A Survey of the Interaction between Security Protocols and Transport ServicesTU BerlinMarchstr. 23Berlin10587Germanyietf@tenghardt.netApple Inc.One Apple Park WayCupertinoCalifornia95014United States of Americatpauly@apple.comUniversity of GlasgowSchool of Computing ScienceGlasgowG12 8QQUnited Kingdomcsp@csperkins.orgAkamai Technologies, Inc.150 BroadwayCambridgeMA02144United States of Americakrose@krose.orgCloudflare101 Townsend StSan FranciscoUnited States of Americacaw@heapingbits.netTransport ProtocolsTransport SecurityThis document provides a survey of commonly used or notable network
security protocols, with a focus on how they interact and integrate with
applications and transport protocols. Its goal is to supplement efforts
to define and catalog Transport Services by describing the interfaces
required to add security protocols. This survey is not limited to
protocols developed within the scope or context of the IETF, and those
included represent a superset of features a Transport Services system
may need to support.Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any
errata, and how to provide feedback on it may be obtained at
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Table of Contents
. Introduction
. Goals
. Non-goals
. Terminology
. Transport Security Protocol Descriptions
. Application Payload Security Protocols
. TLS
. DTLS
. Application-Specific Security Protocols
. Secure RTP
. Transport-Layer Security Protocols
. IETF QUIC
. Google QUIC
. tcpcrypt
. MinimaLT
. CurveCP
. Packet Security Protocols
. IPsec
. WireGuard
. OpenVPN
. Transport Dependencies
. Reliable Byte-Stream Transports
. Unreliable Datagram Transports
. Datagram Protocols with Defined Byte-Stream Mappings
. Transport-Specific Dependencies
. Application Interface
. Pre-connection Interfaces
. Connection Interfaces
. Post-connection Interfaces
. Summary of Interfaces Exposed by Protocols
. IANA Considerations
. Security Considerations
. Privacy Considerations
. Informative References
Acknowledgments
Authors' Addresses
IntroductionServices and features provided by transport protocols have been
cataloged in . This document
supplements that work by surveying commonly used and notable network
security protocols, and identifying the interfaces between these
protocols and both transport protocols and applications. It examines
Transport Layer Security (TLS), Datagram Transport Layer Security
(DTLS), IETF QUIC, Google QUIC (gQUIC), tcpcrypt, Internet Protocol
Security (IPsec), Secure Real-time Transport Protocol (SRTP) with DTLS,
WireGuard, CurveCP, and MinimaLT. For each protocol, this document
provides a brief description. Then, it describes the interfaces between
these protocols and transports in and the interfaces between these protocols and
applications in .A Transport Services system exposes an interface for applications to
access various (secure) transport protocol features. The security
protocols included in this survey represent a superset of functionality
and features a Transport Services system may need to support both
internally and externally (via an API) for applications . Ubiquitous IETF
protocols such as (D)TLS, as well as non-standard protocols such as
gQUIC, are included despite overlapping features. As such, this survey
is not limited to protocols developed within the scope or context of the
IETF. Outside of this candidate set, protocols that do not offer new
features are omitted. For example, newer protocols such as WireGuard
make unique design choices that have implications for and limitations on
application usage. In contrast, protocols such as secure shell (SSH)
, GRE , the Layer 2 Tunneling Protocol (L2TP) , and Application Layer Transport
Security (ALTS) are omitted since they do not provide interfaces
deemed unique.Authentication-only protocols such as the TCP Authentication Option
(TCP-AO) and the IPsec
Authentication Header (AH) are
excluded from this survey. TCP-AO adds authentication to long-lived TCP
connections, e.g., replay protection with per-packet Message
Authentication Codes. (TCP-AO obsoletes TCP MD5 "signature" options
specified in .) One primary use
case of TCP-AO is for protecting BGP connections. Similarly, AH adds
per-datagram authentication and integrity, along with replay
protection. Despite these improvements, neither protocol sees general
use and both lack critical properties important for emergent transport
security protocols, such as confidentiality and privacy
protections. Such protocols are thus omitted from this survey.This document only surveys point-to-point protocols; multicast protocols are out of scope.GoalsThis survey is intended to help identify the most common interface
surfaces between security protocols and transport protocols, and
between security protocols and applications.One of the goals of the Transport Services effort is to define a
common interface for using transport protocols that allows software
using transport protocols to easily adopt new protocols that provide
similar feature sets. The survey of the dependencies security
protocols have upon transport protocols can guide implementations in
determining which transport protocols are appropriate to be able to
use beneath a given security protocol. For example, a security
protocol that expects to run over a reliable stream of bytes, like
TLS, restricts the set of transport protocols that can be used to
those that offer a reliable stream of bytes.Defining the common interfaces that security protocols provide to
applications also allows interfaces to be designed in a way that
common functionality can use the same APIs. For example, many security
protocols that provide authentication let the application be involved
in peer identity validation. Any interface to use a secure transport
protocol stack thus needs to allow applications to perform this action
during connection establishment.Non-goalsWhile this survey provides similar analysis to that which was performed for transport protocols in ,
it is important to distinguish that the use of security protocols requires more consideration.It is not a goal to allow software implementations to automatically
switch between different security protocols, even where their
interfaces to transport and applications are equivalent. Even between
versions, security protocols have subtly different guarantees and
vulnerabilities. Thus, any implementation needs to only use the set of
protocols and algorithms that are requested by applications or by a
system policy.Different security protocols also can use incompatible notions of
peer identity and authentication, and cryptographic options. It is not
a goal to identify a common set of representations for these
concepts.The protocols surveyed in this document represent a superset of
functionality and features a Transport Services system may need to
support. It does not list all transport protocols that a Transport
Services system may need to implement, nor does it mandate that a
Transport Service system implement any particular protocol.A Transport Services system may implement any secure transport
protocol that provides the described features. In doing so, it may
need to expose an interface to the application to configure these
features.TerminologyThe following terms are used throughout this document to describe the
roles and interactions of transport security protocols (some of which
are also defined in ):
Transport Feature:
a specific end-to-end feature that the
transport layer provides to an application. Examples include
confidentiality, reliable delivery, ordered delivery, and
message-versus-stream orientation.
Transport Service:
a set of Transport Features, without an
association to any given framing protocol, that provides
functionality to an application.
Transport Services system:
a software component that exposes an
interface to different Transport Services to an application.
Transport Protocol:
an implementation that provides one or more
different Transport Services using a specific framing and header
format on the wire. A Transport Protocol services an application,
whether directly or in conjunction with a security protocol.
Application:
an entity that uses a transport protocol for
end-to-end delivery of data across the network. This may also be an
upper layer protocol or tunnel encapsulation.
Security Protocol:
a defined network protocol that implements one
or more security features, such as authentication, encryption, key
generation, session resumption, and privacy. Security protocols may be
used alongside transport protocols, and in combination with other
security protocols when appropriate.
Handshake Protocol:
a protocol that enables peers to validate each
other and to securely establish shared cryptographic context.
Record:
framed protocol messages.
Record Protocol:
a security protocol that allows data to be
divided into manageable blocks and protected using shared
cryptographic context.
Session:
an ephemeral security association between
applications.
Connection:
the shared state of two or more endpoints that
persists across messages that are transmitted between these
endpoints. A connection is a transient participant of a session, and a
session generally lasts between connection instances.
Peer:
an endpoint application party to a session.
Client:
the peer responsible for initiating a session.
Server:
the peer responsible for responding to a session initiation.
Transport Security Protocol DescriptionsThis section contains brief transport and security descriptions of
various security protocols currently used to protect data being sent
over a network. These protocols are grouped based on where in the
protocol stack they are implemented, which influences which parts of a
packet they protect: Generic application payload, application payload
for specific application-layer protocols, both application payload and
transport headers, or entire IP packets.Note that not all security protocols can be easily categorized, e.g.,
as some protocols can be used in different ways or in combination with
other protocols. One major reason for this is that channel security
protocols often consist of two components:
A handshake protocol, which is responsible for negotiating parameters, authenticating the
endpoints, and establishing shared keys.
A record protocol, which is used to encrypt traffic using keys and parameters provided by the
handshake protocol.
For some protocols, such as tcpcrypt, these two components are
tightly integrated. In contrast, for IPsec, these components are
implemented in separate protocols: AH and the Encapsulating Security Payload
(ESP) are record protocols, which can use keys supplied by the handshake
protocol Internet Key Exchange Protocol Version 2 (IKEv2), by other
handshake protocols, or by manual configuration. Moreover, some
protocols can be used in different ways: While the base TLS protocol as
defined in has an integrated
handshake and record protocol, TLS or DTLS can also be used to negotiate
keys for other protocols, as in DTLS-SRTP, or the handshake protocol can
be used with a separate record layer, as in QUIC .Application Payload Security ProtocolsThe following protocols provide security that protects application payloads sent over a
transport. They do not specifically protect any headers used for transport-layer functionality.TLSTLS (Transport Layer Security) is a common protocol used to establish a secure
session between two endpoints. Communication over this session
prevents "eavesdropping, tampering, and message forgery." TLS
consists of a tightly coupled handshake and record protocol. The
handshake protocol is used to authenticate peers, negotiate protocol
options such as cryptographic algorithms, and derive
session-specific keying material. The record protocol is used to
marshal and, once the handshake has sufficiently progressed,
encrypt data from one peer to the other. This data may contain
handshake messages or raw application data.DTLSDTLS (Datagram Transport Layer Security) is based on TLS, but differs in that it is
designed to run over unreliable datagram protocols like UDP instead
of TCP. DTLS modifies the protocol to make sure it can still
provide equivalent security guarantees to TLS with the exception of
order protection/non-replayability. DTLS was designed to be as
similar to TLS as possible, so this document assumes that all
properties from TLS are carried over except where specified.Application-Specific Security ProtocolsThe following protocols provide application-specific security by protecting
application payloads used for specific use cases. Unlike the protocols above,
these are not intended for generic application use.Secure RTPSecure RTP (SRTP) is a profile for RTP that provides confidentiality,
message authentication, and replay protection for RTP data packets
and RTP control protocol (RTCP) packets .
SRTP provides a record layer only, and requires a separate handshake
protocol to provide key agreement and identity management.The commonly used handshake protocol for SRTP is DTLS, in the form of
DTLS-SRTP . This is an extension to DTLS that negotiates
the use of SRTP as the record layer and describes how to export keys
for use with SRTP.ZRTP is an alternative key agreement and identity management
protocol for SRTP. ZRTP Key agreement is performed using a Diffie-Hellman
key exchange that runs on the media path. This generates a shared secret
that is then used to generate the master key and salt for SRTP.Transport-Layer Security ProtocolsThe following security protocols provide protection for both application payloads and
headers that are used for Transport Services.IETF QUICQUIC is a new standards-track transport protocol that runs over UDP, loosely based on Google's
original proprietary gQUIC protocol (See for more details).
The QUIC transport layer itself provides support for data confidentiality and integrity. This requires
keys to be derived with a separate handshake protocol. A mapping for QUIC of TLS 1.3
has been specified to provide this handshake.Google QUICGoogle QUIC (gQUIC) is a UDP-based multiplexed streaming protocol
designed and deployed by Google following experience from deploying
SPDY, the proprietary predecessor to HTTP/2. gQUIC was originally
known as "QUIC"; this document uses gQUIC to unambiguously
distinguish it from the standards-track IETF QUIC. The proprietary
technical forebear of IETF QUIC, gQUIC was originally designed with
tightly integrated security and application data transport
protocols.tcpcryptTcpcrypt is a lightweight extension to the TCP protocol for opportunistic encryption. Applications may
use tcpcrypt's unique session ID for further application-level authentication. Absent this authentication,
tcpcrypt is vulnerable to active attacks.MinimaLTMinimaLT is a UDP-based transport security protocol designed to offer confidentiality,
mutual authentication, DoS prevention, and connection mobility. One major
goal of the protocol is to leverage existing protocols to obtain server-side configuration
information used to more quickly bootstrap a connection. MinimaLT uses a variant of TCP's
congestion control algorithm.CurveCPCurveCP is a UDP-based
transport security that, unlike many other security protocols, is
based entirely upon public key algorithms. CurveCP provides its own
reliability for application data as part of its protocol.Packet Security ProtocolsThe following protocols provide protection for IP packets. These
are generally used as tunnels, such as for Virtual Private Networks
(VPNs). Often, applications will not interact directly with these
protocols. However, applications that implement tunnels will interact
directly with these protocols.IPsecIKEv2 and ESP together form the modern IPsec
protocol suite that encrypts and authenticates IP packets, either
for creating tunnels (tunnel-mode) or for direct transport
connections (transport-mode). This suite of protocols separates out
the key generation protocol (IKEv2) from the transport encryption
protocol (ESP). Each protocol can be used independently, but this
document considers them together, since that is the most common
pattern.WireGuardWireGuard is an IP-layer protocol designed as an alternative to IPsec
for certain use cases. It uses UDP to encapsulate IP datagrams between peers.
Unlike most transport security protocols, which rely on Public Key Infrastructure (PKI)
for peer authentication, WireGuard authenticates peers using pre-shared public keys
delivered out of band, each of which is bound to one or more IP addresses.
Moreover, as a protocol suited for VPNs, WireGuard offers no extensibility, negotiation,
or cryptographic agility.OpenVPNOpenVPN is a commonly used protocol designed as an alternative to
IPsec. A major goal of this protocol is to provide a VPN that is simple to
configure and works over a variety of transports. OpenVPN encapsulates either
IP packets or Ethernet frames within a secure tunnel and can run over either UDP or TCP.
For key establishment, OpenVPN can either use TLS as a handshake protocol or use pre-shared keys.Transport DependenciesAcross the different security protocols listed above, the primary dependency on transport
protocols is the presentation of data: either an unbounded stream of bytes, or framed
messages. Within protocols that rely on the transport for message framing, most are
built to run over transports that inherently provide framing, like UDP, but some also define
how their messages can be framed over byte-stream transports.Reliable Byte-Stream TransportsThe following protocols all depend upon running on a transport protocol that provides
a reliable, in-order stream of bytes. This is typically TCP.Application Payload Security Protocols:
TLS
Transport-Layer Security Protocols:
tcpcrypt
Unreliable Datagram TransportsThe following protocols all depend on the transport protocol to provide message framing
to encapsulate their data. These protocols are built to run using UDP, and thus do not
have any requirement for reliability. Running these protocols over a protocol that
does provide reliability will not break functionality but may lead to multiple layers
of reliability if the security protocol is encapsulating other transport protocol traffic.Application Payload Security Protocols:
DTLS
ZRTP
SRTP
Transport-Layer Security Protocols:
QUIC
MinimaLT
CurveCP
Packet Security Protocols:
IPsec
WireGuard
OpenVPN
Datagram Protocols with Defined Byte-Stream MappingsOf the protocols listed above that depend on the transport for message framing, some
do have well-defined mappings for sending their messages over byte-stream transports
like TCP.Application Payload Security Protocols:
DTLS when used as a handshake protocol for SRTP
ZRTP
SRTP
Packet Security Protocols:
IPsec
Transport-Specific DependenciesOne protocol surveyed, tcpcrypt, has a direct dependency on a
feature in the transport that is needed for its
functionality. Specifically, tcpcrypt is designed to run on top of
TCP and uses the TCP Encryption Negotiation Option (TCP-ENO) to negotiate its protocol
support.QUIC, CurveCP, and MinimaLT provide both transport functionality and security functionality. They
depend on running over a framed protocol like UDP, but they add their own layers of
reliability and other Transport Services. Thus, an application that uses one of these protocols
cannot decouple the security from transport functionality.Application InterfaceThis section describes the interface exposed by the security protocols described above.
We partition these interfaces into
pre-connection (configuration), connection, and post-connection interfaces, following
conventions in and .Note that not all protocols support each interface.
The table in summarizes which protocol exposes which of the interfaces.
In the following sections, we provide abbreviations of the interface names to use in the summary table.Pre-connection InterfacesConfiguration interfaces are used to configure the security protocols before a
handshake begins or keys are negotiated.
Identities and Private Keys (IPK):
The application can provide its identity, credentials (e.g.,
certificates), and private keys, or mechanisms to access these, to
the security protocol to use during handshakes.
TLS
DTLS
ZRTP
QUIC
MinimaLT
CurveCP
IPsec
WireGuard
OpenVPN
Supported Algorithms (Key Exchange, Signatures, and Ciphersuites) (ALG):
The application can choose the algorithms that are supported for key exchange,
signatures, and ciphersuites.
TLS
DTLS
ZRTP
QUIC
tcpcrypt
MinimaLT
IPsec
OpenVPN
Extensions (EXT):
The application enables or configures extensions that are to be negotiated by
the security protocol, such as Application-Layer Protocol Negotiation (ALPN) .
TLS
DTLS
QUIC
Session Cache Management (CM):
The application provides the
ability to save and retrieve session state (such as tickets,
keying material, and server parameters) that may be used to resume
the security session.
TLS
DTLS
ZRTP
QUIC
tcpcrypt
MinimaLT
Authentication Delegation (AD):
The application provides access to a separate module that will provide authentication,
using the Extensible Authentication Protocol (EAP) for example.
IPsec
tcpcrypt
Pre-Shared Key Import (PSKI):
Either the handshake protocol or the application directly can supply pre-shared keys for use
in encrypting (and authenticating) communication with a peer.
TLS
DTLS
ZRTP
QUIC
tcpcrypt
MinimaLT
IPsec
WireGuard
OpenVPN
Connection Interfaces
Identity Validation (IV):
During a handshake, the security protocol will conduct identity validation of the peer.
This can offload validation or occur transparently to the application.
TLS
DTLS
ZRTP
QUIC
MinimaLT
CurveCP
IPsec
WireGuard
OpenVPN
Source Address Validation (SAV):
The handshake protocol may interact with the transport protocol or application to
validate the address of the remote peer that has sent data. This involves sending a cookie
exchange to avoid DoS attacks. (This list omits protocols that depend on TCP and therefore
implicitly perform SAV.)
DTLS
QUIC
IPsec
WireGuard
Post-connection Interfaces
Connection Termination (CT):
The security protocol may be instructed to tear down its connection and session information.
This is needed by some protocols, e.g., to prevent application data truncation attacks in
which an attacker terminates an underlying insecure connection-oriented protocol to terminate
the session.
TLS
DTLS
ZRTP
QUIC
tcpcrypt
MinimaLT
IPsec
OpenVPN
Key Update (KU):
The handshake protocol may be instructed to update its keying material, either
by the application directly or by the record protocol sending a key expiration event.
TLS
DTLS
QUIC
tcpcrypt
MinimaLT
IPsec
Shared Secret Key Export (SSKE):
The handshake protocol may provide an interface for producing shared secrets for application-specific uses.
TLS
DTLS
tcpcrypt
IPsec
OpenVPN
MinimaLT
Key Expiration (KE):
The record protocol can signal that its
keys are expiring due to reaching a time-based deadline or a
use-based deadline (number of bytes that have been encrypted with
the key). This interaction is often limited to signaling between
the record layer and the handshake layer.
IPsec
Mobility Events (ME):
The record protocol can be signaled that
it is being migrated to another transport or interface due to connection
mobility, which may reset address and state validation and induce state
changes such as use of a new Connection Identifier (CID).
DTLS (version 1.3 only )
QUIC
MinimaLT
CurveCP
IPsec
WireGuard
Summary of Interfaces Exposed by ProtocolsThe following table summarizes which protocol exposes which interface.
Protocol
IPK
ALG
EXT
CM
AD
PSKI
IV
SAV
CT
KU
SSKE
KE
ME
TLS
x
x
x
x
x
x
x
x
x
DTLS
x
x
x
x
x
x
x
x
x
x
x
ZRTP
x
x
x
x
x
x
QUIC
x
x
x
x
x
x
x
x
x
x
tcpcrypt
x
x
x
x
x
x
x
MinimaLT
x
x
x
x
x
x
x
x
x
CurveCP
x
x
x
IPsec
x
x
x
x
x
x
x
x
x
x
x
WireGuard
x
x
x
x
x
OpenVPN
x
x
x
x
x
x
x = Interface is exposed
(blank) = Interface is not exposedIANA ConsiderationsThis document has no IANA actions.Security ConsiderationsThis document summarizes existing transport security protocols and their interfaces.
It does not propose changes to or recommend usage of reference protocols. Moreover,
no claims of security and privacy properties beyond those guaranteed by the protocols
discussed are made. For example, metadata leakage via timing side channels and traffic
analysis may compromise any protocol discussed in this survey. Applications using
Security Interfaces should take such limitations into consideration when using a particular
protocol implementation.Privacy ConsiderationsAnalysis of how features improve or degrade privacy is intentionally omitted from this survey.
All security protocols surveyed generally improve privacy by using encryption to reduce information
leakage. However, varying amounts of metadata remain in the clear across each
protocol. For example, client and server certificates are sent in cleartext in TLS
1.2 , whereas they are encrypted in TLS 1.3 . A survey of privacy
features, or lack thereof, for various security protocols could be addressed in a
separate document.Informative ReferencesApplication Layer Transport SecurityCurveCP: Usable security for the InternetCurveCPThe Datagram Transport Layer Security (DTLS) Protocol Version 1.3RTFM, Inc.Arm LimitedGoogle, Inc. This document specifies Version 1.3 of the Datagram Transport Layer
Security (DTLS) protocol. DTLS 1.3 allows client/server applications
to communicate over the Internet in a way that is designed to prevent
eavesdropping, tampering, and message forgery.
The DTLS 1.3 protocol is intentionally based on the Transport Layer
Security (TLS) 1.3 protocol and provides equivalent security
guarantees with the exception of order protection/non-replayability.
Datagram semantics of the underlying transport are preserved by the
DTLS protocol.
Work in ProgressMinimaLT: minimal-latency networking through better securityUnited States Military Academy, West Point, NY, USAUniversity of Illinois at Chicago, Chicago, IL, USAUniversity of Illinois at Chicago, Chicago, IL, USAUniversity of Illinois at Chicago, Chicago, IL, USATU Eindhoven, Eindhoven, NetherlandsOpenVPN cryptographic layerOpenVPNUsing TLS to Secure QUICMozillasn3rd This document describes how Transport Layer Security (TLS) is used to
secure QUIC.
Note to Readers
Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/search/?email_list=quic.
Working Group information can be found at https://github.com/quicwg;
source code and issues list for this draft can be found at
https://github.com/quicwg/base-drafts/labels/-tls.
Work in ProgressQUIC: A UDP-Based Multiplexed and Secure TransportFastlyMozilla This document defines the core of the QUIC transport protocol.
Accompanying documents describe QUIC's loss detection and congestion
control and the use of TLS for key negotiation.
Note to Readers
Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org (mailto:quic@ietf.org)), which is
archived at https://mailarchive.ietf.org/arch/search/?email_list=quic
Working Group information can be found at https://github.com/quicwg;
source code and issues list for this draft can be found at
https://github.com/quicwg/base-drafts/labels/-transport.
Work in ProgressProtection of BGP Sessions via the TCP MD5 Signature OptionThis memo describes a TCP extension to enhance security for BGP. [STANDARDS-TRACK]Key and Sequence Number Extensions to GREThis document describes extensions by which two fields, Key and Sequence Number, can be optionally carried in the GRE Header. [STANDARDS-TRACK]The Secure Real-time Transport Protocol (SRTP)This document describes the Secure Real-time Transport Protocol (SRTP), a profile of the Real-time Transport Protocol (RTP), which can provide confidentiality, message authentication, and replay protection to the RTP traffic and to the control traffic for RTP, the Real-time Transport Control Protocol (RTCP). [STANDARDS-TRACK]Extensible Authentication Protocol (EAP)This document defines the Extensible Authentication Protocol (EAP), an authentication framework which supports multiple authentication methods. EAP typically runs directly over data link layers such as Point-to-Point Protocol (PPP) or IEEE 802, without requiring IP. EAP provides its own support for duplicate elimination and retransmission, but is reliant on lower layer ordering guarantees. Fragmentation is not supported within EAP itself; however, individual EAP methods may support this. This document obsoletes RFC 2284. A summary of the changes between this document and RFC 2284 is available in Appendix A. [STANDARDS-TRACK]The Secure Shell (SSH) Transport Layer ProtocolThe Secure Shell (SSH) is a protocol for secure remote login and other secure network services over an insecure network.This document describes the SSH transport layer protocol, which typically runs on top of TCP/IP. The protocol can be used as a basis for a number of secure network services. It provides strong encryption, server authentication, and integrity protection. It may also provide compression.Key exchange method, public key algorithm, symmetric encryption algorithm, message authentication algorithm, and hash algorithm are all negotiated.This document also describes the Diffie-Hellman key exchange method and the minimal set of algorithms that are needed to implement the SSH transport layer protocol. [STANDARDS-TRACK]IP Authentication HeaderThis document describes an updated version of the IP Authentication Header (AH), which is designed to provide authentication services in IPv4 and IPv6. This document obsoletes RFC 2402 (November 1998). [STANDARDS-TRACK]IP Encapsulating Security Payload (ESP)This document describes an updated version of the Encapsulating Security Payload (ESP) protocol, which is designed to provide a mix of security services in IPv4 and IPv6. ESP is used to provide confidentiality, data origin authentication, connectionless integrity, an anti-replay service (a form of partial sequence integrity), and limited traffic flow confidentiality. This document obsoletes RFC 2406 (November 1998). [STANDARDS-TRACK]IKEv2 Mobility and Multihoming Protocol (MOBIKE)This document describes the MOBIKE protocol, a mobility and multihoming extension to Internet Key Exchange (IKEv2). MOBIKE allows the IP addresses associated with IKEv2 and tunnel mode IPsec Security Associations to change. A mobile Virtual Private Network (VPN) client could use MOBIKE to keep the connection with the VPN gateway active while moving from one address to another. Similarly, a multihomed host could use MOBIKE to move the traffic to a different interface if, for instance, the one currently being used stops working. [STANDARDS-TRACK]Framing Real-time Transport Protocol (RTP) and RTP Control Protocol (RTCP) Packets over Connection-Oriented TransportThis memo defines a method for framing Real-time Transport Protocol (RTP) and RTP Control Protocol (RTCP) packets onto connection-oriented transport (such as TCP). The memo also defines how session descriptions may specify RTP streams that use the framing method. [STANDARDS-TRACK]The Transport Layer Security (TLS) Protocol Version 1.2This document specifies Version 1.2 of the Transport Layer Security (TLS) protocol. The TLS protocol provides communications security over the Internet. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. [STANDARDS-TRACK]Layer 2 Tunneling Protocol Version 3 (L2TPv3) Extended Circuit Status ValuesThis document defines additional Layer 2 Tunneling Protocol Version 3 (L2TPv3) bit values to be used within the "Circuit Status" Attribute Value Pair (AVP) to communicate finer-grained error states for Attachment Circuits (ACs) and pseudowires (PWs). It also generalizes the Active bit and deprecates the use of the New bit in the Circuit Status AVP, updating RFC 3931, RFC 4349, RFC 4454, RFC 4591, and RFC 4719. [STANDARDS-TRACK]Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the Secure Real-time Transport Protocol (SRTP)This document describes a Datagram Transport Layer Security (DTLS) extension to establish keys for Secure RTP (SRTP) and Secure RTP Control Protocol (SRTCP) flows. DTLS keying happens on the media path, independent of any out-of-band signalling channel present. [STANDARDS-TRACK]The TCP Authentication OptionThis document specifies the TCP Authentication Option (TCP-AO), which obsoletes the TCP MD5 Signature option of RFC 2385 (TCP MD5). TCP-AO specifies the use of stronger Message Authentication Codes (MACs), protects against replays even for long-lived TCP connections, and provides more details on the association of security with TCP connections than TCP MD5. TCP-AO is compatible with either a static Master Key Tuple (MKT) configuration or an external, out-of-band MKT management mechanism; in either case, TCP-AO also protects connections when using the same MKT across repeated instances of a connection, using traffic keys derived from the MKT, and coordinates MKT changes between endpoints. The result is intended to support current infrastructure uses of TCP MD5, such as to protect long-lived connections (as used, e.g., in BGP and LDP), and to support a larger set of MACs with minimal other system and operational changes. TCP-AO uses a different option identifier than TCP MD5, even though TCP-AO and TCP MD5 are never permitted to be used simultaneously. TCP-AO supports IPv6, and is fully compatible with the proposed requirements for the replacement of TCP MD5. [STANDARDS-TRACK]ZRTP: Media Path Key Agreement for Unicast Secure RTPThis document defines ZRTP, a protocol for media path Diffie-Hellman exchange to agree on a session key and parameters for establishing unicast Secure Real-time Transport Protocol (SRTP) sessions for Voice over IP (VoIP) applications. The ZRTP protocol is media path keying because it is multiplexed on the same port as RTP and does not require support in the signaling protocol. ZRTP does not assume a Public Key Infrastructure (PKI) or require the complexity of certificates in end devices. For the media session, ZRTP provides confidentiality, protection against man-in-the-middle (MiTM) attacks, and, in cases where the signaling protocol provides end-to-end integrity protection, authentication. ZRTP can utilize a Session Description Protocol (SDP) attribute to provide discovery and authentication through the signaling channel. To provide best effort SRTP, ZRTP utilizes normal RTP/AVP (Audio-Visual Profile) profiles. ZRTP secures media sessions that include a voice media stream and can also secure media sessions that do not include voice by using an optional digital signature. This document is not an Internet Standards Track specification; it is published for informational purposes.Datagram Transport Layer Security Version 1.2This document specifies version 1.2 of the Datagram Transport Layer Security (DTLS) protocol. The DTLS protocol provides communications privacy for datagram protocols. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. The DTLS protocol is based on the Transport Layer Security (TLS) protocol and provides equivalent security guarantees. Datagram semantics of the underlying transport are preserved by the DTLS protocol. This document updates DTLS 1.0 to work with TLS version 1.2. [STANDARDS-TRACK]Internet Key Exchange Protocol Version 2 (IKEv2)This document describes version 2 of the Internet Key Exchange (IKE) protocol. IKE is a component of IPsec used for performing mutual authentication and establishing and maintaining Security Associations (SAs). This document obsoletes RFC 5996, and includes all of the errata for it. It advances IKEv2 to be an Internet Standard.Transport Layer Security (TLS) Application-Layer Protocol Negotiation ExtensionThis document describes a Transport Layer Security (TLS) extension for application-layer protocol negotiation within the TLS handshake. For instances in which multiple application protocols are supported on the same TCP or UDP port, this extension allows the application layer to negotiate which protocol will be used within the TLS connection.Registering Values of the SDP 'proto' Field for Transporting RTP Media over TCP under Various RTP ProfilesThe Real-time Transport Protocol (RTP) specification establishes a registry of profile names for use by higher-level control protocols, such as the Session Description Protocol (SDP), to refer to the transport methods. This specification describes the following new SDP transport protocol identifiers for transporting RTP Media over TCP: 'TCP/RTP/AVPF', 'TCP/RTP/SAVP', 'TCP/RTP/SAVPF', 'TCP/DTLS/RTP/SAVP', 'TCP/DTLS/RTP/SAVPF', 'TCP/TLS/RTP/AVP', and 'TCP/TLS/RTP/AVPF'.Services Provided by IETF Transport Protocols and Congestion Control MechanismsThis document describes, surveys, and classifies the protocol mechanisms provided by existing IETF protocols, as background for determining a common set of transport services. It examines the Transmission Control Protocol (TCP), Multipath TCP, the Stream Control Transmission Protocol (SCTP), the User Datagram Protocol (UDP), UDP-Lite, the Datagram Congestion Control Protocol (DCCP), the Internet Control Message Protocol (ICMP), the Real-Time Transport Protocol (RTP), File Delivery over Unidirectional Transport / Asynchronous Layered Coding (FLUTE/ALC) for Reliable Multicast, NACK- Oriented Reliable Multicast (NORM), Transport Layer Security (TLS), Datagram TLS (DTLS), and the Hypertext Transport Protocol (HTTP), when HTTP is used as a pseudotransport. This survey provides background for the definition of transport services within the TAPS working group.TCP Encapsulation of IKE and IPsec PacketsThis document describes a method to transport Internet Key Exchange Protocol (IKE) and IPsec packets over a TCP connection for traversing network middleboxes that may block IKE negotiation over UDP. This method, referred to as "TCP encapsulation", involves sending both IKE packets for Security Association establishment and Encapsulating Security Payload (ESP) packets over a TCP connection. This method is intended to be used as a fallback option when IKE cannot be negotiated over UDP.The Transport Layer Security (TLS) Protocol Version 1.3This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery.This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations.TCP-ENO: Encryption Negotiation OptionDespite growing adoption of TLS, a significant fraction of TCP traffic on the Internet remains unencrypted. The persistence of unencrypted traffic can be attributed to at least two factors. First, some legacy protocols lack a signaling mechanism (such as a STARTTLS command) by which to convey support for encryption, thus making incremental deployment impossible. Second, legacy applications themselves cannot always be upgraded and therefore require a way to implement encryption transparently entirely within the transport layer. The TCP Encryption Negotiation Option (TCP-ENO) addresses both of these problems through a new TCP option kind providing out-of-band, fully backward-compatible negotiation of encryption.Cryptographic Protection of TCP Streams (tcpcrypt)This document specifies "tcpcrypt", a TCP encryption protocol designed for use in conjunction with the TCP Encryption Negotiation Option (TCP-ENO). Tcpcrypt coexists with middleboxes by tolerating resegmentation, NATs, and other manipulations of the TCP header. The protocol is self-contained and specifically tailored to TCP implementations, which often reside in kernels or other environments in which large external software dependencies can be undesirable. Because the size of TCP options is limited, the protocol requires one additional one-way message latency to perform key exchange before application data can be transmitted. However, the extra latency can be avoided between two hosts that have recently established a previous tcpcrypt connection.An Architecture for Transport ServicesApple Inc.Google Switzerland GmbHKarlstad UniversityUniversity of AberdeenUniversity of GlasgowTU BerlinCloudflare This document describes an architecture for exposing transport
protocol features to applications for network communication, the
Transport Services architecture. The Transport Services Application
Programming Interface (API) is based on an asynchronous, event-driven
interaction pattern. It uses messages for representing data transfer
to applications, and it describes how implementations can use
multiple IP addresses, multiple protocols, and multiple paths, and
provide multiple application streams. This document further defines
common terminology and concepts to be used in definitions of
Transport Services APIs and implementations.
Work in ProgressAn Abstract Application Layer Interface to Transport ServicesGoogle Switzerland GmbHUniversity of OsloNetflixUniversity of AberdeenEricssonUniversity of GlasgowTU BerlinCloudflareApple Inc. This document describes an abstract application programming
interface, API, to the transport layer, following the Transport
Services Architecture. It supports the asynchronous, atomic
transmission of messages over transport protocols and network paths
dynamically selected at runtime. It is intended to replace the
traditional BSD sockets API as the common interface to the transport
layer, in an environment where endpoints could select from multiple
interfaces and potential transport protocols.
Work in ProgressWireGuard: Next Generation Kernel Network TunnelWireGuardAcknowledgmentsThe authors would like to thank ,
, , , , and
for their input and feedback on this document.Authors' AddressesTU BerlinMarchstr. 23Berlin10587Germanyietf@tenghardt.netApple Inc.One Apple Park WayCupertinoCalifornia95014United States of Americatpauly@apple.comUniversity of GlasgowSchool of Computing ScienceGlasgowG12 8QQUnited Kingdomcsp@csperkins.orgAkamai Technologies, Inc.150 BroadwayCambridgeMA02144United States of Americakrose@krose.orgCloudflare101 Townsend StSan FranciscoUnited States of Americacaw@heapingbits.net