This document formally deprecates Transport Layer Security (TLS) versions 1.0 (RFC 2246) and 1.1 (RFC 4346). Accordingly, those documents have been moved to Historic status. These versions lack support for current and recommended cryptographic algorithms and mechanisms, and various government and industry profiles of applications using TLS now mandate avoiding these old TLS versions. TLS version 1.2 became the recommended version for IETF protocols in 2008 (subsequently being obsoleted by TLS version 1.3 in 2018), providing sufficient time to transition away from older versions. Removing support for older versions from implementations reduces the attack surface, reduces opportunity for misconfiguration, and streamlines library and product maintenance.¶
This document also deprecates Datagram TLS (DTLS) version 1.0 (RFC 4347) but not DTLS version 1.2, and there is no DTLS version 1.1.¶
This document updates many RFCs that normatively refer to TLS version 1.0 or TLS version 1.1, as described herein. This document also updates the best practices for TLS usage in RFC 7525; hence, it is part of BCP 195.¶
This memo documents an Internet Best Current Practice.¶
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). Further information on BCPs is available in 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 athttps://www.rfc-editor.org/info/rfc8996.¶
Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.¶
Transport Layer Security (TLS) versions 1.0[RFC2246] and 1.1[RFC4346] were superseded by TLS 1.2[RFC5246] in 2008, which has now itself been superseded by TLS 1.3[RFC8446]. Datagram Transport Layer Security (DTLS) version 1.0[RFC4347] was superseded by DTLS 1.2[RFC6347] in 2012. Therefore, it is timely to further deprecate TLS 1.0, TLS 1.1, and DTLS 1.0. Accordingly, the aforementioned documents have been moved to Historic status.¶
Technical reasons for deprecating these versions include:¶
They require the implementation of older cipher suites that are no longer desirable for cryptographic reasons, e.g., TLS 1.0 makes TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA mandatory to implement.¶
There is a lack of support for current recommended cipher suites, especially authenticated encryption with associated data (AEAD) ciphers, which were not supported prior to TLS 1.2. Note that registry entries for no-longer-desirable ciphersuites remain in the registries, but many TLS registries were updated by[RFC8447], which indicates that such entries are not recommended by the IETF.¶
The integrity of the handshake depends on SHA-1 hash.¶
The authentication of the peers depends on SHA-1 signatures.¶
Support for four TLS protocol versions increases the likelihood of misconfiguration.¶
At least one widely used library has plans to drop TLS 1.1 and TLS 1.0 support in upcoming releases; products using such libraries would need to use older versions of the libraries to support TLS 1.0 and TLS 1.1, which is clearly undesirable.¶
Deprecation of these versions is intended to assist developers as additional justification to no longer support older (D)TLS versions and to migrate to a minimum of (D)TLS 1.2. Deprecation also assists product teams with phasing out support for the older versions, to reduce the attack surface and the scope of maintenance for protocols in their offerings.¶
This document updates the following RFCs that normatively reference TLS 1.0, TLS 1.1, or DTLS 1.0. The update is to obsolete usage of these older versions. Fallback to these versions is prohibited through this update. Specific references to mandatory minimum protocol versions of TLS 1.0 or TLS 1.1 are replaced by TLS 1.2, and references to minimum protocol version DTLS 1.0 are replaced by DTLS 1.2. Statements that "TLS 1.0 is the most widely deployed version and will provide the broadest interoperability" are removed without replacement.¶
Note that[RFC4642] has already been updated by[RFC8143], which makes an overlapping, but not quite identical, update as this document.¶
[RFC6614] has a requirement for TLS 1.1 or later, although it only makes an informative reference to[RFC4346]. This requirement is updated to be for TLS 1.2 or later.¶
[RFC6460],[RFC4744], and[RFC4743] are already Historic; they are still listed here and marked as updated by this document in order to reiterate that any usage of the obsolete protocol should use modern TLS.¶
This document updates DTLS[RFC6347].[RFC6347] had allowed for negotiating the use of DTLS 1.0, which is now forbidden.¶
The DES and International Data Encryption Algorithm (IDEA) cipher suites specified in[RFC5469] were specifically removed from TLS 1.2 by[RFC5246]; since the only versions of TLS for which their usage is defined are now Historic,[RFC5469] has been moved to Historic as well.¶
The version-fallback Signaling Cipher Suite Value specified in[RFC7507] was defined to detect when a given client and server negotiate a lower version of (D)TLS than their highest shared version. TLS 1.3 ([RFC8446]) incorporates a different mechanism that achieves this purpose, via sentinel values in the ServerHello.Random field. With (D)TLS versions prior to 1.2 fully deprecated, the only way for (D)TLS implementations to negotiate a lower version than their highest shared version would be to negotiate (D)TLS 1.2 while supporting (D)TLS 1.3; supporting (D)TLS 1.3 implies support for the ServerHello.Random mechanism. Accordingly, the functionality from[RFC7507] has been superseded, and this document marks it as Obsolete.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14[RFC2119][RFC8174] when, and only when, they appear in all capitals, as shown here.¶
Specific details on attacks against TLS 1.0 and TLS 1.1, as well as their mitigations, are provided in[NIST800-52r2],[RFC7457], and other RFCs referenced therein. Although mitigations for the current known vulnerabilities have been developed, any future issues discovered in old protocol versions might not be mitigated in older library versions when newer library versions do not support those old protocols.¶
For example, NIST has provided the following rationale, copied with permission from Section 1.1, "History of TLS", of[NIST800-52r2]:¶
TLS 1.1, specified in RFC 4346 [24], was developed to address weaknesses discovered in TLS 1.0, primarily in the areas of initialization vector selection and padding error processing. Initialization vectors were made explicit to prevent a certain class of attacks on the Cipher Block Chaining (CBC) mode of operation used by TLS. The handling of padding errors was altered to treat a padding error as a bad message authentication code rather than a decryption failure. In addition, the TLS 1.1 RFC acknowledges attacks on CBC mode that rely on the time to compute the message authentication code (MAC). The TLS 1.1 specification states that to defend against such attacks, an implementation must process records in the same manner regardless of whether padding errors exist. Further implementation considerations for CBC modes (which were not included in RFC 4346 [24]) are discussed in Section 3.3.2.¶
TLS 1.2, specified in RFC 5246 [25], made several cryptographic enhancements, particularly in the area of hash functions, with the ability to use or specify the SHA-2 family of algorithms for hash, MAC, and Pseudorandom Function (PRF) computations. TLS 1.2 also adds authenticated encryption with associated data (AEAD) cipher suites.¶
TLS 1.3, specified in RFC 8446 [57], represents a significant change to TLS that aims to address threats that have arisen over the years. Among the changes are a new handshake protocol, a new key derivation process that uses the HMAC-based Extract-and-Expand Key Derivation Function (HKDF) [37], and the removal of cipher suites that use RSA key transport or static Diffie-Hellman ( DH) [sic] key exchanges, the CBC mode of operation, or SHA-1. Many extensions defined for use with TLS 1.2 and previous versions cannot be used with TLS 1.3.¶
The integrity of both TLS 1.0 and TLS 1.1 depends on a running SHA-1 hash of the exchanged messages. This makes it possible to perform a downgrade attack on the handshake by an attacker able to perform 277 operations, well below the acceptable modern security margin.¶
Similarly, the authentication of the handshake depends on signatures made using a SHA-1 hash or a concatenation of MD5 and SHA-1 hashes that is not appreciably stronger than a SHA-1 hash, allowing the attacker to impersonate a server when it is able to break the severely weakened SHA-1 hash.¶
Neither TLS 1.0 nor TLS 1.1 allows the peers to select a stronger hash for signatures in the ServerKeyExchange or CertificateVerify messages, making the only upgrade path the use of a newer protocol version.¶
TLS 1.0MUST NOT be used. Negotiation of TLS 1.0 from any version of TLSMUST NOT be permitted.¶
Any other version of TLS is more secure than TLS 1.0. While TLS 1.0 can be configured to prevent some types of interception, using the highest version available is preferred.¶
Pragmatically, clientsMUST NOT send a ClientHello with ClientHello.client_version set to {03,01}. Similarly, serversMUST NOT send a ServerHello with ServerHello.server_version set to {03,01}. Any party receiving a Hello message with the protocol version set to {03,01}MUST respond with a "protocol_version" alert message and close the connection.¶
Historically, TLS specifications were not clear on what the record layer version number (TLSPlaintext.version) could contain when sending a ClientHello message.Appendix E of [RFC5246] notes that TLSPlaintext.version could be selected to maximize interoperability, though no definitive value is identified as ideal. That guidance is still applicable; therefore, TLS serversMUST accept any value {03,XX} (including {03,00}) as the record layer version number for ClientHello, but theyMUST NOT negotiate TLS 1.0.¶
TLS 1.1MUST NOT be used. Negotiation of TLS 1.1 from any version of TLSMUST NOT be permitted.¶
Pragmatically, clientsMUST NOT send a ClientHello with ClientHello.client_version set to {03,02}. Similarly, serversMUST NOT send a ServerHello with ServerHello.server_version set to {03,02}. Any party receiving a Hello message with the protocol version set to {03,02}MUST respond with a "protocol_version" alert message and close the connection.¶
Any newer version of TLS is more secure than TLS 1.1. While TLS 1.1 can be configured to prevent some types of interception, using the highest version available is preferred. Support for TLS 1.1 is dwindling in libraries and will impact security going forward if mitigations for attacks cannot be easily addressed and supported in older libraries.¶
Historically, TLS specifications were not clear on what the record layer version number (TLSPlaintext.version) could contain when sending a ClientHello message.Appendix E of [RFC5246] notes that TLSPlaintext.version could be selected to maximize interoperability, though no definitive value is identified as ideal. That guidance is still applicable; therefore, TLS serversMUST accept any value {03,XX} (including {03,00}) as the record layer version number for ClientHello, but theyMUST NOT negotiate TLS 1.1.¶
This document updatesSection 3.1.1 of [RFC7525] by changingSHOULD NOT toMUST NOT as follows:¶
ImplementationsMUST NOT negotiate TLS version 1.0[RFC2246].¶
Rationale: TLS 1.0 (published in 1999) does not support many modern, strong cipher suites. In addition, TLS 1.0 lacks a per-record Initialization Vector (IV) for CBC-based cipher suites and does not warn against common padding errors.¶
ImplementationsMUST NOT negotiate TLS version 1.1[RFC4346].¶
Rationale: TLS 1.1 (published in 2006) is a security improvement over TLS 1.0 but still does not support certain stronger cipher suites.¶
This document updatesSection 3.1.2 of [RFC7525] by changingSHOULD NOT toMUST NOT and adding a reference to RFC 6347 as follows:¶
ImplementationsMUST NOT negotiate DTLS version 1.0[RFC4347][RFC6347].¶
Version 1.0 of DTLS correlates to version 1.1 of TLS (see above).¶
This document is part of BCP 195 and, as such, reflects the understanding of the IETF (at the time of this document's publication) as to the best practices for TLS and DTLS usage.¶
Though TLS 1.1 has been obsolete since the publication of[RFC5246] in 2008, and DTLS 1.0 has been obsolete since the publication of[RFC6347] in 2012, there may remain some systems in operation that do not support (D)TLS 1.2 or higher. Adopting the practices recommended by this document for any systems that need to communicate with the aforementioned class of systems will cause failure to interoperate. However, disregarding the recommendations of this document in order to continue to interoperate with the aforementioned class of systems incurs some amount of risk. The nature of the risks incurred by operating in contravention to the recommendations of this document are discussed in Sections2 and3, and knowledge of those risks should be used along with any potential mitigating factors and the risks inherent to updating the systems in question when deciding how quickly to adopt the recommendations specified in this document.¶
This document deprecates two older TLS protocol versions and one older DTLS protocol version for security reasons already described. The attack surface is reduced when there are a smaller number of supported protocols and fallback options are removed.¶
Arkko, J.,Torvinen, V.,Camarillo, G.,Niemi, A., andT. Haukka,"Security Mechanism Agreement for the Session Initiation Protocol (SIP)",RFC 3329,DOI 10.17487/RFC3329,,<https://www.rfc-editor.org/info/rfc3329>.
[RFC3436]
Jungmaier, A.,Rescorla, E., andM. Tuexen,"Transport Layer Security over Stream Control Transmission Protocol",RFC 3436,DOI 10.17487/RFC3436,,<https://www.rfc-editor.org/info/rfc3436>.
[RFC3470]
Hollenbeck, S.,Rose, M., andL. Masinter,"Guidelines for the Use of Extensible Markup Language (XML) within IETF Protocols",BCP 70,RFC 3470,DOI 10.17487/RFC3470,,<https://www.rfc-editor.org/info/rfc3470>.
Rescorla, E. andB. Korver,"Guidelines for Writing RFC Text on Security Considerations",BCP 72,RFC 3552,DOI 10.17487/RFC3552,,<https://www.rfc-editor.org/info/rfc3552>.
Rosenberg, J.,"A Presence Event Package for the Session Initiation Protocol (SIP)",RFC 3856,DOI 10.17487/RFC3856,,<https://www.rfc-editor.org/info/rfc3856>.
[RFC3871]
Jones, G., Ed.,"Operational Security Requirements for Large Internet Service Provider (ISP) IP Network Infrastructure",RFC 3871,DOI 10.17487/RFC3871,,<https://www.rfc-editor.org/info/rfc3871>.
Niemi, A., Ed.,"Session Initiation Protocol (SIP) Extension for Event State Publication",RFC 3903,DOI 10.17487/RFC3903,,<https://www.rfc-editor.org/info/rfc3903>.
Newton, A. andM. Sanz,"Using the Internet Registry Information Service (IRIS) over the Blocks Extensible Exchange Protocol (BEEP)",RFC 3983,DOI 10.17487/RFC3983,,<https://www.rfc-editor.org/info/rfc3983>.
Lee, H.J.,Yoon, J.H., andJ.I. Lee,"Addition of SEED Cipher Suites to Transport Layer Security (TLS)",RFC 4162,DOI 10.17487/RFC4162,,<https://www.rfc-editor.org/info/rfc4162>.
[RFC4168]
Rosenberg, J.,Schulzrinne, H., andG. Camarillo,"The Stream Control Transmission Protocol (SCTP) as a Transport for the Session Initiation Protocol (SIP)",RFC 4168,DOI 10.17487/RFC4168,,<https://www.rfc-editor.org/info/rfc4168>.
Rosenberg, J.,Schulzrinne, H., andR. Mahy, Ed.,"An INVITE-Initiated Dialog Event Package for the Session Initiation Protocol (SIP)",RFC 4235,DOI 10.17487/RFC4235,,<https://www.rfc-editor.org/info/rfc4235>.
[RFC4261]
Walker, J. andA. Kulkarni, Ed.,"Common Open Policy Service (COPS) Over Transport Layer Security (TLS)",RFC 4261,DOI 10.17487/RFC4261,,<https://www.rfc-editor.org/info/rfc4261>.
[RFC4279]
Eronen, P., Ed. andH. Tschofenig, Ed.,"Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)",RFC 4279,DOI 10.17487/RFC4279,,<https://www.rfc-editor.org/info/rfc4279>.
[RFC4346]
Dierks, T. andE. Rescorla,"The Transport Layer Security (TLS) Protocol Version 1.1",RFC 4346,DOI 10.17487/RFC4346,,<https://www.rfc-editor.org/info/rfc4346>.
[RFC4497]
Elwell, J.,Derks, F.,Mourot, P., andO. Rousseau,"Interworking between the Session Initiation Protocol (SIP) and QSIG",BCP 117,RFC 4497,DOI 10.17487/RFC4497,,<https://www.rfc-editor.org/info/rfc4497>.
[RFC4513]
Harrison, R., Ed.,"Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms",RFC 4513,DOI 10.17487/RFC4513,,<https://www.rfc-editor.org/info/rfc4513>.
Siddiqui, A.,Romascanu, D.,Golovinsky, E.,Rahman, M., andY. Kim,"Transport Mappings for Real-time Application Quality-of-Service Monitoring (RAQMON) Protocol Data Unit (PDU)",RFC 4712,DOI 10.17487/RFC4712,,<https://www.rfc-editor.org/info/rfc4712>.
[RFC4732]
Handley, M., Ed.,Rescorla, E., Ed., andIAB,"Internet Denial-of-Service Considerations",RFC 4732,DOI 10.17487/RFC4732,,<https://www.rfc-editor.org/info/rfc4732>.
Lear, E. andK. Crozier,"Using the NETCONF Protocol over the Blocks Extensible Exchange Protocol (BEEP)",RFC 4744,DOI 10.17487/RFC4744,,<https://www.rfc-editor.org/info/rfc4744>.
[RFC4785]
Blumenthal, U. andP. Goel,"Pre-Shared Key (PSK) Ciphersuites with NULL Encryption for Transport Layer Security (TLS)",RFC 4785,DOI 10.17487/RFC4785,,<https://www.rfc-editor.org/info/rfc4785>.
Harding, T. andR. Scott,"FTP Transport for Secure Peer-to-Peer Business Data Interchange over the Internet",RFC 4823,DOI 10.17487/RFC4823,,<https://www.rfc-editor.org/info/rfc4823>.
Allen, A., Ed.,Holm, J., andT. Hallin,"The P-Answer-State Header Extension to the Session Initiation Protocol for the Open Mobile Alliance Push to Talk over Cellular",RFC 4964,DOI 10.17487/RFC4964,,<https://www.rfc-editor.org/info/rfc4964>.
Jennings, C.,Mahy, R., andA. B. Roach,"Relay Extensions for the Message Sessions Relay Protocol (MSRP)",RFC 4976,DOI 10.17487/RFC4976,,<https://www.rfc-editor.org/info/rfc4976>.
[RFC4992]
Newton, A.,"XML Pipelining with Chunks for the Internet Registry Information Service",RFC 4992,DOI 10.17487/RFC4992,,<https://www.rfc-editor.org/info/rfc4992>.
[RFC5018]
Camarillo, G.,"Connection Establishment in the Binary Floor Control Protocol (BFCP)",RFC 5018,DOI 10.17487/RFC5018,,<https://www.rfc-editor.org/info/rfc5018>.
[RFC5019]
Deacon, A. andR. Hurst,"The Lightweight Online Certificate Status Protocol (OCSP) Profile for High-Volume Environments",RFC 5019,DOI 10.17487/RFC5019,,<https://www.rfc-editor.org/info/rfc5019>.
Bormann, C.,Liu, Z.,Price, R., andG. Camarillo, Ed.,"Applying Signaling Compression (SigComp) to the Session Initiation Protocol (SIP)",RFC 5049,DOI 10.17487/RFC5049,,<https://www.rfc-editor.org/info/rfc5049>.
[RFC5054]
Taylor, D.,Wu, T.,Mavrogiannopoulos, N., andT. Perrin,"Using the Secure Remote Password (SRP) Protocol for TLS Authentication",RFC 5054,DOI 10.17487/RFC5054,,<https://www.rfc-editor.org/info/rfc5054>.
[RFC5091]
Boyen, X. andL. Martin,"Identity-Based Cryptography Standard (IBCS) #1: Supersingular Curve Implementations of the BF and BB1 Cryptosystems",RFC 5091,DOI 10.17487/RFC5091,,<https://www.rfc-editor.org/info/rfc5091>.
Phelan, T.,"Datagram Transport Layer Security (DTLS) over the Datagram Congestion Control Protocol (DCCP)",RFC 5238,DOI 10.17487/RFC5238,,<https://www.rfc-editor.org/info/rfc5238>.
[RFC5263]
Lonnfors, M.,Costa-Requena, J.,Leppanen, E., andH. Khartabil,"Session Initiation Protocol (SIP) Extension for Partial Notification of Presence Information",RFC 5263,DOI 10.17487/RFC5263,,<https://www.rfc-editor.org/info/rfc5263>.
[RFC5281]
Funk, P. andS. Blake-Wilson,"Extensible Authentication Protocol Tunneled Transport Layer Security Authenticated Protocol Version 0 (EAP-TTLSv0)",RFC 5281,DOI 10.17487/RFC5281,,<https://www.rfc-editor.org/info/rfc5281>.
[RFC5364]
Garcia-Martin, M. andG. Camarillo,"Extensible Markup Language (XML) Format Extension for Representing Copy Control Attributes in Resource Lists",RFC 5364,DOI 10.17487/RFC5364,,<https://www.rfc-editor.org/info/rfc5364>.
[RFC5422]
Cam-Winget, N.,McGrew, D.,Salowey, J., andH. Zhou,"Dynamic Provisioning Using Flexible Authentication via Secure Tunneling Extensible Authentication Protocol (EAP-FAST)",RFC 5422,DOI 10.17487/RFC5422,,<https://www.rfc-editor.org/info/rfc5422>.
Hardaker, W.,"Transport Layer Security (TLS) Transport Model for the Simple Network Management Protocol (SNMP)",RFC 5953,DOI 10.17487/RFC5953,,<https://www.rfc-editor.org/info/rfc5953>.
Hardaker, W.,"Transport Layer Security (TLS) Transport Model for the Simple Network Management Protocol (SNMP)",STD 78,RFC 6353,DOI 10.17487/RFC6353,,<https://www.rfc-editor.org/info/rfc6353>.
[RFC6367]
Kanno, S. andM. Kanda,"Addition of the Camellia Cipher Suites to Transport Layer Security (TLS)",RFC 6367,DOI 10.17487/RFC6367,,<https://www.rfc-editor.org/info/rfc6367>.
[RFC6739]
Schulzrinne, H. andH. Tschofenig,"Synchronizing Service Boundaries and <mapping> Elements Based on the Location-to-Service Translation (LoST) Protocol",RFC 6739,DOI 10.17487/RFC6739,,<https://www.rfc-editor.org/info/rfc6739>.
Moeller, B. andA. Langley,"TLS Fallback Signaling Cipher Suite Value (SCSV) for Preventing Protocol Downgrade Attacks",RFC 7507,DOI 10.17487/RFC7507,,<https://www.rfc-editor.org/info/rfc7507>.
[RFC7525]
Sheffer, Y.,Holz, R., andP. 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,,<https://www.rfc-editor.org/info/rfc7525>.
[RFC7562]
Thakore, D.,"Transport Layer Security (TLS) Authorization Using Digital Transmission Content Protection (DTCP) Certificates",RFC 7562,DOI 10.17487/RFC7562,,<https://www.rfc-editor.org/info/rfc7562>.
[RFC7568]
Barnes, R.,Thomson, M.,Pironti, A., andA. Langley,"Deprecating Secure Sockets Layer Version 3.0",RFC 7568,DOI 10.17487/RFC7568,,<https://www.rfc-editor.org/info/rfc7568>.
Arkko, J.,Kuijpers, G.,Soliman, H.,Loughney, J., andJ. Wiljakka,"Internet Protocol Version 6 (IPv6) for Some Second and Third Generation Cellular Hosts",RFC 3316,DOI 10.17487/RFC3316,,<https://www.rfc-editor.org/info/rfc3316>.
[RFC3489]
Rosenberg, J.,Weinberger, J.,Huitema, C., andR. Mahy,"STUN - Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs)",RFC 3489,DOI 10.17487/RFC3489,,<https://www.rfc-editor.org/info/rfc3489>.
Moriai, S.,Kato, A., andM. Kanda,"Addition of Camellia Cipher Suites to Transport Layer Security (TLS)",RFC 4132,DOI 10.17487/RFC4132,,<https://www.rfc-editor.org/info/rfc4132>.
[RFC4244]
Barnes, M., Ed.,"An Extension to the Session Initiation Protocol (SIP) for Request History Information",RFC 4244,DOI 10.17487/RFC4244,,<https://www.rfc-editor.org/info/rfc4244>.
Lennox, J.,"Connection-Oriented Media Transport over the Transport Layer Security (TLS) Protocol in the Session Description Protocol (SDP)",RFC 4572,DOI 10.17487/RFC4572,,<https://www.rfc-editor.org/info/rfc4572>.
Mavrogiannopoulos, N.,"Using OpenPGP Keys for Transport Layer Security (TLS) Authentication",RFC 5081,DOI 10.17487/RFC5081,,<https://www.rfc-editor.org/info/rfc5081>.
[RFC5101]
Claise, B., Ed.,"Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information",RFC 5101,DOI 10.17487/RFC5101,,<https://www.rfc-editor.org/info/rfc5101>.
[RFC5246]
Dierks, T. andE. Rescorla,"The Transport Layer Security (TLS) Protocol Version 1.2",RFC 5246,DOI 10.17487/RFC5246,,<https://www.rfc-editor.org/info/rfc5246>.
[RFC5415]
Calhoun, P., Ed.,Montemurro, M., Ed., andD. Stanley, Ed.,"Control And Provisioning of Wireless Access Points (CAPWAP) Protocol Specification",RFC 5415,DOI 10.17487/RFC5415,,<https://www.rfc-editor.org/info/rfc5415>.
[RFC5456]
Spencer, M.,Capouch, B.,Guy, E., Ed.,Miller, F., andK. Shumard,"IAX: Inter-Asterisk eXchange Version 2",RFC 5456,DOI 10.17487/RFC5456,,<https://www.rfc-editor.org/info/rfc5456>.
[RFC6012]
Salowey, J.,Petch, T.,Gerhards, R., andH. Feng,"Datagram Transport Layer Security (DTLS) Transport Mapping for Syslog",RFC 6012,DOI 10.17487/RFC6012,,<https://www.rfc-editor.org/info/rfc6012>.
[RFC6083]
Tuexen, M.,Seggelmann, R., andE. Rescorla,"Datagram Transport Layer Security (DTLS) for Stream Control Transmission Protocol (SCTP)",RFC 6083,DOI 10.17487/RFC6083,,<https://www.rfc-editor.org/info/rfc6083>.
[RFC6084]
Fu, X.,Dickmann, C., andJ. Crowcroft,"General Internet Signaling Transport (GIST) over Stream Control Transmission Protocol (SCTP) and Datagram Transport Layer Security (DTLS)",RFC 6084,DOI 10.17487/RFC6084,,<https://www.rfc-editor.org/info/rfc6084>.
Sheffer, Y.,Holz, R., andP. Saint-Andre,"Summarizing Known Attacks on Transport Layer Security (TLS) and Datagram TLS (DTLS)",RFC 7457,DOI 10.17487/RFC7457,,<https://www.rfc-editor.org/info/rfc7457>.
[RFC8143]
Elie, J.,"Using Transport Layer Security (TLS) with Network News Transfer Protocol (NNTP)",RFC 8143,DOI 10.17487/RFC8143,,<https://www.rfc-editor.org/info/rfc8143>.
[RFC8261]
Tuexen, M.,Stewart, R.,Jesup, R., andS. Loreto,"Datagram Transport Layer Security (DTLS) Encapsulation of SCTP Packets",RFC 8261,DOI 10.17487/RFC8261,,<https://www.rfc-editor.org/info/rfc8261>.