Routing Protocol Security B. Christian, Ed.
Requirements KMC Telecom Solutions
Internet-Draft T. Tauber, Ed.
Expires: October 9, 2006 Comcast
April 7, 2006
BGP Security Requirements
draft-ietf-rpsec-bgpsecrec-05
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Copyright (C) The Internet Society (2006).
Abstract
The security of BGP, the Border Gateway Protocol, is critical to the
proper operation of large-scale internetworks, both public and
private. While securing the information transmitted between two BGP
speakers is a relatively easy technical matter, securing BGP, as a
routing system, is more complex. This document describes a set of
requirements for securing BGP, including communications between BGP
speakers, and the routing information carried within BGP.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. System Description . . . . . . . . . . . . . . . . . . . . 3
1.2. Threats . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Areas to secure . . . . . . . . . . . . . . . . . . . . . 4
2. Underlying Assumptions regarding BGP . . . . . . . . . . . . . 5
3. Operational Requirements . . . . . . . . . . . . . . . . . . . 7
3.1. Convergence speed . . . . . . . . . . . . . . . . . . . . 8
3.2. Incremental deployment . . . . . . . . . . . . . . . . . . 8
3.3. Conditions for initialization . . . . . . . . . . . . . . 9
3.4. Local controls for secure UPDATE acceptance . . . . . . . 9
3.5. Processing on Routers . . . . . . . . . . . . . . . . . . 10
3.6. Configuration on Routers . . . . . . . . . . . . . . . . . 10
4. Infrastructure Requirements . . . . . . . . . . . . . . . . . 11
5. The Trust Model . . . . . . . . . . . . . . . . . . . . . . . 11
6. The AS_PATH Attribute and NLRI Authentication . . . . . . . . 12
7. Address Allocation and Advertisement . . . . . . . . . . . . . 13
8. Logging . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9. NLRI and Path Attribute Tracking . . . . . . . . . . . . . . . 14
10. Transport Layer Protection . . . . . . . . . . . . . . . . . . 15
11. Key Management . . . . . . . . . . . . . . . . . . . . . . . . 15
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
12.1. Normative References . . . . . . . . . . . . . . . . . . . 16
12.2. Informative References . . . . . . . . . . . . . . . . . . 16
Appendix 1. Acknowledgements . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . . . 18
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1. Introduction
1.1. System Description
BGP is described in RFC1771 [4], and, more recently, in an updated
specification, RFC4271 [1], as a path-vector routing protocol. BGP
speakers typically exchange information about reachable destinations
(expressed as address prefixes) in an internetwork through pair-wise
peering sessions. Once this information has been exchanged, each BGP
speaker locally determines a loop free path to each reachable
destination, based on local policy or policy indicators such as
community values and LOCAL_PREF which may be carried in the UPDATE,
and the AS_PATH data carried in the BGP UPDATE messages.
Each BGP speaker represents an Autonomous System (AS). All of the
BGP speakers within an AS operate under a common administrative
policy.
1.2. Threats
Violations of security for network and information systems generally
fall under one of the three categories as defined in RFC 2196 [2]:
o Unauthorized access to resources and/or information
o Unintended and/or unauthorized disclosure of information
o Denial of service
A number of attacks can be realized which, if exploited, can lead to
one of the above mentioned security violations. Attacks against
communications are typically classified as passive or active
wiretapping attacks. Passive attacks are ones where an attacker
simply observes information traversing the network, violating
confidentiality or identifying a means of engaging in further
attacks. Active attacks are ones where the attacker modifies data in
transit. Such attacks include replay attacks, message insertion,
message deletion, and message modification attacks. Some attacks may
be effected by sending data from any where in the Internet. Other
active attacks require a "man-in-the-middle" capability, i.e., the
attacker must be in a position where traffic passes through an
attacker-controlled device. Attacks against BGP may be used by an
attacker to facilitate a wide variety of active or passive
wiretapping attacks against subscriber traffic.
Attacks that do not involve direct manipulation of BGP, and the
information contained within BGP, are outside the scope of this
document.
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Because ASes are autonomous in their operation, it is not possible to
mandate secure operation by all ASes, nor would it be advisable to
assume such operation. Thus the primary goal of BGP security
measures is to provide data to AS operators to enable BGP speakers to
reject advertisements (UPDATE messages) that are not valid. For
example, UPDATE messages that represent erroneous binding of prefixes
to an origin AS, or that advertise invalid paths (as defined later in
this document) should be rejected. Because BGP peering sessions take
place in the context of TCP, the authentication and integrity
guarantees usually association with TCP need to be provided in the
face of possible active wiretapping attacks. Using the terminology
established in RFC 3552 [3], these peering sessions should be
afforded data origin and peer entity authentication and connection-
oriented integrity.
Security for subscriber traffic is outside the scope of this
document, and of BGP security in general. IETF standards for
subscriber data security, e.g., IPsec, TLS, and S/MIME should be
employed for such purposes. While adoption of BGP security measures
may preclude certain classes of attacks on subscriber traffic, these
measures are not a substitute for use of subscriber-based security
mechanisms of the sort noted above.
1.3. Areas to secure
There are two primary points where BGP may be secured; the data
payload of the protocol and the data semantics of the protocol.
The session between two BGP speakers can be secured such that the BGP
data received by the BGP speakers can be cryptographically verified
to have been transmitted by the peer BGP speaker and not a replay of
previously transmitted legitimate data. There are several existing
IETF standards to choose from to ensure that this system functions
with greater effectiveness than the current system. An example might
be IPsec. Some in the Operator community have expressed concerns
that a requiring cryptographic validation could open another vector
for a denial-of-service attack by flooding the processor with bogus
packets which must be cryptographically invalidated before being
discarded.
There are also several questions we can ask about the information
contained within a received UPDATE.
o Is the originating Autonomous System authorized to propagate the
prefix we have received?
o Does the AS_PATH, received via an UPDATE, represent a valid path
through the network?
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The determination of AS_PATH validity falls into two distinct
categories. These categories are ordered from least to most
rigorous.
o Does the AS_PATH specified actually exist as a path in the network
topology and, based on the AS_PATH, is it possible to traverse
that path to reach a given prefix? This AS_PATH Feasibility Check
will be referred to later in this document.
o Has the UPDATE actually traveled the path?
2. Underlying Assumptions regarding BGP
In order to properly identify security requirements it is important
to articulate the fundamental aspects of BGP as related to security
requirements. The following list presents the basic parameters and
application concepts of BGP that are assumed by this document.
o Peer Communication: BGP traffic travels over TCP between peers, so
BGP speakers assume the data delivery guarantees of TCP in a
benign environment. This includes ordered, error-free delivery of
application traffic from a peer identified by an IP address, plus
integrity of the control aspects of TCP. From a security
perspective, these guarantees need to be enforced in the context
of possible active wiretapping.
o Routing and Reachability: BGP is a protocol used to convey routing
and reachability information both internal and external to an
Autonomous System. Typically, interior BGP (iBGP) is used to
distribute prefix reachability information in conjunction with an
Interior Gateway Protocol (IGP) and is used by a distinct network
administrative entity to convey internal routing policy regarding
external and internal information. Exterior BGP (eBGP) is
typically used to distribute route/prefix reachability information
between two distinct routing entities and is used to signal eBGP
preferences and policy decisions.
o Inter-AS UPDATE Message assumptions: When an AS distributes
reachability information to a peer it is done with the intent of
affecting routing decisions by the peer. For example, with regard
to a block of addresses represented by a prefix, AS-A may send
peer AS-B an advertisement which is less specific (shorter in
length of mask) and peer AS-C a more specific advertisement
(longer mask). This prefix distribution decision may have been
made to provide a means for failure resolution between AS-A and
AS-C, i.e., to provide a backup path for the addresses in
question. However, it should be noted that while AS-A tries to
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influence the routing decisions of AS-B and downstream ASes, AS-A
is only providing inputs to a local decision by AS-B, a decision
that is ultimately controlled by AS-B's local policy over which
AS-A has no control. Update messages are sent between AS peers
with the tacit authorization for those messages to be forwarded to
others. A notable exception to this assumption is the use of
policy-based mechanisms between peers such as the NO-EXPORT
community. It is important to note that an UPDATE message itself
generally is not re-transmitted. Instead, the specific UPDATE
message is regenerated continually as it passes from BGP speaker
to BGP speaker. Furthermore, UPDATE messages have no mechanism to
indicate freshness (e.g., timestamps or sequence numbers). This
implies that messages may appear valid at any point in the life of
a BGP peering session. While the AS_PATH information is typically
transitive it is, currently, not clearly mandated and many times
is modified for various utilitarian reasons.
o It is important to note that while preferences regarding routing
can be explicitly managed with direct peers it is markedly more
difficult to influence routing decisions by ASes that are not
directly adjacent.
o Inter-AS withdrawal message assumptions: The processing model of
BGP RFC4271 [1] indicates that only the peer advertising NLRI
information may withdraw it. There are several instances where a
withdrawal may occur. Typical reasons for withdrawal include the
determination of a better path, peer session failure, or local
policy change. There is no specified mechanism for indicating to
a peer the reason for a route withdrawal. Each withdrawal
received via a valid peering session must be taken at face value.
There is no existing method to ensure that an AS will properly
respond to a withdrawal message, e.g., withdraw the route and send
such announcement to its neighbors. Nor do mechanisms exist to
ensure that old UPDATES are not re-propagated after a route was
withdrawn before it is legitimately re-advertised.
o AS_PATH assumptions: Aside from the use of AS_SET, the AS_PATH is
defined as an ordered list of the Autonomous Systems that an
UPDATE has traversed. The rightmost AS in the list is understood
to be the originator of the BGP announcement. Specifications
state that the AS routing graph MUST be loop free. This indicates
that UPDATES received from an external peer which contain the
local AS will be rejected. Prepending one or more instances of an
AS number on inbound advertisements (where the external peer's AS
number is prepended) and outbound advertisements (where the local
AS number is prepended) is a commonly used method to bias routing.
Prepending a peer AS number on inbound UPDATEs is employed for
biasing internal routing and forwarding management while
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prepending one's own AS number on outbound advertisement is
typically used to bias forwarding and routing changes in external
networks. The latter practice is explicitly permitted by RFC4271
[1], but the former is not. Some operators, insert a remote AS
number in an UPDATE, in order to cause the UPDATE to be dropped by
that AS so that traffic will not traverse a given path. Though
this practice appears to run counter to the design of BGP,
anecdotal evidence is that its use is not totally insignificant.
While such a practice can be beneficial to legitimate operators,
it presents a strong potential for misuse. A proposed security
system SHOULD address how to either address this concern or give
specific information on this topic for consideration by the
Operational community.
o Route Origination: BGP speakers may originate routes based either
configured internal data or via data received from peers via
UPDATES. An Autonomous System SHOULD only originate a prefix to
its external peers if that prefix has been allocated to the
administrators of that system, or if authorized by the prefix
holder.
o Originating a route without the ability to forward the traffic
associated with that route is, in most cases, in conflict with the
intent of the BGP specification, notable exceptions include:
* Deployments that make use of route servers which are separate
from forwarding devices
* Deployments that use the temporary propagation of prefixes in
order to effectively block high bandwidth attacks (e.g., DDoS)
against specific IP addresses (and the associated
oversubscription of resources)
o Aggregation and de-aggregation: According to RFC4271 [1], if a BGP
speaker chooses to aggregate a set of more specific prefixes into
a less specific prefix then the ATOMIC_AGGREGATE attribute SHOULD
be set. This creates a significant challenge for solutions to
secure BGP because some origination information is removed (i.e.
the more-specific information which triggered the generation of
the aggregate). Proposed solutions MUST indicate how aggregation
will be accommodated.
3. Operational Requirements
We have determined, through discussion with several large
internetwork operators and equipment vendors, that the following
attributes are important to the ongoing performance of interdomain
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routing systems such as BGP.
3.1. Convergence speed
Convergence speed is a major concern to many operators of large scale
internetworking systems. Networks, and internetworks, are carrying
ever increasing amounts of information that is time and delay
sensitive; increasing convergence times can adversely affect the
usability of the network, and the ability of an internetwork to grow.
BGP's convergence speed, with a security system in operation, SHOULD
strive towards equivalence to BGP running without the security system
in operation. This includes the preservation of optimizations
currently used to produce acceptable convergence speeds on current
hardware, including UPDATE packing, peer groups, etc. Two types of
verification MAY be offered for the NLRI and the AS_PATH in order to
allow for a selection of optimizations:
o Contents of the UPDATE message SHOULD be authenticated in real-
time as the UPDATE message is processed.
o The route information base MAY be authenticated periodically or in
an event-driven manner by scanning the route-table data and
verifying the originating AS and the validity of the AS_PATH list.
All BGP implementations that implement security MUST utilize at least
one of the above methods for validating routing information. Real
time verification is preferred in order to prevent transitive
failures based on periodic or event-driven scan intervals. See the
section on "Local controls ..." below for more discussion.
It is recognized that achieving all of these goals might prove very
difficult or even impossible.
3.2. Incremental deployment
It will not be feasible to deploy a newly secured BGP protocol
throughout the public Internet instantaneously. It also may not be
possible to deploy a such a protocol to all routers in a large AS at
one time. Because of this, there are several requirements that any
proposed mechanism to secure BGP must consider.
o A BGP security mechanism MUST enable each BGP speaker to configure
use of the security mechanism on a per-peer basis.
o A BGP security mechanism MUST provide backward compatibility in
the message formatting, transmission, and processing of routing
information carried through a mixed security environment. Message
formatting in a fully secured environment MAY be handled in a non-
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backward compatible fashion though care must be taken to ensure
UPDATES can traverse intermediate routers which don't support the
new format.
o In an environment where both secured and non-secured systems are
interoperating a mechanism MUST exist for secured systems to
identify whether an originator intended the information to be
secured.
3.3. Conditions for initialization
A key factor in the robust nature of the existing internal and
external relationships maintained in today's Internet is the ability
to maintain and return to a significantly converged state without the
need to rely on systems external to the routing system (the equipment
that is performing the forwarding). In order to ensure the rapid
initialization and/or return to service of failed nodes it is
important to reduce reliance on these external systems to the
greatest extent possible. Therefore, proposed systems SHOULD NOT
require connections to external systems, beyond those directly
involved in peering relationships, in order to return to full
service. Proposed systems MAY require post initialization
synchronization with external systems in order to synchronize
security information.
3.4. Local controls for secure UPDATE acceptance
Each secured environment (e.g., public Internet vs. private
internetwork) may have different metrics of what is acceptable or
unacceptable with regard to routing security. In environments that
require strict security it may not be acceptable to temporarily route
to a destination while waiting for path validation to be performed.
However, in many environments the rapidity of route installation may
be of paramount importance, e.g., in order to facilitate the common
occurrence of route withdrawal due to network failure. Based on the
two divergent requirements, the following criteria apply:
o The security system MUST support a range of possible outputs for
local determination of the trust level for a specific route so
that routing preference and policy can be applied to its inclusion
in the RIB. Any given route should be trustable to a locally
configured degree, based on the completeness of security
information with a received UPDATE and other factors. However,
experience in the security community suggests that trying to
assign trust ratings to inputs to a decision process usually adds
considerable complexity to the management of the process. This
complexity, in turn, may undermine the security offered by the
process.
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o The security system SHOULD allow the operator to determine whether
speed of convergence is more important than security, or whether
security is more important than the speed of convergence. This
facilitates the incremental deployment of security on systems not
designed to support increased processing requirements imposed by
the security system.
3.5. Processing on Routers
The introduction of mechanisms to improve routing security will
generally increase the processing performed by a router. The
increased processing typically will result from additional checks
performed to determine the validity of UPDATEs, especially if these
checks entail cryptographic operations. Since currently deployed
routers generally do not have hardware to accelerate cryptographic
operations, these operations could impose a significant processing
burden under some circumstances. Thus proposed solutions should be
evaluated carefully with regard to the processing burden they may
impose, since deployment may be impeded if network operators perceive
that a solution will impose a processing burden which either:
o provokes substantial capital expense, or
o threatens to destabilize routers.
Given the pervasive number of BGP-speaking routers in a typical ISP
deployment, solutions can increase their appeal by minimizing the
burden imposed on all BGP routers in favor of confining significant
work loads to a relatively small number of devices.
Optional features or increased assurance which provokes more
pervasive processing load MAY be made available for deployments where
the additional resources are economically justifiable.
Some statement as to the expected performance measures and scaling as
a function of prefixes, peers, NLRI, etc. MUST be included with any
proposed solution.
3.6. Configuration on Routers
It is undesirable to have long or very detailed configuration on the
routers, especially it needs to be synchronized on all of them. Long
configuration makes operating the device more difficult, and having
to do very detailed configuration may hinder the adoption of the
security solution; it should be possible to "just start using it" if
possible.
As above, a statement as to the expected configuration burden as a
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function of routers, peers, NLRI, ASNs, etc. MUST be included with
any proposed solution. Additionally, some consideration SHOULD be
given and statement made as to frequency of changes in the case of
dynamic data.
4. Infrastructure Requirements
BGP security mechanisms MAY make use of a security infrastructure to
distribute authenticated data that is an input to routing decisions.
Such data may be needed to verify whether a given AS is authorized to
originate an advertisement for a specified prefix, whether an given
organization is the recognized holder of a block of address space or
of an AS number, etc. Any infrastructure used to distribute data in
support of BGP security is subject to the following criteria:
o It MUST be resilient to attacks on the integrity of the data it
contains.
o It MUST enable network operators to verify the entity which
originted the data.
o It MUST be sufficiently available so as to not degrade the
existing pace of network operations.
o It SHOULD not introduce new organizational entities that have to
be trusted in order to establish the authenticity of the data.
5. The Trust Model
In discussion with the operations community, concerns have emerged
regarding the viability of a security system that requires agreement
on a trust model dependent on a single root. Current operational
practice has many providers engaging in bilateral agreements and
preserving the primacy of local policy choices. The viability of a
solution may well rest on the business imperatives of the provider
community who may be unwilling to surrender their perceived autonomy
or unable to come to communal agreement on this topic.
In other environments, deployments may require an authority which has
been selected by law or other institutional mandate. Moreover, these
two deployment types (single-rooted hierarchy or arbitrary
association) may "touch" (i.e. be part of the same co-extensive BGP
topology).
Solutions MUST account for these differing types of deployments.
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If two internetworks using differing trust models are interconnected
they MUST be able to interoperate using locally determined levels of
assurance to compensate for differences in these trust models. Some
acknowledgement is made that this requirement might render it
difficult to discern an attack from a difference in trust model or
implementation. Any proposed solution MUST mitigate this risk.
6. The AS_PATH Attribute and NLRI Authentication
BGP distributes routing information across the Internet (between BGP
speakers) using BGP UPDATE messages. The UPDATE message contains
withdrawn routes, path attributes and NLRI (Network Layer
Reachability Information, synonymous with advertised prefix(es)).
For the remainder of this section, we will focus on the AS_PATH
Attribute and the NLRI. Attributes such as MED are not transitive
and, as such, are protected by BGP session security.
The AS_PATH for specific prefixes may be protected in any proposed
security system in four ways, outlined below. Special Note: On the
first two categories below, the community has reached consensus; on
the latter two (AS_PATH Feasibiliity Check and Update Transit Check),
the community has not reached consensus.
o Authorization of Originating AS: For the purposes of authorization
of the originating AS, authorization means that it MUST be
possible to verify that the origin AS has been authorized to
originate the route by the prefix holder(s).
o Announcing AS Check: For all BGP peers, a BGP Implementation MUST
ensure that the first element of the AS_PATH list corresponds to
the locally configured AS of the peer from which the UPDATE was
received.
o AS_PATH Feasibility Check: The AS_PATH list MUST correspond to a
valid list of autonomous systems according to the first
verification category listed in the "Areas to Secure" Section
above.
o Update Transit Check: Routing information carried through BGP
SHOULD include information that can be used to verify the re-
advertisement or modification by each autonomous system through
which the UPDATE has passed. This check is more rigorous than the
"valid list of autonomous systems" above.
The results of all of these checks SHOULD be made available to
network operators. Each network operator will decide, on a local
basis, which of these checks to enable.
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There are many ways in which any difference between the speed of
prefix/AS path attribute propagation and the availability of the
information needed to validate the prefix/AS_PATH attribute
information can be exploited to attack the routing system on a
transient basis. These types of attacks primarily exploit the time
it takes to follow the withdrawal of a route via an UPDATE. As a
result of this potential for temporary disruption, BGP security
solutions MUST be capable of distributing security information at the
same rate as the BGP announcements and withdrawals propagate.
All data needed by BGP routers to evaluate the validity of an
advertisement MUST be made available to the routers in a timeframe
consistent with the rate at which advertisement characteristics
change. Two examples are:
o the distribution of information about the AS(es) authorized to
advertise a given block of IP addresses,
o the distribution of information about connectivity between
autonomous systems and about autonomous system policies
Note that in today's operational Internet, the first two pieces of
information, or their analogues, are not a part of the BGP routing
system per se (e.g., information in Routing or Address registries.)
They are consulted by most operators on an irregular basis and are
not consulted in real time by the routing system. Policy information
that is explicitly carried in the routing system is inconsistently
expressed and consulted in Routing registries by operators. For
instance, most providers are reticent to define their interconnection
arrangements as transit or non-transit in Routing registries; some
may do so, most do not. However, the ability to change inter-AS
traffic flows in real time is an important feature of the current
Internet.
7. Address Allocation and Advertisement
As part of the regular operation of the Internet, addresses allocated
to one organization may be, and are quite commonly, advertised by
ASes belonging to other organizations. Common reasons for this
practice include multi-homing and route reduction for the purposes of
resource conservation (e.g., aggregation). There are two modes of
delegation:
o A BGP speaker and listener have chosen to restrict the number of
received prefixes for the listener. The listener has chosen to
honor route announcements sent in a summary fashion by the
speaker.
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o Address space that is being delegated is part of a larger
allocation that is held by an autonomous system. The holder then
delegates the smaller block to another AS for purposes of
advertisement. This mode is commonly observed in multi-homing.
These two modes lead to a single common requirement: Any BGP Security
solution MUST support the ability of an address block holder to
declare (in a secure fashion) the AS(es) that the holder authorizes
to originate routes to its address block(s) or any portion thereof
regardless of the relationship of the entities.
An associated delegation criteria is the requirement to allow for
non-BGP stub networks. As a result, all secured BGP implementations
MUST allow for the contemporaneous origination of a route for a
prefix by more than one AS.
8. Logging
In order to facilitate auditing and troubleshooting, a logging
capability MUST be implemented that will indicate both negative and
positive event behaviors. This data SHALL be for consumption of the
AS operating the device that is producing the logs. Further, the
information MAY be combined with data from other is ASes or devices
with different implementations within the same AS for purposes of
event correlation and tracking. Here follow some considerations in
this regard:
o The data generated by logging may be very large depending on the
number of peers, the number of prefixes received, the
authentication model used, and routing policies. As such,
efficient data structures and storage mechanisms MUST be developed
to allow for an effective means of reproducing incidents and
outages
o Path and NLRI attributes MUST be logged using a standard format.
The format MUST be scalable with the amount of data logged and the
frequency of log generation. The frequency of log generation
should be controllable by the operator. The logging mechanisms
for the tracked information MUST be standardized across all
platforms. Logging ability both on and off line is considered
highly desirable.
9. NLRI and Path Attribute Tracking
The ability for a receiver to know the identity of each AS that
originates and/or forwards a routing UPDATE is a desirable trait. In
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order to rapidly identify attack points and parties at fault for
route table disruption, it is important to be able to track and log
prefix origination information along with associated security
information.
This capability can be afforded by implementation of the
aforementioned directive that any security system SHOULD provide a
method to allow the receiver of an UPDATE to verify that the
originator is actually authorized to originate the update, and that
the AS's listed in the AS_PATH actually forwarded the update.
10. Transport Layer Protection
Transport protection is an important aspect of BGP routing protocol
security. The potential to create a linked transport/NLRI/AS_PATH
authentication mechanism should not be overlooked and may provide for
the accelerated deployment of a BGP security system. Current
security mechanisms for BGP transport (e.g., TCP-MD5 [5] and GTSM
[7]) are inadequate and require significant operator interaction to
maintain a respectable level of security.
Transport protection systems MAY function as a component of the BGP
routing protocol security mechanism. This includes the use of the
same key generation/management systems as the rest of the security
system.
Any proposed security mechanism MUST include provisions for securing
both internal BGP and external BGP peering sessions.
11. Key Management
Current implementations and deployments of TCP-MD5 [5] exhibit
serious shortcomings with regard of key management as described in
RFC 3562 [6].
Key management can be especially onerous for operators. The number
of keys required and the maintenance of keys (issue/revoke/renew) has
had an additive effect as a barrier to deployment. Thus automated
means of managing keys, to reduce operational burdens, MUST be
available in proposed BGP security systems. These security systems
MUST be resistant to compromise of session-level or device-level
keys, i.e., the security implications of such compromises MUST be
limited.
12. References
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12.1. Normative References
[1] Rekhter, Li, and Hares, "RFC 4271 - A Border Gateway Protocol 4
(BGP-4)", October 2005.
12.2. Informative References
[2] Fraser, "RFC 2196 - Site Security Handbook", September 1997.
[3] Rescorla, Korver, and Internet Architecture Board, "RFC 3552 -
Guidelines for Writing RFC Text on Security Considerations",
July 2003.
[4] Rekhter and Li, "RFC 1771 - A Border Gateway Protocol 4
(BGP-4)", March 1995.
[5] Heffernan, "RFC 2385 - Protection of BGP Sessions via the TCP
MD5 Signature Option", August 1998.
[6] Leech, "RFC 3562 - Key Management Considerations for the TCP MD5
Signature Option", July 2003.
[7] Gill, Heasley, and Meyer, "RFC 3682 - The Generalized TTL
Security Mechanism (GTSM)", February 2004.
1. Acknowledgements
The following individuals contributed to the development and review
of this draft. Steve Kent, Russ White, Sandy Murphy, Jeff Haas, Bora
Akyol, Susan Hares, Mike Tibodeau, Thomas Renzy, Kaarthik Sivakumar,
Tao Wan, Radia Perlman, Pekka Savola and Merike Kaeo.
This draft was developed based on conversations with various network
operators including Chris Morrow, Jared Mauch, Tim Battles, and Ryan
McDowell.
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Authors' Addresses
Blaine Christian (editor)
KMC Telecom Solutions
1545 U.S. Highway 206
Bedminster, NJ 07921
US
Tony Tauber (editor)
Comcast
27 Industrial Avenue
Chelmsford, MA 01824
US
Email: ttauber@1-4-5.net
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Internet-Draft BGP Security Requirements April 2006
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