  Data Plane

   [I-D.ietf-nvo3-framework] specifies a NVO3 overlay needs to generate
   tunnels between NVEs for data transportation.  When a data packet
   reaches the boundary of a overlay, it will be encapsulated and
   forwarded to the destination NVE through a proper tunnel.

   REQ6:  Integrity, confidentiality, and origin authentication
      protection for data traffics



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      a: The integrity and origin authentication of data traffics MUST
      be guaranteed when the underlying network is not secure.

      During the transportation of data packets, it is the
      responsibility of the NVO3 overlay to deal with the attacks from
      the underlying network.  For instance, an inside attacker
      compromising a underlying network device may intercept an
      encapsulated data packet transported within a tunnel, modify the
      contents in the encapsulating tunnel packet and, transfer it into
      another tunnel without being detected.  When the modified packet
      reaches a NVE, the NVE may decapsulated the data packet and
      forward it into a VN according to the information within the
      encapsulating header generated by the attacker.  Similarly, a
      compromised NVE may try to redirect the data packets within a VN
      into another VN by adding improper encapsulating tunnel headers to
      the data packets.

      Under such circumstances, in order to enforce the VN isolation
      property, underlying security protocols need to provided.
      Signatures or digests need to be generated for both data packets
      and the encapsulating tunnel headers in order to provide data
      origin authentication and integrity protection.

      b: The confidentiality protection of data traffics SHOULD be
      provided, when the underlying network is not secure.

      If the data traffics from the TSes is sensitive, they needs to be
      encrypted during the tunnels.  However, if the data traffics is
      not valuable and sensitive, the encryption is not necessary.

   REQ7:  Different tunnels SHOULD be secured with different keys

      This requirement can be used to provide a basic attack confinement
      capability.  When different tunnels secured with different keys,
      the compromise of a key in a tunnel will not affect the security
      of others.

5.2.  Control/Data Traffic between NVEs and Hypervisors

   Assume there is a VNE providing a logical L2/L3 interconnect for a
   set of TSes.  Apart from data traffics, the NVE and certain TSes
   (i.e., Hypervisors) also need to exchange signaling packets in order
   to facilitate, e.g., VM online detection, VM migration detection, or
   auto-provisioning/service discovery [I-D.ietf-nvo3-framework].







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   The NVE and its associated TSes can be deployed in a distributed way
   (e.g., a NVE is implemented in an individual device, and VMs are
   located on servers) or in a co-located way (e.g., a NVE and the TSes
   it serves are located on the same server).

5.2.1.  Distributed Deployment of NVE and Hypervisor

   In this case, the data and control traffic between the NVE and the
   TSes are exchanged over network.

5.2.1.1.  Control Plane

   REQ8:  Mutual authentication MUST be performed between a NVE and a TS
      at the beginning of their communication, if the network connecting
      them is not secure.

      Mutual authentication is used to guarantee that an attacker cannot
      impersonate a legal NVE or a hypervisor without being detected.

      There are various ways to perform mutual authentication.  If there
      are auto key management mechanism (e.g., IKEv2, EAP), the NVE and
      the TS can use their credential to perform authentication.  If
      there a key pre-distributed between a NVE and a TS, an entity can
      also use the key verify the identity of is remote peer.

      If practice, a NVE and a TS may simply use IP or MAC addresses to
      identify each other.  This type of technique can be used as a
      complementary approach although it may becomes vulnerable if
      attackers can inject bogus control packets the network and modify
      the packets transported between the NVE and TS.

   REQ9:  Before accepting a control packet, the receiver device MUST
      verify whether the packet comes from one which has the privilege
      to send that packet.

      This is an authorization requirement.  A device needs to clarify
      the roles (e.g., a TS or a NVE) of the device that it is
      communicating with.  Therefore, if a compromised TS attempts to
      use it credentials to impersonate a NVE to communicate with other
      TSes, it will be detected.

      Authorization is very important to guarantee the isolation
      property.  For instance, if a compromised hypervisor tries to
      elevate its privilege and interfere the VNs that it is not
      supposed to be involved within, its attempt will be detected and
      rejected.





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      Normally, it is assumed that the access control operations are
      based on the authentication results.  The simple authorization
      mechanisms (such as ACLs which filters packets based on the packet
      addresses) can be used as complementary solutions.

   REQ10:  Integrity, Confidentiality, and Origin Authentication for
      Control Packets

      a:The security solution of a NVE network MUST be able to provide
      integrity protection and origin authentication for the control
      packets exchanged between a NVE and a TS if they have to use an
      insecure network to transport their packet.

      This requirement can prevent an attacker from illegally interfere
      with the normal operations of NVEs and TSes by injecting bogus
      control packets into the network.

      b:The confidentiality protection for the control packet exchange
      SHOULD be provided.

      When the contents of the control packets (e.g., the location of a
      ES, when a VM migration happens) are sensitive to a tenant, the
      control packet needs to be encrypted.

      There are various security protocols (such as IPsec, SSL, and TCP-
      AO) can be used for transport control packets.  In addition, it is
      possible to define integrated security solutions for the control
      packets.

      In order to secure the control traffic, cryptographic keys need to
      be distributed to generate digests or signatures for the control
      packets.  Such cryptographic keys can be manually deployed in
      advance or dynamically generated with certain automatic key
      management protocols (e.g., TLS [RFC5246]).

   REQ11:  The key management solution MUST be able to confine the scope
      of key distribution and provide different keys to isolate the
      control traffic according to different security requirements.

      a: If assuming TSes (hypervisors) will not be compromised, the
      TSes belonging to different Tenants MUST use different keys to
      secure the control packet exchanges with their NVE.









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      This requirement is used to enforce the security boundaries of
      different tenant networks.  Since different tenants belong to
      different security domains and may be competitive to each other,
      the control plane traffics need to be carefully isolated so that
      an attacker from a tenant cannot affect the operations of another
      tenant network.

      b: If assuming the hypervisors can be compromised, the TSes
      belonging to different VNs MUST use different keys to secure the
      control packets exchanges with their NVE.

      Therefore, if a key used for a VN is compromised, other VNs will
      not be affected.  This requirement is used to ensure the VN
      isolation property.

5.2.1.2.  Data Plane

   REQ12:  The data traffic isolation of different VNs MUST be
      guaranteed.

      In [I-D.ietf-nvo3-overlay-problem-statement], the data plane
      isolation requirement amongst different VNs has been discussed.
      The traffic within a virtual network can only be transited into
      another one in a controlled fashion (e.g., via a configured router
      and/or a security gateway).  Therefore, if the NVE supports
      multiple VNs concurrently, the data traffic in different VNs MUST
      be isolated.

      a:The security solution of a NVE network MUST be able to provide
      integrity protection and origin authentication for the data
      packets exchanged between a NVE and a TS if they have to use an
      insecure network to transport their data packet.

      In practice, the data traffics in different VNs can be isolated
      physically or by using VPN technologies.  If the network
      connecting the NVE and the TSes is potentially accessible to
      attackers, security solutions need to be considered to prevent an
      attacker locating in the middle between the NVE and TS from
      modifying the VN identification information in the packet headers
      so as to manipulate the NVE to transport the data packets within a
      VN to another.  The security protocols such as IPsec and TCP-AO,
      can be used to enforce the isolation property if necessary.

   The key management requirement R11 can be applied here for data
   traffic

5.3.  Key Management




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   REQ13:  A security solution for NVO3 SHOULD provide automated key
      management mechanisms.

      In the cases where there are a large amount of NVEs working within
      a NVO3 overlay, manual key management may become infeasible.
      First, it could be burdensome to deploy pre-shared keys for
      thousands of NVEs, not to mention that multiple keys may need to
      be deployed on a single device for different purposes.  Key
      derivation can be used to mitigate this problem.  Using key
      derivation functions, multiple keys for different usages can be
      derived from a pre-shared master key.  However, key derivation
      cannot protect against the situation where a system was
      incorrectly trusted to have the key used to perform the
      derivation.  If the master key were somehow compromised, all the
      resulting keys would need to be changed [RFC4301].  In addition,
      VM migration will introduce challenges to manual key management.
      The migration of a VM in a VN may cause the change of the NVEs
      which are involved within the NV.  When a NVE is newly involved
      within a VN, it needs to get the key to join the operations within
      the VN.  If a NVE stops supporting a VN, it should not keep the
      keys associated with that VN.  All those key updates need to be
      performed at run time, and difficult to be handled by human
      beings.  As a result, it is reasonable to introduce automated key
      management solutions such as EAP [RFC4137] for NVO3 overlays.

      Without the support automated key management mechanisms, some
      security functions of certain security protocols cannot work
      properly.  For instance, the anti-replay mechanism of IPsec is
      turned off without the support of automated key management
      mechanisms.  Therefore, if IPsec is selected to protect the
      control packets.  In this case, the system may suffer from the
      replay attacks.

6.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.

7.  Security Considerations

   TBD

8.  Acknowledgements

   Thanks a lot for the comments from Melinda Shore, and Zu Qiang.




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9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

9.2.  Informative References

   [I-D.ietf-ipsecme-ad-vpn-problem]
              Manral, V. and S. Hanna, "Auto Discovery VPN Problem
              Statement and Requirements", draft-ietf-ipsecme-ad-vpn-
              problem-09 (work in progress), July 2013.

   [I-D.ietf-nvo3-framework]
              Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
              Rekhter, "Framework for DC Network Virtualization", draft-
              ietf-nvo3-framework-03 (work in progress), July 2013.

   [I-D.ietf-nvo3-overlay-problem-statement]
              Narten, T., Gray, E., Black, D., Fang, L., Kreeger, L.,
              and M. Napierala, "Problem Statement: Overlays for Network
              Virtualization", draft-ietf-nvo3-overlay-problem-
              statement-04 (work in progress), July 2013.

   [I-D.kreeger-nvo3-hypervisor-nve-cp]
              Kreeger, L., Narten, T., and D. Black, "Network
              Virtualization Hypervisor-to-NVE Overlay Control Protocol
              Requirements", draft-kreeger-nvo3-hypervisor-nve-cp-01
              (work in progress), February 2013.

   [I-D.mahalingam-dutt-dcops-vxlan]
              Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "VXLAN: A
              Framework for Overlaying Virtualized Layer 2 Networks over
              Layer 3 Networks", draft-mahalingam-dutt-dcops-vxlan-05
              (work in progress), October 2013.

   [RFC4046]  Baugher, M., Canetti, R., Dondeti, L., and F. Lindholm,
              "Multicast Security (MSEC) Group Key Management
              Architecture", RFC 4046, April 2005.

   [RFC4137]  Vollbrecht, J., Eronen, P., Petroni, N., and Y. Ohba,
              "State Machines for Extensible Authentication Protocol
              (EAP) Peer and Authenticator", RFC 4137, August 2005.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.



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   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
              "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
              5996, September 2010.

Authors' Addresses

   Sam Hartman
   Painless Security
   356 Abbott Street
   North Andover, MA  01845
   USA

   Email: hartmans@painless-security.com
   URI:   http://www.painless-security.com


   Dacheng Zhang
   Huawei
   Beijing
   China

   Email: zhangdacheng@huawei.com


   Margaret Wasserman
   Painless Security
   356 Abbott Street
   North Andover, MA  01845
   USA

   Phone: +1 781 405 7464
   Email: mrw@painless-security.com
   URI:   http://www.painless-security.com















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