< draft-wkumari-capport-icmp-unreach-00.txt   draft-wkumari-capport-icmp-unreach-01.txt >
template D. Bird template D. Bird
Internet-Draft W. Kumari Internet-Draft W. Kumari
Intended status: Informational Google Intended status: Informational Google
Expires: October 31, 2015 April 29, 2015 Expires: October 31, 2015 April 29, 2015
Captive Portal ICMP Destination Unreachable Captive Portal ICMP Destination Unreachable
draft-wkumari-capport-icmp-unreach-00 draft-wkumari-capport-icmp-unreach-01
Abstract Abstract
This document defines a multi-part ICMP extension to signal that a This document defines a multi-part ICMP extension to ICMP Destination
user's device is behind a Captive Portal. Unreachable messages to signal that a user is behind a Captive
Portal.
[ Editor note: The IETF is currently discussing improvements in [ Editor note: The IETF is currently discussing improvements in
captive portal interactions and user experience improvements. See: captive portal interactions and user experience improvements. See:
https://www.ietf.org/mailman/listinfo/captive-portals ] https://www.ietf.org/mailman/listinfo/captive-portals ]
[RFC Editor: Please remove this before publication. This document is [RFC Editor: Please remove this before publication. This document is
being stored in github at https://github.com/wkumari/draft-wkumari- being stored in github at https://github.com/wkumari/draft-wkumari-
capport-icmp-unreach . Authors gratefully accept pull requests, and capport-icmp-unreach . Authors gratefully accept pull requests, and
keep the latest (edit buffer) versions there, so commenters can keep the latest (edit buffer) versions there, so commenters can
follow along at home.] follow along at home.]
skipping to change at page 2, line 18 skipping to change at page 2, line 21
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
2. ICMP Dest Unreachable Captive Portal Object . . . . . . . . . 3 2. ICMP Dest Unreachable Captive Portal Object . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . 5
Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 5 Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
Captive Portals work by blocking (or redirecting) communications Captive Portals work by blocking (or redirecting) communications
skipping to change at page 2, line 51 skipping to change at page 3, line 5
This document defines an extension object that can be appended to This document defines an extension object that can be appended to
selected multi-part ICMP messages to inform the user that they are selected multi-part ICMP messages to inform the user that they are
behind a captive portal. This informs the user after they have behind a captive portal. This informs the user after they have
attempted an initial connection and is generated by the Captive attempted an initial connection and is generated by the Captive
Portal NAS itself. Portal NAS itself.
[ Editor note: This is complementary, but solves a different problem [ Editor note: This is complementary, but solves a different problem
to: https://tools.ietf.org/html/draft-wkumari-dhc-capport-12 - to: https://tools.ietf.org/html/draft-wkumari-dhc-capport-12 -
wkumari-dhc-capport provides information from a DHCP server (and so wkumari-dhc-capport provides information from a DHCP server (and so
doesn't need any changes to deployed CPs, and provides information doesn't need any changes to deployed CPs), and provides information
*before* the client attempts a connection. It does not, however, *before* the client attempts a connection. It does not, however,
have a way of noting that an existing connection has been have a way of noting that an existing connection has been
interrupted.] interrupted.]
1.1. Requirements notation 1.1. Requirements notation
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].
2. ICMP Dest Unreachable Captive Portal Object 2. ICMP Dest Unreachable Captive Portal Object
This document defines an extension object that can be appended to This document defines an extension object that can be appended to
selected multi-part ICMP messages ([RFC4884]). This extension selected multi-part ICMP messages ([RFC4884]). This extension
permits Captive Portal (CP) NAS devices to inform user devices that permits Captive Portal (CP) NAS devices to inform user devices that
their connection has been blocked by the Captive Portal NAS, and, their connection has been blocked by the Captive Portal NAS.
optionally, how to contact the Captive Portal to satisfy it.
The Dest Unreachable Captive Portal Object can be appended to the The Dest Unreachable Captive Portal Object can be appended to the
ICMP Destination Unreachable messages. Figure 1 depicts the Dest ICMP Destination Unreachable messages. Figure 1 depicts the Dest
Unreachable Captive Portal Object. It must be preceded by an ICMP Unreachable Captive Portal Object. It must be preceded by an ICMP
Extension Structure Header and an ICMP Object Header. Both are Extension Structure Header and an ICMP Object Header. Both are
defined in [RFC4884]. defined in [RFC4884].
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|W| Reserved | Validity (seconds) | |W| Reserved | Validity (seconds) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Captive Portal URL ~
~ (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
W - 1 bit Warning. Indicates that the Validity refers to when the W - 1 bit Warning. Indicates that the Validity refers to when the
service will be interrupted. Note that the "offending" traffic service will be interrupted. Note that the "offending" traffic
was forwarded, not dropped. was forwarded, not dropped.
Validity - 24 bits Time, in seconds, that this result should be Validity - 24 bits Time, in seconds, that this result should be
considered valid (and the OS should not attempt to access the same considered valid (and the OS should not attempt to access the same
resource in the meantime). resource in the meantime).
Captive Portal URL - Variable The optional URL of the Captive
Portal. This allows Captive Portal detection software running on
the user's device to locate and connect to the captive portal to
improve the user experience. The length of the URL is calculated
from the ICMP Extension Object header Length minue the ICMP
Extension Object and Captive Portal Object header lengths, which
is zero when no URL is provided.
Editor note / questions. We are trying to get some feedback on A: Editor note / questions. We are trying to get some feedback on A:
this general idea and B: this implementation. this general idea and B: this implementation.
Some open questions. Some open questions.
W bit or C-Type We have currently specified a single bit (W) to W bit or C-Type We have currently specified a single bit (W) to
indicate that the remaining lease time is running low, and the the indicate that the remaining lease time is running low, and the the
connection will be interrupted sometime "soon". We could, connection will be interrupted sometime "soon". We could,
instead, use a differnt C-Type. I think a bit is cleaner (and we instead, use a differnt C-Type. I think a bit is cleaner (and we
have reserved 7 bits for future flags), but could be convinced have reserved 7 bits for future flags), but could be convinced
skipping to change at page 5, line 12 skipping to change at page 4, line 47
C-Type values are assignable on a first-come-first-serve (FCFS) C-Type values are assignable on a first-come-first-serve (FCFS)
basis. basis.
[ Editor note: Currently we are not using the C-Type for anything, [ Editor note: Currently we are not using the C-Type for anything,
but I filled this in anyway. Probably we would overload it at a but I filled this in anyway. Probably we would overload it at a
version identifier type thing, but it could also allow further version identifier type thing, but it could also allow further
extension, for example, a pointer to a status page. ] extension, for example, a pointer to a status page. ]
4. Security Considerations 4. Security Considerations
The obvious security consideration is how to confirm that the This method simply annotates existing ICMP Destination Unreachable
received ICMP Message actually came from a Captive Portal, and was messages to inform users why their connection was blocked. This
not generated from a passive observer on the network (to force the technique can be used to inform captive portal detection probe
user to connect to a malicious device.). software that there is a captive portal present (and potentially to
connect to the URL handed out using draft-wkumari-dhc-capport. We
anticipate that there will be a new solution devised (such as a well
known URL / URI on captive portals) to allow the user / captive
portal probe to do sometyhing more useful with this information.
5. Acknowledgements 5. Acknowledgements
The authors wish to thank the authors of RFC4950 (especially Ron The authors wish to thank the authors of RFC4950 (especially Ron
Bonica ) - I stole much of his text when writing the extension Bonica ) - I stole much of his text when writing the extension
definition. definition.
6. References 6. References
6.1. Normative References 6.1. Normative References
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981. RFC 792, September 1981.
[RFC1122] Braden, R., "Requirements for Internet Hosts - [RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989. Communication Layers", STD 3, RFC 1122, October 1989.
[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.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005.
[RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro, [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
"Extended ICMP to Support Multi-Part Messages", RFC 4884, "Extended ICMP to Support Multi-Part Messages", RFC 4884,
April 2007. April 2007.
6.2. Informative References 6.2. Informative References
[I-D.ietf-sidr-iana-objects] [I-D.ietf-sidr-iana-objects]
Manderson, T., Vegoda, L., and S. Kent, "RPKI Objects Manderson, T., Vegoda, L., and S. Kent, "RPKI Objects
issued by IANA", draft-ietf-sidr-iana-objects-03 (work in issued by IANA", draft-ietf-sidr-iana-objects-03 (work in
progress), May 2011. progress), May 2011.
Appendix A. Changes / Author Notes. Appendix A. Changes / Author Notes.
[RFC Editor: Please remove this section before publication ] [RFC Editor: Please remove this section before publication ]
From -00 to 01.
o Changed the Captive Portal URL to a URI, and specificed that this
can ONLY contain a path element, which is appened to
http://<gateway_ip>. This is to prevent hijacking connections to
other addresses.
o Then removed the entire URL / URI scheme entirely.
From -genesis to -00. From -genesis to -00.
o Initial text. o Initial text.
Authors' Addresses Authors' Addresses
David Bird David Bird
Google Google
1600 Amphitheatre Parkway 1600 Amphitheatre Parkway
Mountain View, CA 94043 Mountain View, CA 94043
 End of changes. 11 change blocks. 
23 lines changed or deleted 29 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/