ANCP Working Group H. Moustafa
Internet-Draft France Telecom
Intended status: Informational H. Tschofenig
Expires: January 10, 2010 Nokia Siemens Networks
S. De Cnodder
Alcatel-Lucent
July 9, 2009
Security Threats and Security Requirements for the Access Node Control
Protocol (ANCP)
draft-ietf-ancp-security-threats-08.txt
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Abstract
The Access Node Control Protocol (ANCP) aims to communicate QoS-
related, service-related and subscriber-related configurations and
operations between a Network Access Server (NAS) and an Access Node
(e.g., a Digital Subscriber Line Access Multiplexer (DSLAM)). The
main goal of this protocol is to allow the NAS to configure, manage
and control access equipments including the ability for the access
nodes to report information to the NAS.
The present document investigates security threats that all ANCP
nodes could encounter. This document develops a threat model for
ANCP security aiming to decide which security functions are required.
Based on this, security requirements regarding the Access Node
Control Protocol are defined.
Table of Contents
1. Specification Requirements . . . . . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. System Overview and Threat Model . . . . . . . . . . . . . . . 5
4. Objectives of Attackers . . . . . . . . . . . . . . . . . . . 7
5. Potential Attacks . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Denial of Service (DoS) . . . . . . . . . . . . . . . . . 8
5.2. Integrity Violation . . . . . . . . . . . . . . . . . . . 8
5.3. Downgrading . . . . . . . . . . . . . . . . . . . . . . . 8
5.4. Traffic Analysis . . . . . . . . . . . . . . . . . . . . . 9
5.5. Management Attacks . . . . . . . . . . . . . . . . . . . . 9
6. Attack Forms . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Attacks Against ANCP . . . . . . . . . . . . . . . . . . . . . 11
7.1. Dynamic Access Loop Attributes . . . . . . . . . . . . . . 12
7.2. Access Loop Configuration . . . . . . . . . . . . . . . . 13
7.3. Remote Connectivity Test . . . . . . . . . . . . . . . . . 14
7.4. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 14
8. Security Requirements . . . . . . . . . . . . . . . . . . . . 16
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
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11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
12.1. Normative References . . . . . . . . . . . . . . . . . . . 17
12.2. Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Specification Requirements
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 [RFC2119], with the
qualification that unless otherwise stated they apply to the design
of the Access Node Control Protocol (ANCP), not its implementation or
application.
The relevant components are described in Section 3.
2. Introduction
The Access Node Control Protocol (ANCP) aims to communicate QoS-
related, service-related and subscriber-related configurations and
operations between a Network Access Server (NAS) and an Access Node
(e.g., a Digital Subscriber Line Access Multiplexer (DSLAM)).
[I-D.ietf-ancp-framework] illustrates the framework, usage scenarios
and general requirements for ANCP. This document focuses on
describing security threats and deriving security requirements for
the Access Node Control Protocol, considering the ANCP use cases
defined in [I-D.ietf-ancp-framework] as well as the guidelines for
IETF protocols' security requirements given in [RFC3365]. Section 5
and Section 6 respectively describe the potential attacks and the
different attack forms that are liable to take place within ANCP,
while Section 7 applies the described potential attacks to ANCP and
its different use cases. Security policy negotiation,including
authentication and authorization to define the per-subscriber policy
at the policy/AAA server, is out of the scope of this work. As a
high-level summary, the following aspects need to be considered:
Message Protection:
Signaling message content can be protected against eavesdropping,
modification, injection and replay while in transit. This applies
to both ANCP header and payloads.
Prevention against Impersonation:
It is important that protection be available against a device
impersonating an ANCP node (i.e. an unauthorized device generating
an ANCP message and pretending it was generated by a valid ANCP
node).
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Prevention of Denial of Service Attacks:
ANCP nodes and the network have finite resources (state storage,
processing power, bandwidth). Exhaustion attacks against these
resources and not allowing ANCP nodes to be used to launch attacks
on other network elements is of great importance.
3. System Overview and Threat Model
As described in [I-D.ietf-ancp-framework] and schematically shown in
Figure 1, the Access Node Control system consists of the following
components:
Network Access Server (NAS):
A NAS provides access to a service (e.g., network access) and
operates as a client of the AAA protocol. The AAA client is
responsible for passing authentication information to designated
AAA servers and then acting on the response that is returned.
Authentication, Authorization and Accounting (AAA) server:
A AAA server is responsible for authenticating users, for
authorizing access to services, and for returning authorization
information including configuration parameters back to the AAA
client to deliver service to the user. As a consequence, service
usage accounting might be enabled and information about the user's
resource usage will be sent to the AAA server.
Access Node (AN):
The AN is a network device, usually located at a service provider
central office or street cabinet, that terminates access loop
connections from subscribers. In case the access loop is a
Digital Subscriber Line (DSL), this is often referred to as a DSL
Access Multiplexer (DSLAM).
Customer Premises Equipment (CPE):
A CPE is a device located inside a subscriber's premise that is
connected at the LAN side of the HGW.
Home Gateway (HGW):
The HGW connects the different Customer Premises Equipments (CPE)
to the Access Node and the access network. In case of DSL, the
HGW is a DSL Network Termination (NT) that could either operate as
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a layer 2 bridge or as a layer 3 router. In the latter case, such
a device is also referred to as a Routing Gateway (RG).
Aggregation Network:
The aggregation network provides traffic aggregation from multiple
ANs towards the NAS. ATM or Ethernet transport technologies can
be used.
For the threat analysis, this document focuses on the ANCP protocol
communication between the Access Node and the NAS. However,
communications with the other components, such as HGW, CPE, AAA
server play a role in the understanding of the system architecture
and of what triggers ANCP protocol communications. Note that the NAS
and the AN might belong to two different administrative realms. The
threat model and the security requirments in this draft consider this
latter case.
+--------+
| AAA |
| Server |
+--------+
|
|
+---+ +---+ +------+ +-----------+ +-----+ +--------+
|CPE|---|HGW|---| | |Aggregation| | | | |
+---+ +---+ |Access| | Network | | | |Internet|
| Node |----| |----| NAS |---| / |
+---+ +---+ | (AN) | | | | | |Regional|
|CPE|---|HGW|---| | | | | | |Network |
+---+ +---+ +------+ +-----------+ +-----+ +--------+
Figure 1: System Overview
In the absence of an attack, the NAS receives configuration
information from the AAA server related to a CPE attempting to access
the network. A number of parameters, including Quality of Service
information, need to be conveyed to the Access Node in order to
become effective. The Access Node Control Protocol is executed
between the NAS and the AN to initiate control requests. The AN
returns responses to these control requests and provides information
reports.
For this to happen, the following individual steps must occur:
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o The AN discovers the NAS.
o The AN needs to start the protocol communication with the NAS to
announce its presence.
o The AN and the NAS perform a capability exchange.
o The NAS sends requests to the AN.
o The AN processes these requests, authorizes the actions and
responds with the appropriate answer. In order to fulfill the
commands it might be necessary for the AN to communicate with the
HGW or other nodes, for example as part of a keep alive mechanism.
o The AN provides status reports to the NAS.
Attackers can be:
o off-path, i.e., they cannot see the messages exchange between the
AN and the NAS;
o on-path, i.e., they can see the messages exchange between the AN
and the NAS.
Both off-path and on-path attackers can be:
o passive, i.e., they do not participate in the network operation
but rather listen to all transfers to obtain the maximum possible
information;
o active, i.e., they participate to the network operation and can
inject falsified packets.
We assume the following threat model:
o An off-path adversary located at the CPE or the HGW.
o An off-path adversary located on the Internet or a regional
network that connects one or more NASes and associated Access
Networks to Network Service Providers (NSPs) and Application
Service Providers (ASPs).
o An on-path adversary located at network elements between the AN
and the NAS.
o An on-path adversary taking control over the NAS.
o An on-path adversary taking control over the AN.
4. Objectives of Attackers
Attackers may direct their efforts either against an individual
entity or against a large portion of the access network. Attacks
fall into three classes:
o attacks to disrupt the communication for individual customers.
o attacks to disrupt the communication of a large fraction of
customers in an access network. These also include attacks to the
network itself or a portion of it such as attacks to disrupt the
network services or attacks to destruct the network functioning.
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o attacks to gain profit for the attacker through modifying the QoS
settings. Also, through replaying old packets, of another
privileged client for instance, an attacker can attempt to
configure a better QoS profile on its own DSL line increasing its
own benefit.
5. Potential Attacks
This section discusses the different types of attacks against ANCP,
while Section 6 describes the possible means of their occurrence.
ANCP is mainly susceptible to the following types of attacks:
5.1. Denial of Service (DoS)
A number of denial of service (DoS) attacks can cause ANCP nodes to
malfunction. When state is established or certain functions are
performed without requiring prior authorization there is a chance to
mount denial of service attacks. An adversary can utilize this fact
to transmit a large number of signaling messages to allocate state at
nodes and to cause resources' consumption. Also, an adversary,
through DoS, can prevent certain subscribers to access certain
services.Moreover, DoS can take place at the AN or the NAS
themselves, where it is possible for the NAS (or the AN) to
intentionally ignore the requests received from the AN (or the NAS)
through not replying to them. This causes the sender of the request
to retransmit the request, which might allocate additional state at
the sender side to process the reply. Allocating more state may
result in memory depletion.
5.2. Integrity Violation
Adversaries gaining illegitimate access on the transferred messages
can act on these messages causing integrity violation. Integrity
violation can cause unexpected network behavior leading to a
disturbance in the network services as well as the network
functioning.
5.3. Downgrading
Protocols may be useful in a variety of scenarios with different
security and functional requirements. Different parts of a network
(e.g., within a building, across a public carrier's network, or over
a private microwave link) may need different levels of protection.
It is often difficult to meet these (sometimes conflicting)
requirements with a single mechanism or fixed set of parameters, so
often a selection of mechanisms and parameters is offered. A
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protocol is required to agree on certain (security) mechanisms and
parameters. An insecure parameter exchange or security negotiation
protocol can give the oppurtunity to an adversary to mount a
downgrading attack to force selection of mechanisms weaker than those
mutually desired. Thus, without binding the negotiation process to
the legitimate parties and protecting it, ANCP might only be as
secure as the weakest mechanism provided (e.g., weak authentication)
and the benefits of defining configuration parameters and a
negotiation protocol are lost.
5.4. Traffic Analysis
An adversary can be placed at the NAS, or the AN, or any other
network element capturing all traversing packets. Adversaries can
thus have unauthorized information access. As well, they can gather
information relevant to the network and then use this information in
gaining later unauthorized access. This attack can also help
adversaries in other malicious purposes, as for example capturing
messages sent from the AN to the NAS announcing that a DSL line is up
and containing some information related to the connected client.
This could be any form of information about the client and could also
be an indicator whether the DSL subscriber is at home or not at a
particular moment.
5.5. Management Attacks
Since the ANCP sessions are configured in the AN and not in the NAS
[I-D.ietf-ancp-framework], most configurations of ANCP is done in the
AN. Consequently, the management attacks to ANCP mainly concern the
AN configuration phase. In this context, the AN MIB module could
create disclosure and misconfiguration related attacks.
[I-D.ietf-ancp-mib-an] defines the vulnerabilities on the management
objects within the AN MIB module. These attacks mainly concern the
unauthorized changes of the management objects leading to a number of
attacks as session deletion, session using undesired/unsupported
protocol, disabling certain ANCP capabilities or enabling undesired
capabilities, ANCP packets being sent out to the wrong interface (and
thus received by an unintended receiver), harming the synchronization
between the AN and the NAS, and impacting other traffic in the
network than ANCP.
6. Attack Forms
The attacks mentioned above in Section 5 can be carried out through
the following means:
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Message Replay:
This threat scenario covers the case in which an adversary
eavesdrops, collects signaling messages, and replays them at a
later time (or at a different place or in a different way; e.g.,
cut-and-paste attacks). Through replaying of signaling messages,
an adversary might mount a denial of service and a theft of
service attacks.
Faked Message Injection:
An adversary may be able to inject false error or response
messages causing unexpected protocol behavior and succeeding with
a DoS attack. This could be achieved at the signaling protocol
level, at the level of a specific signaling parameters (e.g., QoS
information), or at the transport layer. An adversary might, for
example, inject a signaling message to request allocation of QoS
resources. As a consequence, other user's traffic might be
impacted. The discovery protocol, especially, exhibits
vulnerabilities with regard to this threat scenario.
Messages Modification:
This involves integrity violation, where an adversary can modify
signaling messages in order to cause unexpected network behavior.
Possible related actions an adversary might consider for its
attack are reordering and delaying of messages causing a
protocol's process failure.
Man-in-the-Middle:
An adversary might claim to be a NAS or an AN acting as a man-in-
the-middle to later cause communication and services disruption.
The consequence can range from DoS to fraud. An adversary acting
as a man-in-the-middle could modify the intercepted messages
causing integrity violation, or could drop or truncate the
intercepted messages causing DoS and a protocol's process failure.
In addition, a man-in-the-middle adversary can signal information
to an illegitimate entity in place of the right destination. In
this case the protocol could appear to continue working correctly.
This may result in an AN contacting a wrong NAS. For the AN, this
could mean that the protocol failed for unknown reasons. A man-
in-the-middle adversary can also cause downgrading attacks through
initiating faked configuration parameters and through forcing
selection of weak security parameters or mechanisms.
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Eavesdropping:
This is related to adversaries that are able to eavesdrop on
transferred messages. The collection of the transferred packets
by an adversary may allow traffic analysis or be used later to
mount replay attacks. The eavesdropper might learn QoS
parameters, communication patterns, policy rules for firewall
traversal, policy information, application identifiers, user
identities, NAT bindings, authorization objects, network
configuration and performance information, and more.
7. Attacks Against ANCP
ANCP is susceptible to security threats, causing disruption/
unauthorized access to network services, manipulation of the
transferred data, and interference with network functions. Based on
the threat model given in Section 3 and the potential attacks
presented in Section 5, this section describes the possible attacks
against ANCP, considering the four use cases defined in
[I-D.ietf-ancp-framework].
Although ANCP protocol is not involved in the communication between
the NAS and the AAA/policy server, the secure communication between
the NAS and the AAA/policy server is important for ANCP security.
Consequently, this draft considers the attacks that are related to
the ANCP operation associated with the communication between the NAS
and the AAA/Policy server. In other words, the threat model and
security requirements in this draft take into consideration the data
transfer between the NAS and the AAA server, when this data is used
within the ANCP operation.
Besides the attacks against the four ANCP use cases described in the
following subsections, ANCP is susceptible to a number of attacks
that can take place during the protocol establishment phase. These
attacks are mainly on-path attacks, taking the form of DoS or man-in-
the-middle attacks, which could be as follows:
o Attacks during the session initiation from the AN to the NAS: DoS
attacks could take place affecting the session establishment
process. Also, Man-in-the-middle attacks could take place,
causing message truncation or message modification and leading to
session establishment failure.
o Attacks during the peering establishment: DoS attacks could take
place during states synchronization between the AN and the NAS.
Also, man-in-the-middle attack could take place through messages
modification during identity discovery that may lead to loss of
contact between the AN and the NAS.
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o Attacks during capabilities negotiation: Messages replay could
take place leading to DoS. Also, man-in-the-middle attack could
take place leading to message modification, message truncation, or
downgrading through advertising lesser capabilities.
7.1. Dynamic Access Loop Attributes
This use case concerns the communication of access loop attributes
for dynamic access line topology discovery. Since the access loop
rate may change overtime, advertisement is beneficial to the NAS to
gain knowledge about the topology of the access network for QoS
scheduling. Besides data rates and access loop links identification,
other information may also be transferred from the AN to the NAS
(examples in case of DSL access loop are: DSL Type, Maximum
achievable data rate, and maximum data rate configured for the access
loop). This use case is thus vulnerable to a number of on-path and
off-path attacks that can be either active or passive.
On-path attacks can take place between the AN and the NAS, on the AN
or on the NAS during the access loop attributes transfer. These
attacks may be:
o Active, acting on the transferred attributes and injecting
falsified packets. The main attacks here are:
* Man-in-the-middle attack can cause access loop attributes
transfer between the AN and a forged NAS or a forged AN and the
NAS which can directly cause faked attributes and message
modification or truncation.
* Signaling replay, by an attacker between the AN and the NAS, on
the AN or on the NAS itself, causing DoS.
* An adversary acting as man-in-the-middle can cause downgrading
through changing the access loop actual data rate, which
impacts the downstream shaping from the NAS.
o Passive, only learning these attributes. The main attacks here
are caused by:
* Eavesdropping through learning access loop attributes and
learning information about the clients' connection state and
thus impacting their privacy protection.
* Traffic analysis allowing unauthorized information access, that
could allow later unauthorized access to the NAS.
Off-path attacks can take place on the Internet affecting the access
loop attributes sharing between the NAS and the policy server. These
attacks may be:
o Active attacks, which are mainly concerning:
* DoS through flooding the communication links to the policy
server causing service disruption.
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* Man-in-the-middle, causing access loop configuration retrieval
by an illegitimate NAS.
o Passive attacks, gaining information on the access loop
attributes. The main attacks in this case are:
* Eavesdropping through learning access loop attributes and
learning information about the clients'connection state and
thus impacting their privacy protection.
* Traffic analysis allowing unauthorized information access, that
could allow later unauthorized access to the NAS.
7.2. Access Loop Configuration
This use case concerns the dynamic local loop line configuration
through allowing the NAS to change the access loop parameters (e.g.
rate) in a dynamic fashion. This allows for centralized subcriber-
related service data. This dynamic configuration can be achieved for
instance through profiles that are pre-configured on ANs. This use
case is vulnerable to a number of on-path and off-path attacks.
On-path attacks can take place, where the attacker is between the AN
and the NAS, is on the AN, or is on the NAS. These can be as
follows:
o Active attacks, taking the following forms:
* DoS attacks of the AN can take place by an attacker, through
replaying of the Configure Request messages.
* An attacker on the AN can prevent the AN from reacting on the
NAS request for the access loop configuration, leading to the
NAS continually sending the configure request message and hence
allocating additional states.
* Damaging clients' profiles at ANs can take place by hackers
that gained control on the network through discovery of users
information from a previous Traffic Analysis.
* An adversary can replay old packets, modify messages, or inject
faked messages. Such adversary can also be a man-in-the-
middle. These attack forms can be related to a privileged
client profile (having more services), so that to configure
this profile on the adversary's own DSL line which is less
privileged. In order that the attacker does not expose its
identity, he may also use these attack forms related to the
privileged client profile to configure a number of illegitimate
DSL lines. The adversary can also force other configuration
parameters than the selected ones leading to for instance
downgrading the service for a privileged client.
o Passive attacks, where the attacker listens to the ANCP messages.
This can take place as follows:
* Learning configuration attributes is possible during the update
of the access loop configuration. An adversary might profit to
see the configuration that someone else gets (e.g. one ISP
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might be interested to know what the customers of another ISP
gets and therefore might break into the AN to see this).
Off-path attacks can take place as follows:
o Off-path passive adversary on the Internet can exert eavesdropping
during the access loop configuration retrieval by the NAS from the
policy server.
o Off-path active adversary on the Internet can threaten the
centralized subscribers-related service data in the policy server,
through for instance making subscribers records inaccessible.
7.3. Remote Connectivity Test
In this use case, the NAS can carryout Remote Connectivity Test using
ANCP to initiate an access loop test between the AN and the HGW.
Thus, multiple access loop technologies can be supported. This use
case is vulnerable to a number of active attacks. Most of the
attacks in this use case concern the network operation.
On-path active attacks can take place in the following forms:
o Man-in-the-middle attack during the NAS triggering to the AN to
carryout the test, where an adversary can inject falsified signals
or can truncate the triggering.
o Message modification can take place during the Subscriber Response
message transfer from the AN to the NAS announcing the test
results, causing failure of the test operation.
o An adversary on the AN can prevent the AN from sending the
Subscriber Response message to the NAS announcing the test
results, and hence the NAS will continue triggering the AN to
carryout the test, which results in more state being allocated at
the NAS. This may result in unavailability of the NAS to the ANs.
Off-path active attacks can take place as follows:
o An adversary can cause DoS during the access loop test, in case of
ATM based access loop, when the AN generates loopback cells. This
can take place through signal replaying.
o Message truncating can take place by an adversary during the
access loop test, which can lead to service disruption due to test
failures assumption.
7.4. Multicast
In this use case, ANCP could be used in exchanging information
between the AN and the NAS allowing the AN to perform replication
inline with the policy and configuration of the subscriber. Also,
this allows the NAS to follow subscribers' multicast (source, group)
membership and control replication performed by the AN. Four
multicast uses cases are expected to take place, making use of ANCP
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protocol, these are typically: multicast conditional access,
multicast admission control, multicast accounting, and multicast
termination. This section gives a high-level description of the
possible attacks that can take place in this case. Attacks that can
occur are mostly active attacks.
On-path active attacks can be as follows:
o DoS attacks, causing certain subscribers inability to access
particular multicast streams, or only access the multicast stream
at a reduced bandwidth impacting the quality of the possible video
stream. This can take place through messages replay by an
attacker between the AN and the NAS, on the AN or on the NAS.
Such DoS attacks can also be done by tempering, for instance, with
White/Black list configuration or by placing attacks to the
bandwidth admission control mechanism.
o An adversary on the NAS can prevent the NAS from reacting on the
AN requests for white/black/grey lists or for admission control
for the access line. The AN in this case would not receive a
reply and would continue sending its requests resulting in more
states being allocated at the AN. A similar case happens for
admission control when the NAS can also send requests to the AN.
When the NAS does not receive a response, it could also retransmit
requests resulting in more state being allocated at the NAS side
to process responses. This may result in unavailability of the
NAS to the ANs.
o Man-in-the-middle causing messages' exchange between the AN and a
forged NAS or a forged AN and the NAS. This can lead to the
following:
* Messages' modification, which can cause services' downgrading
for legitimate subscriber, as for instance, an illegitimate
change of a subscriber's policy.
* Messages truncation between the AN and the NAS, which can
result in service's non continuity.
* Messages replay between the AN and the NAS, on the AN or on the
NAS leading to a DoS or services' fraud.
* Messages' modifications to temper with accounting information,
for example in order to avoid service charges or conversely in
order to artificially increase service charges on other users.
An off-path active attack is as follows:
o DoS could take place through message replay of join/leave requests
by the HGW or CPE, frequently triggering the ANCP protocol
activity between the AN and the NAS. DoS could also result from
generating heaps of IGMP join/leaves by the HGW or CPE, leading to
very high rate of ANCP query/response.
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8. Security Requirements
This section presents a number of requirements motivated by the
different types of attacks defined in the previous section. These
requirements are as follows:
o The protocol solution MUST offer authentication of the AN to the
NAS.
o The protocol solution MUST offer authentication of the NAS to the
AN.
o The protocol solution MUST allow authorization to take place at
the NAS and the AN.
o The protocol solution MUST offer replay protection.
o The protocol solution MUST provide data origin authentication.
o The protocol solution MUST be robust against denial of service
(DoS) attacks. In this context, the protocol solution MUST
consider a specific mechansim for the DoS that the user might
create by sending many IGMP messages.
o The protocol solution SHOULD offer confidentiality protection.
o The protocol solution SHOULD ensure that operations in default
configuration guarantees low level of AN/NAS protocol
interactions.
o The protocol solution SHOULD ensure the access control of the
management objects and possibly encrypt the values of these
objects when sending them over the networks.
o The protocol solution SHOULD ensure the security of the management
channels.
9. Security Considerations
This document focuses on security threats deriving a threat model for
ANCP and presenting the security requirements to be considered for
the design of ANCP protocol.
10. IANA Considerations
This document does not require actions by IANA.
11. Acknowledgments
Many thanks go to Francois Le Faucher for reviewing this draft and
for all his useful comments. The authors would also like to thank
Philippe Niger, Curtis Sherbo and Michael Busser for reviewing this
draft. Other thanks go to Bharat Joshi, Mark Townsley, Wojciech Dec,
and Kim Hylgaard who have had valuable comments during the
development of this work.
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12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC3365] Schiller, J., "Strong Security Requirements for Internet
Engineering Task Force Standard Protocols", August 2002.
12.2. Informative References
[I-D.ietf-ancp-framework]
Ooghe, S., Voigt, N., Platnic, M., Haag, T., and S.
Wadhwa, "Framework and Requirements for an Access Node
Control Mechanism in Broadband Multi-Service Networks",
draft-ietf-ancp-framework-10 (work in progress), May 2009.
[I-D.ietf-ancp-mib-an]
Cnodder, S. and M. Morgenstern, "Access Node Control
Protocol (ANCP) MIB module for Access Nodes",
draft-ietf-ancp-mib-an-03 (work in progress), June 2008.
Authors' Addresses
Hassnaa Moustafa
France Telecom
38-40 rue du General Leclerc
Issy Les Moulineaux, 92794 Cedex 9
France
Email: hassnaa.moustafa@orange-ftgroup.com
Hannes Tschofenig
Nokia Siemens Networks
Linnoitustie 6
Espoo 02600
Finland
Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at
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Stefaan De Cnodder
Alcatel-Lucent
Copernicuslaan 50
B-2018 Antwerp,
Belgium
Phone: +32 3 240 85 15
Email: stefaan.de_cnodder@alcatel-lucent.com
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