Internet Engineering Task Force
Internet Draft J. Palet
A. Vives
Consulintel
Document: draft-palet-v6ops-ipv6security-00.txt G. Martinez
A. Gomez
Univ. of Murcia
Category:
Expires: August 2004 February 2004
IPv6 distributed security requirements
draft-palet-v6ops-ipv6security-00.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
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Internet Draft IPv6 distributed security requirements February 2004
Abstract
The security policies currently applied in Internet with IPv4,
doesnÆt longer apply for end-to-end security models which IPv6 will
enable.
Today, each network is often secured by a unique device (i.e.
security gateway or firewall), that becomes a bottleneck for the end-
to-end security model with IPv6.
In addition, users and devices start to be nomadic, moving between
different networks that could have different security policies.
A distributed and dynamic approach is consequently required.
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Conventions used in this document
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 [ii].
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Table of Contents
1. Introduction...................................................4
2. Distributed security model.....................................5
3. Interior security..............................................6
4. The visiting node..............................................6
5. Default security...............................................6
6. The security policy server and protocol........................7
7. Single versus multiple point of attack.........................8
8. Non-security-capable nodes and security workload distribution..9
9. Location of the security policy server.........................9
10. Virus and spam................................................9
11. Security Considerations......................................10
12. References...................................................10
Acknowledgments..................................................10
Authors' Addresses...............................................10
Intellectual Property Statement..................................11
Full Copyright Statement.........................................11
Acknowledgement..................................................12
1.
Introduction
The todayÆs Internet paradigms for security need a revision with the
deployment of IPv6, offering end-to-end security capabilities.
Current security policies based on a centric approach with unique
border devices donÆt longer apply. Often they are based in a firewall
or security gateway and statically configured rules.
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Users and devices start to be nomadic. They often move from one
network to another and this needs to be taken in consideration to
keep the security of the complete visited network.
Keeping todayÆs static security model is a wrong approach, which
disables the end-to-end features and advantages of IPv6.
Enforcing the nomadic users and devices to connect to Internet by
means of the security device, is almost equivalent to disable the
IPsec stack on each node, thus invalidating one of the key IPv6
advantages.
On the other hand, is also true and perfectly understandable that
there is a need to enforce security in the networks, in such way that
the network administrator has always the control over it.
2.
Distributed security model
The paradigm is to keep or even being able to increase the security
in the network as a whole and keep the control of it under the
network administrator hands, while the individual nodes can take
advantage of end-to-end and secure end-to-end communications.
This can be achieved with a distributed model replacing the current
central one.
The distributed security model implies the use of node or personal
firewalls.
These node or personal firewalls must respect the security policy of
the network where they are attached.
The effect is simple to understand: instead of a single firewall, a
single point of failure for the complete network, that could be
easily attacked or fail, and create a single bottleneck for all the
communications, there will be a number of firewalls, configured
according a central policy, which increase the reliability,
efficiency and performance of the complete network.
This is possible in most of the situations because, even if IPsec and
encryption are enforced for most of the communications, nodes often
have powerful CPUs with unused cycles that will easily accommodate
the extra required workload.
On the other hand, the central firewalls will be able to dedicate CPU
cycles to new functions, or be able to protect bigger networks.
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3.
Interior security
With this approach, the security of each node is not only towards
communications with Internet or other networks, but also with the
rest of the nodes in the same network.
This means an increase in the overall security and the possibility to
isolate individual nodes if required.
4.
The visiting node
This distributed security model is valid not only for fixed nodes,
i.e. desktop computers, but specially interesting and important for
those nodes like laptops and PDAs, which keep moving among different
networks. Vice versa, this model is of key importance for those
networks that receive visits from nodes that are not under the
control of the network administrator.
Different visited networks have different security requirements.
Consequently is required that those nomadic nodes dynamically
accommodate their own security policy to the one defined in the
visited network.
Nodes attaching to a network via VPNs, RAS, directly attached modems
or other similar means can also be considered as visiting nodes, as
they can also create a path between the visited network and any other
network where they are actually connected. They must also be able to
dynamically configure their own security to match the one existing in
then visited network.
The alternative often used today to accomplish this, is by means of
manual changes in the configuration of the visiting node, but they
are always prone to errors and dangerous to be considered useful and
secure enough.
5.
Default security
Implementing IPsec in the IPv6 stack of the nodes is only a first
step for a sophisticated security model.
A more complete approach is needed. These nodes can be attached to a
network which doesnÆt offer any protection means, not only against
external attacks, but also those coming from the same network.
This is the common case, for example, in hotspots, public networks,
ad-hoc networks or even networks temporarily setup for conferences.
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In order to keep the appropriate security level, each node should
incorporate a kind of personal or node firewall.
The node firewall must be configured by default with a very
restrictive set of rules. At this way, the node is self-defended, in
any circumstance.
The node firewall must act as a policy enforcer.
The node firewall should offer a simple user interface to facilitate
to relax the security restrictions, if required by certain
applications or services, assuming the lack of expertise of the user.
6.
The security policy server and protocol
In order to achieve the benefits of the distributed security model,
and at the same time provide a mean for an adequate control of the
overall network security by the network administrator, a security
policy server is required.
The policy server(s) could replace the central firewall and
complement it. The network administrator will define the security
rules required by all the network and/or individual nodes.
The different nodes should query to the policy server to learn about
the network security policy and adapt themselves in order to match
it.
When a node is attached to a visited network and receives the visited
network security policy, basically there are two possible situations:
a) The network security policy is less or same restrictive than the
node configuration. In this case, the node will not change its
security policy configuration.
b) The network security policy is more restrictive than the node
configuration. In this case, the node will adapt its security
configuration to at least match the one indicated by the security
policy.
Until the node performs and acknowledge the required security policy
configuration update, it will not be allowed to transfer/receive data
to/from other nodes either in the network or other connected
networks.
The security policy server can also dynamically update the security
policy for the complete network or specific nodes. This can be done
in response to a network administrator decision, or other situations,
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like information received from an external or internal attack,
detected by an intrusion detection system, firewall or even by nodes
inside the network.
The security policy can be setup at a network level or individually
for every node, upon decision of the network administrator.
A single standard language or protocol for the signaling between the
nodes, security policy servers, firewalls (including node firewalls),
intrusion detections systems, honey pots, routers, and any other
elements implicated in the overall network and nodes security is
required.
For simplicity, the policy server could be integrated in the border
router, firewall, or other network elements (AAA, DHCP, COPS, ...).
A possible approach is to align this with the existing COPS [iii] and
COPS-PR [iv] standards.
According this, the network administrator will use a PMT (Policy
Management Tool), to edit the policies, distributed them via PMP
(Policy Decision Points), to the PEP (Policy Enforcement Points).
For the interaction with IPsec policies, it seems appropriate the
existing IPsecCPIM [v].
To guarantee the self-security of this model, the security policy
being communicated to the nodes should be digitally signed, in order
to provide integrity, origin authentication and non-repudiate
authenticity of the source.
7.
Single versus multiple point of attack
The single security gateway approach is a single point of failure and
consequently a bottleneck.
At the same time, is easier to attack a single device, so the
possibilities of a security threat are higher.
On the other hand, the distributed approach reduces the risk of a
single point of failure and increases the difficulties for potential
attackers to succeed (port scanning is more difficult).
The failure of the central firewall could completely disconnect the
network from Internet or other networks. In the case of a central
policy server fail, the nodes can be configured by the security
policy in such way that continue working, keeping the same security
restrictions imposed by the policy server.
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8.
Non-security-capable nodes and security workload distribution
Increase in security often means increase in processing power.
Some nodes could not have the required CPU cycles to afford the
complete required security policy.
The firewalls or even other security-capable nodes with free
resources, could act as trusted security gateways for the non-
security-capable nodes.
This seems only possible if minimum security verification can be done
by those nodes, i.e. digital signature verification.
It could be even considered a system to provide a kind of security
workload-balancing.
Some work is still required to define if the security level that can
be achieved by those nodes is good enough, and to avoid possible
attacks.
This section needs to be completed in further revisions of this
document.
9.
Location of the security policy server
Firewalls and security gateways are expensive devices and they are
required to sit at the border of the network. They also require
qualified personal to manage them.
In the case of the distributed security model, the security policy
server isnÆt required to be collocated as a border device.
This provides the opportunity to have this device not only inside the
network, but also at any other point in Internet.
This opens the doors to new services and business models that provide
very sophisticated security services, especially for SOHO and SMEs.
Internet Exchanges, PoPs, ISPs, and other similar central Internet
locations seem to be ideal locations for the security policy servers.
10.
Virus and spam
As part of the services offered by the distributed security model, it
should be considered means to alleviate the effects of virus and
spam.
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This could mean for example, extensions to protocols as SMTP.
To be completed in next versions of the document.
11.
Security Considerations
To be completed in next versions of the document.
12.
References
i S. Bradner, "The Internet Standards Process -- Revision 3", BCP 9,
RFC 2026, October 1996.
ii S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
iii D. Durham, Ed., "The COPS (Common Open Policy Service) Protocol",
RFC 2748, January 2000.
iv K. Chan et al, "COPS Usage for Policy Provisioning (COPS-PR)", RFC
3084, March 2001.
v J. Jason et al, "IPsec Configuration Policy Information Model",
RFC 3585, August 2003.
Acknowledgments
The authors would also like to acknowledge the inputs from Cesar
Olvera and the European Commission support in the co-funding of the
Euro6IX project, where this work is being developed.
Authors' Addresses
Jordi Palet Martinez
Consulintel
San Jose Artesano, 1
28108 - Alcobendas (Madrid - Spain)
Phone: +34 91 151 81 99
Fax: +34 91 151 81 98
Email: jordi.palet@consulintel.es
Alvaro Vives
Consulintel
San Jose Artesano, 1
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28108 - Alcobendas (Madrid - Spain)
Phone: +34 91 151 81 99
Fax: +34 91 151 81 98
Email: alvaro.vives@consulintel.es
Gregorio Martinez
University of Murcia (UMU)
Campus de Espinardo s/n
30071 - Murcia (Spain)
Phone: +34
Fax: +34
Email: gregorio@dif.um.es
Antonio Gomez Skarmeta
Consulintel
Campus de Espinardo s/n
30071 - Murcia (Madrid - Spain)
Phone: +34
Fax: +34
Email: skarmeta@dif.um.es
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