draft-ietf-babel-dtls-07.txt   draft-ietf-babel-dtls-08.txt 
Network Working Group A. Decimo Network Working Group A. Decimo
Internet-Draft IRIF, University of Paris-Diderot Internet-Draft IRIF, University of Paris-Diderot
Intended status: Standards Track D. Schinazi Intended status: Standards Track D. Schinazi
Expires: January 6, 2020 Google LLC Expires: February 10, 2020 Google LLC
J. Chroboczek J. Chroboczek
IRIF, University of Paris-Diderot IRIF, University of Paris-Diderot
July 5, 2019 August 9, 2019
Babel Routing Protocol over Datagram Transport Layer Security Babel Routing Protocol over Datagram Transport Layer Security
draft-ietf-babel-dtls-07 draft-ietf-babel-dtls-08
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 protect messages sent between them. This document neighbours or provide integrity or confidentiality for messages sent
specifies a mechanism to ensure these properties, using Datagram between them. This document specifies a mechanism to ensure these
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 Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 6, 2020. This Internet-Draft will expire on February 10, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Specification of Requirements . . . . . . . . . . . . . . 2 1.1. Specification of Requirements . . . . . . . . . . . . . . 2
1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Operation of the Protocol . . . . . . . . . . . . . . . . . . 3 2. Operation of the Protocol . . . . . . . . . . . . . . . . . . 3
2.1. DTLS Connection Initiation . . . . . . . . . . . . . . . 3 2.1. DTLS Connection Initiation . . . . . . . . . . . . . . . 3
2.2. Protocol Encoding . . . . . . . . . . . . . . . . . . . . 4 2.2. Protocol Encoding . . . . . . . . . . . . . . . . . . . . 4
2.3. Transmission . . . . . . . . . . . . . . . . . . . . . . 4 2.3. Transmission . . . . . . . . . . . . . . . . . . . . . . 4
2.4. Reception . . . . . . . . . . . . . . . . . . . . . . . . 5 2.4. Reception . . . . . . . . . . . . . . . . . . . . . . . . 5
2.5. Neighbour table entry . . . . . . . . . . . . . . . . . . 5 2.5. Neighbour table entry . . . . . . . . . . . . . . . . . . 5
2.6. Simultaneous operation of both Babel over DTLS and 2.6. Simultaneous operation of both Babel over DTLS and
unprotected Babel . . . . . . . . . . . . . . . . . . . . 5 unprotected Babel on a Node . . . . . . . . . . . . . . . 5
2.7. Simultaneous operation of both Babel over DTLS and
unprotected Babel on a Network . . . . . . . . . . . . . 6
3. Interface Maximum Transmission Unit Issues . . . . . . . . . 6 3. Interface Maximum Transmission Unit Issues . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Normative References . . . . . . . . . . . . . . . . . . 7 6.1. Normative References . . . . . . . . . . . . . . . . . . 8
6.2. Informative References . . . . . . . . . . . . . . . . . 7 6.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Performance Considerations . . . . . . . . . . . . . 8 Appendix A. Performance Considerations . . . . . . . . . . . . . 9
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 9 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
The Babel Routing Protocol [RFC6126bis] does not contain any means to The Babel Routing Protocol [RFC6126bis] 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 which 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.
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authentication, integrity, replay protection, confidentiality and authentication, integrity, replay protection, confidentiality and
asymmetric keying. It is therefore expected to be applicable in a asymmetric keying. It is therefore expected to be applicable in a
wide range of environments. wide range of environments.
There exists another mechanism for securing Babel, namely Babel HMAC There exists another mechanism for securing Babel, namely Babel HMAC
authentication [BABEL-HMAC]. HMAC only offers basic features, namely authentication [BABEL-HMAC]. HMAC only offers basic features, namely
authentication, integrity and replay protection with a small number 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 [RFC6126bis].
Note that Babel over DTLS provides a single authentication domain,
meaning that all nodes that have the right credentials can convey any
and all routing information.
2. Operation of the Protocol 2. Operation of the Protocol
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 over to both unicast and multicast Babel packets can be sent over to both unicast and multicast
destinations. destinations.
2.1. DTLS Connection Initiation 2.1. DTLS Connection Initiation
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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 TBD, 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 [RFC6126bis]).
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
IPv6 link-local address with its own, using network byte ordering. IP address with its own, using network byte ordering. If a node's
If a node's address is lower than the recently discovered neighbour's address is lower than the recently discovered neighbour's address, it
address, it acts as a client and connects to the neighbour. In other acts as a client and connects to the neighbour. In other words, the
words, the node with the lowest address is the DTLS client for this node with the lowest address is the DTLS client for this pairwise
pairwise relationship. As an example, fe80::1:2 is considered lower relationship. As an example, fe80::1:2 is considered lower than
than fe80::2:1. fe80::2:1.
The node acting as DTLS client initiates its DTLS connection from an The node acting as DTLS client initiates its DTLS connection from an
ephemeral UDP port. Nodes SHOULD ensure that new client DTLS ephemeral UDP port. Nodes SHOULD ensure that new client DTLS
connections use different ephemeral ports from recently used connections use different ephemeral ports from recently used
connections to allow servers to differentiate between the new and old connections to allow servers to differentiate between the new and old
DTLS connections. Alternatively, nodes MAY use DTLS connection DTLS connections. Alternatively, nodes could use DTLS connection
identifiers [DTLS-CID] as a higher-entropy mechanism to distinguish identifiers [DTLS-CID] as a higher-entropy mechanism to distinguish
between connections. between connections.
When a node receives a new DTLS connection, it MUST verify that the When a node receives a new DTLS connection, it MUST verify that the
source IP address is an IPv6 link-local address; if it is not, it source IP address is either an IPv6 link-local address or an IPv4
MUST reject the connection. Nodes use mutual authentication address belonging to the local network; if it is neither, it MUST
(authenticating both client and server); servers MUST send a reject the connection. Nodes use mutual authentication
CertificateRequest message and subsequently authenticate the client. (authenticating both client and server); clients MUST authenticate
Implementations MUST support authenticating peers against a local servers and servers MUST authenticate clients. Implementations MUST
store of credentials. If either node fails to authenticate its peer support authenticating peers against a local store of credentials.
against its local policy, it MUST abort the DTLS handshake. Nodes If either node fails to authenticate its peer against its local
MUST only negotiate DTLS version 1.2 or higher. Nodes MUST use DTLS policy, it MUST abort the DTLS handshake. The guidance given in
replay protection to prevent attackers from replaying stale [BCP195] MUST be followed to avoid attacks on DTLS. Additionally,
nodes MUST only negotiate DTLS version 1.2 or higher. Nodes MUST use
DTLS replay protection to prevent attackers from replaying stale
information. Nodes SHOULD drop packets that have been reordered by information. Nodes SHOULD drop packets that have been reordered by
more than two IHU intervals, to avoid letting attackers make stale more than two IHU (I Heard You) intervals, to avoid letting attackers
information last longer. If a node receives a new DTLS connection make stale information last longer. If a node receives a new DTLS
from a neighbour to whom it already has a connection, the node MUST connection from a neighbour to whom it already has a connection, the
NOT discard the older connection until it has completed the handshake node MUST NOT discard the older connection until it has completed the
of the new one and validated the identity of the peer. handshake of the new one and validated the identity of the peer.
2.2. Protocol Encoding 2.2. Protocol Encoding
Babel over DTLS sends all unicast Babel packets protected by DTLS. Babel over DTLS sends all unicast Babel packets protected by DTLS.
The entire Babel packet, from the Magic byte at the start of the The entire Babel packet, from the Magic byte at the start of the
Babel header to the last byte of the Babel packet trailer, is sent Babel header to the last byte of the Babel packet trailer, is sent
protected by DTLS. protected by DTLS.
2.3. Transmission 2.3. Transmission
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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.
2.6. Simultaneous operation of both Babel over DTLS and unprotected 2.6. Simultaneous operation of both Babel over DTLS and unprotected
Babel Babel on a Node
Implementations MAY implement both Babel over DTLS and unprotected Implementations MAY implement both Babel over DTLS and unprotected
Babel. However, accepting unprotected Babel packets (other than Babel. Additionally, a node MAY simultaneously run both Babel over
multicast Hellos) loses the security properties of Babel over DTLS. DTLS and unprotected Babel. However, a node running both MUST ensure
A node MAY allow configuration options to allow unprotected Babel on that it runs them on separate interfaces, as the security properties
some interfaces but not others; this effectively gives nodes on that of Babel over DTLS rely on not accepting unprotected Babel packets
interface the same access as authenticated nodes, and SHOULD NOT be (other than multicast Hellos). A node MAY allow configuration
done unless that interface has a mechanism to authenticate nodes at a options to allow unprotected Babel on some interfaces but not others;
lower layer (e.g., IPsec). this effectively gives nodes on that interface the same access as
authenticated nodes, and SHOULD NOT be done unless that interface has
a mechanism to authenticate nodes at a lower layer (e.g., IPsec).
2.7. Simultaneous operation of both Babel over DTLS and unprotected
Babel on a Network
If Babel over DTLS and unprotected Babel are both operated on the
same network, the Babel over DTLS implementation will receive
unprotected multicast Hellos and attempt to initiate a DTLS
connection. These connection attempts can be sent to nodes that only
run unprotected Babel, who will not respond. Babel over DTLS
implementations SHOULD therefore rate-limit their DTLS connection
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 [RFC6126bis], 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 ciphers in use, and SHOULD NOT send Babel packets larger than on the ciphersuites in use, and SHOULD NOT send Babel packets larger
the interface maximum transmission unit (MTU) minus the overhead of than the interface maximum transmission unit (MTU) minus the overhead
IP, UDP and DTLS. Nodes MUST NOT send Babel packets larger than the of IP, UDP and DTLS. Nodes MUST NOT send Babel packets larger than
attached interface's MTU adjusted for known lower-layer headers (at the attached interface's MTU adjusted for known lower-layer headers
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 overhead per packet. Therefore, the can have different amounts of overhead per packet. Therefore, the
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o Transport Protocols: UDP only o Transport Protocols: UDP only
o Service Code: None o Service Code: None
o Service Name: babel-dtls o Service Name: babel-dtls
o Desired Port Number: 6699 o Desired Port Number: 6699
o Description: Babel Routing Protocol over DTLS o Description: Babel Routing Protocol over DTLS
o Reference: This document o Reference: This document
o Defined TXT Keys: None o Defined TXT Keys: None
5. Security Considerations 5. Security Considerations
Confidential interaction between two Babel peers requires Datagram
Transport Layer Security (DTLS) with a cipher suite offering
confidentiality protection. The guidance given in [RFC7525] MUST be
followed to avoid attacks on DTLS.
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 and can be obfuscated with IPv6 temporary addresses, by the protocol until the handshake completes and can be obfuscated
a server needs to mitigate the impact of such an attack. Such with IPv6 temporary addresses, a server needs to mitigate the impact
mitigation might involve rate limiting handshakes from a given subnet of such an attack. Note that attackers might attempt to keep in-
or more advanced denial of service avoidance techniques beyond the progress handshakes open for as long as possible by using variants on
scope of this document. the attack commonly known as Slowloris [SLOWLORIS]. Mitigating these
attacks might involve rate limiting handshakes from a given subnet or
more advanced denial of service avoidance techniques beyond the scope
of this document.
Babel over DTLS allows sending multicast Hellos unprotected;
attackers can therefore tamper with them. For example, an attacker
could send erroneous values for the Seqno and Interval fields,
causing bidirectional reachability detection to fail. While
implementations MAY use multicast Hellos for link quality estimation,
they SHOULD also emit protected unicast Hellos to prevent this class
of denial-of-service attack.
6. References 6. References
6.1. Normative References 6.1. Normative References
[BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <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] [RFC6126bis]
Chroboczek, J. and D. Schinazi, "The Babel Routing Chroboczek, J. and D. Schinazi, "The Babel Routing
Protocol", Internet Draft draft-ietf-babel-rfc6126bis-11, Protocol", Internet Draft draft-ietf-babel-rfc6126bis-12,
June 2019. August 2019.
[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 6.2. Informative References
[BABEL-HMAC] [BABEL-HMAC]
Do, C., Kolodziejak, W., and J. Chroboczek, "Babel Do, C., Kolodziejak, W., and J. Chroboczek, "Babel
Cryptographic Authentication", Internet Draft draft-ietf- Cryptographic Authentication", Internet Draft draft-ietf-
babel-hmac-07, June 2019. babel-hmac-08, June 2019.
[DTLS-CID] [DTLS-CID]
Rescorla, E., Tschofenig, H., Fossati, T., and T. Gondrom, Rescorla, E., Tschofenig, H., Fossati, T., and T. Gondrom,
"Connection Identifiers for DTLS 1.2", Internet Draft "Connection Identifiers for DTLS 1.2", Internet Draft
draft-ietf-tls-dtls-connection-id-05, October 2018. draft-ietf-tls-dtls-connection-id-06, July 2019.
[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>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[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,
<https://www.rfc-editor.org/info/rfc7918>. <https://www.rfc-editor.org/info/rfc7918>.
[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>.
[SLOWLORIS]
Hansen, R., "Welcome to Slowloris...", June 2009,
<https://web.archive.org/web/20150315054838/
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 Appendix B. Acknowledgments
The authors would like to thank Donald Eastlake, Thomas Fossati, The authors would like to thank Roman Danyliw, Donald Eastlake,
Gabriel Kerneis, Antoni Przygienda, Henning Rogge, Dan Romascanu, Thomas Fossati, Benjamin Kaduk, Gabriel Kerneis, Mirja Kuehlewind,
Barbara Stark, Markus Stenberg, Dave Taht, Martin Thomson, Sean Antoni Przygienda, Henning Rogge, Dan Romascanu, Barbara Stark,
Turner and Martin Vigoureux for their input and contributions. The Markus Stenberg, Dave Taht, Martin Thomson, Sean Turner and Martin
performance considerations in this document were inspired from the Vigoureux for their input and contributions. The performance
ones for DNS over DTLS [RFC8094]. considerations in this document were inspired from the ones for DNS
over DTLS [RFC8094].
Authors' Addresses Authors' Addresses
Antonin Decimo Antonin Decimo
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
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