0.4.0
- status: current
Captive portal test.
- An association to a captive portal.
The ability to detect a captive portal.
The test is split in four smaller tests:
1. Http test that compares a requested document against the control one (vendor_tests).
2. DNS test that checks a NXDOMAIN response to random hostnames requests (part of the vendor_dns_tests).
3. DNS test that compares an A request to a static domain against its IP (part of the vendor_dns_tests).
4. DNS test that check for 0x20 encoding (check0x20 tests).
Most of the vendor tests (from Microsoft, Apple, and Google) do an HTTP request and verify the status code or body content matches some expected value. One of the tests (from Microsoft) only checks that a DNS lookup returns the correct IP address.
https://technet.microsoft.com/en-us/library/cc766017(v=ws.10).aspx
https://forums.developer.apple.com/thread/26867
Relevant data to think about the existence of a captive portal grouped between the http and dns tests.
df-001-httpt
df-002-dnst
- The result of the http tests
- The result of the dns tests
- The result of the 0x20 encoding tests
In addition to the data specified in the parent data format, the following fields are added to the report.
Version 0.2:
{
"vendor_dns_tests": {
"google_dns_cp": [
"IP address(es) of the random hostnames that don't resolve "
"to NXDOMAIN"
],
"ms_dns_cp": [
"IP address of the requested domain name"
]
},
"vendor_tests": {
"result": "true|false"
"vt": [
"URL",
"http_status_summary",
"http_status_number",
"User_Agent",
"name_test"
]
},
"check0x20": [
["name_match", "serial_match", "querynames", "answernames", "SOA_serials"]
]
}
Version 0.3:
{
"vendor_dns_tests": {
"google_dns_cp": {
"result": "true|false"
"addresses": [
"IP address(es) of the random hostnames that don't resolve to NXDOMAIN"
]
}
"ms_dns_cp": {
"result": "true|false"
"address": "IP address of the requested domain name"
}
},
"vendor_tests": {
"MS HTTP Captive Portal": {
"result": "true|false",
"url": "string",
"http_status_summary": "string",
"http_status_number": "number",
"User_Agent": "string"
},
"W3 Captive Portal": {
"result": "true|false",
"url": "string",
"http_status_summary": "string",
"http_status_number": "number",
"User_Agent": "string"
},
"Apple HTTP Captive Portal": {
"result": "true|false",
"url": "string",
"http_status_summary": "string",
"http_status_number": "number",
"User_Agent": "string"
}
},
"check0x20": {
"result": "true|false",
"name_match": "true|false"
"serial_match": "true|false"
"querynames": ["domain names of requested hostnames"]
"answernames": ["domain names of answered requests"]
"SOA_serials": ["serials of the DNSs zones of the requested queries"]
}
}
Version 0.4.0:
"vendor_dns_tests": [
{
"result": true,
"hostname": "dns.msftncsi.com",
"name": "Microsoft DNS",
"expected_ip": "131.107.255.255",
"failure": null,
"actual_ips": [
"131.107.255.255"
]
}
],
"vendor_http_tests": [
{
"expected_status": null,
"url": "http://captive.apple.com/hotspot_detect.html",
"name": "Apple HTTP 2",
"result": true,
"failure": null,
"actual_status": 200,
"actual_body": "<HTML><HEAD><TITLE>Success</TITLE></HEAD><BODY>Success</BODY></HTML>\n",
"expected_body": "<HTML><HEAD><TITLE>Success</TITLE></HEAD><BODY>Success</BODY></HTML>\n"
}, ...
]
Whether or not the tester is under a captive portal.
XXX update this
###########################################
# OONI Probe Report for captiveportal (0.2)
# Sun May 11 16:39:09 2014
###########################################
---
input_hashes: []
options: []
probe_asn: AS0
probe_cc: ES
probe_city: null
probe_ip: 127.0.0.1
software_name: ooniprobe
software_version: 1.0.2
start_time: 1399826349.184915
test_name: captiveportal
test_version: '0.2'
...
---
agent: agent
check0x20:
- true
- true
- [OoNI.Nu, OoNI.Nu, OoNI.Nu, OoNI.Nu, OoNI.Nu]
- [OoNI.Nu, OoNI.Nu, OoNI.Nu, OoNI.Nu]
- ['2014011200', '2014011200', '2014011200', '2014011200']
input: null
queries:
- addrs: [131.107.255.255]
answers:
- [<RR name=dns.msftncsi.com type=A class=IN ttl=18s auth=False>, <A address=131.107.255.255
ttl=18>]
query: '[Query(''dns.msftncsi.com'', 1, 1)]'
query_type: A
resolver: null
- addrs: [dns2.registrar-servers.com, dns4.registrar-servers.com, dns5.registrar-servers.com,
dns3.registrar-servers.com, dns1.registrar-servers.com]
answers:
- [<RR name=ooni.nu type=NS class=IN ttl=1800s auth=False>, <NS name=dns2.registrar-servers.com
ttl=1800>]
- [<RR name=ooni.nu type=NS class=IN ttl=1800s auth=False>, <NS name=dns4.registrar-servers.com
ttl=1800>]
- [<RR name=ooni.nu type=NS class=IN ttl=1800s auth=False>, <NS name=dns5.registrar-servers.com
ttl=1800>]
- [<RR name=ooni.nu type=NS class=IN ttl=1800s auth=False>, <NS name=dns3.registrar-servers.com
ttl=1800>]
- [<RR name=ooni.nu type=NS class=IN ttl=1800s auth=False>, <NS name=dns1.registrar-servers.com
ttl=1800>]
query: '[Query(''ooni.nu'', 2, 1)]'
query_type: NS
resolver: null
- addrs: [208.64.122.244, 208.64.122.242]
answers:
- [<RR name=dns2.registrar-servers.com type=A class=IN ttl=580s auth=False>, <A
address=208.64.122.244 ttl=580>]
- [<RR name=dns2.registrar-servers.com type=A class=IN ttl=580s auth=False>, <A
address=208.64.122.242 ttl=580>]
query: '[Query(''dns2.registrar-servers.com'', 1, 1)]'
query_type: A
resolver: null
- addrs: [173.245.58.17, 173.245.59.40, 173.245.58.45, 173.245.59.16]
answers:
- [<RR name=dns4.registrar-servers.com type=A class=IN ttl=1445s auth=False>, <A
address=173.245.58.17 ttl=1445>]
- [<RR name=dns4.registrar-servers.com type=A class=IN ttl=1445s auth=False>, <A
address=173.245.59.40 ttl=1445>]
- [<RR name=dns4.registrar-servers.com type=A class=IN ttl=1445s auth=False>, <A
address=173.245.58.45 ttl=1445>]
- [<RR name=dns4.registrar-servers.com type=A class=IN ttl=1445s auth=False>, <A
address=173.245.59.16 ttl=1445>]
query: '[Query(''dns4.registrar-servers.com'', 1, 1)]'
query_type: A
resolver: null
- addrs: [208.64.122.244, 208.64.122.242]
answers:
- [<RR name=dns5.registrar-servers.com type=A class=IN ttl=1609s auth=False>, <A
address=208.64.122.244 ttl=1609>]
- [<RR name=dns5.registrar-servers.com type=A class=IN ttl=1609s auth=False>, <A
address=208.64.122.242 ttl=1609>]
query: '[Query(''dns5.registrar-servers.com'', 1, 1)]'
query_type: A
resolver: null
- addrs: [69.197.21.28, 69.197.21.29]
answers:
- [<RR name=dns3.registrar-servers.com type=A class=IN ttl=602s auth=False>, <A
address=69.197.21.28 ttl=602>]
- [<RR name=dns3.registrar-servers.com type=A class=IN ttl=602s auth=False>, <A
address=69.197.21.29 ttl=602>]
query: '[Query(''dns3.registrar-servers.com'', 1, 1)]'
query_type: A
resolver: null
- addrs: [173.245.59.16, 173.245.58.17, 173.245.58.45, 173.245.59.40]
answers:
- [<RR name=dns1.registrar-servers.com type=A class=IN ttl=816s auth=False>, <A
address=173.245.59.16 ttl=816>]
- [<RR name=dns1.registrar-servers.com type=A class=IN ttl=816s auth=False>, <A
address=173.245.58.17 ttl=816>]
- [<RR name=dns1.registrar-servers.com type=A class=IN ttl=816s auth=False>, <A
address=173.245.58.45 ttl=816>]
- [<RR name=dns1.registrar-servers.com type=A class=IN ttl=816s auth=False>, <A
address=173.245.59.40 ttl=816>]
query: '[Query(''dns1.registrar-servers.com'', 1, 1)]'
query_type: A
resolver: null
- addrs:
- [OoNI.Nu, 2014011200]
answers:
- [<RR name=OoNI.Nu type=SOA class=IN ttl=3601s auth=True>, <SOA mname=dns1.registrar-servers.com
rname=hostmaster.registrar-servers.com serial=2014011200 refresh=3600 retry=1801
expire=604800 minimum=3601 ttl=3601>]
query: '[Query(''OoNI.Nu'', 6, 1)]'
query_type: SOA
resolver: [208.64.122.244, 53]
- addrs:
- [OoNI.Nu, 2014011200]
answers:
- [<RR name=OoNI.Nu type=SOA class=IN ttl=3601s auth=True>, <SOA mname=dns1.registrar-servers.com
rname=hostmaster.registrar-servers.com serial=2014011200 refresh=3600 retry=1801
expire=604800 minimum=3601 ttl=3601>]
query: '[Query(''OoNI.Nu'', 6, 1)]'
query_type: SOA
resolver: [173.245.58.45, 53]
- query: '[Query(''OoNI.Nu'', 6, 1)]'
query_type: SOA
resolver: [69.197.21.28, 53]
- addrs:
- [OoNI.Nu, 2014011200]
answers:
- [<RR name=OoNI.Nu type=SOA class=IN ttl=3601s auth=True>, <SOA mname=dns1.registrar-servers.com
rname=hostmaster.registrar-servers.com serial=2014011200 refresh=3600 retry=1801
expire=604800 minimum=3601 ttl=3601>]
query: '[Query(''OoNI.Nu'', 6, 1)]'
query_type: SOA
resolver: [173.245.58.17, 53]
- addrs:
- [OoNI.Nu, 2014011200]
answers:
- [<RR name=OoNI.Nu type=SOA class=IN ttl=3601s auth=True>, <SOA mname=dns1.registrar-servers.com
rname=hostmaster.registrar-servers.com serial=2014011200 refresh=3600 retry=1801
expire=604800 minimum=3601 ttl=3601>]
query: '[Query(''OoNI.Nu'', 6, 1)]'
query_type: SOA
resolver: [208.64.122.244, 53]
requests:
- request:
body: null
headers:
- [User-Agent, 'Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) AppleWebKit/420+
(KHTML, like Gecko) Version/3.0 Mobile/1A543a Safari/419.3']
method: GET
tor: {is_tor: false}
url: http://www.apple.com/library/test/success.html
response:
body: <HTML><HEAD><TITLE>Success</TITLE></HEAD><BODY>Success</BODY></HTML>
code: 200
headers:
- - Date
- ['Sun, 11 May 2014 16:39:17 GMT']
- - Content-Length
- ['68']
- - Content-Type
- [text/html]
- - Connection
- [close]
- request:
body: null
headers:
- [User-Agent, 'Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0']
method: GET
tor: {is_tor: false}
url: http://tools.ietf.org/html/draft-nottingham-http-portal-02
response:
body: "3e80\r\n<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\"\
\n \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">\n<html xmlns=\"\
http://www.w3.org/1999/xhtml\" xml:lang=\"en\" lang=\"en\">\n<head profile=\"\
http://dublincore.org/documents/2008/08/04/dc-html/\">\n <meta http-equiv=\"\
Content-Type\" content=\"text/html; charset=utf-8\" />\n <meta name=\"robots\"\
\ content=\"index,follow\" />\n <meta name=\"creator\" content=\"rfcmarkup\
\ version 1.107\" />\n <link rel=\"schema.DC\" href=\"http://purl.org/dc/elements/1.1/\"\
\ />\n<meta name=\"DC.Identifier\" content=\"urn:ietf:id:nottingham-http-portal\"\
\ />\n<meta name=\"DC.Description.Abstract\" content=\""Captive portals"\
\ are a commonly-deployed means of obtaining access\\ncredentials and/or payment\
\ for a network. This memo introduces a new\\nHTTP status code as a means of\
\ addressing issues found in these\\ndeployments. This memo should be discussed\
\ on the [email protected]\\nmailing list, although it is not a work item\
\ of the HTTPbis WG.\" />\n<meta name=\"DC.Creator\" content=\"mnot <[email protected]>\"\
\ />\n<meta name=\"DC.Date.Issued\" content=\"2011-02-17\" />\n<meta name=\"\
DC.Title\" content=\"The Network Authentication Required HTTP Status Code\"\
\ />\n\n <link rel=\"icon\" href=\"/images/id.png\" type=\"image/png\" />\n\
\ <link rel=\"shortcut icon\" href=\"/images/id.png\" type=\"image/png\"\
\ />\n <title>draft-nottingham-http-portal-02 - The Network Authentication\
\ Required HTTP Status Code</title>\n \n \n <style type=\"text/css\"\
>\n\tbody {\n\t margin: 0px 8px;\n font-size: 1em;\n\t}\n \
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\ white-space: pre;\n font-family: monospace;\n \
\ font-size: 1em;\n\t font-weight: bold;\n }\n pre {\n \
\ font-size: 1em;\n margin-top: 0px;\n margin-bottom:\
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\ @media print {\n body {\n font-family: monospace;\n\
\ font-size: 10.5pt;\n }\n h1, h2, h3,\
\ h4, h5, h6 {\n font-size: 1em;\n }\n \n \
\ a:link, a:visited {\n color: inherit;\n \
\ text-decoration: none;\n }\n .noprint {\n \
\ display: none;\n }\n }\n\t@media screen {\n\t\
\ .grey, .grey a:link, .grey a:visited {\n\t\tcolor: #777;\n\t }\n \
\ .docinfo {\n background-color: #EEE;\n }\n\
\ .top {\n border-top: 7px solid #EEE;\n \
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\ { font-size: 90%; }\n .cplate { font-size: 70%; border: solid\
\ grey 1px; }\n\t}\n </style>\n <!--[if IE]>\n <style>\n body {\n\
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\ <![endif]-->\n\n <script type=\"text/javascript\"><!--\n function\
\ addHeaderTags() {\n\tvar spans = document.getElementsByTagName(\"span\");\n\
\tfor (var i=0; i < spans.length; i++) {\n\t var elem = spans[i];\n\t \
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\ <table> <tr><td>Unknown:</td> <td><span class='cplate\
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\ <td><span class='cplate bgred'> </span></td></tr>\
\ <tr><td>Informational:</td> <td><span class='cplate bgorange'> </span></td></tr>\
\ <tr><td>Experimental:</td> <td><span class='cplate bgyellow'> </span></td></tr>\
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\ <tr><td>Proposed Standard:</td> <td><span class='cplate bgblue'> </span></td></tr>\
\ <tr><td>Draft Standard (old designation):</td> <td><span class='cplate\
\ bgcyan'> </span></td></tr> <tr><td>Internet\
\ Standard:</td> <td><span class='cplate bggreen'> </span></td></tr>\
\ <tr><td>Historic:</td> <td><span class='cplate bggrey'> </span></td></tr>\
\ <tr><td>Obsolete:</td> <td><span class='cplate bgbrown'> </span></td></tr>\
\ </table>\";\n function showElem(id) {\n var elem = document.getElementById(id);\n\
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\ elem.style.visibility='hidden'; \n elem.innerHTML = \"\
\";\n }\n // -->\n </script>\n</head>\n<body onload=\"addHeaderTags()\"\
>\n <div style=\"height: 13px;\">\n <div onmouseover=\"this.style.cursor='pointer';\"\
\n onclick=\"showElem('legend');\"\n onmouseout=\"hideElem('legend')\"\
\n\t style=\"height: 6px; position: absolute;\"\n class=\"pre noprint\
\ docinfo bgred\"\n title=\"Click for colour legend.\" > \
\ </div>\n \
\ <div id=\"legend\"\n class=\"docinfo noprint pre legend\"\n \
\ style=\"position:absolute; top: 4px; left: 4ex; visibility:hidden; background-color:\
\ white; padding: 4px 9px 5px 7px; border: solid #345 1px; \"\n onmouseover=\"\
showElem('legend');\"\n onmouseout=\"hideElem('legend');\">\n \
\ </div>\n </div>\n<span class=\"pre noprint docinfo top\">[<a href=\"../html/\"\
\ title=\"Document search and retrieval page\">Docs</a>] [<a href=\"http://tools.ietf.org/id/draft-nottingham-http-portal-02.txt\"\
\ title=\"Plaintext version of this document\">txt</a>|<a href=\"/pdf/draft-nottingham-http-portal-02.txt\"\
\ title=\"PDF version of this document\">pdf</a>|<a href=\"/id/draft-nottingham-http-portal-02.xml\"\
\ title=\"XML source for this document\">xml</a>|<a href=\"/id/draft-nottingham-http-portal-02.html\"\
\ title=\"HTML version of this document, from XML2RFC\">html</a>] [<a href='https://datatracker.ietf.org/doc/draft-nottingham-http-portal'\
\ title='IESG Datatracker information for this document'>Tracker</a>] [<a href=\"\
mailto:[email protected]?subject=draft-nottingham-http-portal%20\"\
\ title=\"Send email to the document authors\">Email</a>] [<a href=\"/rfcdiff?difftype=--hwdiff&url2=draft-nottingham-http-portal-02.txt\"\
\ title=\"Inline diff (wdiff)\">Diff1</a>] [<a href=\"/rfcdiff?url2=draft-nottingham-http-portal-02.txt\"\
\ title=\"Side-by-side diff\">Diff2</a>] [<a href=\"/idnits?url=http://tools.ietf.org/id/draft-nottingham-http-portal-02.txt\"\
\ title=\"Run an idnits check of this document\">Nits</a>] </span><br />\n\
<span class=\"pre noprint docinfo\"> \
\ </span><br />\n<span class=\"pre noprint docinfo\"\
>Versions: <a href=\"./draft-nottingham-http-portal-00\">00</a> <a href=\"./draft-nottingham-http-portal-01\"\
>01</a> <a href=\"./draft-nottingham-http-portal-02\">02</a> \
\ </span><br />\n<span class=\"pre noprint\
\ docinfo\"> \
\ </span><br />\n<pre>\nNetwork Working Group \
\ M. Nottingham\nInternet-Draft \
\ February 18, 2011\nIntended status: Standards Track\nExpires: August\
\ 22, 2011\n\n\n <span class=\"h1\">The Network Authentication Required\
\ HTTP Status Code</span>\n <span class=\"h1\">draft-nottingham-http-portal-02</span>\n\
\nAbstract\n\n \"Captive portals\" are a commonly-deployed means of obtaining\
\ access\n credentials and/or payment for a network. This memo introduces\
\ a new\n HTTP status code as a means of addressing issues found in these\n\
\ deployments.\n\n This memo should be discussed on the [email protected]\
\ mailing\n list, although it is not a work item of the HTTPbis WG.\n\nStatus\
\ of this Memo\n\n This Internet-Draft is submitted in full conformance with\
\ the\n provisions of <a href=\"./bcp78\">BCP 78</a> and <a href=\"./bcp79\"\
>BCP 79</a>.\n\n Internet-Drafts are working documents of the Internet Engineering\n\
\ Task Force (IETF). Note that other groups may also distribute\n working\
\ documents as Internet-Drafts. The list of current Internet-\n Drafts is\
\ at <a href=\"http://datatracker.ietf.org/drafts/current/\">http://datatracker.ietf.org/drafts/current/</a>.\n\
\n Internet-Drafts are draft documents valid for a maximum of six months\n\
\ and may be updated, replaced, or obsoleted by other documents at any\n \
\ time. It is inappropriate to use Internet-Drafts as reference\n material\
\ or to cite them other than as \"work in progress.\"\n\n This Internet-Draft\
\ will expire on August 22, 2011.\n\nCopyright Notice\n\n Copyright (c) 2011\
\ IETF Trust and the persons identified as the\n document authors. All rights\
\ reserved.\n\n This document is subject to <a href=\"./bcp78\">BCP 78</a>\
\ and the IETF Trust's Legal\n Provisions Relating to IETF Documents\n (<a\
\ href=\"http://trustee.ietf.org/license-info\">http://trustee.ietf.org/license-info</a>)\
\ in effect on the date of\n publication of this document. Please review\
\ these documents\n carefully, as they describe your rights and restrictions\
\ with respect\n to this document. Code Components extracted from this document\
\ must\n include Simplified BSD License text as described in <a href=\"#section-4\"\
>Section 4</a>.e of\n\n\n\n<span class=\"grey\">Nottingham Expires\
\ August 22, 2011 [Page 1]</span>\n</pre><!--NewPage--><pre class='newpage'><a\
\ name=\"page-2\" id=\"page-2\" href=\"#page-2\" class=\"invisible\"> </a>\n\
<span class=\"grey\">Internet-Draft Network Authentication Required \
\ February 2011</span>\n\n\n the Trust Legal Provisions and are provided\
\ without warranty as\n described in the Simplified BSD License.\n\n\nTable\
\ of Contents\n\n <a href=\"#section-1\">1</a>. Introduction . . . . . .\
\ . . . . . . . . . . . . . . . . . . . <a href=\"#page-3\">3</a>\n <a href=\"\
#section-2\">2</a>. 428 Network Authentication Required . . . . . . . . . .\
\ . . . . <a href=\"#page-3\">3</a>\n <a href=\"#section-3\">3</a>. Security\
\ Considerations . . . . . . . . . . . . . . . . . . . . <a href=\"#page-4\"\
>4</a>\n <a href=\"#section-4\">4</a>. IANA Considerations . . . . . . .\
\ . . . . . . . . . . . . . . . <a href=\"#page-4\">4</a>\n <a href=\"#appendix-A\"\
>Appendix A</a>. Using the 428 Status Code . . . . . . . . . . . . . . <a\
\ href=\"#page-4\">4</a>\n <a href=\"#appendix-B\">Appendix B</a>. Issues\
\ Raised by Captive Portals . . . . . . . . . . . <a href=\"#page-5\">5</a>\n\
\ <a href=\"#appendix-C\">Appendix C</a>. Non-HTTP Applications and Techniques\
\ . . . . . . . . . <a href=\"#page-6\">6</a>\n <a href=\"#appendix-D\">Appendix\
\ D</a>. Acknowledgements . . . . . . . . . . . . . . . . . . . <a href=\"\
#page-6\">6</a>\n Author's Address . . . . . . . . . . . . . . . . . . .\
\ . . . . . . <a href=\"#page-6\">6</a>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n<span class=\"grey\">Nottingham \
\ Expires August 22, 2011 [Page 2]</span>\n</pre><!--NewPage--><pre\
\ class='newpage'><a name=\"page-3\" id=\"page-3\" href=\"#page-3\" class=\"\
invisible\"> </a>\n<span class=\"grey\">Internet-Draft Network Authentication\
\ Required February 2011</span>\n\n\n<span class=\"h2\"><a class=\"selflink\"\
\ name=\"section-1\" href=\"#section-1\">1</a>. Introduction</span>\n\n It\
\ has become common for networks to require authentication, payment\n and/or\
\ acceptance of terms of service before granting access.\n Typically, this\
\ occurs when accessing \"public\" networks such as those\n in hotels, trains,\
\ conference centres and similar networks.\n\n While there are several potential\
\ means of providing credentials to a\n network, these are not yet universally\
\ supported, and in some\n instances the network administrator requires that\
\ information (e.g.,\n terms of service, login information) be displayed to\
\ end users.\n\n In such cases, it has become widespread practice to use a\
\ \"captive\n portal\" that diverts HTTP requests to the administrator's web\
\ page.\n Once the user has satisfied requirements (e.g., for payment,\n \
\ acceptance of terms), the diversion is ended and \"normal\" access to\n \
\ the network is allowed.\n\n Typically, this diversion is accomplished by\
\ one of several possible\n techniques;\n o IP interception - all requests\
\ on port 80 are intercepted and send\n to the portal.\n o HTTP redirects\
\ - all requests on port 80 are intercepted and an\n HTTP redirect to the\
\ portal's URL is returned.\n o DNS interception - all DNS lookups return\
\ the portal's IP address.\n\n In each case, the intent is that users connecting\
\ to the network will\n open a Web browser and see the portal.\n\n However,\
\ because port 80 is used for non-browser traffic, a number of\n issues (see\
\ <a href=\"#appendix-B\">Appendix B</a>) have been encountered.\n\n This\
\ memo introduces a new HTTP status code, 428 Network\n Authentication Required,\
\ as a solution to some of these issues.\n <a href=\"#appendix-A\">Appendix\
\ A</a> outlines how it might be used in typical deployments.\n\n\n<span class=\"\
h2\"><a class=\"selflink\" name=\"section-2\" href=\"#section-2\">2</a>. 428\
\ Network Authentication Required</span>\n\n This status code indicates that\
\ the client should authenticate to\n gain network access before resubmitting\
\ the request.\n\n The response body SHOULD indicate how to do this; e.g.,\
\ with an HTML\n form for submitting credentials.\n\n Responses with the\
\ 428 status code MUST NOT be stored by a cache.\n\n\n\n\n\n<span class=\"grey\"\
>Nottingham Expires August 22, 2011 [Page 3]</span>\n\
</pre><!--NewPage--><pre class='newpage'><a name=\"page-4\" id=\"page-4\" href=\"\
#page-4\" class=\"invisible\"> </a>\n<span class=\"grey\">Internet-Draft \
\ Network Authentication Required February 2011</span>\n\n\n<span class=\"\
h2\"><a class=\"selflink\" name=\"section-3\" href=\"#section-3\">3</a>. Security\
\ Considerations</span>\n\n In common use, a response carrying the 428 status\
\ code will not come\n from the origin server indicated in the request's URL.\
\ This presents\n many security issues; e.g., an attacking intermediary may\
\ be\n inserting cookies into the original domain's name space, may be\n \
\ observing cookies or HTTP authentication credentials sent from the\n user\
\ agent, and so on.\n\n However, these risks are not unique to the 428 status\
\ code; in other\n words, a captive portal that is not using this status code\
\ introduces\n the same issues.\n\n\n<span class=\"h2\"><a class=\"selflink\"\
\ name=\"section-4\" href=\"#section-4\">4</a>. IANA Considerations</span>\n\
\n The HTTP Status Codes Registry should be updated with the following\n \
\ entry:\n\n o Code: 428\n o Description: Network Authentication Required\n\
\ o Specification: [ this document ]\n\n\n<span class=\"h2\"><a class=\"\
selflink\" name=\"appendix-A\" href=\"#appendix-A\">Appendix A</a>\r\n1c15\r\
\n. Using the 428 Status Code</span>\n\n This appendix demonstrates a typical\
\ use of the 428 status code; it\n is not normative.\n\n A network operator\
\ wishing to require some authentication, acceptance\n of terms or other user\
\ interaction before granting access usually\n does so by identify clients\
\ who have not done so (\"unknown clients\")\n using their MAC addresses.\n\
\n Unknown clients then have all traffic blocked, except for that on TCP\n\
\ port 80, which is sent to a HTTP server (the \"login server\")\n dedicated\
\ to \"logging in\" unknown clients, and of course traffic to\n the login\
\ server itself.\n\n For example, a user agent might connect to a network\
\ and make the\n following HTTP request on TCP port 80:\n\n GET /index.htm\
\ HTTP/1.1\n Host: www.example.com\n User-Agent: ExampleAgent\n\n Upon\
\ receiving such a request, the login server would generate a 428\n response:\n\
\n\n\n<span class=\"grey\">Nottingham Expires August 22, 2011\
\ [Page 4]</span>\n</pre><!--NewPage--><pre class='newpage'><a\
\ name=\"page-5\" id=\"page-5\" href=\"#page-5\" class=\"invisible\"> </a>\n\
<span class=\"grey\">Internet-Draft Network Authentication Required \
\ February 2011</span>\n\n\n HTTP/1.1 428 Network Authentication Required\n\
\ Refresh: 0; url=https://login.example.net/\n Content-Type: text/html\n\
\n <html>\n <head>\n </head>\n <body>\n\
\ <h1>You are being redirected to log into the network...</h1>\n\
\ </body>\n </html>\n\n Here, the 428 status code assures\
\ that non-browser clients will not\n interpret the response as being from\
\ the origin server, and the\n Refresh header redirects the user agent to\
\ the login server (an HTML\n META element can be used for this as well).\n\
\n Note that the 428 response can itself contain the login interface,\n \
\ but it may not be desirable to do so, because browsers would show the\n \
\ login interface as being associated with the originally requested\n URL,\
\ which may cause confusion.\n\n\n<span class=\"h2\"><a class=\"selflink\" name=\"\
appendix-B\" href=\"#appendix-B\">Appendix B</a>. Issues Raised by Captive\
\ Portals</span>\n\n Since clients cannot differentiate between a portal's\
\ response and\n that of the HTTP server that they intended to communicate\
\ with, a\n number of issues arise.\n\n One example is the \"favicon.ico\"\
\n <<a href=\"http://en.wikipedia.org/wiki/Favicon\">http://en.wikipedia.org/wiki/Favicon</a>>\
\ commonly used by browsers to\n identify the site being accessed. If the\
\ favicon for a given site is\n fetched from a captive portal instead of the\
\ intended site (e.g.,\n because the user is unauthenticated), it will often\
\ \"stick\" in the\n browser's cache (most implementations cache favicons\
\ aggressively)\n beyond the portal session, so that it seems as if the portal's\n\
\ favicon has \"taken over\" the legitimate site.\n\n Another browser-based\
\ issue comes about when P3P\n <<a href=\"http://www.w3.org/TR/P3P/\">http://www.w3.org/TR/P3P/</a>>\
\ is supported. Depending on how it is\n implemented, it's possible a browser\
\ might interpret a portal's\n response for the p3p.xml file as the server's,\
\ resulting in the\n privacy policy (or lack thereof) advertised by the portal\
\ being\n interpreted as applying to the intended site. Other Web-based\n\
\ protocols such as WebFinger\n <<a href=\"http://code.google.com/p/webfinger/wiki/WebFingerProtocol\"\
>http://code.google.com/p/webfinger/wiki/WebFingerProtocol</a>>, CORS\n \
\ <<a href=\"http://www.w3.org/TR/cors/\">http://www.w3.org/TR/cors/</a>>\
\ and OAuth\n <<a href=\"http://tools.ietf.org/html/draft-ietf-oauth-v2\"\
>http://tools.ietf.org/html/draft-ietf-oauth-v2</a>> may also be\n\n\n\n\
<span class=\"grey\">Nottingham Expires August 22, 2011 \
\ [Page 5]</span>\n</pre><!--NewPage--><pre class='newpage'><a name=\"\
page-6\" id=\"page-6\" href=\"#page-6\" class=\"invisible\"> </a>\n<span class=\"\
grey\">Internet-Draft Network Authentication Required February 2011</span>\n\
\n\n vulnerable to such issues.\n\n Although HTTP is most widely used with\
\ Web browsers, a growing number\n of non-browsing applications use it as\
\ a substrate protocol. For\n example, WebDAV <<a href=\"http://tools.ietf.org/html/rfc4918\"\
>http://tools.ietf.org/html/rfc4918</a>> and CalDAV\n <<a href=\"http://www.ietf.org/rfc/rfc4791.txt\"\
>http://www.ietf.org/rfc/rfc4791.txt</a>> both use HTTP as the basis (for\n\
\ network filesystem access and calendaring, respectively). Using\n these\
\ applications from behind a captive portal can result in\n spurious errors\
\ being presented to the user, and might result in\n content corruption, in\
\ extreme cases.\n\n Similarly, other non-browser applications using HTTP\
\ can be affected\n as well; e.g., widgets <<a href=\"http://www.w3.org/TR/widgets/\"\
>http://www.w3.org/TR/widgets/</a>>, software\n updates, and other specialised\
\ software such as Twitter clients and\n the iTunes Music Store.\n\n It\
\ should be noted that it's sometimes believed that using HTTP\n redirection\
\ to direct traffic to the portal addresses these issues.\n However, since\
\ many of these uses \"follow\" redirects, this is not a\n good solution.\n\
\n\n<span class=\"h2\"><a class=\"selflink\" name=\"appendix-C\" href=\"#appendix-C\"\
>Appendix C</a>. Non-HTTP Applications and Techniques</span>\n\n This memo\
\ does not address non-HTTP applications, such as IMAP, POP,\n or even TLS-encapsulated\
\ HTTP. Since captive portals almost always\n target Web browsers (has anyone\
\ ever seen one that inserts an e-mail\n into your inbox asking you to authenticate?),\
\ this is appropriate.\n\n Instead, it is anticipated that well-behaved portals\
\ will block all\n non-HTTP ports (especially port 443) until the user has\
\ successfully\n authenticated.\n\n Overall, there may also be an interesting\
\ discussion to be had about\n improving network access methods to the point\
\ where a user interface\n can be presented for the same purposes, without\
\ resorting to\n intercepting HTTP traffic. However, since such a mechanism\
\ would by\n necessity require modifying the network stack and operating system\
\ of\n the client, this memo takes a more modest approach.\n\n\n<span class=\"\
h2\"><a class=\"selflink\" name=\"appendix-D\" href=\"#appendix-D\">Appendix\
\ D</a>. Acknowledgements</span>\n\n The author takes all responsibility\
\ for errors and omissions.\n\n\n\n\n\n\n\n<span class=\"grey\">Nottingham \
\ Expires August 22, 2011 [Page 6]</span>\n</pre><!--NewPage--><pre\
\ class='newpage'><a name=\"page-7\" id=\"page-7\" href=\"#page-7\" class=\"\
invisible\"> </a>\n<span class=\"grey\">Internet-Draft Network Authentication\
\ Required February 2011</span>\n\n\nAuthor's Address\n\n Mark Nottingham\n\
\n Email: [email protected]\n URI: <a href=\"http://www.mnot.net/\">http://www.mnot.net/</a>\n\
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\
\n\n\n\n\n\n\nNottingham Expires August 22, 2011 \
\ [Page 7]\n\n</pre><br />\n<span class=\"noprint\"><small><small>Html markup\
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