Internet DRAFT - draft-abraitis-bgp-version-capability
draft-abraitis-bgp-version-capability
Network Working Group D. Abraitis
Internet-Draft Hostinger
Intended status: Informational 1 February 2023
Expires: 5 August 2023
Software Version Capability for BGP
draft-abraitis-bgp-version-capability-13
Abstract
In this document, we introduce a new BGP capability that allows the
advertisement of a BGP speaker's routing daemon version.
This BGP capability is an optional advertisement. Implementations
are not required to advertise the version nor to process received
advertisements.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 5 August 2023.
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
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Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Specification of Requirements . . . . . . . . . . . . . . . . 2
3. Software Version Capability . . . . . . . . . . . . . . . . . 2
3.1. Capabilities Length Overflow . . . . . . . . . . . . . . 4
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Example Usage . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
In modern data center designs, we tend to have conventional routers
participating in the routing process. And the fleet of routers has
different versions of routing daemon. This means that knowing which
versions of the routing daemons are running the various routers in
the network can be a crucial factor in quickly identifying the root
cause of any protocol or network problems.
This BGP capability is an optional advertisement. Implementations
are not required to advertise the version nor to process received
advertisements.
Information about the version of the routing daemon could also be
exchanged in protocols such as LLDP and CDP. However, in
containerized environments, it is very hard and not recommended to
exchange this information between background processes. Therefore,
and to help minimize operational costs, it is helpful to exchange the
routing daemon information between BGP peers directly.
2. Specification of Requirements
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.
3. Software Version Capability
Although this document is not an IETF Standards Track document, it
makes use of the terminology from BCP 14 in order to clearly state
the implementation behaviors.
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Capabilities advertisements with BGP are defined in [RFC5492]. They
utilize the BGP Capabilities Optional Parameter that contains one or
more triples <Capability Code, Capability Length, Capability Value>.
This document defines a new BGP capability, the Software Version
Capability, with Capability Code TBD and Capability Length and
Capability Value as described below.
The inclusion of the Software Version Capability is OPTIONAL. If an
implementation supports the inclusion of the capability, the
implementation MUST include a configuration switch to enable or
disable its use, and that switch MUST be off by default.
The Software Version Capability is intended for environments where
more visibility is needed for troubleshooting purposes. It is NOT
RECOMMENDED for use outside a single Autonomous System, or a set of
Autonomous Systems under a common administration.
An implementation that does not recognize or support the Software
Version Capability but receives one must ignore it, as described in
[RFC5492].
The triple for the Software Version Capability is as follows:
Capability Code
75
Capability Length
The Capability Length for the Software Version Capability MUST be
greater than zero. A value of zero SHALL be treated as an
encoding error and the Capability MUST be ignored.
The Capability Length SHOULD be no greater than 64. This is the
limit to allow other capabilities as much space as they require.
Capability Length is a one-octet unsigned binary integer that
contains the length of the Capability Value field in octets.
Capability Value
The Capability Value field is encoded in UTF-8 [RFC3629]. It is
unstructured data and can be formatted in any way that the
implementor decides.
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+--------------------------------+
| Version Length (1 octet) |
+--------------------------------+
| Version (variable) |
+--------------------------------+
Figure 1
Version Length:
The number of characters in the Version
Version:
The Version field MUST be encoded using UTF-8. A receiving BGP
speaker MUST NOT interpret invalid UTF-8 sequences.
The value of consists of one identifier, which identifies the
software and its significant version. Software version identifier
consists of a product and optional product version.
identifier = product ["/" product-version]
A sender SHOULD limit generated product identifiers to what is
necessary to identify the product; a sender MUST NOT generate
advertising or other nonessential information within the product
identifier. A sender SHOULD NOT generate information in product-
version that is not a version identifier (i.e., successive
versions of the same product name ought to differ only in the
product-version portion of the product identifier).
Example:
frrouting/8.4.2, ios/12.5.1, junos/12.1
3.1. Capabilities Length Overflow
As defined in [RFC5492] the total length of capabilities that can be
carried by the BGP Capabilities Optional Parameter is 255 bytes. If
an implementation is constructing a BGP Capabilities Optional
Parameter and its length exceeds 255 bytes, there is not enough space
for other more important capabilities. An implementation is REQUIRED
Extended Optional Parameters Length for BGP OPEN Message support as
defined in [RFC9072].
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A rogue node can prevent the proper operation of a BGP session, or
the advertisement of other Capabilities, by not excluding the
Software Version Capability as required in Section 3.1. This risk is
equivalent to a rogue node simply not advertising a specific
Capability and is not new to BGP.
4. Operation
The Software Version Capability MUST only be used for displaying the
version of a BGP speaker's router daemon to make troubleshooting
easier.
Consider a group of routers each with a number of upstream nodes, and
suppose that each router has a different operating system and
different routing daemon at a different version installed. Assuming
that a specific feature is not working or that there is a bug which
has not been fixed in a particular version of the code, knowledge of
the routing daemon versions would allow an operator to quickly
identify the pattern of which versions are affected.
Enabling (i.e., turning on) this capability requires bouncing all
existing BGP sessions and the feature MUST be explicitly configured
before an implementation advertizes the Software Version Capability.
4.1. Example Usage
Below is an example from the [FRRouting] and [GoBGP] implementation
showing both the received and advertised Software Version Capability:
:~# vtysh -c 'show ip bgp summary failed'
...
Neighbor EstdCnt DropCnt ResetTime Reason
ens192 3 3 00:00:35 Waiting for peer OPEN (n/a)
ens224 3 3 00:01:12 Waiting for NHT (frrouting/7.2)
eth0 3 3 00:00:14 Neighbor deleted (frrouting/7.3)
...
Figure 2
software-version: advertised and received
Local:
GoBGP/3.10.0
Remote:
FRRouting/8.5-dev-MyOwnFRRVersion-gdc92f44a4
Figure 3
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:~# vtysh -c 'show ip bgp neighbors 198.51.100.1 json' \
> | jq '."198.51.100.1".neighborCapabilities.versions'
{
"advertisedVersion": "frrouting/7.2",
"receivedVersion": "frrouting/7.3"
}
Figure 4
5. IANA Considerations
IANA has assigned capability number 75 for the Software Version
Capability described in this document. This registration is in the
BGP Capability Codes registry.
+=======+=============================+
| Value | Description |
+=======+=============================+
| 75 | Software Version Capability |
+-------+-----------------------------+
Table 1: Software Version Capability
6. Security Considerations
The Software Version Capability should be treated as sensitive
information: it could be easier for an attacker to exploit the system
if they know the specific software version and manufacturer of a BGP
speaker. This information could be gathered by inspecting BGP OPEN
messages that carry the Software Version Capability defined in this
document. Furthermore, this knowledge may facilitate a number of
social-engineering attacks.
Modifying the information advertised by a router might lead to
attacks including bogus software upgrades and also might mask the
causes of faults in the network.
Users of this mechanism should be aware that unless a transport that
provides integrity is used for the BGP session in question, the
Software Version Capability can be forged. Unless a transport that
provides confidentiality is used, the Version Capability could be
snooped by an attacker. These issues are common to any BGP message
but may be of greater interest in the context of this extension as
explained above. Refer to the related considerations in [RFC4271]
and [RFC4272].
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Users of this mechanism should consider applying data minimization
practices as outlined in Section 6.1 of [RFC6973], as appropriate
within the deployment context.
Sensitive information leaks can be minimized by using the [RFC5082]
mechanism or firewalls to filter out TCP 179 port from untrusted
networks. This capability can be disabled per neighbor, thus the
sensitive information can't be disclosed to untrusted neighbors.
7. References
7.1. Normative References
[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/info/rfc2119>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>.
[RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007,
<https://www.rfc-editor.org/info/rfc5082>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013,
<https://www.rfc-editor.org/info/rfc6973>.
[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/info/rfc8174>.
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[RFC9072] Chen, E. and J. Scudder, "Extended Optional Parameters
Length for BGP OPEN Message", RFC 9072,
DOI 10.17487/RFC9072, July 2021,
<https://www.rfc-editor.org/info/rfc9072>.
7.2. Informative References
[FRRouting]
Abraitis, D., "FRRouting - BGP Software Version
Capability", 2023,
<https://github.com/FRRouting/frr/commit/
c4257900c4ca320117bcd1f88b7f036e0c8f7fcb>.
[GoBGP] Abraitis, D., "Add Software Version capability", 2023,
<https://github.com/osrg/gobgp/
commit/15f9d5c64c98d1db273cc45e95fcc11843fba4b5>.
Author's Address
Donatas Abraitis
Hostinger
Email: donatas.abraitis@hostinger.com
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