draft-ietf-babel-dtls-10.txt   rfc8968.txt 
Network Working Group A. Decimo Internet Engineering Task Force (IETF) A. Décimo
Internet-Draft IRIF, University of Paris-Diderot Request for Comments: 8968 IRIF, University of Paris-Diderot
Intended status: Standards Track D. Schinazi Category: Standards Track D. Schinazi
Expires: January 1, 2021 Google LLC ISSN: 2070-1721 Google LLC
J. Chroboczek J. Chroboczek
IRIF, University of Paris-Diderot IRIF, University of Paris-Diderot
June 30, 2020 January 2021
Babel Routing Protocol over Datagram Transport Layer Security Babel Routing Protocol over Datagram Transport Layer Security
draft-ietf-babel-dtls-10
Abstract Abstract
The Babel Routing Protocol does not contain any means to authenticate The Babel Routing Protocol does not contain any means to authenticate
neighbours or provide integrity or confidentiality for messages sent neighbours or provide integrity or confidentiality for messages sent
between them. This document specifies a mechanism to ensure these between them. This document specifies a mechanism to ensure these
properties, using Datagram Transport Layer Security (DTLS). properties using Datagram Transport Layer Security (DTLS).
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on January 1, 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8968.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
1.1. Specification of Requirements . . . . . . . . . . . . . . 2 1.1. Specification of Requirements
1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Applicability
2. Operation of the Protocol . . . . . . . . . . . . . . . . . . 3 2. Operation of the Protocol
2.1. DTLS Connection Initiation . . . . . . . . . . . . . . . 3 2.1. DTLS Connection Initiation
2.2. Protocol Encoding . . . . . . . . . . . . . . . . . . . . 4 2.2. Protocol Encoding
2.3. Transmission . . . . . . . . . . . . . . . . . . . . . . 4 2.3. Transmission
2.4. Reception . . . . . . . . . . . . . . . . . . . . . . . . 5 2.4. Reception
2.5. Neighbour table entry . . . . . . . . . . . . . . . . . . 5 2.5. Neighbour Table Entry
2.6. Simultaneous operation of both Babel over DTLS and 2.6. Simultaneous Operation of Babel over DTLS and Unprotected
unprotected Babel on a Node . . . . . . . . . . . . . . . 5 Babel on a Node
2.7. Simultaneous operation of both Babel over DTLS and 2.7. Simultaneous Operation of Babel over DTLS and Unprotected
unprotected Babel on a Network . . . . . . . . . . . . . 6 Babel on a Network
3. Interface Maximum Transmission Unit Issues . . . . . . . . . 6 3. Interface Maximum Transmission Unit Issues
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 6. References
6.1. Normative References . . . . . . . . . . . . . . . . . . 8 6.1. Normative References
6.2. Informative References . . . . . . . . . . . . . . . . . 8 6.2. Informative References
Appendix A. Performance Considerations . . . . . . . . . . . . . 9 Appendix A. Performance Considerations
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 9 Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses
1. Introduction 1. Introduction
The Babel Routing Protocol [RFC6126bis] does not contain any means to The Babel routing protocol [RFC8966] does not contain any means to
authenticate neighbours or protect messages sent between them. authenticate neighbours or protect messages sent between them.
Because of this, an attacker is able to send maliciously crafted Because of this, an attacker is able to send maliciously crafted
Babel messages which could lead a network to route traffic to an Babel messages that could lead a network to route traffic to an
attacker or to an under-resourced target causing denial of service. attacker or to an under-resourced target, causing denial of service.
This document specifies a mechanism to prevent such attacks, using This document specifies a mechanism to prevent such attacks using
Datagram Transport Layer Security (DTLS) [RFC6347]. Datagram Transport Layer Security (DTLS) [RFC6347].
1.1. Specification of Requirements 1.1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
1.2. Applicability 1.2. Applicability
The protocol described in this document protects Babel packets with The protocol described in this document protects Babel packets with
DTLS. As such, it inherits the features offered by DTLS, notably DTLS. As such, it inherits the features offered by DTLS, notably
authentication, integrity, optional replay protection, authentication, integrity, optional replay protection,
confidentiality and asymmetric keying. It is therefore expected to confidentiality, and asymmetric keying. It is therefore expected to
be applicable in a wide range of environments. be applicable in a wide range of environments.
There exists another mechanism for securing Babel, namely Babel HMAC There exists another mechanism for securing Babel, namely Message
authentication [BABEL-HMAC]. HMAC only offers basic features, namely Authentication Code (MAC) authentication for Babel (Babel-MAC)
authentication, integrity and replay protection with a small number [RFC8967]. Babel-MAC only offers basic features, namely
authentication, integrity, and replay protection with a small number
of symmetric keys. A comparison of Babel security mechanisms and of symmetric keys. A comparison of Babel security mechanisms and
their applicability can be found in [RFC6126bis]. their applicability can be found in [RFC8966].
Note that Babel over DTLS provides a single authentication domain, Note that Babel over DTLS provides a single authentication domain,
meaning that all nodes that have the right credentials can convey any meaning that all nodes that have the right credentials can convey any
and all routing information. and all routing information.
DTLS supports several mechanisms by which nodes can identify DTLS supports several mechanisms by which nodes can identify
themselves and prove possession of secrets tied to these identities. themselves and prove possession of secrets tied to these identities.
This document does not prescribe which of these mechanisms to use; This document does not prescribe which of these mechanisms to use;
details of identity management are left to deployment profiles of details of identity management are left to deployment profiles of
Babel over DTLS. Babel over DTLS.
skipping to change at page 3, line 40 skipping to change at line 127
Babel over DTLS requires some changes to how Babel operates. First, Babel over DTLS requires some changes to how Babel operates. First,
DTLS is a client-server protocol, while Babel is a peer-to-peer DTLS is a client-server protocol, while Babel is a peer-to-peer
protocol. Second, DTLS can only protect unicast communication, while protocol. Second, DTLS can only protect unicast communication, while
Babel packets can be sent to both unicast and multicast destinations. Babel packets can be sent to both unicast and multicast destinations.
2.1. DTLS Connection Initiation 2.1. DTLS Connection Initiation
Babel over DTLS operates on a different port than unencrypted Babel. Babel over DTLS operates on a different port than unencrypted Babel.
All Babel over DTLS nodes MUST act as DTLS servers on a given UDP All Babel over DTLS nodes MUST act as DTLS servers on a given UDP
port, and MUST listen for unencrypted Babel traffic on another UDP port and MUST listen for unencrypted Babel traffic on another UDP
port, which MUST be distinct from the first one. The default port port, which MUST be distinct from the first one. The default port
for Babel over DTLS is registered with IANA as the "babel-dtls" port for Babel over DTLS is registered with IANA as the "babel-dtls" port
(UDP port TBD, see Section 4), and the port exchanging unencrypted (UDP port 6699, see Section 4), and the port exchanging unencrypted
Babel traffic is registered as the "babel" port (UDP port 6696, see Babel traffic is registered as the "babel" port (UDP port 6696, see
Section 5 of [RFC6126bis]). Section 5 of [RFC8966]).
When a Babel node discovers a new neighbour (generally by receiving When a Babel node discovers a new neighbour (generally by receiving
an unencrypted multicast Babel packet), it compares the neighbour's an unencrypted multicast Babel packet), it compares the neighbour's
IP address with its own, using network byte ordering. If a node's IP address with its own, using network byte ordering. If a node's
address is lower than the recently discovered neighbour's address, it address is lower than the recently discovered neighbour's address, it
acts as a client and connects to the neighbour. In other words, the acts as a client and connects to the neighbour. In other words, the
node with the lowest address is the DTLS client for this pairwise node with the lowest address is the DTLS client for this pairwise
relationship. As an example, fe80::1:2 is considered lower than relationship. As an example, fe80::1:2 is considered lower than
fe80::2:1. fe80::2:1.
skipping to change at page 4, line 50 skipping to change at line 186
2.3. Transmission 2.3. Transmission
When sending packets, Babel over DTLS nodes MUST NOT send any TLVs When sending packets, Babel over DTLS nodes MUST NOT send any TLVs
over the unprotected "babel" port, with the exception of Hello TLVs over the unprotected "babel" port, with the exception of Hello TLVs
without the Unicast flag set. Babel over DTLS nodes MUST NOT send without the Unicast flag set. Babel over DTLS nodes MUST NOT send
any unprotected unicast packets. This ensures the confidentiality of any unprotected unicast packets. This ensures the confidentiality of
the information sent in Babel packets (e.g., the network topology) by the information sent in Babel packets (e.g., the network topology) by
only sending it encrypted by DTLS. Unless some out-of-band neighbour only sending it encrypted by DTLS. Unless some out-of-band neighbour
discovery mechanism is available, nodes SHOULD periodically send discovery mechanism is available, nodes SHOULD periodically send
unprotected multicast Hellos to ensure discovery of new neighbours. unprotected Multicast Hellos to ensure discovery of new neighbours.
In order to maintain bidirectional reachability, nodes can either In order to maintain bidirectional reachability, nodes can either
rely entirely on unprotected multicast Hellos, or send protected rely entirely on unprotected Multicast Hellos, or send protected
unicast Hellos in addition to the multicast Hellos. Unicast Hellos in addition to the Multicast Hellos.
Since Babel over DTLS only protects unicast packets, implementors may Since Babel over DTLS only protects unicast packets, implementors may
implement Babel over DTLS by modifying an implementation of Babel implement Babel over DTLS by modifying an implementation of Babel
without DTLS support, and replacing any TLV previously sent over without DTLS support and replacing any TLV previously sent over
multicast with a separate TLV sent over unicast for each neighbour. multicast with a separate TLV sent over unicast for each neighbour.
TLVs previously sent over multicast can be replaced with the same TLVs previously sent over multicast can be replaced with the same
contents over unicast, with the exception of Hellos as described contents over unicast, with the exception of Hellos as described
above. Some implementations could also change the contents of IHU above. Some implementations could also change the contents of IHU
TLVs when converting to unicast in order to remove redundant TLVs when converting to unicast in order to remove redundant
information. information.
2.4. Reception 2.4. Reception
Babel over DTLS nodes can receive Babel packets either protected over Babel over DTLS nodes can receive Babel packets either protected over
a DTLS connection, or unprotected directly over the "babel" port. To a DTLS connection or unprotected directly over the "babel" port. To
ensure the security properties of this mechanism, unprotected packets ensure the security properties of this mechanism, unprotected packets
are treated differently. Nodes MUST silently ignore any unprotected are treated differently. Nodes MUST silently ignore any unprotected
packet sent over unicast. When parsing an unprotected packet, a node packet sent over unicast. When parsing an unprotected packet, a node
MUST silently ignore all TLVs that are not of type Hello. Nodes MUST MUST silently ignore all TLVs that are not of type Hello. Nodes MUST
also silently ignore any unprotected Hello with the Unicast flag set. also silently ignore any unprotected Hello with the Unicast flag set.
Note that receiving an unprotected packet can still be used to Note that receiving an unprotected packet can still be used to
discover new neighbours, even when all TLVs in that packet are discover new neighbours, even when all TLVs in that packet are
silently ignored. silently ignored.
2.5. Neighbour table entry 2.5. Neighbour Table Entry
It is RECOMMENDED for nodes to associate the state of their DTLS It is RECOMMENDED for nodes to associate the state of their DTLS
connection with their neighbour table. When a neighbour entry is connection with their neighbour table. When a neighbour entry is
flushed from the neighbour table (Appendix A of [RFC6126bis]), its flushed from the neighbour table (Appendix A of [RFC8966]), its
associated DTLS state SHOULD be discarded. The node SHOULD send a associated DTLS state SHOULD be discarded. The node SHOULD send a
DTLS close_notify alert to the neighbour if it believes the link is DTLS close_notify alert to the neighbour if it believes the link is
still viable. still viable.
2.6. Simultaneous operation of both Babel over DTLS and unprotected 2.6. Simultaneous Operation of Babel over DTLS and Unprotected Babel on
Babel on a Node a Node
Implementations MAY implement both Babel over DTLS and unprotected Implementations MAY implement both Babel over DTLS and unprotected
Babel. Additionally, a node MAY simultaneously run both Babel over Babel. Additionally, a node MAY simultaneously run both Babel over
DTLS and unprotected Babel. However, a node running both MUST ensure DTLS and unprotected Babel. However, a node running both MUST ensure
that it runs them on separate interfaces, as the security properties that it runs them on separate interfaces, as the security properties
of Babel over DTLS rely on not accepting unprotected Babel packets of Babel over DTLS rely on ignoring unprotected Babel packets (other
(other than multicast Hellos). An implementation MAY offer than Multicast Hellos). An implementation MAY offer configuration
configuration options to allow unprotected Babel on some interfaces options to allow unprotected Babel on some interfaces but not others,
but not others; this effectively gives nodes on that interface the which effectively gives nodes on that interface the same access as
same access as authenticated nodes, and SHOULD NOT be done unless authenticated nodes; however, this SHOULD NOT be done unless that
that interface has a mechanism to authenticate nodes at a lower layer interface has a mechanism to authenticate nodes at a lower layer
(e.g., IPsec). (e.g., IPsec).
2.7. Simultaneous operation of both Babel over DTLS and unprotected 2.7. Simultaneous Operation of Babel over DTLS and Unprotected Babel on
Babel on a Network a Network
If Babel over DTLS and unprotected Babel are both operated on the If Babel over DTLS and unprotected Babel are both operated on the
same network, the Babel over DTLS implementation will receive same network, the Babel over DTLS implementation will receive
unprotected multicast Hellos and attempt to initiate a DTLS unprotected Multicast Hellos and attempt to initiate a DTLS
connection. These connection attempts can be sent to nodes that only connection. These connection attempts can be sent to nodes that only
run unprotected Babel, who will not respond. Babel over DTLS run unprotected Babel, who will not respond. Babel over DTLS
implementations SHOULD therefore rate-limit their DTLS connection implementations SHOULD therefore rate-limit their DTLS connection
attempts to avoid causing undue load on the network. attempts to avoid causing undue load on the network.
3. Interface Maximum Transmission Unit Issues 3. Interface Maximum Transmission Unit Issues
Compared to unprotected Babel, DTLS adds header, authentication tag Compared to unprotected Babel, DTLS adds header, authentication tag,
and possibly block-size padding overhead to every packet. This and possibly block-size padding overhead to every packet. This
reduces the size of the Babel payload that can be carried. This reduces the size of the Babel payload that can be carried. This
document does not relax the packet size requirements in Section 4 of document does not relax the packet size requirements in Section 4 of
[RFC6126bis], but recommends that DTLS overhead be taken into account [RFC8966] but recommends that DTLS overhead be taken into account
when computing maximum packet size. when computing maximum packet size.
More precisely, nodes SHOULD compute the overhead of DTLS depending More precisely, nodes SHOULD compute the overhead of DTLS depending
on the ciphersuites in use, and SHOULD NOT send Babel packets larger on the ciphersuites in use and SHOULD NOT send Babel packets larger
than the interface maximum transmission unit (MTU) minus the overhead than the interface maximum transmission unit (MTU) minus the overhead
of IP, UDP and DTLS. Nodes MUST NOT send Babel packets larger than of IP, UDP, and DTLS. Nodes MUST NOT send Babel packets larger than
the attached interface's MTU adjusted for known lower-layer headers the attached interface's MTU adjusted for known lower-layer headers
(at least UDP and IP) or 512 octets, whichever is larger, but not (at least UDP and IP) or 512 octets, whichever is larger, but not
exceeding 2^16 - 1 adjusted for lower-layer headers. Every Babel exceeding 2^(16) - 1 adjusted for lower-layer headers. Every Babel
speaker MUST be able to receive packets that are as large as any speaker MUST be able to receive packets that are as large as any
attached interface's MTU adjusted for UDP and IP headers or 512 attached interface's MTU adjusted for UDP and IP headers or 512
octets, whichever is larger. Note that this requirement on reception octets, whichever is larger. Note that this requirement on reception
does not take into account the overhead of DTLS because the peer may does not take into account the overhead of DTLS because the peer may
not have the ability to compute the overhead of DTLS and the packet not have the ability to compute the overhead of DTLS, and the packet
may be fragmented by lower layers. may be fragmented by lower layers.
Note that distinct DTLS connections can use different ciphers, which Note that distinct DTLS connections can use different ciphers, which
can have different amounts of per-packet overhead. Therefore, the can have different amounts of per-packet overhead. Therefore, the
MTU to one neighbour can be different from the MTU to another MTU to one neighbour can be different from the MTU to another
neighbour on the same link. neighbour on the same link.
4. IANA Considerations 4. IANA Considerations
If this document is approved, IANA is requested to register a UDP IANA has registered a UDP port number, called "babel-dtls", for use
port number, called "babel-dtls", for use by Babel over DTLS. by Babel over DTLS:
Details of the request to IANA are as follows:
o Assignee: IESG, iesg@ietf.org
o Contact Person: IETF Chair, chair@ietf.org Service Name: babel-dtls
o Transport Protocols: UDP only Port Number: 6699
o Service Code: None Transport Protocols: UDP only
o Service Name: babel-dtls Description: Babel Routing Protocol over DTLS
o Desired Port Number: 6699 Assignee: IESG, iesg@ietf.org
o Description: Babel Routing Protocol over DTLS Contact: IETF Chair, chair@ietf.org
o Reference: This document Reference: RFC 8968
o Defined TXT Keys: None Service Code: None
5. Security Considerations 5. Security Considerations
A malicious client might attempt to perform a high number of DTLS A malicious client might attempt to perform a high number of DTLS
handshakes with a server. As the clients are not uniquely identified handshakes with a server. As the clients are not uniquely identified
by the protocol until the handshake completes and can be obfuscated by the protocol until the handshake completes and can be obfuscated
with IPv6 temporary addresses, a server needs to mitigate the impact with IPv6 temporary addresses, a server needs to mitigate the impact
of such an attack. Note that attackers might attempt to keep in- of such an attack. Note that attackers might attempt to keep in-
progress handshakes open for as long as possible by using variants on progress handshakes open for as long as possible by using variants on
the attack commonly known as Slowloris [SLOWLORIS]. Mitigating these the attack commonly known as Slowloris [SLOWLORIS]. Mitigating these
attacks might involve rate limiting handshakes from a given subnet or attacks might involve limiting the rate of handshakes from a given
more advanced denial of service avoidance techniques beyond the scope subnet or more advanced denial of service avoidance techniques beyond
of this document. the scope of this document.
Babel over DTLS allows sending multicast Hellos unprotected; Babel over DTLS allows sending Multicast Hellos unprotected;
attackers can therefore tamper with them. For example, an attacker attackers can therefore tamper with them. For example, an attacker
could send erroneous values for the Seqno and Interval fields, could send erroneous values for the Seqno and Interval fields,
causing bidirectional reachability detection to fail. While causing bidirectional reachability detection to fail. While
implementations MAY use multicast Hellos for link quality estimation, implementations MAY use Multicast Hellos for link quality estimation,
they SHOULD also emit protected unicast Hellos to prevent this class they SHOULD also emit protected Unicast Hellos to prevent this class
of denial-of-service attack. of denial-of-service attack.
While DTLS provides protection against an attacker that replays valid While DTLS provides protection against an attacker that replays valid
packets, DTLS is not able to detect when an active on-path attacker packets, DTLS is not able to detect when an active on-path attacker
intercepts valid packets and resends them at a later time. This intercepts valid packets and resends them at a later time. This
attack could be used to make a node believe it has bidirectional attack could be used to make a node believe it has bidirectional
reachability to a neighbour even though that neighbour has reachability to a neighbour even though that neighbour has
disconnected from the network. To prevent this attack, nodes MUST disconnected from the network. To prevent this attack, nodes MUST
discard the DTLS state associated with a neighbour after a finite discard the DTLS state associated with a neighbour after a finite
time of not receiving valid DTLS packets. This can be implemented time of not receiving valid DTLS packets. This can be implemented
by, for example, discarding a neighbour's DTLS state when its by, for example, discarding a neighbour's DTLS state when its
associated IHU timer fires. Note that relying solely on the receipt associated IHU timer fires. Note that relying solely on the receipt
of Hellos is not sufficient as multicast Hellos are sent unprotected. of Hellos is not sufficient as Multicast Hellos are sent unprotected.
Additionally, an attacker could save some packets and replay them Additionally, an attacker could save some packets and replay them
later in hopes of propagating stale routing information at a later later in hopes of propagating stale routing information at a later
time. This can be mitigated by discarding received packets that have time. This can be mitigated by discarding received packets that have
been reordered by more than two IHU intervals. been reordered by more than two IHU intervals.
6. References 6. References
6.1. Normative References 6.1. Normative References
[BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre, [BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer "Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May (DTLS)", BCP 195, RFC 7525, May 2015,
2015, <https://www.rfc-editor.org/info/bcp195>. <https://www.rfc-editor.org/info/bcp195>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC6126bis]
Chroboczek, J. and D. Schinazi, "The Babel Routing
Protocol", Internet Draft draft-ietf-babel-rfc6126bis-17,
February 2020.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>. January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
6.2. Informative References [RFC8966] Chroboczek, J. and D. Schinazi, "The Babel Routing
Protocol", RFC 8966, DOI 10.17487/RFC8966, January 2021,
<https://www.rfc-editor.org/info/rfc8966>.
[BABEL-HMAC] 6.2. Informative References
Do, C., Kolodziejak, W., and J. Chroboczek, "Babel
Cryptographic Authentication", Internet Draft draft-ietf-
babel-hmac-10, August 2019.
[DTLS-CID] [DTLS-CID] Rescorla, E., Tschofenig, H., and T. Fossati, "Connection
Rescorla, E., Tschofenig, H., Fossati, T., and T. Gondrom, Identifiers for DTLS 1.2", Work in Progress, Internet-
"Connection Identifiers for DTLS 1.2", Internet Draft Draft, draft-ietf-tls-dtls-connection-id-08, 2 November
draft-ietf-tls-dtls-connection-id-07, October 2019. 2020, <https://tools.ietf.org/html/draft-ietf-tls-dtls-
connection-id-08>.
[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J., [RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250, Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <https://www.rfc-editor.org/info/rfc7250>. June 2014, <https://www.rfc-editor.org/info/rfc7250>.
[RFC7918] Langley, A., Modadugu, N., and B. Moeller, "Transport [RFC7918] Langley, A., Modadugu, N., and B. Moeller, "Transport
Layer Security (TLS) False Start", RFC 7918, Layer Security (TLS) False Start", RFC 7918,
DOI 10.17487/RFC7918, August 2016, DOI 10.17487/RFC7918, August 2016,
skipping to change at page 9, line 26 skipping to change at line 391
[RFC7924] Santesson, S. and H. Tschofenig, "Transport Layer Security [RFC7924] Santesson, S. and H. Tschofenig, "Transport Layer Security
(TLS) Cached Information Extension", RFC 7924, (TLS) Cached Information Extension", RFC 7924,
DOI 10.17487/RFC7924, July 2016, DOI 10.17487/RFC7924, July 2016,
<https://www.rfc-editor.org/info/rfc7924>. <https://www.rfc-editor.org/info/rfc7924>.
[RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram [RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram
Transport Layer Security (DTLS)", RFC 8094, Transport Layer Security (DTLS)", RFC 8094,
DOI 10.17487/RFC8094, February 2017, DOI 10.17487/RFC8094, February 2017,
<https://www.rfc-editor.org/info/rfc8094>. <https://www.rfc-editor.org/info/rfc8094>.
[RFC8967] Dô, C., Kolodziejak, W., and J. Chroboczek, "MAC
Authentication for the Babel Routing Protocol", RFC 8967,
DOI 10.17487/RFC8967, January 2021,
<https://www.rfc-editor.org/info/rfc8967>.
[SLOWLORIS] [SLOWLORIS]
Hansen, R., "Welcome to Slowloris...", June 2009, Hansen, R., "Slowloris HTTP DoS", June 2009,
<https://web.archive.org/web/20150315054838/ <https://web.archive.org/web/20150315054838/
http://ha.ckers.org/slowloris/>. http://ha.ckers.org/slowloris/>.
Appendix A. Performance Considerations Appendix A. Performance Considerations
To reduce the number of octets taken by the DTLS handshake, To reduce the number of octets taken by the DTLS handshake,
especially the size of the certificate in the ServerHello (which can especially the size of the certificate in the ServerHello (which can
be several kilobytes), Babel peers can use raw public keys [RFC7250] be several kilobytes), Babel peers can use raw public keys [RFC7250]
or the Cached Information Extension [RFC7924]. The Cached or the Cached Information Extension [RFC7924]. The Cached
Information Extension avoids transmitting the server's certificate Information Extension avoids transmitting the server's certificate
and certificate chain if the client has cached that information from and certificate chain if the client has cached that information from
a previous TLS handshake. TLS False Start [RFC7918] can reduce round a previous TLS handshake. TLS False Start [RFC7918] can reduce round
trips by allowing the TLS second flight of messages trips by allowing the TLS second flight of messages
(ChangeCipherSpec) to also contain the (encrypted) Babel packet. (ChangeCipherSpec) to also contain the (encrypted) Babel packet.
Appendix B. Acknowledgments Acknowledgments
The authors would like to thank Roman Danyliw, Donald Eastlake, The authors would like to thank Roman Danyliw, Donald Eastlake,
Thomas Fossati, Benjamin Kaduk, Gabriel Kerneis, Mirja Kuehlewind, Thomas Fossati, Benjamin Kaduk, Gabriel Kerneis, Mirja Kühlewind,
Antoni Przygienda, Henning Rogge, Dan Romascanu, Barbara Stark, Antoni Przygienda, Henning Rogge, Dan Romascanu, Barbara Stark,
Markus Stenberg, Dave Taht, Martin Thomson, Sean Turner and Martin Markus Stenberg, Dave Taht, Martin Thomson, Sean Turner, and Martin
Vigoureux for their input and contributions. The performance Vigoureux for their input and contributions. The performance
considerations in this document were inspired from the ones for DNS considerations in this document were inspired from the ones for DNS
over DTLS [RFC8094]. over DTLS [RFC8094].
Authors' Addresses Authors' Addresses
Antonin Decimo Antonin Décimo
IRIF, University of Paris-Diderot IRIF, University of Paris-Diderot
Paris Paris
France France
Email: antonin.decimo@gmail.com Email: antonin.decimo@gmail.com
David Schinazi David Schinazi
Google LLC Google LLC
1600 Amphitheatre Parkway 1600 Amphitheatre Parkway
Mountain View, California 94043 Mountain View, CA 94043
USA United States of America
Email: dschinazi.ietf@gmail.com Email: dschinazi.ietf@gmail.com
Juliusz Chroboczek Juliusz Chroboczek
IRIF, University of Paris-Diderot IRIF, University of Paris-Diderot
Case 7014 Case 7014
75205 Paris Cedex 13 75205 Paris CEDEX 13
France France
Email: jch@irif.fr Email: jch@irif.fr
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