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Versions: (draft-hartman-nvo3-security-requirements)
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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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Internet-Draft NVO3 security October 2014
[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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