draft-ietf-rtcweb-stun-consent-freshness-05.txt   draft-ietf-rtcweb-stun-consent-freshness-06.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: January 5, 2015 R. Ravindranath Expires: February 13, 2015 R. Ravindranath
T. Reddy T. Reddy
Cisco Systems Cisco Systems
M. Thomson M. Thomson
Mozilla Mozilla
July 4, 2014 August 12, 2014
STUN Usage for Consent Freshness STUN Usage for Consent Freshness
draft-ietf-rtcweb-stun-consent-freshness-05 draft-ietf-rtcweb-stun-consent-freshness-06
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 STUN usage.
This same mechanism can also determine connection loss ("liveness") This same mechanism can also determine connection loss ("liveness")
with a remote peer. with a remote peer.
skipping to change at page 1, line 40 skipping to change at page 1, line 40
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 January 5, 2015. This Internet-Draft will expire on February 13, 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 3, line 10 skipping to change at page 3, line 10
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 WebRTC endpoints are required to support full ICE as specified in
section 3.4 of [I-D.ietf-rtcweb-transports]. However, when WebRTC section 3.4 of [I-D.ietf-rtcweb-transports]. However, when WebRTC
endpoints interwork with other endpoints that support only ICE-lite endpoints interwork with other endpoints that support only ICE-lite
(e.g. gateways) those endpoints will not generate consent checks, but (e.g., gateways) those endpoints will not generate consent checks,
just respond to consent checks they receive. 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 4, line 11 skipping to change at page 4, line 11
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 browser performs a combined consent freshness and session
liveness test using STUN request/response as described below: 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) on an ICE-initiated connection unless the receiving endpoint DTLS), over any transport protocol (e.g., UDP, TCP) on an ICE-
consents to receive the data. After a successful ICE connectivity initiated connection unless the receiving endpoint consents to
check on a particular transport address, subsequent consent MUST be receive the data. After a successful ICE connectivity check on a
obtained following the procedure described in this document. The particular transport address, subsequent consent MUST be obtained
consent expires after a fixed amount of time. following the procedure described in this document. The consent
expires after a fixed amount of time. During ICE restart consent
checks MUST continue to be sent on previously validated pair, and
MUST be responded to on the previously validated pair, until ICE
restart completes.
Note: Although TCP has its own consent mechanism (TCP
acknowledgements), consent is necessary over a TCP connection
because it could be translated to a UDP connection (e.g.,
[RFC6062]).
Explicit consent to send is obtained by sending an ICE binding Explicit consent to send is obtained by sending an ICE binding
request to the remote peer's Transport Address and receiving a request to the remote peer's Transport Address and receiving a
matching, authenticated, non-error ICE binding response from the matching, authenticated, non-error ICE binding response from the
remote peer's Transport Address. These ICE binding requests and remote peer's Transport Address. These ICE binding requests and
responses are authenticated using the same short-term credentials as responses are authenticated using the same short-term credentials as
the initial ICE exchange. Implementations MUST cease sending data if the initial ICE exchange. Implementations MUST cease sending data if
their consent expires. To prevent expiry of consent, a STUN binding their consent expires. To prevent expiry of consent, a STUN binding
request is sent every N milliseconds, where N SHOULD be 5000 request MUST be sent every N milliseconds, where N is chosen randomly
milliseconds and MUST be randomized at least 20% above and 20% below with each consent check in the interval [.8N, 1.2N] (to prevent
that value (to prevent prevent network synchronization). Using the network synchronization), where N SHOULD be 5000. Using the value
value 5000 milliseconds and that 20% randomization range, N would be 5000 milliseconds and that 20% randomization range, N would be a
a value between 4000 and 6000. These STUN binding requests for value between 4000 and 6000. These STUN binding requests for consent
consent are not re-transmitted. Each STUN binding request for are not re-transmitted. Each STUN binding request for consent re-
consent re-calculates a new random value N and a new calculates a new random value N and a new cryptographically-random
cryptographically-random [RFC4086] STUN transaction ID. [RFC4086] STUN transaction ID.
The initial Consent to send traffic is obtained by ICE. Consent The initial Consent to send traffic is obtained by ICE. Consent
expires after 30 seconds. That is, if a valid STUN binding response expires after 30 seconds. That is, if a valid STUN binding response
corresponding to one of the STUN requests sent in the last 30 seconds corresponding to one of the STUN requests sent in the last 30 seconds
has not been received from the remote peer's Transport Address, the has not been received from the remote peer's Transport Address, the
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,
skipping to change at page 5, line 21 skipping to change at page 5, line 29
consent has expired. consent has expired.
4.2. Immediate Revocation of Consent 4.2. Immediate Revocation of Consent
The previous section explained how consent expires due to a timeout. The previous section explained how consent expires due to a timeout.
In some cases it is useful to signal a connection is terminated, In some cases it is useful to signal a connection is terminated,
rather than relying on a timeout. This is done by immediately rather than relying on a timeout. This is done by immediately
revoking consent. revoking consent.
Consent for sending traffic on the media or data channel is Consent for sending traffic on the media or data channel is
immediately revoked by receipt of a an authenticated message that immediately revoked by receipt of an authenticated message that
closes the connection (e.g., a TLS fatal alert) or receipt of a valid closes the connection (e.g., a TLS fatal alert) or receipt of a valid
and authenticated STUN response with error code Forbidden (403). and authenticated STUN response with error code Forbidden (403).
Those consent revocation messages can be lost on the network, so an
implementation wanting to immediately revoke consent needs to
remember those credentials until consent expiry (30 seconds).
Receipt of an unauthenticated message that closes a connection (e.g., Receipt of an unauthenticated message that closes a connection (e.g.,
TCP FIN) does not indicate revocation of consent. Thus, an endpoint TCP FIN) does not indicate revocation of consent. Thus, an endpoint
receiving an unauthenticated end-of-session message SHOULD continue receiving an unauthenticated end-of-session message SHOULD continue
sending media (over connectionless transport) or attempt to re- sending media (over connectionless transport) or attempt to re-
establish the connection (over connection-oriented transport) until establish the connection (over connection-oriented transport) until
consent expires or it receives an authenticated message revoking consent expires or it receives an authenticated message revoking
consent. consent.
Note that an authenticated SRTCP BYE does not terminate consent; it Note that an authenticated SRTCP BYE does not terminate consent; it
skipping to change at page 7, line 12 skipping to change at page 7, line 18
distributions, receipt of an authenticated SRTP packet is not distributions, receipt of an authenticated SRTP packet is not
sufficient to verify consent. sufficient to verify consent.
9. IANA Considerations 9. IANA Considerations
This document does not require any action from IANA. This document does not require any action from IANA.
10. Acknowledgement 10. Acknowledgement
Thanks to Eric Rescorla, Harald Alvestrand, Bernard Aboba, Magnus Thanks to Eric Rescorla, Harald Alvestrand, Bernard Aboba, Magnus
Westerland, Cullen Jennings, Christer Holmberg and Simon Perreault Westerland, Cullen Jennings, Christer Holmberg, Simon Perreault, Paul
for their valuable inputs and comments. Kyzivat, Emil Ivov, and Jonathan Lennox for their valuable inputs and
comments.
11. References 11. References
11.1. Normative References 11.1. Normative References
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness [RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005. Requirements for Security", BCP 106, RFC 4086, June 2005.
skipping to change at page 8, line 20 skipping to change at page 8, line 26
Description Protocol (SDP) Security Descriptions for Media Description Protocol (SDP) Security Descriptions for Media
Streams", RFC 4568, July 2006. Streams", RFC 4568, July 2006.
[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", RFC [RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", RFC
4953, July 2007. 4953, July 2007.
[RFC5961] Ramaiah, A., Stewart, R., and M. Dalal, "Improving TCP's [RFC5961] Ramaiah, A., Stewart, R., and M. Dalal, "Improving TCP's
Robustness to Blind In-Window Attacks", RFC 5961, August Robustness to Blind In-Window Attacks", RFC 5961, August
2010. 2010.
[RFC6062] Perreault, S. and J. Rosenberg, "Traversal Using Relays
around NAT (TURN) Extensions for TCP Allocations", RFC
6062, November 2010.
Authors' Addresses Authors' Addresses
Muthu Arul Mozhi Perumal Muthu Arul Mozhi Perumal
Ericsson Ericsson
Mahadevapura Mahadevapura
Bangalore, Karnataka 560048 Bangalore, Karnataka 560048
India India
Email: muthu.arul@gmail.com Email: muthu.arul@gmail.com
 End of changes. 11 change blocks. 
22 lines changed or deleted 39 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/