Inter-domain Source Address Validation (SAVNET) Architecture
draft-wu-savnet-inter-domain-architecture-04
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| Authors | Jianping Wu , Dan Li , Mingqing(Michael) Huang , Li Chen , Nan Geng , Libin Liu , Lancheng Qin | ||
| Last updated | 2023-09-30 (Latest revision 2023-07-25) | ||
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draft-wu-savnet-inter-domain-architecture-04
Internet Engineering Task Force J. Wu
Internet-Draft D. Li
Intended status: Standards Track Tsinghua University
Expires: 2 April 2024 M. Huang
Huawei
L. Chen
Zhongguancun Laboratory
N. Geng
Huawei
L. Liu
Zhongguancun Laboratory
L. Qin
Tsinghua University
30 September 2023
Inter-domain Source Address Validation (SAVNET) Architecture
draft-wu-savnet-inter-domain-architecture-04
Abstract
This document introduces an inter-domain SAVNET architecture,
providing a comprehensive framework for guiding the design of inter-
domain SAV mechanisms. The proposed architecture empowers ASes to
establish SAV rules by sharing SAV-specific Information between
themselves. During the incremental or partial deployment of SAV-
specific Information, it can rely on general information, such as
routing information from the RIB, to construct the SAV table when
SAV-specific Information for an AS's prefixes is unavailable. Rather
than delving into protocol extensions or implementations, this
document primarily concentrates on proposing SAV-specific and general
information and guiding how to utilize them to generate SAV rules.
It also defines the architectural components and their relations.
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
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material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 2 April 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Design Goals . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Inter-domain SAVNET Architecture . . . . . . . . . . . . . . 5
4.1. SAV Information Base . . . . . . . . . . . . . . . . . . 7
4.2. SAV-specific Information . . . . . . . . . . . . . . . . 10
4.3. SAV Information Base Manager . . . . . . . . . . . . . . 12
4.4. Management Channel and Information Channel . . . . . . . 13
5. Partial/Incremental Deployment . . . . . . . . . . . . . . . 14
6. Convergence Considerations . . . . . . . . . . . . . . . . . 15
7. Management Considerations . . . . . . . . . . . . . . . . . . 16
8. Security Considerations . . . . . . . . . . . . . . . . . . . 17
9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
11. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
12. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 20
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
14.1. Normative References . . . . . . . . . . . . . . . . . . 21
14.2. Informative References . . . . . . . . . . . . . . . . . 22
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
Attacks based on source IP address spoofing, such as reflective DDoS
and flooding attacks, continue to present significant challenges to
Internet security. Mitigating these attacks in inter-domain networks
requires effective source address validation (SAV). While BCP84
[RFC3704] [RFC8704] offers some SAV solutions, such as ACL-based
ingress filtering and uRPF-based mechanisms, existing inter-domain
SAV mechanisms have limitations in terms of validation accuracy and
operational overhead in different scenarios [inter-domain-ps].
To address these issues, the inter-domain SAVNET architecture focuses
on providing a comprehensive framework and guidelines for the design
and implementation of new inter-domain SAV mechanisms. By proposing
the SAV-specific Information which consists of prefixes of ASes and
their corresponding legitimate incoming interfaces and is specialized
for generating SAV rules, the inter-domain SAVNET architecture
empowers ASes to generate accurate SAV rules. Meanwhile, a SAV-
specific communication mechanism is used to define the data structure
or format for communicating the SAV-specific Information, and the
operations and timing for origination, processing, propagation, and
termination of the messages which carry the SAV-specific Information,
to achieve the delivery and automatic update of SAV-specific
Information. Moreover, during the incremental/partial deployment
period of the SAV-specific Information, the inter-domain SAVNET
architecture can leverage the general information, such as the
routing information from the RIB or the {prefix, maximum length,
origin AS} information from the RPKI ROA Objects and the {AS, AS's
Provider} information from the RPKI ASPA Objects, to generate the SAV
rules when the SAV-specific Information is not available. To achieve
this, the inter-domain SAVNET architecture assigns priorities to the
SAV-specific Information and general information and generates the
SAV rules based on priorities of the information in the SAV
Information Base, and the SAV-specific Information has higher
priority compared to the general information.
In addition, by defining the architectural components, relationships,
and the SAV-specific Information and general information used in
inter-domain SAV deployments, this document aims to promote
consistency, interoperability, and collaboration among ASes. This
document primarily describes a high-level architecture for
consolidating SAV-specific Information and general information and
deploying an inter-domain SAV mechanism between ASes. The document
does not specify protocol extensions or implementations. Its purpose
is to provide a conceptual framework and guidance for the development
of inter-domain SAV mechanisms, allowing implementers to adapt and
implement the architecture based on their specific requirements and
network environments.
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1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
SAV Rule:
The rule that indicates the validity of a specific source IP
address or source IP prefix.
SAV Table:
The table or data structure that implements the SAV rules and is
used for source address validation in the data plane.
SAV-specific Information:
The information consists of the source prefixes and their
legitimate incoming interfaces to enter an AS.
SAV-related Information:
The information is used to be consolidated to generate SAV rules
and can be from SAV-specific Information or general information.
False Positive:
The validation results that the packets with legitimate source
addresses are considered invalid improperly due to inaccurate SAV
rules.
False Negative:
The validation results that the packets with spoofed source
addresses are considered valid improperly due to inaccurate SAV
rules.
SAV Information Base:
A table or data structure for storing SAV-related information
collected from SAV-specific Information and general information.
3. Design Goals
The inter-domain SAVNET architecture aims to improve SAV accuracy,
facilitate partial deployment with low operational overhead, and
develop a communication approach to communicate SAV-specific
Information between ASes, while achieving efficient convergence and
providing security guarantees to communicated information, which
correspond to the requirements for new inter-domain SAV mechanisms
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[inter-domain-ps]. The overall goal can be broken down into the
following aspects:
* First, the inter-domain SAVNET architecture should learn the real
paths of source prefixes to any destination prefixes or
permissible paths that can cover their real paths, and generate
accurate SAV rules automatically based on the learned information
to avoid false positives and reduce false negatives as much as
possible.
* Second, the inter-domain SAVNET architecture should provide
sufficient protection for the source prefixes of ASes that deploy
it, even if only a portion of the Internet implements the
architecture.
* Third, the inter-domain SAVNET architecture should adapt to
dynamic networks and asymmetric routing scenarios automatically.
* Fourth, the inter-domain SAVNET architecture should communicate
SAV-specific Information between ASes automatically with a
communication approach.
* Fifth, the inter-domain SAVNET architecture should promptly detect
the network changes and launch the convergence process quickly,
while reducing false positives and false negatives during the
convergence process.
* Last, the inter-domain SAVNET architecture should provide security
guarantees for the communicated SAV-specific Information.
Other design goals, such as low operational overhead and easy
implementation, are also very important and should be considered in
specific protocols or protocol extensions.
4. Inter-domain SAVNET Architecture
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+-------------------------------------------------------+
| Other ASes |
+-------------------------------------------------------+
| SAV-specific
| Messages
+-------------------------------------------------------+
| | AS |
| \/ |
| +~~~~~~~~~~~~~~~~~~~~~+ +--------------------------+ |
| | General Information | | SAV-specific Information | |
| +~~~~~~~~~~~~~~~~~~~~~+ +--------------------------+ |
| | | |
| \/ \/ |
| +---------------------------------------------------+ |
| | +-----------------------------------------------+ | |
| | | SAV Information Base | | |
| | +-----------------------------------------------+ | |
| | SAV Information Base Manager | |
| +---------------------------------------------------+ |
| |SAV Rules |
| \/ |
| +------------------------------------------------+ |
| | SAV Table | |
| +------------------------------------------------+ |
+-------------------------------------------------------+
Figure 1: The inter-domain SAVNET architecture
Figure 1 shows the overview of the inter-domain SAVNET architecture.
The inter-domain SAVNET architecture collects SAV-specific
Information from the SAV-specific Messages of other ASes. The SAV-
specific Information consists of the prefixes and their legitimate
incoming interfaces to enter an AS. As a result, the SAV-specific
Information can be used to generate SAV rules and build an accurate
SAV table on each AS directly. In order to exchange SAV-specific
Information between ASes, a new SAV-specific communication mechanism
should be developed to carry the SAV-specific Information. Compared
against existing inter-domain SAV mechanisms which rely on the
general information such as routing information from the RIB, the
SAV-specific Information can generate more accurate SAV rules, the
root cause is that the SAV-specific Information is specially designed
and communicated for inter-domain SAV, while the general information
is not.
A SAV-specific communication mechanism should be developed to define
the data structure or format for communicating the SAV-specific
Information and the operations and timing for originating,
processing, propagating, and terminating the messages which carry the
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information. Additionally, the SAV-specific Information will not be
available for all ASes when the SAV-specific communication mechanism
is on the incremental/partial deployment. Therefore, in the stage of
incremental/partial deployment, the inter-domain SAVNET architecture
can use the general information to generate SAV rules.
The SAV Information Base (SIB) can store the information from the
SAV-specific Information and general information and is maintained by
the SAV Information Base Manager (SIM), and then the SIM generates
SAV rules based on the SIB and fills out the SAV table in the
dataplane. The SIB can be managed by network operators using various
methods such as YANG, Command-Line Interface (CLI), remote triggered
black hole (RTBH) [RFC5635], and Flowspec [RFC8955].
Inter-domain SAVNET architecture does not prescribe any specific
deployment models.
4.1. SAV Information Base
The SIB is managed by the SAV Information Base Manager, which can
consolidate SAV-related information from different sources. The SAV
information sources of SIB include SAV-specific Information and
general information, which are illustrated below:
* SAV-specific Information is the specifically collected information
for SAV and exactly consists of the prefixes and their legitimate
incoming interfaces to enter ASes.
* General information refers to the information that is not directly
related to SAV but can be utilized to generate SAV rules, and
includes routing information from the RIB or FIB, the {prefix,
maximum length, origin AS} information from the RPKI ROA Objects,
and the {AS, AS's Provider} information from the RPKI ASPA
Objects.
In the future, if an information source is created but is not
initially and specially used for SAV, the information can be
categorized into general information. Therefore, the general
information can be considered as the dual-use information.
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+---------------------------------------------------+----------+
| SAV Information Sources |Priorities|
+---------------------------------------------------+----------+
| SAV-specific Information | 1 |
+---------------------+-----------------------------+----------+
| | RPKI ROA Obj. and ASPA Obj. | 2 |
| +-----------------------------+----------+
| General Information | RIB | 3 |
| +-----------------------------+----------+
| | FIB | 4 |
+---------------------+-----------------------------+----------+
Figure 2: Priority ranking for the SAV information sources
Figure 2 presents a priority ranking for the SAV-specific Information
and general information. SAV-specific Information has higher
priority (i.e., 1) than the general information (i.e., 2), since the
inter-domain SAVNET architecture uses the SAV-specific Information to
carry more accurate information which comprises ASes' prefixes and
their legitimate incoming interfaces. Therefore, once the SAV-
specific Information for a prefix is available within the SIB, the
inter-domain SAVNET generates SAV rules based on the information from
the SAV-specific Information; otherwise, the inter-domain SAVNET
generates SAV rules based on the general information. In other
words, the inter-domain SAVNET architecture assigns priorities to the
information from different SAV information sources, and always
generates the SAV rules using the information with the highest
priority.
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+------------------+
| AS 3(P3) |
+-+/\------+/\+----+
/ \
/ \
/ \
Itf.1 / (C2P) \
+------------------+ \
| AS 4(P4) | \
++/\+---+/\+---+/\++ \
Itf.2 / | Itf.3 \ Itf.4 \
P6[AS 1, AS 2] / | \ \
P2[AS 2] / | \ \
/ (C2P) | \ \
+----------------+ | \ \
| AS 2(P2) | | P1[AS 1] \ P5[AS 5] \ P5[AS 5]
+----------+/\+--+ | P6[AS 1] \ \
\ | NO_EXPORT \ \
P6[AS 1] \ | \ \
P1[AS 1] \ | \ \
NO_EXPORT \ (C2P) | (C2P) (C2P) \ (C2P) \
+----------------+ +----------------+
| AS 1(P1, P6) | | AS 5(P5) |
+----------------+ +----------------+
Figure 3: An example of AS topology
+-----+------+------------------+---------+------------------------+
|Index|Prefix|AS-level Interface|Direction| SAV Information Source |
+-----+------+------------------+---------+------------------------+
| 0 | P3 | Itf.1 |Provider | General Information |
+-----+------+------------------+---------+------------------------+
| 1 | P2 | Itf.2 |Customer | General Information |
+-----+------+------------------+---------+------------------------+
| 2 | P1 | Itf.2 |Customer |SAV-specific Information|
+-----+------+------------------+---------+------------------------+
| 3 | P1 | Itf.3 |Customer | General Information |
+-----+------+------------------+---------+------------------------+
| 4 | P6 | Itf.2 |Customer | General Information |
+-----+------+------------------+---------+------------------------+
| 5 | P6 | Itf.3 |Customer |SAV-specific Information|
| | | | | General Information |
+-----+------+------------------+---------+------------------------+
| 6 | P5 | Itf.4 |Customer | General Information |
+-----+------+------------------+---------+------------------------+
| 7 | P5 | Itf.1 |Provider | General Information |
+-----+------+------------------+---------+------------------------+
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Figure 4: An example for the SAV information base in AS 4
We use the examples shown in Figure 3 and Figure 4 to introduce SIB
and illustrate how to generate SAV rules based on the SIB. Figure 3
shows an example of AS topology and Figure 4 depicts an example of
the SIB established in AS 4. As shown in Figure 3, AS 4 has four AS-
level interfaces, each connected to a different AS. Specifically,
Itf.1 is connected to AS 3, Itf.2 to AS 2, Itf.3 to AS 1, and Itf.4
to AS 5. The arrows in the figure represent the commercial
relationships between ASes. AS 3 is the provider of AS 4 and AS 5,
while AS 4 is the provider of AS 1, AS 2, and AS 5, and AS 2 is the
provider of AS 1. Assuming prefixes P1, P2, P3, P4, P5, and P6 are
all the prefixes in the network.
Each row of the SIB contains an index, prefix, AS-level incoming
interface for the prefix, incoming direction, and the corresponding
sources of these information. The incoming direction consists of
customer, provider, and peer. For example, in Figure 4, the row with
index 0 indicates prefix P3's valid incoming interface is Itf.1, the
ingress direction of P3 is AS 4's provider AS (AS 3), and these
information is from the RIB. Note that the same SAV-related
information may have multiple sources and the SIB records them all.
Recall that the inter-domain SAVNET architecture generates SAV rules
based on the SAV-related information in the SIB and their priorities.
In addition, in the case of an AS's provider/peer interfaces where
loose SAV rules are applicable, the inter-domain SAVNET architecture
recommends to use blocklist at such interfaces to only block the
prefixes that are sure not to come at these interfaces, while in the
case of an AS's customer interfaces that necessitate stricter SAV
rules, the inter-domain SAVNET architecture recommends to use
allowlist to only permit the prefixes that are allowed to come at
these interfaces.
Based on the above rules, take the SIB in Figure 4 as an example to
illustrate how the inter-domain SAVNET architecture generates the SAV
table to perform SAV in the data plane. AS 4 can conduct SAV at its
interfaces as follows: SAV at the interface Itf.1 blocks P1, P2, and
P6 according to the rows with indexes 0, 1, 2, and 5 in the SIB, SAV
at the interface Itf.2 permits P1 and P2 according to the rows with
indexes 1 and 2 in the SIB, SAV at the interface Itf.3 permits P6
according to the row with index 5 in the SIB, and SAV at the
interface Itf.4 permits P5 according to the row with index 6 in the
SIB.
4.2. SAV-specific Information
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+----------------------+ +----------------------+
| AS | SAV-specific | AS |
| +-----------------+ | Messages | +-----------------+ |
| | SAV-specific |<-|--------------|->| SAV-specific | |
| |Message Processor| | | |Message Processor| |
| +-----------------+ | | +-----------------+ |
+----------------------+ +----------------------+
Figure 5: Exchanging SAV-specific Information with SAV-specific
Messages between ASes
The SAV-specific Information is the information consisting of source
prefixes and their legitimate incoming interfaces entering an AS, and
the legitimate incoming interfaces are the interfaces where the
packets whose source addresses are encompassed in the source prefixes
come. Therefore, the SAV-specific Information can be expressed as
<Prefix, Interface> pairs. It is noted that the same prefix may have
different legitimate incoming interfaces for an AS, since the
dataplane packets with the source addresses encompassed in the source
prefixes may have different destination addresses.
The SAV-specific Information can be exchanged between ASes by the
SAV-specific messages. As shown in Figure 5, the SAV-specific
messages are used to propagate or originate the SAV-specific
Information between ASes by the SAV-specific message processor.
Within an AS, the SAV-specific message processor can obtain the next
hop of the corresponding prefixes based on the local RIB and use SAV-
specific messages to carry its own prefixes and/or the prefixes
received from other ASes to the next hops for the corresponding
destinations. When a SAV-specific processor receives the SAV-
specific messages, it parses them to obtain the carried source
prefixes, as well as the corresponding legitimate incoming interfaces
by checking the interfaces which the SAV-specific messages arrive at.
The SAV-specific message processor also checks the destination
addresses of the SAV-specific messages, if the destination address of
the SAV-specific message is itself, it will terminate the message,
otherwise, it will forward it based on the local RIB. Following
this, the SAV-specific messages can propagate the SAV-specific
Information between ASes.
Moreover, if SAV-specific messages are used to exchange SAV-specific
Information between ASes, a new SAV-specific communication mechanism
would need to be developed to communicate the SAV-specific messages.
The SAV-specific communication mechanism need to define the data
structure or format to communicate the SAV-specific messages and the
operations and timing for originating, processing, propagating, and
terminating the messages. If an extension to an existing protocol is
used to exchange SAV-specific Information, the corresponding existing
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protocol should not be affected. The SAV-specific message processor
is the entity to support the SAV-specific communication mechanism.
By parsing the SAV-specific messages, it obtains the ASN, the
prefixes, the AS-level interfaces to receive the messages, and their
incoming AS direction for maintaining the SIB. It is important to
note that the SAV-specific message processor within an AS has the
capability to establish connections with multiple SAV-specific
message processors within different ASes, relying on either manual
configurations by operators or an automatic mechanism.
The need for a SAV-specific communication mechanism arises from the
facts that the SAV-specific Information needs to be obtained and
communicated between ASes. Different from the general information
such as routing information from the RIB, there are no existing
mechanisms which can support the perception and communication of SAV-
specific Information between ASes. Hence, a SAV-specific
communication mechanism is needed to provide a medium and set of
rules to establish communication between different ASes for the
exchange of SAV-specific Information.
Additionally, the preferred AS paths of an AS may change over time
due to route changes or network failures. The SAV-specific message
processor should launch SAV-specific messages to adapt to the route
changes in a timely manner. The SAV-specific communication mechanism
should handle route changes carefully to avoid false positives. The
reasons for leading to false positives may include late detection of
route changes, delayed message transmission, or packet losses.
However, the detailed design of the SAV-specific communication
mechanism for dealing with route changes is outside the scope of this
document.
4.3. SAV Information Base Manager
SAV Information Base Manager (SIM) consolidates SAV-related
information from the SAV-specific Information and general information
to initiate or update the SIB, while it generates SAV rules to
populate the SAV table in the dataplane according to the SIB. The
detailed collection methods of the SAV-related information depend on
the deployment and implementation of the inter-domain SAV mechanisms
and are out of scope for this document.
Using the SIB, SIM produces <Prefix, Interface> pairs to populate the
SAV table, which represents the prefix and its legitimate incoming
interface. It is worth noting that the interfaces in the SIB are
logical AS-level interfaces and need to be mapped to the physical
interfaces of the AS border routers.
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4.4. Management Channel and Information Channel
+------+
| | Management Channel +--------------------------------+
| |<========================| Network Operators |
| | +--------------------------------+
| |
| | Information Channel +--------------------------------+
| |<------------------------| SAV-specific Message Processor |
| | +--------------------------------+
| SIM |
| | Information Channel +--------------------------------+
| |<------------------------| RPKI ROA Obj. and ASPA Obj. |
| | +--------------------------------+
| |
| | Information Channel +--------------------------------+
| |<------------------------| RIB |
| | +--------------------------------+
+------+
Figure 6: The management channel and information channel for
collecting SAV- related information from different SAV
information sources
The SAV-specific Information relies on the communication between SAV-
specific message processors within ASes and the general information
may be from multiple sources, such as the RIB and RPKI ROA objects
and ASPA objects. Therefore, as illustrated in Figure 6, the SIM
needs to receive the SAV-related information from these SAV
information sources. We abstract the connections used to collect the
SAV-related information from the sources as Information Channel.
Also, the network operators can operate the SIB by manual
configurations, such as YANG, CLI, RTBH [RFC5635], and Flowspec
[RFC8955], where the approaches to implement these are abstracted as
Management Channel.
The primary purpose of the management channel is to deliver manual
configurations of network operators. Examples of such information
include, but are not limited to:
* SAV configurations using YANG, CLI, RTBH, or Flowspec.
* SAVNET operation and management.
* Inter-domain SAVNET provisioning.
Note that the information can be delivered at any time and requires
reliable delivery for the management channel implementation.
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The information channel serves as a means to transmit the SAV-
specific Information and general information from various sources
including the RIB and RPKI ROA objects and RPKI ASPA Objects.
Additionally, it can carry telemetry information, such as metrics
pertaining to forwarding performance, the count of spoofing packets
and discarded packets, provided that the inter-domain SAVNET has
access to such data. The information channel can include information
regarding the prefixes associated with the spoofing traffic, as
observed until the most recent time.
5. Partial/Incremental Deployment
The inter-domain SAVNET architecture MUST ensure support for partial/
incremental deployment as it is not feasible to deploy it
simultaneously in all ASes. The partial/incremental deployment of
the inter-domain SAVNET architecture consists of different aspects,
which include the partial/incremental deployment of the architecture
and the partial/incremental deployment of the information sources.
Within the architecture, the general information like the prefixes
and topological information from RPKI ROA Objects and ASPA Objects
and the routing information from the RIB can be obtained locally when
the corresponding sources are available. Even when both SAV-specific
Information and the information from RPKI ROA Objects and ASPA
Objects are not available, the routing information from the RIB can
be used to generate SAV rules.
Furthermore, it is not mandatory for all ASes to deploy SAV-specific
message processors for SAV-specific Information. Instead, a SAV-
specific message processor should be able to effortlessly establish a
logical neighboring relationship with another AS that has deployed a
SAV-specific message processor. The connections for communicating
SAV-specific Information can be achieved by manual configurations set
by operators or an automatic neighbor discovery mechanism. This
flexibility enables the architecture to accommodate varying degrees
of deployment, promoting interoperability and collaboration among
participating ASes. During the partial/incremental deployment of
SAV-specific message processor, the SAV-specific Information for the
ASes which do not deploy SAV-specific message processor can not be
obtained. To protect the prefixes of these ASes, inter-domain SAVNET
architecture can use the SAV-related information from the general
information in the SIB to generate SAV rules. At least, the routing
information from the RIB can be always available in the SIB.
As more ASes adopt the inter-domain SAVNET architecture, the
"deployed area" expands, thereby increasing the collective defense
capability against source address spoofing. Furthermore, if multiple
"deployed areas" can be logically interconnected across "non-deployed
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areas", these interconnected "deployed areas" can form a logical
alliance, providing enhanced protection against address spoofing.
Especially, along with more ASes deploy SAV-specific message
processor and support the communication of SAV-specific Information,
the generated SAV rules of the inter-domain SAVNET architecture to
protect these ASes will become more accurate, as well as enhancing
the protection capability against source address spoofing for the
inter-domain SAVNET architecture.
In addition, releasing the SAV functions of the inter-domain SAVNET
architecture incrementally is one potential way to reduce the
deployment risks and can be considered in its deployment by network
operators:
* First, the inter-domain SAVNET can only do the measurement in the
data plane and do not take any other actions. Based on the
measurement data, the operators can evaluate the effect of the
inter-domain SAVNET on the legitimate traffic, including
validation accuracy and forwarding performance, as well as the
operational overhead.
* Second, the inter-domain SAVNET can open the function to limit the
rate of the traffic that is justified as spoofing traffic. The
operators can further evaluate the effect of the inter-domain
SAVNET on the legitimate traffic and spoofing traffic, such as
limiting the rate of all the spoofing traffic without hurting the
legitimate traffic.
* Third, when the validation accuracy, forwarding performance, and
operational overhead have been verified on a large scale by the
live network, the inter-domain SAVNET can open the function to
directly block the spoofing traffic that is justified by the SAV
table in the data plane.
6. Convergence Considerations
Convergence issues SHOULD be carefully considered in inter-domain SAV
mechanisms due to the dynamic nature of the Internet. Internet
routes undergo continuous changes, and SAV rules MUST proactively
adapt to these changes, such as prefix and topology changes, in order
to prevent false positives and reduce false negatives. To
effectively track these changes, the SIM should promptly collect SAV-
related information from various SAV information sources and
consolidate them in a timely manner.
In particular, it is essential for the SAV-specific message
processors to proactively communicate the changes of the SAV-specific
Information between ASes and adapt to route changes promptly.
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However, during the routing convergence process, the traffic paths of
the source prefixes can undergo rapid changes within a short period.
The changes of the SAV-specific Information may not be communicated
in time between ASes to update SAV rules, false positives or false
negatives may happen. Such inaccurate validation is caused by the
delays in communicating SAV-specific Information between ASes, which
occur due to the factors like packet losses, unpredictable network
latencies, or message processing latencies. The design of the SAV-
specific communication mechanism should consider these issues to
reduce the inaccurate validation.
Besides, for the inter-domain SAVNET architecture, the potential ways
to deal with the inaccurate validation issues during the convergence
of the SAV-specific communication mechanism is to consider using the
information from RPKI ROA Objects and ASPA objects to generate SAV
rules until the convergence process of the SAV-specific communication
mechanism is finished, since these information is more stable and can
help avoid false positives, and thus avoiding the impact to the
legitimate traffic.
7. Management Considerations
It is crucial to consider the operations and management aspects of
SAV information sources, the SAV-specific communication mechanism,
SIB, SIM, and SAV table in the inter-domain SAVNET architecture. The
following guidelines should be followed for their effective
management:
First, management interoperability should be supported across devices
from different vendors or different releases of the same product,
based on a unified data model such as YANG [RFC6020]. This is
essential because the Internet comprises devices from various vendors
and different product releases that coexist simultaneously.
Second, scalable operation and management methods such as NETCONF
[RFC6241] and syslog protocol [RFC5424] should be supported. This is
important as an AS may have hundreds or thousands of border routers
that require efficient operation and management.
Third, management operations, including default initial
configuration, alarm and exception reporting, logging, performance
monitoring and reporting for the control plane and data plane, as
well as debugging, should be designed and implemented in the
protocols or protocol extensions. These operations can be performed
either locally or remotely, based on the operational requirements.
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By adhering to these rules, the management of SAV information sources
and related components can be effectively carried out, ensuring
interoperability, scalability, and efficient operations and
management of the inter-domain SAVNET architecture.
8. Security Considerations
In the inter-domain SAVNET architecture, the SAV-specific message
processor plays a crucial role in generating and disseminating SAV-
specific Messages across different ASes. To safeguard against the
potential risks posed by a malicious AS generating incorrect or
forged SAV-specific Messages, it is important for the SAV-specific
message processors to employ security authentication measures for
each received SAV-specific Message. The majour security threats
faced by inter-domain SAVNET can be categorized into two aspects:
session security and content security. Session security pertains to
verifying the identities of both parties involved in a session and
ensuring the integrity of the session content. Content security, on
the other hand, focuses on verifying the authenticity and reliability
of the session content, thereby enabling the identification of forged
SAV-specific Messages.
The threats to session security include:
* Session identity impersonation: This occurs when a malicious
router deceitfully poses as a legitimate peer router to establish
a session with the targeted router. By impersonating another
router, the malicious entity can gain unauthorized access and
potentially manipulate or disrupt the communication between the
legitimate routers.
* Session integrity destruction: In this scenario, a malicious
intermediate router situated between two peering routers
intentionally tampers with or destroys the content of the relayed
SAV-specific Message. By interfering with the integrity of the
session content, the attacker can disrupt the reliable
transmission of information, potentially leading to
miscommunication or inaccurate SAV-related data being propagated.
The threats to content security include:
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* Message alteration: A malicious router has the ability to
manipulate or forge any portion of a SAV-specific Message. For
example, the attacker may employ techniques such as using a
spoofed Autonomous System Number (ASN) or modifying the AS Path
information within the message. By tampering with the content,
the attacker can potentially introduce inaccuracies or deceive the
receiving ASes, compromising the integrity and reliability of the
SAV-related information.
* Message injection: A malicious router injects a seemingly
"legitimate" SAV-specific Message into the communication stream
and directs it to the corresponding next-hop AS. This type of
attack can be likened to a replay attack, where the attacker
attempts to retransmit previously captured or fabricated messages
to manipulate the behavior or decisions of the receiving ASes.
The injected message may contain malicious instructions or false
information, leading to incorrect SAV rule generation or improper
validation.
* Path deviation: A malicious router intentionally diverts a SAV-
specific Message to an incorrect next-hop AS, contrary to the
expected path defined by the AS Path. By deviating from the
intended routing path, the attacker can disrupt the proper
dissemination of SAV-related information and introduce
inconsistencies or conflicts in the validation process. This can
undermine the effectiveness and accuracy of source address
validation within the inter-domain SAVNET architecture.
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Overall, inter-domain SAVNET shares similar security threats with BGP
and can leverage existing BGP security mechanisms to enhance both
session and content security. Session security can be enhanced by
employing session authentication mechanisms used in BGP, such as MD5,
TCP-AO, or Keychain. Similarly, content security can benefit from
the deployment of existing BGP security mechanisms like RPKI, BGPsec,
and ASPA. While these mechanisms can address content security
threats, their widespread deployment is crucial. Until then, it is
necessary to develop an independent security mechanism specifically
designed for inter-domain SAVNET. One potential approach is for each
origin AS to calculate a digital signature for each AS path and
include these digital signatures within the SAV-specific Messages.
Upon receiving a SAV-specific Message, the SAV-specific message
processor can verify the digital signature to ascertain the message's
authenticity. Furthermore, it is worth noting that the information
channel of the inter-domain SAVNET architecture may need to operate
over a network link that is currently under a source address spoofing
attack. As a result, it may experience severe packet loss and high
latency due to the ongoing attack, and the implementation of the
information channel should ensure uninterrupted communication.
Detailed security designs and considerations will be addressed in a
separate draft, ensuring the robust security of inter-domain SAVNET.
9. Privacy Considerations
TBD
10. IANA Considerations
This document has no IANA requirements.
11. Scope
In this architecture, the choice of protocols used for communication
between the SIM and different SAV information sources is not limited.
The inter-domain SAVNET architecture presents considerations on how
to consolidate SAV-related information from various sources to
generate SAV rules and perform SAV using the SAV table in the
dataplane. The detailed design and implementation for SAV rule
generation and SAV execution depend on the specific inter-domain SAV
mechanisms employed.
This document does not cover administrative or business agreements
that may be established between the involved inter-domain SAVNET
parties. These considerations are beyond the scope of this document.
However, it is assumed that authentication and authorization
mechanisms can be implemented to ensure that only authorized ASes can
communicate SAV-related information.
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12. Assumptions
This document makes the following assumptions:
* All ASes where the inter-domain SAVNET is deployed are assumed to
provide the necessary connectivity between SAV-specific message
processor and any intermediate network elements. However, the
architecture does not impose any specific limitations on the form
or nature of this connectivity.
* Congestion and resource exhaustion can occur at various points in
the inter-domain networks. Hence, in general, network conditions
should be assumed to be hostile. The inter-domain SAVNET
architecture must be capable of functioning reliably under all
circumstances, including scenarios where the paths for delivering
SAV-related information are severely impaired. It is crucial to
design the inter-domain SAVNET system with a high level of
resilience, particularly under extremely hostile network
conditions. The architecture should ensure uninterrupted
communication between inter-domain SAV-specific message
processors, even when data-plane traffic saturates the link.
* The inter-domain SAVNET architecture does not impose rigid
requirements for the SAV information sources that can be used to
generate SAV rules. Similarly, it does not dictate strict rules
on how to utilize the SAV-related information from diverse sources
or perform SAV in the dataplane. Network operators have the
flexibility to choose their approaches to generate SAV rules and
perform SAV based on their specific requirements and preferences.
Operators can either follow the recommendations outlined in the
inter-domain SAVNET architecture or manually specify the rules for
governing the use of SAV-related information, the generation of
SAV rules, and the execution of SAV in the dataplane.
* The inter-domain SAVNET architecture does not impose restrictions
on the selection of the local AS with which AS to communicate SAV-
specific Information. The ASes have the flexibility to establish
connections for SAV-specific communication based on the manual
configurations set by operators or other automatic mechanisms.
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* The inter-domain SAVNET architecture provides the flexibility to
accommodate Quality-of-Service (QoS) policy agreements between
SAVNET-enabled ASes or local QoS prioritization measures, but it
does not make assumptions about their presence. These agreements
or prioritization efforts are aimed at ensuring the reliable
delivery of SAV-specific Information between SAV-specific message
processors. It is important to note that QoS is considered as an
operational consideration rather than a functional component of
the inter-domain SAVNET architecture.
* The information and management channels are loosely coupled and
are used for collecting SAV-related information from different
sources, and how the inter-domain SAVNET synchronize the
management and operation configurations is out of scope of this
document.
13. Contributors
Igor Lubashev
Akamai Technologies
145 Broadway
Cambridge, MA, 02142
United States of America
Email: ilubashe@akamai.com
Many thanks to Igor Lubashev for the significantly helpful revision
suggestions.
14. References
14.1. Normative References
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed
Networks", BCP 84, RFC 3704, DOI 10.17487/RFC3704, March
2004, <https://www.rfc-editor.org/rfc/rfc3704>.
[RFC8704] Sriram, K., Montgomery, D., and J. Haas, "Enhanced
Feasible-Path Unicast Reverse Path Forwarding", BCP 84,
RFC 8704, DOI 10.17487/RFC8704, February 2020,
<https://www.rfc-editor.org/rfc/rfc8704>.
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[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/rfc/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/rfc/rfc6241>.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424,
DOI 10.17487/RFC5424, March 2009,
<https://www.rfc-editor.org/rfc/rfc5424>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
14.2. Informative References
[inter-domain-ps]
"Source Address Validation in Inter-domain Networks Gap
Analysis, Problem Statement, and Requirements", 2023,
<https://datatracker.ietf.org/doc/draft-ietf-savnet-inter-
domain-problem-statement/>.
[RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole
Filtering with Unicast Reverse Path Forwarding (uRPF)",
RFC 5635, DOI 10.17487/RFC5635, August 2009,
<https://www.rfc-editor.org/rfc/rfc5635>.
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/rfc/rfc8955>.
Acknowledgements
Many thanks to Alvaro Retana, Kotikalapudi Sriram, Rüdiger Volk,
Xueyan Song, Ben Maddison, Jared Mauch, Joel Halpern, Aijun Wang,
Jeffrey Haas, Xiangqing Chang, Changwang Lin, Mingxing Liu, Zhen Tan,
etc. for their valuable comments on this document.
Authors' Addresses
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Jianping Wu
Tsinghua University
Beijing
China
Email: jianping@cernet.edu.cn
Dan Li
Tsinghua University
Beijing
China
Email: tolidan@tsinghua.edu.cn
Mingqing Huang
Huawei
Beijing
China
Email: huangmingqing@huawei.com
Li Chen
Zhongguancun Laboratory
Beijing
China
Email: lichen@zgclab.edu.cn
Nan Geng
Huawei
Beijing
China
Email: gengnan@huawei.com
Libin Liu
Zhongguancun Laboratory
Beijing
China
Email: liulb@zgclab.edu.cn
Lancheng Qin
Tsinghua University
Beijing
China
Email: qlc19@mails.tsinghua.edu.cn
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