Internet DRAFT - draft-gersch-grow-revdns-bgp
draft-gersch-grow-revdns-bgp
Network Working Group J. Gersch
Internet-Draft Secure64 SW Corp
Intended status: Standards Track D. Massey
Expires: August 29, 2013 C. Olschanowsky
Colorado State University
L. Zhang
UCLA
February 25, 2013
DNS Resource Records for Authorized Routing Information
draft-gersch-grow-revdns-bgp-02
Abstract
This draft discusses the use of two DNS record types for storing BGP
routing information in the reverse DNS. The RLOCK record allows
prefix owners to indicate whether the DNS is being used to publish
routing data. The SRO record allows operators to indicate whether an
IPv4 or IPv6 prefix ought to appear in global routing tables and
identifies authorized origin Autonomous System Number(s) for that
prefix. The resulting published data can be used in a variety of
contexts from routing security to address ownership.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2013.
Copyright Notice
Copyright (c) 2013 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used In This Document . . . . . . . . . . . . . . 4
3. Overview of Route Publishing . . . . . . . . . . . . . . . . . 5
4. Overview of Route Verification . . . . . . . . . . . . . . . . 6
5. The RLOCK Resource Record . . . . . . . . . . . . . . . . . . 8
5.1. RLOCK RDATA Wire Format . . . . . . . . . . . . . . . . . 9
5.1.1. The Activation Time field . . . . . . . . . . . . . . 9
5.2. RLOCK Presentation Format . . . . . . . . . . . . . . . . 10
5.3. RLOCK RR Examples . . . . . . . . . . . . . . . . . . . . 10
6. The SRO Resource Record . . . . . . . . . . . . . . . . . . . 11
6.1. SRO RDATA Wire Format . . . . . . . . . . . . . . . . . . 11
6.1.1. The Origin AS Number field . . . . . . . . . . . . . . 12
6.1.2. The Flags field . . . . . . . . . . . . . . . . . . . 12
6.1.3. The Prefix Limit field . . . . . . . . . . . . . . . . 12
6.1.4. The Activation Time field . . . . . . . . . . . . . . 12
6.2. SRO RRDATA Presentation Format . . . . . . . . . . . . . . 13
6.3. SRO RR Examples . . . . . . . . . . . . . . . . . . . . . 14
7. Discussion and Related Work . . . . . . . . . . . . . . . . . 15
7.1. Prior Work on CIDR names for Routing . . . . . . . . . . . 15
7.2. RPKI . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 17
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
11. Change History . . . . . . . . . . . . . . . . . . . . . . . . 20
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
12.1. Normative References . . . . . . . . . . . . . . . . . . . 21
12.2. Informative References . . . . . . . . . . . . . . . . . . 21
Appendix A. Discussion of Prefix Limits use in conjunction
with DNS wildcards . . . . . . . . . . . . . . . . . 23
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 25
B.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 25
B.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28
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1. Introduction
1.1. Overview
This draft describes a method in which a prefix owner can exploit the
existing reverse DNS tree structure, along with the authentication
provided by DNSSEC [RFC4033], to publish information about whether a
prefix can be announced and identify the origin Autonomous System(s)
that may originate a route to that prefix. This data is
complementary to a variety of other data sources ranging from
existing databases to new directions.
Publishing route information in the Reverse DNS takes advantage of
infrastructure that already exists and has been globally deployed.
No new infrastructure deployment is required, in contrast with
approaches that use purpose-built resource certification.
Other key advantages to using the Reverse DNS are that it 1) has been
in successful operation for many years, 2) has an existing
operational model where prefix owners currently manage their IP
address space (through various models from local operation to hosting
companies), 3) has an existing operational model where both
registries and providers delegate authority to entities receiving
address space, 4) the resulting reverse DNS data can be authenticated
using DNSSEC [RFC4033], and 5) the data can be easily checked using
simple tools ranging from DNS query tools such as DIG to more
elaborate systems.
A prefix owner must OPT-IN to the approach. Prefix owners who do not
take any action are not impacted, but also do not gain any
advantages. Prefix owners that do choose to participate would
thereby enable a number of tools to make use of the published data.
The objective of this draft is to standardize the format for
indicating participation and publishing data. A variety of potential
uses for the data are discussed later in the document, but are
provided only to illustrate the usefulness of the data and should not
be taken as a comprehensive list of all possible applications.
1.2. Scope
We limit the scope of this internet draft to associating an origin AS
number with a prefix. Armed with this information, one can address
both origin hijacks and sub-prefix hijacks in a manner that can be
deployed in a reasonable time frame. Future expansion is readily
made possible: the SRO record is kept simple for now, but is designed
to reference additional future records that enable additional
capabilities.
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2. Conventions Used In This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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3. Overview of Route Publishing
This document defines two new DNS resource records types (RRTypes)
and describes how these record types can be associated with prefixes.
1. The RLOCK RRType (Route Lock)
* Purpose: Indicates that the Reverse DNS zone has enabled BGP
route publishing.
* The presence of the RLOCK Record at the apex of a Reverse DNS
zone indicates that a prefix owner has OPTED-IN to BGP Route
Publishing. All route announcements that map to this zone
will be denied as INVALID unless an SRO record exists that
specifically authorizes the announcement.
2. The SRO RRType (Secure Route Origin)
* Purpose: Declare an authorized route origin ASN for comparison
against BGP route announcements.
* Placed in the Reverse DNS at the domain name corresponding to
the associated CIDR address block.
Organizations that have been assigned and/or allocated CIDR address
blocks also have Reverse-DNS delegations assigned to them from either
the Regional Internet Registries (RIPE, ARIN, APNIC, etc.) or from a
sub-delegation.
Address-block owners may use these record types to declare
authoritative data for route origins associated with that address
block. This data may be declared statically, with a long TTL (Time
To Live) if the routing data changes infrequently. Alternatively,
dynamic DNS and short TTLs can be used to rapidly publish and
disseminate the authoritative information on a world-wide basis in
near real-time.
The RLOCK and SRO records are to be stored in the reverse-DNS in
zones with domain names that correspond to the associated CIDR
address block. These domain names are to be constructed per the
naming specification described in [I-D.gersch-dnsop-revDNS-CIDR].
The RLOCK and SRO records MUST be signed with DNSSEC and have a valid
DNSSEC chain-of-trust.
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4. Overview of Route Verification
Various applications could be written to use BGP records published in
the Reverse DNS. One example is an application to perform near-real-
time route origin verification that alerts operators of hijacks or
directly interacts with a router to prevent the hijack. Another
application could perform a nightly analysis that generates router
prefix filters. A third application could cross-check data in the
Internet Routing Registries (IRR) against the data in the reverse
DNS. This list is not intended to be comprehensive, but instead aims
to illustrate the potential uses of the published data.
These applications analyze BGP announcements by performing DNS
queries to classify route route announcements into one of the
following three categories:
1. "VALID": a DNSSEC-validated SRO RRSET was received and one of the
route origins in the RRSET matches the origin contained in the
BGP route announcement.
2. "INVALID": a route hijack was detected.
A. The DNSSEC-validated SRO responses received did NOT match the
origin of the route announcement. This is indicative of an
origin hijack.
B. There was no SRO record at the domain name corresponding to
this address block, but the authoritative zone did contain an
RLOCK statement. This is indicative of a sub-prefix hijacks.
3. "NOTFOUND": there was no SRO record for this prefix and no RLOCK
record to protect the zone, or the data did not properly validate
with DNSSEC. In this case, the algorithm cannot authoritatively
state that the prefix is valid or invalid, so it is simply marked
as not found. Most routes today are in this category, as it
takes a specific action to OPT-IN to this methodology.
This verification algorithm MUST "fail-safe". If a query for a DNS
record fails, or if DNSSEC fails to validate the record, the
algorithm MUST behave as if no DNS records were present in the first
place. This results in marking a BGP announcement as "NOTFOUND".
One could completely unplug a router verification application at any
time and internet routing would continue to work just as it does
today. The default state is always "not found".
Note that this implies the verification algorithm MUST use DNSSEC-
enabled queries (set the DO bit) and MUST check for a validated
response (the AD bit). A successful DNSSEC-downgrade attack would
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result in classifying records as "NOTFOUND". However the redundancy
in DNS would allow checking of multiple slave DNS servers should
DNSSEC fail to validate.
The core of the verification algorithm can be summarized as follows:
1. Given a BGP announcement from a router feed, offline database,
prefix filter, or other source, perform a DNSSEC-validated query
for the SRO records at the domain name corresponding to the CIDR
prefix in the BGP announcement.
2. Case 1: If no records exist (NXDOMAIN or NOERROR with number of
answers=0), use the AUTHORITY section of the answer to determine
the covering zone. Perform a query to that domain name (the zone
apex) for an RLOCK record. There are two possible responses to
the RLOCK query:
A. NOERROR, answer=0: the RLOCK does not exist; the zone owner
has not opted in. Mark the announcement as "NOTFOUND".
B. RLOCK exists: the zone owner has OPTED-IN. Mark the
announcement as "INVALID" since no SRO record exists to vouch
for the announcement. This may be an example of a sub-prefix
hijack.
3. Case 2: One or more SRO records were returned from the query.
Loop through each SRO in the RRSET to compare the origin with the
data in the route announcement. If a record with a matching set
of data is found, mark the announcement as "VALID". If no match
is found, mark the announcement as "INVALID".
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5. The RLOCK Resource Record
The RLOCK resource record indicates "Route Lock". This record is
placed at the apex of a reverse-DNS zone to indicate that the zone is
being used to publish routing information. If this record is
present, all route announcements for the CIDR address block covered
by this zone MUST be marked as "INVALID" unless they are specifically
authorized by a SRO record.
The main purpose of the RLOCK statement is to indicate participation
(OPT-IN) and as a side-effect prevent sub-prefix route hijacks.
Applications that query for an SRO record may get an NXDOMAIN or
NOERROR with 0 answers. In this case, the application queries the
domain name specified in the AUTHORITY section for an RLOCK record
(this will be at the zone apex). If the RLOCK is present, the route
announcement MUST be marked as "INVALID". Otherwise there is no SRO
and no RLOCK, so the route announcement MUST be marked as "NOTFOUND".
The effective span of control for an RLOCK is dependent on the
structure of the Reverse DNS zone. To be more specific, a Reverse
DNS zone that has no delegations will have a span of control that
covers all prefixes at or below the CIDR prefix specified by the
domain name at the zone apex. Any zone delegation (also known as a
"cut point") starts a new zone authority. Those prefixes in the
delegated zone will not be covered by the parent zone's RLOCK. As an
example, consider the zone at 129.82.0.0/16 and assume that it has
only one delegation at 129.82.138.0/24. The /16 RLOCK covers all
prefixes within the /16 to /32 range with the exception of prefixes
within the 129.82.138.0/24 through /32 range. The child zone would
need to have its own RLOCK.
The RLOCK record MUST be signed with DNSSEC and have an associated
RRSIG record. If a resolving DNS server cannot validate the DNSSEC
signature, the SRO record should be ignored as if it were not even
present in the zone.
The Type value for the RLOCK RR type is currently unassigned. We are
temporarily using private RRTYPE TYPE65400 until a formal number is
assigned by IANA.
The RLOCK RR is class independent.
The RLOCK RR has no special TTL requirements.
Example use of RLOCK records, taken directly from the current
testbed, are included in the appendix.
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5.1. RLOCK RDATA Wire Format
The SRO RDATA wire format consists of one optional field, a 4 octet
Activation Time field. If the Activation Time field is not present,
the RDATA length is 0 octets. If the Activation Time field is
present, the RDATA Length is 4 octets.
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Activation Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.1.1. The Activation Time field
The optional Activation Time field specifies a starting date and time
from which the RLOCK record is considered to be active and may be
used for route origin validation. The RLOCK record MUST NOT be used
for validation prior to this activation time.
The Activation Time field value specifies a date and time in the form
of a 32-bit unsigned number of seconds elapsed since 1 January 1970
00:00:00 UTC, ignoring leap seconds, in network byte order. The
longest interval that can be expressed by this format without
wrapping is approximately 136 years.
If the Activation Time field is not present, or if it contains a
value of 0, immediate activation for the RLOCK record is in effect.
The purpose of the Activation Time field is to permit publication of
RLOCK records in the reverse DNS prior to its use in formal route
validation. This enables two key capabilities: first,it allows for
the testing of RLOCK records in a safe manner by informing an
application to "don't validate, but tell me what you would have
done". Second, it allows an ISP to publish an RLOCK and SRO record
that defines a large covering prefix to give advance warning to that
ISP's customers. Customers that have their own AS number and a
delegated address block within the ISP's larger block may want to
publish their own SRO record if they share a zone with the ISP, or
they will risk having their announcements being marked INVALID
because the ISP has claimed a larger covering prefix. Alternatively,
the customer may be independent from the ISP's zone and manage their
own reverse-DNS zone that has been delegated to them. In this case
they may choose to publish an SRO record or to do nothing. The cut
point of the zone delegation stops the ISP's covering prefix from
extending into the new zone.
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5.2. RLOCK Presentation Format
The presentation format of the RDATA portion is as follows:
[ ACTIVATION_TIME ]
where the ACTIVATION TIME is an optional field.
The optional Activation Time field value, if present, MUST be
represented either as an unsigned decimal integer indicating seconds
since 1 January 1970 00:00:00 UTC, or in the form YYYYMMDDHHmmSS in
UTC, where:
YYYY is the year (0001-9999);
MM is the month number (01-12);
DD is the day of the month (01-31);
HH is the hour, in 24 hour notation (00-23);
mm is the minute (00-59); and
SS is the second (00-59).
Note that it is always possible to distinguish between these two
formats because the YYYYMMDDHHmmSS format will always be exactly 14
digits, while the decimal representation of a 32-bit unsigned integer
can never be longer than 10 digits.
5.3. RLOCK RR Examples
The following examples shows an RLOCK resource record that enables
routing security for the zone covering 129.82.0.0/16. The first
example specifies immediate activation. The second specifies
activation starting on July 4, 2013 at 9:30 UTC.
82.129.in-addr.arpa. 86400 IN RLOCK
120.15.in-addr.arpa. 86400 IN RLOCK 20130704093000
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6. The SRO Resource Record
Zones that participate in this approach to BGP route security use
"Secure Route Origin" (SRO) resource records to identify authorized
origin Autonomous System Number(s) for a prefix.
The SRO record contains one mandatory field, the ORIGIN ASN field.
The SRO record MAY contain also contain one to three optional fields
in the following order: a FLAGS field, a PREFIX LIMIT field, and an
ACTIVATION TIME field. These fields MUST be appended to the RDATA in
that specific order.
The SRO record MUST be signed with DNSSEC [RFC4033] and have an
associated RRSIG record. If a resolving DNS server cannot validate
the DNSSEC signature, the SRO record should be ignored and an attempt
should be made to query an alternate DNS server. If all servers
fail, the route prefix should be classified as "NOTFOUND".
The Type value for the SRO RR type is currently unassigned. We are
temporarily using TYPE65401 until a formal number is assigned by
IANA.
The SRO RR is class independent.
The SRO RR has no special TTL requirements.
6.1. SRO RDATA Wire Format
The SRO RDATA wire format consists of four fields: a 4 octet ORIGIN
AS NUMBER field, a 1 octet FLAGS field, a 1 octet PREFIX LIMIT field,
and a 4 octet SRO ACTIVATION TIME field. The RDATA Length is a
constant 10 octets. Missing fields in the presentation format are
filled with 0's in the wire data format.
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ORIGIN AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| flags | prefix limit | Activation Time /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Activation Time, continued |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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6.1.1. The Origin AS Number field
The Origin AS Number field is used to specify an AS Number that is
authorized to originate a route announcement for the CIDR address
block corresponding to the SRO record's reverse DNS domain name. If
a CIDR address block can be announced from multiple AS numbers, then
multiple SRO records should be defined at the domain name
corresponding to that CIDR address block.
The Origin AS Number field accommodates both 2 octet and 4 octet AS
Numbers. 2 octet AS numbers MUST be encoded with leading zeroes to
construct a complete 4 octet field.
6.1.2. The Flags field
The Flags field is reserved for future expansion; currently there are
no flags defined and the Flags field, if present, MUST be set to 0.
In the future various bits of the field will be used to define
extensions and additional records related to the SRO record.
6.1.3. The Prefix Limit field
The Prefix Limit field specifies the maximum length of a prefix that
the SRO statement is authorizing. If the field contains a value of 0
then the origin AS is only authorized for the exact prefix
corresponding to that domain name.
Any other integer value from 1 to 32 for IPv4 and 1 to 128 for IPv6
specifies the length of the most specific IP prefix that the SRO is
authorizing. For example, if an IP address prefix is 10.0/16 and the
prefix limit is 22, the AS is authorized to advertise any prefix
under 10.0/16, as long as it is no more specific than /22. In this
example, the AS would be authorized to advertise 10.0/16, 10.0.128/20
or 10.0.255/22, but not 10.0.255.0/24. An SRO statement must be
present at each domain name corresponding to these prefixes (see
Appendix A for a discussion on how to create multiple SRO records
using wildcard DNS names). The Prefix Limit field is used to inform
a route validation algorithm that if an SRO response is returned for
a domain name past the prefix limit, the SRO statement MUST be
ignored as if it were not present.
6.1.4. The Activation Time field
The Activation Time field specifies a starting date and time from
which the RLOCK record is considered to be active and may be used for
route origin validation. The RLOCK record MUST NOT be used for
validation prior to this activation time.
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The Activation Time field value specifies a date and time in the form
of a 32-bit unsigned number of seconds elapsed since 1 January 1970
00:00:00 UTC, ignoring leap seconds, in network byte order. The
longest interval that can be expressed by this format without
wrapping is approximately 136 years.
If the Activation Time field contains a value of 0, immediate
activation for the RLOCK record is in effect.
The purpose of the Activation Time field is to permit publication of
SRO records in the reverse DNS prior to its use in formal route
validation. This enables two key capabilities: first,it allows for
the testing of RLOCK records in a safe manner by informing an
application to "don't validate, but tell me what you would have
done". Second, it allows an ISP to publish an RLOCK and SRO record
that defines a large covering prefix to give advance warning to that
ISP's customers. Customers that have their own AS number and a
delegated address block within the ISP's larger block may want to
publish their own SRO record if they share a zone with the ISP, or
they will risk having their announcements being marked INVALID
because the ISP has claimed a larger covering prefix. Alternatively,
the customer may be independent from the ISP's zone and manage their
own reverse-DNS zone that has been delegated to them. In this case
they may choose to publish an SRO record or to do nothing. The cut
point of the zone delegation stops the ISP's covering prefix from
extending into the new zone.
6.2. SRO RRDATA Presentation Format
The presentation format of the RDATA portion is as follows:
ORIGIN_ASN [ FLAGS [ PREFIX_LIMIT [ [ ACTIVATION_TIME ] ] ]
where ORIGIN_ASN is the mandatory Origin AS Number field, and the
remaining fields are optional. If not present, the wire data format
will be filled with zeroes.
The Flags field is represented by an unsigned integer. The current
accepted value MUST be 0.
The Prefix Limit field is represented by an unsigned integer in the
range 0 to 128.
The ORIGIN AS NUMBER field is represented in asdot notation which is
a combination of asplain and asdot+ notation. That is, any ASN in
the 2-octet range is represented in asplain (simple decimal
representation of the ASN). Any ASN above the 2-octet range is
represented in asdot+ notation which breaks an ASN into two 16-bit
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values separated by a dot. For example, AS65535 will be represented
by the decimal number "65535" while AS65536 will be represented as
"1.0".
The Activation Time field values MUST be represented either as an
unsigned decimal integer indicating seconds since 1 January 1970 00:
00:00 UTC, or in the form YYYYMMDDHHmmSS in UTC, where:
YYYY is the year (0001-9999);
MM is the month number (01-12);
DD is the day of the month (01-31);
HH is the hour, in 24 hour notation (00-23);
mm is the minute (00-59); and
SS is the second (00-59).
Note that it is always possible to distinguish between these two
formats because the YYYYMMDDHHmmSS format will always be exactly 14
digits, while the decimal representation of a 32-bit unsigned integer
can never be longer than 10 digits.
6.3. SRO RR Examples
The following example shows an SRO RR authorizing AS12145 as the
origin for CIDR address block 129.82.0.0/16 and only for that prefix.
Its activation time is immediate.
m.82.129.in-addr.arpa. 86400 IN SRO 12145
The second example shows the use of a prefix limit field to authorize
AS 12145 to cover the range from 129.82/16 through and including
announcements to the /24 limit. Its activation is set to June 1,
2013 at 00:00 UTC.
m.82.129.in-addr.arpa. 86400 IN SRO 12145 0 24 20130601000000
The third example shows two separate origins to be authorized for a
prefix. This example also illustrates the use of the asdot notation.
Two different prefix limits are used. Activation is immediate for
the first SRO; the second is to be used after July 15, 2013 at noon
UTC.
m.82.129.in-addr.arpa. 86400 IN SRO 12145 0 24
86400 IN SRO 3.421 0 18 20130715120000
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7. Discussion and Related Work
This work is not the first to propose entering routing data in the
Reverse DNS and there are also many other proposed approaches for
publishing routing data. We first review some of the past work and
then discusses the differences presented in this approach.
7.1. Prior Work on CIDR names for Routing
Over a decade ago, [I-D.bates-bgp4-nlri-orig-verif] proposed to use
the reverse DNS to verify the origin AS associated with a prefix.
This requires both a naming convention for converting the name into a
prefix and additional resource record types for storing origin
information, along with recommendations on their use. More recently
[I-D.donnerhacke-sidr-bgp-verification-dnssec] including links to IRR
data and also includes the notion of policy in adjacency, but this
approach also introduces a new reverse DNS tree under "BGP.ARPA."
CNAME and DNAME records must be used in publishing the data.
Our approach differs in several respects. We rely on the existing
reverse DNS tree without creating a new hierarchy such as
"BGP.ARPA.". We exploit the naming convention in
[I-D.gersch-dnsop-revDNS-CIDR] so one does not need to introduce
CNAME or DNAME records (though an operator could choose to do so if
so desired). We assume optional participation and introduce the
concept of an RLOCK resource record to indicate participation. We
currently limit our approach to detecting false sub-prefix and false
origin route announcements. Extensions to include links to other
databases such as IRR can be achieved in combination with or in lieu
of an SRO record and further path validation can be included, but the
scope of this document is intentionally limited, both for clarity and
to match actual implementation. Finally, we separate the publishing
technique which is specified in this document from the variety of
ways in which one may make use of the data, recognizing that
different operators will make different choices on how to make use of
the data.
7.2. RPKI
A great deal of work has been done in the sidr working group on
Resource Public Key Infrastructure
[RFC6480][RFC6481][RFC6482][RFC6483].
RPKI, also known as Resource Certification, is a specialized public
key infrastructure (PKI) framework designed to secure Border Gateway
Protocol (BGP). RPKI provides a way to connect Internet number
resource information (such as Autonomous System numbers and IP
Addresses) to a trust anchor. The certificate structure mirrors the
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way in which Internet number resources are distributed. That is,
resources are initially distributed by the IANA to the Regional
Internet Registries (RIRs), who in turn distribute them to Local
Internet Registries (LIRs), who then distribute the resources to
their customers. RPKI can be used by the legitimate holders of the
resources to control the operation of Internet routing protocols to
prevent route hijacking and other attacks. [cited from Wikipedia].
The publication of BGP route origin information in the reverse-DNS is
a complementary technique to RPKI. While there is some overlap in
the techniques, there are also different goals for the reverse-DNS.
The Reverse-DNS publication method uses DNSSEC as its base trust
model, not a chain of certificates. If an organization has a DNSSEC-
signed delegation for a reverse-DNS address block, that organization
is the legitimate owner and may place SRO and RLOCK statements in
their zone without the interaction of any other organization. If an
address block is sold or transferred, either the RIR (Regional
Internet Registry) will change its signed delegation records to
reflect the change, or the organization itself may independently
implement a signed sub-delegation.
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8. Security Considerations
Applications that query the DNS for SRO and RLOCK records MUST
request them from DNSSEC-enabled servers and have the DO bit set.
Responses that are returned MUST be checked to verify that the D bit
is set indicating that the responses have been validated. Otherwise
the response should be ignored.
The absence of DNSSEC or the inability to contact any nameservers
MUST indicate the route is viable (NOTFOUND).
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9. IANA Considerations
RRType numbers need to be assigned for the SRO and RLOCK records.
The current testbed temporarily substitutes TYPE65400 for the RLOCK
record and TYPE65401 for the SRO record.
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10. Acknowledgments
We would like to thank Danny McPherson for his comments and
suggestions. In addition, this document was aided via numerous
discussions at NANOG, IETF and private meetings with ISPs, telecomm
carriers, and research organizations too numerous to mention by name.
Thanks to all for your comments and advice.
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11. Change History
Changes from version 01 to 02
Removed the last_hop field from the SRO record
Changed the structure of the RLOCK to accommodate an activation
date.
Changed the structure of the SRO record to accommodate activation
date, prefix limit and flag fields. These changes were suggested
from a year's practical experience in running a reverse-DNS
testbed.
Added appendix A discussing the use of DNS wildcards with SRO
prefix limits.
Modified the examples in Appendix B to reflect changes to the SRO
and RLOCK records.
Changes from version 00 to 01
Removed all discussion of an "alternate naming scheme". A related
draft on prefix naming had proposed both a standard naming scheme
and an alternate naming scheme, but the alternate naming scheme
was removed. Since the alternate naming scheme no longer exists,
it was no longer necessary to discuss how this draft would deal
with the alternate alternate naming scheme.
An optional transit provider field was added the SRO record.
Examples were updated based on the SRO change and operational
experience.
Added Cathie Olschanowsky as a co-author
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12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
12.2. Informative References
[I-D.bates-bgp4-nlri-orig-verif]
Bates, T., Bush, R., Li, T., and Y. Rekhter, "DNS-based
NLRI origin AS verification in BGP",
draft-bates-bgp4-nlri-orig-verif-00 (work in progress),
January 1998.
[I-D.donnerhacke-sidr-bgp-verification-dnssec]
Donnerhacke, L. and W. Wijngaards, "DNSSEC protected
routing announcements for BGP",
draft-donnerhacke-sidr-bgp-verification-dnssec-04 (work in
progress), May 2008.
[I-D.gersch-dnsop-revDNS-CIDR]
Gersch, J. and D. Massey, "Reverse DNS Naming Convention
for CIDR Address Blocks",
draft-gersch-dnsop-revDNS-CIDR-04 (work in progress),
May 2012.
[RFC1876] Davis, C., Vixie, P., Goodwin, T., and I. Dickinson, "A
Means for Expressing Location Information in the Domain
Name System", RFC 1876, January 1996.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, March 2005.
[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, February 2012.
[RFC6481] Huston, G., Loomans, R., and G. Michaelson, "A Profile for
Resource Certificate Repository Structure", RFC 6481,
February 2012.
[RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
Origin Authorizations (ROAs)", RFC 6482, February 2012.
[RFC6483] Huston, G. and G. Michaelson, "Validation of Route
Origination Using the Resource Certificate Public Key
Infrastructure (PKI) and Route Origin Authorizations
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(ROAs)", RFC 6483, February 2012.
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Appendix A. Discussion of Prefix Limits use in conjunction with DNS
wildcards
The combination of RLOCK and SRO records may be used to detect and/or
prevent sub-prefix hijacks. For example, the zone file shown in
appendix B has one SRO record for the /16 and four SRO records for
the /18's. If a BGP announcement is made at any other prefix, say a
/19, no SRO record will be found. In this case the verification
algorithm must query for the RLOCK record. If present, a sub-prefix
hijack is indicated.
This behavior is desirable in most situations. On the other hand,
some organizations may want the ability to advertise an announcement
at any arbitrary sub-prefix (e.g. traffic control). The semantics of
the SRO statement dictates that if an organization intends to
advertise any prefix, an SRO statement must be present to authorize
it. This can be done by statically creating multiple SRO statements
in a zone for each prefix that could be announced, or by using
dynamic DNS to add and remove SRO statements on demand.
There are two ways to create a range of SRO statements within a zone
file. The first method is to simply create all of the individual SRO
statements required and put them in the zone. To cover the full
octet from /16 to /23, for example, the administrator would need one
SRO for the /16, two for the /17's, four for the /18's, eight for the
/19's, and so on. This would be a total of 255 SRO records. One can
see that this becomes impractical for IPv6 address ranges; the number
of SRO records to authorize a /32 through /64 is enormous.
To manage this situation, administrators may use the Prefix Limit
field in combination with a DNS wildcard domain name. Assume that
the administrator of address block 2002:1488::/32 wants to pre-
authorize any announcement from the /32 up to and including /64.
Assume also that the zone apex is at the /32. In this case a single
SRO record in the zone will suffice:
*.8.8.4.1.2.0.0.2.ip6.arpa. IN SRO 12345 0 64 0
A query for an SRO record for any prefix, (e.g. /32, or /36 or /48 or
even a /96) covered by this zone (i.e., up to any zone cut) will
return this SRO record and the announcement can be verified. The
prefix limit tells the verification algorithm when to stop using the
SRO statement. If an announcement is made for a /96, for example,
the SRO record will be returned. Since the prefix limit is 64, the
validation algorithm MUST ignore this SRO record as if it did not
exist, and perform a query for the RLOCK record. Furthermore, any
zone cut also stops the extent of the SRO statement. Any new zone
declared below the /32 can declare (or not declare) its own SRO and
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RLOCK statements.
This method allows the creation of zone files for a sparsely
populated IPv6 delegation. Individual zones can be created that
manage their own sub-prefixes, and the top level zone can handle all
the covering prefixes.
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Appendix B. Examples
B.1. Example 1
This example shows data entered for the prefix 129.82.0.0/16. The
prefix owner has authorized the announcement of 129.82.0.0/16 and the
four /18's at 129.82.0.0/18, 129.82.64.0/18, 129.82.128.0/18, and
129.82.192.0/18. All the prefixes originate from AS12145.
Note: this data is directly cut and paste from actual deployment.
TYPE 65400 is being used for RLOCK and TYPE 65401 for SRO records.
This draft requests IANA to assign numbers for RLOCK and SRO, the
values here are purely for illustrative purposes.
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$TTL 3600
$ORIGIN 82.129.in-addr.arpa.
@ IN SOA rush.colostate.edu. dnsadmin.colostate.edu. (
2012082800 ; serial number
900 ; refresh, 15 minutes
600 ; update retry, 10 minutes
86400 ; expiry, 1 day
3600 ; minimum, 1 hour
)
IN NS dns1.colostate.edu.
IN NS dns2.colostate.edu.
@ IN TYPE65400 \#0
; RLOCK
; OPT-IN; deny all route announcements
; except those authorized
; effective date = immediate
m IN TYPE65401 \# 10 00002f71000000000000
; 129.82.0.0/16 SRO 12145
0.0.m IN TYPE65401 \# 10 00002f71000000000000
; 129.82.0.0/18 SRO 12145
1.0.m IN TYPE65401 \# 10 00002f71000000000000
; 129.82.64.0/18 SRO 12145
0.1.m IN TYPE65401 \# 10 00002f71000000000000
; 129.82.128.0/18 SRO 12145
1.1.m IN TYPE65401 \# 10 00002f71000000000000
; 129.82.192.0/18 SRO 12145
; delegations required for 256 /24 zones which contain PTR records
1 IN NS dns1.colostate.edu.
IN NS dns2.colostate.edu.
2 IN NS dns1.colostate.edu.
IN NS dns2.colostate.edu.
; continuation to 255 is left out for the sake of brevity
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B.2. Example 2
This example shows data entered for the prefix 216.17.128.0/17. The
prefix owner has authorized the announcement of 216.17.128.0/17. The
prefix originates from AS6582.
1.m.17.216.in-addr.arpa NS ns.frii.net
This delegation refers to the new /17 zone and the domain name is not
in conflict with any of the pre-existing /24 zones at IN-ADDR.ARPA.
This delegation is to be placed at the IN-ADDR.ARPA zone.
$TTL 3600
$ORIGIN 1.m.17.216.in-addr.arpa.
@ IN SOA ns1.frii.net. hostmaster.frii.net. (
2012021300 ; serial number
14400 ; refresh, 4 hours
3600 ; update retry, 1 hour
604800 ; expiry, 7 days
600 ; minimum, 10 minutes
)
IN NS ns1.frii.net.
IN NS ns2.frii.net.
$ORIGIN 17.216.in-addr.arpa.
1.m IN TYPE65400 \# 0
; RLOCK
; OPT-IN; deny all route announcements
; except those authorized
; activation date = immediate
1.m IN TYPE65401 \# 10 000019b6000000000000
; 216.17.128.0/17 SRO 6582
; no other delegations or PTR records are needed in this zone file
; since the /24 delegations are at ARIN at xxx.17.216.IN-ADDR.ARPA
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Authors' Addresses
Joe Gersch
Secure64 SW Corp
Fort Collins, CO
US
Email: joe.gersch@secure64.com
Dan Massey
Colorado State University
Fort Collins, CO
US
Email: massey@cs.colostate.edu
Cathie Olschanowsky
Colorado State University
Fort Collins, CO
US
Email: cathie@cs.colostate.edu
Lixia Zhang
UCLA
Los Angeles, CA
US
Email: lixia@cs.ucla.edu
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