draft-ietf-rtcweb-stun-consent-freshness-06.txt   draft-ietf-rtcweb-stun-consent-freshness-07.txt 
RTCWEB M. Perumal RTCWEB M. Perumal
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track D. Wing Intended status: Standards Track D. Wing
Expires: February 13, 2015 R. Ravindranath Expires: March 19, 2015 R. Ravindranath
T. Reddy T. Reddy
Cisco Systems Cisco Systems
M. Thomson M. Thomson
Mozilla Mozilla
August 12, 2014 September 15, 2014
STUN Usage for Consent Freshness STUN Usage for Consent Freshness
draft-ietf-rtcweb-stun-consent-freshness-06 draft-ietf-rtcweb-stun-consent-freshness-07
Abstract Abstract
To prevent sending excessive traffic to an endpoint, periodic consent To prevent sending excessive traffic to an endpoint, periodic consent
needs to be obtained from that remote endpoint. needs to be obtained from that remote endpoint.
This document describes a consent mechanism using a new STUN usage. This document describes a consent mechanism using a new Session
This same mechanism can also determine connection loss ("liveness") Traversal Utilities for NAT (STUN) usage. This same mechanism can
with a remote peer. also determine connection loss ("liveness") with a remote peer.
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 February 13, 2015. This Internet-Draft will expire on March 19, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://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
skipping to change at page 2, line 34 skipping to change at page 2, line 34
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . 7 11.1. Normative References . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . 7 11.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
To prevent attacks on peers, RTP endpoints have to ensure the remote To prevent attacks on peers, RTP endpoints have to ensure the remote
peer wants to receive traffic. This is performed both when the peer wants to receive traffic. This is performed both when the
session is first established to the remote peer using ICE session is first established to the remote peer using Interactive
connectivity checks, and periodically for the duration of the session Connectivity Establishment ICE [RFC5245] connectivity checks, and
using the procedures defined in this document. periodically for the duration of the session using the procedures
defined in this document.
When a session is first established, WebRTC implementations are When a session is first established, ICE implementations obtain
required to perform STUN connectivity checks as part of ICE initial consent by performing STUN connectivity checks as part of
[RFC5245]. That initial consent is not described further in this ICE. That initial consent is not described further in this document
document and it is assumed that ICE is being used for that initial and it is assumed that ICE is being used for that initial consent.
consent.
Related to consent is loss of connectivity ("liveness"). Many Related to consent is loss of connectivity ("liveness"). Many
applications want notification of connection loss to take appropriate applications want notification of connection loss to take appropriate
actions (e.g., alert the user, try switching to a different actions (e.g., alert the user, try switching to a different
interface). interface).
This document describes a new STUN usage with exchange of request and This document describes a new STUN usage with exchange of request and
response messages to verify the remote peer's consent to receive response messages to verify the remote peer's consent to receive
traffic, and the absence of which for a period of time indicates a traffic, and the absence of which for a period of time indicates a
loss of liveness. loss of liveness.
WebRTC endpoints are required to support full ICE as specified in When a (full) ICE implementation interworks with an ICE-lite
section 3.4 of [I-D.ietf-rtcweb-transports]. However, when WebRTC implementation the ICE-lite implementation will not generate consent
endpoints interwork with other endpoints that support only ICE-lite checks, but will just just respond to consent checks it receives.
(e.g., gateways) those endpoints will not generate consent checks,
but just respond to consent checks they receive.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
Consent: It is the mechanism of obtaining permission to send traffic Consent: It is the mechanism of obtaining permission to send traffic
to a certain transport address. This is the initial consent to to a certain transport address. This is the initial consent to
send traffic, which is obtained by ICE or a TCP handshake. send traffic, which is obtained by ICE or a TCP handshake.
skipping to change at page 3, line 42 skipping to change at page 3, line 40
port number. port number.
3. Design Considerations 3. Design Considerations
Although ICE requires periodic keepalive traffic to keep NAT bindings Although ICE requires periodic keepalive traffic to keep NAT bindings
alive (Section 10 of [RFC5245], [RFC6263]), those keepalives are sent alive (Section 10 of [RFC5245], [RFC6263]), those keepalives are sent
as STUN Indications which are send-and-forget, and do not evoke a as STUN Indications which are send-and-forget, and do not evoke a
response. A response is necessary both for consent to continue response. A response is necessary both for consent to continue
sending traffic, as well as to verify session liveness. Thus, we sending traffic, as well as to verify session liveness. Thus, we
need a request/response mechanism for consent freshness. ICE can be need a request/response mechanism for consent freshness. ICE can be
used for that mechanism because ICE already requires ICE agents used for that mechanism because ICE implementations are already
continue listening for ICE messages, as described in section 10 of required to continue listening for ICE messages, as described in
[RFC5245]. section 10 of [RFC5245].
4. Solution 4. Solution
There are two ways consent to send traffic is revoked: expiration of There are two ways consent to send traffic is revoked: expiration of
consent and immediate revocation of consent, which are discussed in consent and immediate revocation of consent, which are discussed in
the following sections. the following sections.
4.1. Expiration of Consent 4.1. Expiration of Consent
A WebRTC browser performs a combined consent freshness and session A WebRTC implementation [I-D.ietf-rtcweb-overview], which implements
liveness test using STUN request/response as described below: ICE, MUST perform a combined consent freshness and session liveness
test using STUN request/response as described below:
An endpoint MUST NOT send application data (e.g., RTP, RTCP, SCTP, An endpoint MUST NOT send application data (e.g., RTP, RTCP, SCTP,
DTLS), over any transport protocol (e.g., UDP, TCP) on an ICE- DTLS), over any transport protocol (e.g., UDP, TCP) on an ICE-
initiated connection unless the receiving endpoint consents to initiated connection unless the receiving endpoint consents to
receive the data. After a successful ICE connectivity check on a receive the data. After a successful ICE connectivity check on a
particular transport address, subsequent consent MUST be obtained particular transport address, subsequent consent MUST be obtained
following the procedure described in this document. The consent following the procedure described in this document. The consent
expires after a fixed amount of time. During ICE restart consent expires after a fixed amount of time. During ICE restart consent
checks MUST continue to be sent on previously validated pair, and checks MUST continue to be sent on previously validated pair, and
MUST be responded to on the previously validated pair, until ICE MUST be responded to on the previously validated pair, until ICE
skipping to change at page 5, line 8 skipping to change at page 5, line 8
endpoint MUST cease transmission on that 5-tuple. endpoint MUST cease transmission on that 5-tuple.
To meet the security needs of consent, an untrusted application To meet the security needs of consent, an untrusted application
(e.g., JavaScript) MUST NOT be able to obtain or control the STUN (e.g., JavaScript) MUST NOT be able to obtain or control the STUN
transaction ID, because that enables spoofing STUN responses, transaction ID, because that enables spoofing STUN responses,
falsifying consent. falsifying consent.
While TCP affords some protection from off-path attackers ([RFC5961], While TCP affords some protection from off-path attackers ([RFC5961],
[RFC4953]), there is still a risk an attacker could cause a TCP [RFC4953]), there is still a risk an attacker could cause a TCP
sender to send packets forever by spoofing ACKs. To prevent such an sender to send packets forever by spoofing ACKs. To prevent such an
attack, consent checks MUST be performed over all WebRTC-initiated attack, consent checks MUST be performed over all transport
transport connections, including TCP. In this way, an off-path connections, including TCP. In this way, an off-path attacker
attacker spoofing TCP segments can not cause a TCP sender to send spoofing TCP segments can not cause a TCP sender to send packets
packets longer than the consent timer (30 seconds). longer than the consent timer (30 seconds).
An endpoint that is not sending any application traffic does not need An endpoint that is not sending any application traffic does not need
to obtain consent which can slightly conserve its resources. to obtain consent which can slightly conserve its resources.
However, the endpoint needs to ensure its NAT or firewall mappings However, the endpoint needs to ensure its NAT or firewall mappings
persist which can be done using keepalive or other techniques (see persist which can be done using keepalive or other techniques (see
Section 10 of [RFC5245] and see [RFC6263]). If the endpoint wants to Section 10 of [RFC5245] and see [RFC6263]). If the endpoint wants to
send application traffic, it needs to first obtain consent if its send application traffic, it needs to first obtain consent if its
consent has expired. consent has expired.
4.2. Immediate Revocation of Consent 4.2. Immediate Revocation of Consent
skipping to change at page 7, line 48 skipping to change at page 7, line 48
Keeping Alive the NAT Mappings Associated with RTP / RTP Keeping Alive the NAT Mappings Associated with RTP / RTP
Control Protocol (RTCP) Flows", RFC 6263, June 2011. Control Protocol (RTCP) Flows", RFC 6263, June 2011.
11.2. Informative References 11.2. Informative References
[I-D.ietf-avtcore-srtp-ekt] [I-D.ietf-avtcore-srtp-ekt]
McGrew, D. and D. Wing, "Encrypted Key Transport for McGrew, D. and D. Wing, "Encrypted Key Transport for
Secure RTP", draft-ietf-avtcore-srtp-ekt-02 (work in Secure RTP", draft-ietf-avtcore-srtp-ekt-02 (work in
progress), February 2014. progress), February 2014.
[I-D.ietf-rtcweb-transports] [I-D.ietf-rtcweb-overview]
Alvestrand, H., "Transports for RTCWEB", draft-ietf- Alvestrand, H., "Overview: Real Time Protocols for
rtcweb-transports-05 (work in progress), June 2014. Browser-based Applications", draft-ietf-rtcweb-overview-11
(work in progress), August 2014.
[I-D.ietf-tsvwg-rtcweb-qos] [I-D.ietf-tsvwg-rtcweb-qos]
Dhesikan, S., Jennings, C., Druta, D., Jones, P., and J. Dhesikan, S., Jennings, C., Druta, D., Jones, P., and J.
Polk, "DSCP and other packet markings for RTCWeb QoS", Polk, "DSCP and other packet markings for RTCWeb QoS",
draft-ietf-tsvwg-rtcweb-qos-02 (work in progress), June draft-ietf-tsvwg-rtcweb-qos-02 (work in progress), June
2014. 2014.
[RFC3830] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. [RFC3830] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K.
Norrman, "MIKEY: Multimedia Internet KEYing", RFC 3830, Norrman, "MIKEY: Multimedia Internet KEYing", RFC 3830,
August 2004. August 2004.
skipping to change at page 8, line 34 skipping to change at page 8, line 34
2010. 2010.
[RFC6062] Perreault, S. and J. Rosenberg, "Traversal Using Relays [RFC6062] Perreault, S. and J. Rosenberg, "Traversal Using Relays
around NAT (TURN) Extensions for TCP Allocations", RFC around NAT (TURN) Extensions for TCP Allocations", RFC
6062, November 2010. 6062, November 2010.
Authors' Addresses Authors' Addresses
Muthu Arul Mozhi Perumal Muthu Arul Mozhi Perumal
Ericsson Ericsson
Mahadevapura Ferns Icon
Bangalore, Karnataka 560048 Doddanekundi, Mahadevapura
Bangalore, Karnataka 560037
India India
Email: muthu.arul@gmail.com Email: muthu.arul@gmail.com
Dan Wing Dan Wing
Cisco Systems Cisco Systems
821 Alder Drive 821 Alder Drive
Milpitas, California 95035 Milpitas, California 95035
USA USA
 End of changes. 13 change blocks. 
34 lines changed or deleted 35 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/