Network Working Group Paul E. Jones
Internet Draft Gonzalo Salgueiro
Intended status: Standards Track Cisco Systems
Expires: June 21, 2013 Joseph Smarr
Google
December 21, 2012
WebFinger
draft-ietf-appsawg-webfinger-08.txt
Abstract
This specification defines the WebFinger protocol, which can be used
to discover information about people or other entities on the
Internet using standard HTTP methods.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 21, 2013.
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Table of Contents
1. Introduction...................................................2
2. Terminology....................................................3
3. Example Uses of WebFinger......................................3
3.1. Locating a User's Blog....................................3
3.2. Identity Provider Discovery for OpenID Connect............5
3.3. Auto-Configuration of Email Clients.......................6
3.4. Retrieving Device Information.............................7
4. WebFinger Protocol.............................................8
4.1. Constructing a WebFinger Query............................8
4.2. Performing a WebFinger Query..............................8
4.3. The "rel" Parameter.......................................9
4.4. The JSON Resource Descriptor (JRD).......................10
4.4.1. expires.............................................11
4.4.2. subject.............................................11
4.4.3. aliases.............................................11
4.4.4. properties..........................................12
4.4.5. links...............................................12
4.5. WebFinger and URIs.......................................14
5. Cross-Origin Resource Sharing (CORS)..........................14
6. Access Control................................................15
7. Hosted WebFinger Services.....................................15
8. Security Considerations.......................................16
9. IANA Considerations...........................................17
10. Acknowledgments..............................................18
11. References...................................................18
11.1. Normative References....................................18
11.2. Informative References..................................19
Author's Addresses...............................................20
1. Introduction
WebFinger is used to discover information about people or other
entities on the Internet that are identified by a URI [6] or IRI [7]
using standard Hypertext Transfer Protocol (HTTP) [2] methods over a
secure transport [14]. A WebFinger server returns a JavaScript
Object Notation (JSON) [5] object that describes a resource that is
queried. The JSON object is referred to as the JSON Resource
Descriptor (JRD).
For a person, the kinds of information that might be discoverable via
WebFinger include a personal profile address, identity service,
telephone number, or preferred avatar. For other entities on the
Internet, a WebFinger server might return JRDs containing link
relations that allow a client to discover, for example, the amount of
toner in a printer or the physical location of a server.
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Information returned via WebFinger might be for direct human
consumption (e.g., looking up someone's phone number), or it might be
used by systems to help carry out some operation (e.g., facilitate
logging into a web site by determining a user's identity service).
Use of WebFinger is illustrated in the examples in Section 3 and
described more formally in Section 4.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [1].
WebFinger makes heavy use of "Link Relations". Briefly, a Link
Relation is an attribute and value pair used on the Internet wherein
the attribute identifies the type of link to which the associated
value refers. In HTTP and Web Linking [4], the attribute is a "rel"
and the value is an "href". WebFinger also uses the "rel" attribute,
where the "rel" value is either a single IANA-registered link
relation type [10] or a URI [6].
3. Example Uses of WebFinger
This non-normative section shows a few sample uses of WebFinger.
3.1. Locating a User's Blog
Assume you receive an email from Bob and he refers to something he
posted on his blog, but you do not know where Bob's blog is located.
It would be simple to discover the address of Bob's blog if he makes
that information available via WebFinger.
Assume your email client can discover the blog for you. After
receiving the message from Bob (bob@example.com), you instruct your
email client to perform a WebFinger query. It does so by issuing the
following HTTPS [14] query to example.com:
GET /.well-known/webfinger?
resource=acct%3Abob%40example.com HTTP/1.1
Host: example.com
The server might then respond with a message like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
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"expires" : "2012-11-16T19:41:35Z",
"subject" : "acct:bob@example.com",
"aliases" :
[
"http://www.example.com/~bob/"
],
"properties" :
{
"http://example.com/ns/role/" : "employee"
},
"links" :
[
{
"rel" : "http://webfinger.net/rel/avatar",
"type" : "image/jpeg",
"href" : "http://www.example.com/~bob/bob.jpg"
},
{
"rel" : "http://webfinger.net/rel/profile-page",
"href" : "http://www.example.com/~bob/"
},
{
"rel" : "blog",
"type" : "text/html",
"href" : "http://blogs.example.com/bob/",
"titles" :
{
"en-us" : "The Magical World of Bob",
"fr" : "Le monde magique de Bob"
}
},
{
"rel" : "vcard",
"href" : "https://www.example.com/~bob/bob.vcf"
}
]
}
The email client would take note of the "blog" link relation in the
above JRD that refers to Bob's blog. This URL would then be
presented to you so that you could then visit his blog. The email
client might also note that Bob has published an avatar link relation
and use that picture to represent Bob inside the email client.
Lastly, the client might consider the vcard [16] link relation in
order to update contact information for Bob.
In the above example, an "acct" URI [8] is used in the query, though
any valid alias for the user might also be used. An alias is a URI
that is different from the "subject" URI that identifies the same
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entity. In the above example, there is one "http" alias returned,
though there might have been more than one. Had the "http:" URI
shown as an alias been used to query for information about Bob, the
query would have appeared as:
GET /.well-known/webfinger?
resource=http%3A%2F%2Fwww.example.com%2F~bob%2F HTTP/1.1
Host: example.com
The response would have been substantially the same, with the subject
and alias information changed as necessary. Other information, such
as the expiration time might also change, but the set of link
relations and properties would be the same with either response.
3.2. Identity Provider Discovery for OpenID Connect
Suppose Carol wishes to authenticate with a web site she visits using
OpenID Connect [18]. She would provide the web site with her OpenID
Connect identifier, say carol@example.com. The visited web site
would perform a WebFinger query looking for the OpenID Connect
Provider. Since the site is interested in only one particular link
relation, the server might utilize the "rel" parameter as described
in Section 4.3:
GET /.well-known/webfinger?
resource=acct%3Acarol%40example.com&
rel=http%3A%2F%2Fopenid.net%2Fspecs%2Fconnect%2F1.0%2Fissuer
HTTP/1.1
Host: example.com
The server might respond with a JRD like this:
{
"expires" : "2012-11-16T19:41:35Z",
"subject" : "acct:carol@example.com",
"aliases" :
[
"http://www.example.com/~carol/"
],
"properties" :
{
"http://example.com/ns/role/" : "employee"
},
"links" :
[
{
"rel" : "http://openid.net/specs/connect/1.0/issuer",
"href" : "https://openid.example.com/"
}
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]
}
Since the "rel" parameter only filters the link relations returned by
the server, other name/value pairs in the response, including any
aliases or properties, would be returned. Also, since support for
the "rel" parameter is optional, the client must not assume the
"links" array will contain only the requested link relation.
3.3. Auto-Configuration of Email Clients
WebFinger could be used to auto-provision an email client with basic
configuration data. Suppose that sue@example.com wants to configure
her email client. Her email client might issue the following query:
GET /.well-known/webfinger?
resource=mailto%3Asue%40example.com HTTP/1.1
Host: example.com
The response from the server would contain entries for the various
protocols, transport options, and security options. If there are
multiple options, the server might return a link relation that for
each of the valid options and the client or Sue might select which
option to choose. Since JRDs list link relations in a specific
order, then the most-preferred choices could be presented first.
Consider this response:
{
"subject" : "mailto:sue@example.com",
"links" :
[
{
"rel" : "http://example.net/rel/smtp-server",
"properties" :
{
"http://example.net/email/host" : "smtp.example.com",
"http://example.net/email/port" : "587",
"http://example.net/email/login-required" : "yes",
"http://example.net/email/transport" : "starttls"
}
},
{
"rel" : "http://example.net/rel/imap-server",
"properties" :
{
"http://example.net/email/host" : "imap.example.com",
"http://example.net/email/port" : "993",
"http://example.net/email/transport" : "ssl"
}
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}
]
}
In this example, you can see that the WebFinger server advertises an
SMTP service and an IMAP service. In this example, the "href"
entries associated with the link relation are absent. This is valid
when there is no external reference that needs to be made.
3.4. Retrieving Device Information
As another example, suppose there are printers on the network and you
would like to check the current toner level for a particular printer
identified via the URI device:p1.example.com. While the "device" URI
scheme is not presently specified, we use it here for illustrative
purposes.
Following the procedures similar to those above, a query may be
issued to get link relations specific to this URI like this:
GET /.well-known/webfinger?
resource=device%3Ap1.example.com HTTP/1.1
Host: example.com
The link relations that are returned for a device may be quite
different than those for user accounts. Perhaps we may see a
response like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"subject" : "device:p1.example.com",
"links" :
[
{
"rel" : "http://example.com/rel/tipsi",
"href" : "http://192.168.1.5/npap/"
}
]
}
While this example is fictitious, you can imagine that perhaps the
Transport Independent, Printer/System Interface [17] may be enhanced
with a web interface that allows a device that understands the TIP/SI
web interface specification to query the printer for toner levels.
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4. WebFinger Protocol
WebFinger is a simple HTTP-based web service that returns a JSON
Resource Descriptor (JRD) to convey information about an entity on
the Internet and the Cross-Origin Resource Sharing (CORS) [9]
specification to facilitate queries made via a web browser.
4.1. Constructing a WebFinger Query
This specification defines URI parameters that are passed from the
client to the server when issuing a request. These parameters,
"resource" and "rel", and the parameter values are included in the
"query" component of the URI (see Section 3.4 of RFC 3986). To
construct the "query" component, the client performs the following
steps. First, each parameter value is percent-encoded as per Section
2.1 of RFC 3986. Next, the client constructs a string to be placed
in the query component by concatenating the name of the first
parameter together with an equal sign ("=") and the percent-encoded
parameter value. For any subsequent parameters, the client appends
an ampersand ("&") to the string, the name of the next parameter, an
equal sign, and percent-encoded parameter value. The client MUST NOT
insert any spaces while constructing the string. The order in which
the client places each parameter and its corresponding parameter
value is unspecified.
4.2. Performing a WebFinger Query
A WebFinger client issues a query to the well-known [3] resource
/.well-known/webfinger. A query MUST include the "resource"
parameter exactly once and set to the value of the URI for which
information is being sought. If the "resource" parameter is absent
or malformed, the WebFinger server MUST indicate that the request is
bad as per Section 10.4.1 of RFC 2616 [2].
A client MUST query the WebFinger server using HTTPS only. If the
client determines that the server has an invalid certificate, the
server returns a 4xx or 5xx status code, or the HTTPS connection
cannot be established for any reason, the client MUST accept that the
WebFinger query has failed and MUST NOT attempt to reissue the
WebFinger request using HTTP over a non-secure connection.
A WebFinger server MUST return a JRD as the representation for the
resource if the client requests no other supported format explicitly
via the HTTP "Accept" header. The client MAY include the "Accept"
header to indicate a desired representation, though no other
representation than JRD is defined in this specification. The media
type used for the JSON Resource Descriptor (JRD) is
"application/json" [5].
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A WebFinger server MAY redirect the client, but MUST only redirect
the client to an HTTPS URI.
A WebFinger server can include cache validators in a response to
enable conditional requests by the client and/or expiration times as
per Section 13 of RFC 2616.
4.3. The "rel" Parameter
When issuing a request to the server, the client MAY utilize the
"rel" parameter to request only a subset of the information that
would otherwise be returned without the "rel" parameter. When the
"rel" parameter is used, only the link relations that match the link
relations provided via "rel" are included in the array of links
returned in the JRD. All other information normally present in a
resource descriptor is present in the resource descriptor, even when
"rel" is employed.
The "rel" parameter MAY be transmitted to the server multiple times
in order to request multiple types of link relations.
The purpose of the "rel" parameter is to return a subset of
resource's link relations. Use of the parameter might reduce
processing requirements on either the client or server, and it might
also reduce the bandwidth required to convey the partial resource
descriptor, especially if there are numerous link relation values to
convey for a given resource.
Support for the "rel" parameter is OPTIONAL, but RECOMMENDED on the
server. Should the server not support the "rel" parameter, it MUST
ignore it and process the request as if no "rel" parameter values
were present.
The following example presents the same example as found in Section
3.1, but uses the "rel" parameter in order to select two link
relations:
GET /.well-known/webfinger?
resource=acct%3Abob%40example.com&
rel=http%3A%2F%2Fwebfinger.net%2Frel%2Fprofile-page&
rel=vcard HTTP/1.1
Host: example.com
In this example, the client requests the link relations of type
"http://webfinger.net/rel/profile-page" and "vcard". The server then
responds with a message like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
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Content-Type: application/json; charset=UTF-8
{
"expires" : "2012-11-16T19:41:35Z",
"subject" : "acct:bob@example.com",
"aliases" :
[
"http://www.example.com/~bob/"
],
"properties" :
{
"http://example.com/ns/role/" : "employee"
},
"links" :
[
{
"rel" : "http://webfinger.net/rel/profile-page",
"href" : "http://www.example.com/~bob/"
},
{
"rel" : "vcard",
"href" : "http://www.example.com/~bob/bob.vcf"
}
]
}
As you can see, the server returned only the link relations requested
by the client, but also included the other parts of the JRD.
In the event that a client requests links for link relations that are
not defined for the specified resource, a resource descriptor MUST be
returned. In the returned JRD, the "links" array MAY be absent,
empty, or contain only links that did match a provided "rel" value.
4.4. The JSON Resource Descriptor (JRD)
The JSON Resource Descriptor (JRD), originally introduced in RFC 6415
[19] and based on the Extensible Resource Descriptor (XRD) format
[20], is a JSON object that is comprised of the following name/value
pairs:
o expires
o subject
o aliases
o properties
o links
The members "expires" and "subject" are name/value pairs whose value
are strings, "aliases" is an array of strings, "properties" is an
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object comprised of name/value pairs whose values are strings, and
"links" is an array of objects that contain link relation
information.
When processing a JRD, the client MUST ignore any unknown member and
not treat the presence of an unknown member as an error.
Below, each of these members of the JRD is described in more detail.
4.4.1. expires
The value of the "expires" member is a string that indicates the date
and time after which the JRD SHOULD be considered expired and no
longer utilized.
This format is formally defined in RFC 3339 [15].
The "expires" member MUST NOT use fractional seconds and MUST express
time only Universal Coordinate Time via the "Z" designation on the
end of the string.
An example of the "expires" member is:
"expires" : "2012-11-16T19:41:35Z"
The "expires" member is optional in a JRD, but SHOULD be honored if
present.
4.4.2. subject
The value of the "subject" member is a URI that identifies the entity
that the JRD describes.
The "subject" value returned by a WebFinger server MAY differ from
the value of the "resource" parameter used in the client's request.
This may happen, for example, when the subject's identity changes
(e.g., a user moves his or her account to another service) or when
the server prefers to express URIs in canonical form.
The "subject" member MUST be present.
4.4.3. aliases
The "aliases" array is an array of zero or more URI strings that
identify the same entity as the "subject" URI. Each URI must be an
absolute URI.
The "aliases" array is optional.
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4.4.4. properties
The "properties" object is comprised of zero or more name/value pairs
whose names are absolute URIs and whose values are strings or null.
Properties are used to convey additional information about the
subject of the JRD. As an example, consider this use of
"properties":
"properties" : { "http://webfinger.net/ns/name" : "Bob Smith" }
The "properties" member is optional.
4.4.5. links
The "links" array contains zero or more elements that contain the
link relation information. Each element of the array is an object
comprised of the following name/value pairs:
o rel
o type
o href
o titles
o properties
The members "rel", "type", and "href" are a name/value pairs whose
values are strings, "titles" and "properties" are objects comprised
of name/value pairs whose values are strings.
The order of elements in the "links" array indicates an order of
preference. Thus, if there are two or more link relations having the
same "rel" value, the first link relation would indicate the user's
preferred link relation.
The "links" array is optional in the JRD.
Below, each of the members of the objects found in the "links" array
is described in more detail. Each object in the "links" array,
referred to as a "link relation object", is completely independent
from any other object in the array; any requirement to include a
given member in the link relation object refers only to that
particular object.
4.4.5.1. rel
The value of the "rel" member is a string that is either an absolute
URI or a registered relation type [10] (see RFC 5988 [4]). The value
of the "rel" member MUST contain exactly one URI string or registered
relation type and MUST NOT contain a space-separated list of URIs or
registered relation types. The URI or registered relation type
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identifies the type of the link relation. The other members of the
object have meaning only once the type of link relation is
understood. In some instances, the link relation will have
associated semantics that allow a client to query for other resources
on the Internet. In other instances, the link relation will have
associated semantics that allow the client to utilize the other
members of the link relation object without fetching additional
external resources.
The "rel" member MUST be present in the link relation object.
4.4.5.2. type
The value of the "type" member is a string that indicates the media
type [11] of the linked resource (see RFC 4288 [12]).
The "type" member is optional in the link relation object.
4.4.5.3. href
The value of the "href" member is a string that contains a URI
pointing to the linked resource.
The "href" member is optional in the link relation object.
4.4.5.4. titles
The "titles" object is comprised of zero or more name/value pairs
whose name is a language tag [13] or the string "default". The
string is human-readable and describes the link relation. More than
one title for the link relation MAY be provided for the benefit of
users who utilize the link relation and, if used, a language
identifier SHOULD be duly used as the name. If the language is
unknown or unspecified, then the name is "default".
A JRD SHOULD NOT include more than one title identified with the same
language tag (or "default") within the link relation object. Meaning
is undefined if a link relation object includes more than one title
named with the same language tag (or "default"), though this MUST NOT
treat this as an error. A client MAY select whichever title or
titles it wishes to utilize.
Here is an example of the titles object:
"titles" :
{
"en-us" : "The Magical World of Bob",
"fr" : "Le monde magique de Bob"
}
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The "titles" member is optional in the link relation object.
4.4.5.5. properties
The "properties" object within the link relation object is comprised
of zero or more name/value pairs whose names are absolute URIs and
whose values are strings or null. Properties are used to convey
additional information about the link relation. As an example,
consider this use of "properties":
"properties" : { "http://example.net/mail/port" : "993" }
The "properties" member is optional in the link relation object.
4.5. WebFinger and URIs
WebFinger requests can include a parameter specifying the URI of an
account, device, or other entity. WebFinger is agnostic regarding
the scheme of such a URI: it could be an "acct" URI [7], an "http" or
"https" URI, a "mailto" URI [21], or some other scheme.
For resources associated with a user account at a host, use of the
"acct" URI scheme is RECOMMENDED, since it explicitly identifies an
account accessible via WebFinger. Further, the "acct" URI scheme is
not associated with other protocols as, by way of example, the
"mailto" URI scheme is associated with email. Since not every host
offers email service, using the "mailto" URI scheme is not ideal for
identifying user accounts on all hosts. That said, use of the
"mailto" URI scheme would be ideal for use with WebFinger to discover
mail server configuration information for a user.
5. Cross-Origin Resource Sharing (CORS)
WebFinger resources might not be accessible from a web browser due to
"Same-Origin" policies. The current best practice is to make
resources available to browsers through Cross-Origin Resource Sharing
(CORS) [9], and servers MUST include the Access-Control-Allow-Origin
HTTP header in responses. Servers SHOULD support the least
restrictive setting by allowing any domain access to the WebFinger
resources:
Access-Control-Allow-Origin: *
There are cases where defaulting to the least restrictive setting is
not appropriate, for example a WebFinger server on an intranet that
provides sensitive company information should not allow CORS requests
from any domain, as that could allow leaking of that sensitive
information. A WebFinger server that wishes to restrict access to
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information from external entities SHOULD use a more restrictive
Access-Control-Allow-Origin header.
6. Access Control
As with all web resources, access to the /.well-known/webfinger
resource MAY require authentication. Further, failure to provide
required credentials MAY result in the server forbidding access or
providing a different response than had the client authenticated with
the server.
Likewise, a server MAY provide different responses to different
clients based on other factors, such as whether the client is inside
or outside a corporate network. As a concrete example, a query
performed on the internal corporate network might return link
relations to employee pictures, whereas link relations for employee
pictures might not be provided to external entities.
Further, link relations provided in a WebFinger server response MAY
point to web resources that impose access restrictions. For example,
the aforementioned corporate server may provide both internal and
external entities with URIs to employee pictures, but further
authentication might be required in order for the client to access
the picture resources if the request comes from outside the corporate
network.
The decisions made with respect to what set of link relations a
WebFinger server provides to one client versus another and what
resources require further authentication, as well as the specific
authentication mechanisms employed, are outside the scope of this
document.
7. Hosted WebFinger Services
As with most services provided on the Internet, it is possible for a
domain owner to utilize "hosted" WebFinger services. By way of
example, a domain owner might control most aspects of their domain,
but use a third-party hosting service for email. In the case of
email, mail servers for a domain are identified by MX records. An MX
record points to the mail server to which mail for the domain should
be delivered. It does not matter to the sending mail server whether
those MX records point to a server in the destination domain or a
different domain.
Likewise, a domain owner might utilize the services of a third party
to provide WebFinger services on behalf of its users. Just as a
domain owner was required to insert MX records into DNS to allow for
hosted email serves, the domain owner is required to redirect HTTP
queries to its domain to allow for hosted WebFinger services.
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When a query is issued to /.well-known/webfinger, the web server MUST
return a response with a redirection status code that includes a
Location header pointing to the location of the hosted WebFinger
service URL. The WebFinger service URL does not need to point to
/.well-known/* on the hosting service provider server.
As an example, assume that example.com's WebFinger services are
hosted by example.net. Suppose a client issues a query for
acct:alice@example.com like this:
GET /.well-known/webfinger?
resource=acct%3Aalice%40example.com HTTP/1.1
Host: example.com
The server might respond with this:
HTTP/1.1 307 Temporary Redirect
Access-Control-Allow-Origin: *
Location: https://wf.example.net/example.com/webfinger?
resource=acct%3Aalice%40example.com HTTP/1.1
The client can then follow the redirection, re-issuing the request to
the URL provided in the Location header. Note that the server will
include any required URI parameters in the Location header value,
which could be different than the URI parameters the client
originally used.
8. Security Considerations
Since this specification utilizes Cross-Origin Resource Sharing
(CORS) [9], all of the security considerations applicable CORS are
also applicable to this specification.
The required use of HTTPS is to ensure that information is not
modified during transit. It should be appreciated that in
environments where a web server is normally available, there exists
the possibility that a compromised network might have its WebFinger
server operating on HTTPS replaced with one operating only over HTTP.
As such, clients MUST NOT issue queries over a non-secure connection.
Clients MUST verify that the certificate used on an HTTPS connection
is valid and accept a response only if the certificate is valid.
Service providers and users should be aware that placing information
on the Internet accessible through WebFinger means that any user can
access that information. While WebFinger can be an extremely useful
tool for allowing quick and easy access to one's avatar, blog, or
other personal information, users should understand the risks, too.
If one does not wish to share certain information with the world, do
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not allow that information to be freely accessible through WebFinger
and do not use any service supporting WebFinger. Further, a
WebFinger server MUST NOT be used to provide any personal information
to any party unless explicitly or implicitly authorized by the person
whose information is being shared. Implicit authorization can be
determined by the user's voluntary utilization of a service as
defined by that service's relevant terms of use or published privacy
policy.
The aforementioned word of caution is perhaps worth emphasizing again
with respect to dynamic information one might wish to share, such as
the current location of a user. WebFinger can be a powerful tool
used to assemble information about a person all in one place, but
service providers and users should be mindful of the nature of that
information shared and the fact that it might be available for the
entire world to see. Sharing location information, for example,
would potentially put a person in danger from any individual who
might seek to inflict harm on that person.
The easy access to user information via WebFinger was a design goal
of the protocol, not a limitation. If one wishes to limit access to
information available via WebFinger, such as a WebFinger server for
use inside a corporate network, the network administrator must take
measures necessary to limit access from outside the network. Using
standard methods for securing web resources, network administrators
do have the ability to control access to resources that might return
sensitive information. Further, a WebFinger server can be employed
in such a way as to require authentication and prevent disclosure of
information to unauthorized entities.
Finally, a WebFinger server has no means of ensuring that information
provided by a user is accurate. Likewise, neither the server nor the
client can be absolutely guaranteed that information has not been
manipulated either at the server or along the communication path
between the client and server. Use of HTTPS helps to address some
concerns with manipulation of information along the communication
path, but it clearly cannot address issues where the server provided
incorrect information, either due to being provided false information
or due to malicious behavior on the part of the server administrator.
As with any information service available on the Internet, users
should wary of information received from untrusted sources.
9. IANA Considerations
This specification registers the "webfinger" well-known URI in the
Well-Known URI Registry as defined by [3].
URI suffix: webfinger
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Change controller: IETF
Specification document(s): RFC QQQ
Related information: The response from WebFinger server will be a
JSON Resource Descriptor (JRD) as described in section 4.4 of RFC
QQQ.
[RFC EDITOR: Please replace "QQQ" references in this section with the
number for this RFC.]
10. Acknowledgments
The authors would like to acknowledge Eran Hammer-Lahav, Blaine Cook,
Brad Fitzpatrick, Laurent-Walter Goix, Joe Clarke, Michael B. Jones,
Peter Saint-Andre, Dick Hardt, Tim Bray, and Joe Gregorio for their
invaluable input.
11. References
11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999.
[3] Nottingham, M., Hammer-Lahav, E., "Defining Well-Known Uniform
Resource Identifiers (URIs)", RFC 5785, April 2010.
[4] Nottingham, M., "Web Linking", RFC 5988, October 2010.
[5] Crockford, D., "The application/json Media Type for JavaScript
Object Notation (JSON)", RFC 4627, July 2006.
[6] Berners-Lee, T., Fielding, R., and Masinter, L., "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
January 2005.
[7] Duerst, M., "Internationalized Resource Identifiers (IRIs)",
RFC 3987, January 2005.
[8] Saint-Andre, P., "The 'acct' URI Scheme", draft-ietf-appsawg-
acct-uri-01, October 2012.
[9] Van Kesteren, A., "Cross-Origin Resource Sharing", W3C CORS
http://www.w3.org/TR/cors/, July 2010.
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Internet-Draft WebFinger December 2012
[10] IANA, "Link Relations", http://www.iana.org/assignments/link-
relations/.
[11] IANA, "MIME Media Types",
http://www.iana.org/assignments/media-types/index.html.
[12] Freed, N., Klensin, J., "Media Type Specifications and
Registration Procedures", RFC 4288, December 2005.
[13] Phillips, A., Davis, M., "Tags for Identifying Languages", RFC
5646, January 2001.
[14] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[15] Klyne, G., Newman, C., "Date and Time on the Internet:
Timestamps", RFC 3339, July 2002.
11.2. Informative References
[16] Perreault, S., "vCard Format Specification", RFC 6350, August
2011.
[17] "Transport Independent, Printer/System Interface", IEEE Std
1284.1-1997, 1997.
[18] Sakimura, N., Bradley, J., Jones, M., de Medeiros, B.,
Mortimore, C., and E. Jay, "OpenID Connect Messages 1.0", June
2012, http://openid.net/specs/openid-connect-messages-1_0.html.
[19] Hammer-Lahav, E. and Cook, B., "Web Host Metadata", RFC 6415,
October 2011.
[20] Hammer-Lahav, E. and W. Norris, "Extensible Resource Descriptor
(XRD) Version 1.0", http://docs.oasis-
open.org/xri/xrd/v1.0/xrd-1.0.html.
[21] Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto' URI
Scheme", RFC 6068, October 2010.
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Author's Addresses
Paul E. Jones
Cisco Systems, Inc.
7025 Kit Creek Rd.
Research Triangle Park, NC 27709
USA
Phone: +1 919 476 2048
Email: paulej@packetizer.com
IM: xmpp:paulej@packetizer.com
Gonzalo Salgueiro
Cisco Systems, Inc.
7025 Kit Creek Rd.
Research Triangle Park, NC 27709
USA
Phone: +1 919 392 3266
Email: gsalguei@cisco.com
IM: xmpp:gsalguei@cisco.com
Joseph Smarr
Google
Email: jsmarr@google.com
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