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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 30, 2015                                           Huawei
                                                            M. Wasserman
                                                       Painless Security
                                                        October 27, 2014


                     Security Requirements of NVO3
                draft-ietf-nvo3-security-requirements-03

Abstract

   The draft describes a list of essential requirements in order to
   benefit the design of NOV3 security solutions.  In addition, this
   draft introduces the candidate techniques which could be used to
   construct a security solution fulfilling these 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 30, 2015.

Copyright Notice

   Copyright (c) 2014 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 . . . . . . . . . . . . . . . . . .   4
   4.  Threat Model  . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Capabilities of Outsiders . . . . . . . . . . . . . . . .   5
     4.2.  Capabilities of Insiders  . . . . . . . . . . . . . . . .   5
     4.3.  Capabilities of Malicious TSes  . . . . . . . . . . . . .   6
     4.4.  Security Issues In Scope and Out of Scope . . . . . . . .   6
   5.  Security Requirements . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Control/Data Plane of NVO3 Overlay  . . . . . . . . . . .   7
       5.1.1.  NVE-NVA Control Plane . . . . . . . . . . . . . . . .   7
       5.1.2.  NVA-NVA Control Plane . . . . . . . . . . . . . . . .   9
       5.1.3.  NVE-NVE Control Plane . . . . . . . . . . . . . . . .  10
       5.1.4.  NVE-NVE Data Plane  . . . . . . . . . . . . . . . . .  10
     5.2.  Control/Data Plane between NVEs and Hypervisors . . . . .  12
       5.2.1.  Distributed Deployment of NVE and Hypervisor  . . . .  12
   6.  Candidate Techniques  . . . . . . . . . . . . . . . . . . . .  15
     6.1.  Entity Authentication . . . . . . . . . . . . . . . . . .  15
     6.2.  Packet Level Security . . . . . . . . . . . . . . . . . .  15
     6.3.  Authorization . . . . . . . . . . . . . . . . . . . . . .  15
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
     8.1.  Automated Key Management in NVO3  . . . . . . . . . . . .  16
     8.2.  Issues not Discussed  . . . . . . . . . . . . . . . . . .  16
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  17
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     10.2.  Informative References . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   Security is a key issue which needs to be considered during the
   design of a data center network.  This document discusses the
   security risks that a NVO3 network may encounter and tries to provide
   a list of essential security requirements that a NVO3 network needs



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   to fulfill.  In addition, this draft introduces the candidate
   techniques which could be potentially used to construct a security
   solution fulfilling the security requirements.

   The remainder of this document is organized as follows.  Section 2
   introduces several key terms used in this memo.  Section 3 gives a
   brief introduction of the NVO3 network architecture.  Section 4
   discusses the attack model of this work.  Section 5 provides a list
   of security requirements as well as the associated justifications.
   In Section 6, the candidate techniques are introduced.

2.  Terminology

   This document uses the same terminology as found in the NVO3
   Framework document [RFC7365] and [I-D.ietf-nvo3-hpvr2nve-cp-req].
   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.

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






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3.  NVO3 Overlay Architecture

                +--------+                                    +--------+
                | Tenant +--+                            +----| Tenant |
                | System |  |                           (')   | System |
                +--------+  |    .................     (   )  +--------+
                            |  +---+           +---+    (_)
                            +--|NVE|---+   +---|NVE|-----+
                               +---+   |   |   +---+
                               / .    +-----+      .
                              /  . +--| NVA |      .
                             /   . |  +-----+      .
                            |    . |               .
                            |    . |  L3 Overlay +--+--++--------+
                +--------+  |    . |   Network   | NVE || Tenant |
                | Tenant +--+    . |             |     || System |
                | System |       .  \ +---+      +--+--++--------+
                +--------+       .....|NVE|.........
                                      +---+
                                        |
                                        |
                              =====================
                                |               |
                            +--------+      +--------+
                            | Tenant |      | Tenant |
                            | System |      | System |
                            +--------+      +--------+

   Figure 1: Generic Reference Model for DC Network Virtualization
   Overlays [RFC7365]

   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 ingress NVE.  Then
   encapsulated packet is then sent to the remote NVE through a proper
   tunnel.  When reaching the egress NVE of the tunnel, the packet is
   decapsulated and forwarded to the target tenant system.  The address
   advertisements and tunnel mappings are distributed to the NVEs by a
   logically centralized server (i.e., NVA).

4.  Threat Model

   To benefit describing the threats a NVO3 network may have to face,
   the attacks considered in this document are classified into three
   categories: the attacks from compromised NVO3 devices (inside
   attacks), the attacks from compromised tenant systems, and the
   attacks from underlying networks (outside attacks).



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   The adversaries performing the first type of attack are called as
   insiders or inside attackers because they need to get certain
   privileges in changing the configuration or software of NVO3 devices
   beforehand and initiate the attacks within the overlay security
   perimeter.  In the second type of attack, an attacker (e.g., a
   malicious tenant, or an attacker who has compromised a virtual
   machine of an innocent tenant) has got certain privileges in changing
   the configuration or software of tenant systems and attempts to
   manipulate the controlled tenant systems to interfere with the normal
   operations of the NVO3 overlay.  The third type of attack is referred
   to as the outside attack since adversaries do not have to obtain any
   privilege on the NVO3 devices or tenant systems in advance in order
   to perform this type attack, and thus the adversaries performing
   outside attacks are called as outside attackers or outsiders.

4.1.  Capabilities of Outsiders

   In practice, an outside attacker may perform attacks by intercepting
   packets, deleting packets, and/or inserting bogus packets.  With a
   successful outside attack, an attacker may be able to:

   1.  Analyze the traffic pattern within the network by performing
       passive attacks,

   2.  Disrupt the network connectivity or degrade the network service
       quality (e.g., by performing DoS attacks), or

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

4.2.  Capabilities of Insiders

   Besides intercepting packets, deleting packets, and/or inserting
   bogus packets, an inside attacker may use already obtained privilege
   to,

   1.  Interfere with the normal operations of the overlay as a legal
       NVO3 device, by sending packets containing invalid information or
       with improper frequencies,

   2.  Perform spoofing attacks and impersonate another legal NVO3
       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.





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4.3.  Capabilities of Malicious TSes

   It is assumed that the attacker performing attacks from compromised
   TSes is able to intercept packets, delete packets, and/or insert
   bogus packets.  In addition, after compromising a TS, an attacker may
   be able to:

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

   2.  Perform spoofing attacks and impersonate another legal TS or NVE
       to communicate with victims (other legal NVEs or TSes) 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.

4.4.  Security Issues In Scope and Out of Scope

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

   1.  A underlying network connecting NOV3 devices (NVEs and NVAs) is
       relatively secure if it is located within a data center and
       cannot be directly accessed by any tenants or outsiders.
       However, a NVO3 overlay for virtual data center may scatter
       across different geographically distributed sites which are
       connected through the public Internet.  In this case, outside
       attacks may be raised from the underlying network connecting NVO3
       devices.

   2.  During the design of a security solution for a NVO3 network, the
       attacks raised from compromised NVEs and hypervisors needs to be
       considered.

   3.  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 consideration 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.  For instance, an attack caused by a
       weakness in a cryptographic algorithm is out of scope, while an




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       attack caused by failure to use confidentiality when
       confidentiality is a security requirement is in scope.

   2.  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.  This type of attack
       is out of scope of this memo.

   3.  NVAs are centralized servers and play a critical role in NVO3
       overlays.  A NVE will believe in the mapping information obtained
       from its NVA.  After compromising a NVA, the attacker can
       distribute bogus mapping information to NVEs under the management
       of NVA.  This work does not consider how to deal with this
       problem.

5.  Security Requirements

5.1.  Control/Data Plane of NVO3 Overlay

   In this section, the security requirements associated with the NVE-
   NVA control plane, the NVA-NVA control plane, and the NVE-NVE data
   plane are proposed.

5.1.1.  NVE-NVA Control Plane

   In a NVE-NVA control plane, it is assumed that a NVE only exchanges
   control traffics with its NVA using unicast.

   REQ 1:  The security solution for NVO3 SHOULD enable two NVO3 devices
      to mutually authenticate each other.

      Entity authentication can protect a network device against
      imposter attacks and then reduce the risk of DoS attacks and man-
      in-the-middle attacks.  In addition, a successful authentication
      normally results in the distribution key materials for the
      security protection for subsequent communications.  Note that in
      the circumstance where no authentication protocols are applied
      there could be no entity authentication and communicating NOV3
      devices use message authentication mechanisms to verify each
      other's identity.  More detailed discussions are provided in
      Section 8.1.

   REQ 2:  The security solution of NVO3 MUST be able to provide
      integrity protection, replay protection, and packet origin
      authentication for the control packets.

      Unlike entity authentication mentioned in REQ 1, message
      authentication is performed on each incoming packet.  Through



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      message authentication, the NOV3 device receiving a control packet
      can verify whether the packet is generated by a legitimate NVO3
      device, is not antique, and is not tampered during transportation.
      Such protection be deployed when the control packets could be
      accessed by outside attackers.  In addition, with the support of
      properly distributed keys, these level protection can also benefit
      the detection of spoofing attacks raised from insiders.

   REQ 3:  The security solution of a NVO3 network MAY provide
      confidentiality protection for the control packets.

      On many occasions, the control packets can be transported in
      plaintext.  However, under the circumstances where some
      information contained within the control packets is considered to
      be sensitive or valuable, the information needs to be encrypted in
      order to prevent outsiders from accessing the sensitive data. when
      the underlying network is not secure.  Note that encryption will
      impose additional overhead in processing control packets and make
      NVAs more vulnerable to DoS/DDoS attacks.

   REQ 4:  Before adopting the information within a control packet, a
      NOV3 device receiving the packet MUST be able to verify whether
      the packet comes from one who has the privilege to send that
      packet.

      When receiving a control packet, besides authentication,
      authorization needs to be carried out by the receiver to identify
      the role that the packet sender acts as in the overlay and then
      assess the sender's privileges.  If a compromised NVE tries to
      illegally elevate its privilege (e.g., using its credentials to
      communicate with other NVEs as a NVA, or attempting to access the
      mapping information of the VNs which it is not authorized to
      serve), it will be detected and rejected.

   REQ 5:  The security solution of NVO3 SHOULD be able to provide
      distinct keys to protect the unicast control traffics exchanged
      between a NVA and different NVEs respectively.

      During the exchange of control packets, keys are critical in
      authenticating the packet senders.  The purpose of this
      requirement is to provide a basic capability to confine the damage
      caused by inside attacks.  After compromising a NVE, an attacker
      will not be able to use the keys it obtained to breach the
      security of the control traffics exchanged between the NVA and
      other NVEs.

   In a NVO3 overlay, NVAs can be the valuable targets of DoS/DDoS
   attacks, and large amount of NVEs can be potentially used as



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   reflectors in reflection attacks.  Therefore, the DoS/DDoS risks
   needs be considered during designing the control planes for NOV3.
   The following two requirements are used to benefit the migration of
   DoS/DDoS issue.

   REQ 6:  A NVO3 device MUST send its control packets with limited
      frequencies.

      Without this limitation, an attacker can attempt to perform DDoS
      attacks to exhaust the limited computing and memory resources of a
      NVA by manipulating the NVEs attached to the NVA to generate a
      significant member of mapping queries in a short period.

   REQ 7:  The amplification effect SHOULD be avoided

      If in certain conditions the responses generated by a NVE are much
      longer than the received requests, the NVE may be taken advantage
      of by an attacker as a reflector to carry out DDoS attacks.
      Specifically, the attacker can concurrently send out a large
      amount of spoofed short requests to multiple NVEs with the source
      address of a victim (e.g., a NVA).  The responses generated by the
      NVEs will be forwarded to the victim and overwhelm the victim's
      processing capability.

5.1.2.  NVA-NVA Control Plane

   Multiple NVAs may be deployed in a NVO3 overlay for better
   scalability and fault tolerance capability.  The NVAs may use unicast
   and/or multicast to exchange signaling packets within the control
   plane.

   Except the key deployment requirement (REQ 5), all the other
   requirements in the NVE-NVA control plane (REQs 1,2,3,4, 6, and 7)
   are applicable in the NVA-NVA control plane as well.  Before two NVA
   communicate with each other, they should be able to mutually
   authenticated.  In addition, message authentication can help a NVO3
   device to verify the authenticity of the received packets, and the
   sensitive information in the control packets need to be encrypted.
   Authorization is important to filter the invalid control packets and
   any un-privileged requests.  Moreover, the approach to mitigating
   DoS/DDoS attacks needs to be considered in the control plane
   protocols.

   The key deployment requirements for the NVA-NVA control plane are
   described as follows:






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   REQ 8:  The security solution of NVO3 SHOULD be able to provide
      different keys to protect the unicast control traffics exchanged
      between different NVO3 devices respectively.

      The purpose of this requirement is to provide a basic capability
      to confine the damage caused by compromised key.  The compromise
      of a key will not affect the traffics protected by other keys.

   REQ 9:  If there are multicast packets, the security solution of NVO3
      SHOULD be able to assign distinct cryptographic group keys to
      protect the multicast packets exchanged among the NVO3 devices
      within different multicast groups.

      In order to provide an essential packet level security protection
      specified in REQs 2 and 3, at least a group key may need to be
      shared among the NVEs in a same mutlicast group.  It is
      recommended to use different keys for different mutlicast groups.

5.1.3.  NVE-NVE Control Plane

   As specified in [RFC7365], in order to obtain reachability
   information, NVEs may exchange information directly between
   themselves via a control-plane protocol.

   The requirements in the NVA-NVA control plane (REQs 1,2,3,4, 6, 7,8,
   and 9) are applicable in the NVE-NVE control plane as well.

5.1.4.  NVE-NVE Data Plane

   As specified in [RFC7365], a NVO3 overlay needs to generate tunnels
   between NVEs for data packet transportation.  When a data packet
   reaches the boundary of a overlay, the ingress NVE will encapsulate
   the packet and forward it to the destination egress NVE through a
   proper tunnel.

   REQ 10:  The security solution for NVO3 SHOULD enable two NVEs to
      mutually authenticate each other before establishing a tunnel
      connecting them for data transportation.

      This entity authentication requirement is used to protect a NVE
      against imposter attacks.  Also, this requirement can help
      guarantee a data tunnel is generated between two proper NVEs and
      reduce the risk of man-in-the-middle attacks.

   In order to protect the data packets transported over the overlay
   against the attacks raised from the underlying network, the NVO3
   overlay needs to provide essential security protection for data
   packets.



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   REQ 11:  The security solution of NVO3 MUST be able to provide
      integrity protection, replay protection, and packet origin
      authentication for data traffics exchanged between NVEs.

      This requirement is used to prevent an attacker who has
      compromised a underlying network devices on the path from
      replaying antique packets or injecting bogus data packets without
      being detected.

   REQ 12:  The security solution of NVO3 MAY provide confidentiality
      protection for data traffics exchanged between NVEs.

      If the data traffics from the TSes are sensitive, they needs to be
      encrypted when being transported within the overlay.  Otherwise,
      encryption will be unnecessary.  In addition, in practice, tenants
      may also select to encrypt their sensitive data during
      transportation.  Therefore this confidentiality requirement for
      data plane is then not as crucial as the integrity requirement.

   REQ 13:  The security solution of NVO3 SHOULD be able to assign
      different cryptographic keys to protect the unicast tunnels
      between NVEs respectively.

      This requirement is used to confine the damage caused by inside
      attacks.  When different tunnels secured with different keys, the
      compromise of a key in a tunnel will not affect the security of
      others.  In addition, if the key used to protect a tunnel is only
      shared by the NVEs on the both sides, the egress NVE receiving a
      data packet is able to distinctively prove the identity of the
      ingress NVE encapsulating the data packet during the message
      authentication.

   REQ 14:  If there are multicast packets, the security solution of
      NVO3 SHOULD be able to assign distinct cryptographic group keys to
      protect the multicast packets exchanged among the NVEs within
      different multicast groups.

      In practice, a NVE may need to use the multicast capability
      provided by the underlying network to transfer multicast packets
      to other NVEs.  In this case, in order to provide an essential
      packet level security protection specified in requirements 11 and
      12, at least a group key may need to be shared among the NVEs in a
      same mutlicast group, in order to provide packet level
      authentication or optionally confidentiality protection for the
      multicast packets transferred within the group.  It is recommended
      to deploy different keys for different mutlicast groups, in order
      to confine the insider attacks on NVEs.




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   REQ 15:  Upon receiving a data packet, an egress NVE must be able to
      verify whether the packet is from a proper ingress NVE which is
      authorized to forward that packet.

      In cooperation with authentication, authorization enables a egress
      NVE to detect the data packets which violate certain security
      policies, even when they are forwarded from a legal NVE.  For
      instance, if a data packet belonging to a VN is forwarded from an
      ingress NVE which is not supposed to support that VN, the packet
      needs to be detected and discarded.  Note that the detection of a
      invalid packet may not indicate that the system is under a
      malicious attack.  Mis-configuration or byzantine failure of a NVE
      may also result in such invalid packets.

5.2.  Control/Data Plane between NVEs and Hypervisors

   Apart from data traffics, the NVE and hypervisors may also need to
   exchange signaling packets in order to facilitate, e.g., VM online
   detection, VM migration detection, or auto-provisioning/service
   discovery [RFC7365].

   A NVE and the hypervisors working with it can be deployed in a
   distributed way (e.g., the NVE is implemented in an individual
   device, and the hypervisors are located on servers) or in a co-
   located way (e.g., the NVE and the hypervisors are located on the
   same server).  In the former case, the data and control traffic
   between the NVE and the hypervisors are exchanged over network.

5.2.1.  Distributed Deployment of NVE and Hypervisor

   Five security requirements appliabled for both control and data
   packets exchanged between NVEs and hypervisors are listed as follows:

   REQ 16:  The security solution for NVO3 SHOULD enable the
      communicating NVE and hypervisor to mutually authenticate each
      other before exchanging any control/ data packets.

      Mutual authentication is used to prevent an attacker from
      impersonating a legal NVE or a hypervisor without being detected
      and then reduce the risks of man-in-the-middle attacks.  A
      successful authentication normally results in the distribution key
      materials to protect the security of subsequent communications.

   REQ 17:  The security solution of NVO3 MUST be able to provide
      integrity protection, replay protection and origin authentication
      for the control/ data packets exchanged between a NVE and a
      hypervisor.




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      Packet level security protection can prevent an attacker from
      illegally interfere with the normal operations of NVEs and
      hypervisors by injecting bogus control packets into the network.
      In addition, because it is assumed the network connecting the NVE
      and the hypervisor is potentially accessible to attackers,
      security solutions need to prevent an attacker locating in the
      middle between the NVE and the hypervisor 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.

   REQ 18:  If a NVE needs to communicate with multiple hypervisors, the
      security solution of a NVO3 network SHOULD be able to provide
      different keys and ciphers to secure the control /data packets
      exchanged between different hypervisors and their NVEs
      respectively.

      This requirement is used to benefit the damage confinement of
      inside attacks.  For instance, the compromise of a hypervisor will
      not affect the security of control/data traffics exchanged between
      the NVE and other hypervisors.

   REQ 19:  Before accepting a control/data packet, a NVE or a
      hypervisor receiving the packet MUST verify that the device
      sending the packet is authorized to do so.

      This is an authorization requirement.  When receiving a control/
      data packet, besides authentication, authorization needs to be
      carried out by a NVE or a hypervisor to identify the role that the
      packet sender acts as and then assess the sender's privileges.
      Therefore, if a compromised hypervisor attempts to use it
      credentials to impersonate a NVE to communicate with other
      hypervisors, it will be detected.

   REQ 20:  The security solution of a NVO3 SHOULD be able to provide
      different security levels of protections for the control/data
      traffics exchanged between a NVE or a hypervisor.

      The control and data traffics between a NVE and a hypervisor may
      be transported over the same path or even within the same security
      channel.  However, when the control traffics and data traffics
      have different levels of sensitivity, the protection on them needs
      be different.  In this case, the security solution may need to
      different security channels for control and data traffics
      respectively and so protect the data and control traffics
      exchanged between a hypervisor and a NVE with different keys and
      ciphers.




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5.2.1.1.  Control Plane

   REQ 21:  The security solution of a NVO3 network MAY provide
      confidentiality protection for the control traffics exchanged
      between a NVE and a hypervisor.

      The contents of the control/data packets need to be encrypted when
      they are considered to be sensitive.

   Similar to REQs 6 and 7, the following two requirements are used to
   mitigate potential DDoS risks.

   REQ 22:  The frequency in forwarding control packets from a NVE or a
      hypervisors MUST be limited.

      This is a common security requirement that can effectively avoid
      the capability of a device in processing control packets to be
      overwhelmed by the high frequent control packets generated by the
      devices attached to it.

   REQ 23:  Amplification effect SHOULD be Addressed.

      If the responses generated by a NVE or a hypervisor are much
      longer than the received requests, an attacker may take advantage
      of the device as a reflector to perform DDoS attacks.
      Specifically, the attacker sends a large amount of spoofed short
      requests to NVEs or hypervisors with the source address of a
      victim.  The responses will then be generated by the NVEs and
      forwarded to the victim and overwhelm its process capability.
      This issues should be considered in the design of the control
      protocols.

5.2.1.2.  Data Plane

   REQ 24:  The security solution of a NVO3 network MUST provide
      security gateways to control the data traffics across the
      boundaries of different VNs according to specified security
      policies.

      In [RFC7364], 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).

   REQ 25:  The security solution of a NVO3 network MAY provide
      confidentiality protection for the data traffics exchanged between
      a NVE and a hypervisor.




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      When the contents of the data packets are sensitive to a tenant,
      the data packet needs to be encrypted.  The security solution of a
      NVE network may need to provide confidentiality for the data
      packets exchanged between a NVE and a hypervisor if they have to
      use an insecure network to transport their data packet and the
      tenants cannot encrypt their sensitive data themselves.

6.  Candidate Techniques

   This section introduces the techniques which can potentially be used
   to fulfill the security requirements introduced in Section 5.

6.1.  Entity Authentication

   Entity authentication is normally performed as a part of automated
   key management, and a successful authentication may result in the key
   materials used in subsequent communications.

   The widely adopted protocols supporting entity authentication
   include: IKE[RFC2409], IKEv2[RFC4306], EAP[RFC4137], TLS [RFC5246]
   and etc.

   It is recommended to cryptographically verify the devices' identities
   during authentication.  Therefore, an inside attacker cannot use the
   keys or credentials got from the compromised device to impersonate
   other victims.

6.2.  Packet Level Security

   There are requirements about protecting the integrity,
   confidentiality, and provide packet origin authentication for
   control/ data packets.  Such functions can be provided through using
   the underlying security protocols (e.g., IPsec AH[RFC4302], IPsec
   ESP[RFC4303], TLS[RFC5246]).  Also, when designing the control
   protocols people can select to provide embedded security approaches
   (just like the packet level security mechanism provided in
   OSPFv2[RFC2328]).  The cryptographic keys can be manually deployed or
   dynamically generated by using certain automatic key management
   protocols.  Note that when using manual key management, the replay
   protection mechanism of IPsec will be switched off.

6.3.  Authorization

   Without any cryptographic supports, the authorization mechanisms
   (e.g., packet filters) could be much easier to be bypassed by
   attackers, and thus the authorization mechanisms deployed on NOV3
   devices should interoperate with entity authentication and other
   packet level security mechanisms, and be able to make the access



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   control decisions based on the cryptographically proved results.  An
   exception is packet filtering.  Because packet filters are efficient
   and can effectively drop some un-authorized packets before they have
   to be cryptographically verified, it is worthwhile to use packet
   filters as an auxiliary approach to dealing with some simple attacks
   and increasing the difficulties of DoS/DDoS attacks targeting at the
   security protocol implementations.

7.  IANA Considerations

   This document makes no request of IANA.

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

8.  Security Considerations

8.1.  Automated Key Management in NVO3

   Because entity authentication and automated key distribution are
   normally performed in the same process, the requirements of entity
   authentication have already implied that it is recommended to use
   automated key management in the security solutions for NVO3 networks.
   In the cases where there are a large amount of NVEs working within a
   NVO3 overlay, manual key management becomes infeasible.  First, it
   could be tedious 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].  Moreover, some
   security protocols need the support of automated key management in
   order to perform certain security functions properly.  As mentioned
   above, the replay protecting mechanism of IPsec will be turned off
   without the support of automated key management mechanisms.

8.2.  Issues not Discussed

   Because this memo only tries to provide the most essential high level
   requirements, some important issues in designing concret security
   mechanisms are not covered in the requirements.  Such issues include:

   o  How to manage keys/credentials during their life periods

   o  How to support algorithm agility



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   o  How to provide accountability

   o  How to secure the management interfaces

   o  Use underlying security protocols versus design integrated
      security extensions

9.  Acknowledgements

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

10.  References

10.1.  Normative References

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

10.2.  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-hpvr2nve-cp-req]
              Yizhou, L., Yong, L., Kreeger, L., Narten, T., and D.
              Black, "Hypervisor to NVE Control Plane Requirements",
              draft-ietf-nvo3-hpvr2nve-cp-req-00 (work in progress),
              July 2014.

   [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-09
              (work in progress), April 2014.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC2409]  Harkins, D. and D. Carrel, "The Internet Key Exchange
              (IKE)", RFC 2409, November 1998.

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





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   [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.

   [RFC4302]  Kent, S., "IP Authentication Header", RFC 4302, December
              2005.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)", RFC
              4303, December 2005.

   [RFC4306]  Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC
              4306, December 2005.

   [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.

   [RFC7364]  Narten, T., Gray, E., Black, D., Fang, L., Kreeger, L.,
              and M. Napierala, "Problem Statement: Overlays for Network
              Virtualization", RFC 7364, October 2014.

   [RFC7365]  Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
              Rekhter, "Framework for Data Center (DC) Network
              Virtualization", RFC 7365, October 2014.

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










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   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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