One document matched: draft-ietf-xmpp-dna-01.txt
Differences from draft-ietf-xmpp-dna-00.txt
Network Working Group R. Barnes
Internet-Draft BBN Technologies
Intended status: Standards Track J. Lindberg
Expires: September 15, 2011 Google
March 14, 2011
Domain Name Assertions
draft-ietf-xmpp-dna-01
Abstract
The current authentication process in XMPP requires the XMPP server
for a domain to present a certificate that contains that domain's
name. This requirement causes several problems in scenarios where
XMPP services have been delegated from one domain to another,
especially when one domain provides XMPP services for many domains.
This document describes an extension to the XMPP authentication
process that allows domains to be securely delegated, simplifying
authorization in delegation scenarios.
Requirements Language
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 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 15, 2011.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4
4. Connection Model . . . . . . . . . . . . . . . . . . . . . . . 8
5. Channel Establishment and Authentication . . . . . . . . . . . 9
6. Authorizing XMPP Stanzas . . . . . . . . . . . . . . . . . . . 13
7. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 15
8. Operational Considerations . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
10. Security Considerations . . . . . . . . . . . . . . . . . . . 16
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
12. Normative References . . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
When connecting two XMPP services to provide inter-domain
communication, it is important for a service to be able to determine
the identity of a peer service to prevent traffic spoofing. The
Jabber communities first approach to identity verification was the
Server Dialback protocol. When the Jabber protocols were formalized
by the XMPP working group of the IETF 2002-04, support for strong
identity verification using TLS + SASL was added.
Server Dialback [XEP-0220] provides weak identity verification and
makes it more difficult to spoof hostnames of servers XMPP network.
However, it does not provide authentication between servers and is
not a security mechanism. It is susceptible to DNS poisoning attacks
(unless DNSSEC is used) and cannot protect against attackers capable
of hijacking the IP address of a remote service.
TLS + SASL provides strong identity verification but requires a
obtaining a digital certificate by a trusted CA (or the XMPP
Intermediate Certification Authority) and using it in the XMPP
service, which may be hosted by a 3rd party. This solution does not
allow for multiplexing traffic for multiple domain pairs over a
connection, possibly requiring a large number of connections between
two hosting providers.
Server Dialback can be used with TLS. When STARTTLS negotiation
succeeds with a peer service but the peer's certificate cannot be
used to establish the peer's identity, the remote domain may use on
Server Dialback for (weak) identity verification. One use case can
be an originating server that wish to use TLS for encryption, but
only can present a self signed certificate.
In practice, many XMPP server deployments rely on Server Dialback and
either do not support XMPP 1.0 or do not offer negotiation of TLS +
SASL.
This goal of this document is to describe secure authentication using
a hosting provide TLS certificate from a trusted CA, combined with a
dialback mechanism providing secure delegation based on DNS record
delgation verified using DNSSEC.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
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We will refer to four different types of domains in this document:
o Sender domain: The domain that initially sends out an XMPP message
o Target domain: The ultimate destination of an XMPP message
o Originating domain: The originating domain of a particular server-
to-server connection
o Receiving domain: The receiving domain of a particular server-to-
server connection
In outsourcing scenarios, the sending and receiving domains are
outsourced to the originating and receiving domains, respectively.
3. Protocol Overview
Consider a scenario in which the domain sender.tld has outsourced
XMPP services to originating.tld, and target.tld has outsourced to
receiving.tld. The particular hosts providing services are
xmpp1.originating.tld and xmpp1.receiving.tld. Users
romeo@sender.tld and juliet@target.tld maintain client-to-server
connections to these servers.
romeo@sender.tld -- xmpp1.originating.tld
.
.
xmpp1.receiving.tld -- juliet@target.tld
When Romeo wants to send a message to Juliet, Provider A's server
will have to establish a server-to-server connection to Provider B's
server. Since they are both acting on behalf of other domains,
however, each side will have to verify that the other is authorized
to act in that role.
The first step is to provision records that can be used to verify
these delegations. In order for XMPP to work, when the hosting
relationships are set up, sender.tld and target.tld have to provision
SRV records pointing to their providers' servers. To make this
delegation secure, they sign these records using DNSSEC [RFC4033].
On the XMPP servers themselves, the originating and receiving domains
provision certificates that can be used to authenticate the names
xmpp1.originating.tld and xmpp1.receiving.tld.
When Romeo wants to send a stanza to Juliet, he will first send it to
his server, xmpp1.originating.tld. Seeing that the 'to' domain of
the stanza is target.tld, the server will retrieve the SRV records
for _xmpp-server._tcp.target.tld, plus any associated DNSSEC records
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[RFC4034].
_xmpp-server._tcp.target.tld. 400 IN SRV
20 0 5269 xmpp1.receiving.tld
_xmpp-server._tcp.target.tld. 400 IN RRSIG
SRV 5 3 400 20030322173103 (
20030220173103 2642 _tcp.target.tld.
oJB1W6WNGv+ldvQ3WDG0MQkg5IEhjRip8WTr
PYGv07h108dUKGMeDPKijVCHX3DDKdfb+v6o
B9wfuh3DTJXUAfI/M0zmO/zz8bW0Rznl8O3t
GNazPwQKkRN20XPXV6nwwfoXmJQbsLNrLfkG
J5D6fwFm8nN+6pBzeDQfsS3Ap3o= )
If there are no DNSSEC records, or if the DNSSEC records do not
validate, then there is nothing new to do; the server simply connects
to the remote domain using normal XMPP procedures. If there is a
valid DNSSEC signature on the SRV record, then the server knows that
he can allow the remote server to authenticate as either target.tld
or xmpp1.receiving.tld.
Once the TLS connection is established, the two sides negotiate a
single bidirectional stream to run over it, using their own names:
I: <?xml version='1.0'?>
<stream:stream
from='xmpp1.originating.tld'
to='xmpp1.receiving.tld'
version='1.0'
xml:lang='en'
xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams'>
R: <?xml version='1.0'?>
<stream:stream
from='xmpp1.receiving.tld'
id='++TR84Sm6A3hnt3Q065SnAbbk3Y='
to='xmpp1.originating.tld'
version='1.0'
xml:lang='en'
xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams'>
R: <stream:features>
<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
<bidi xmlns='urn:xmpp:bidi'/>
</stream:features>
When this stream is created, it can immediately carry stanzas
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directly between the two servers. In order to send messages to and
from other domains, the servers have to authenticate and request
permission. So to send Romeo's stanza to Juliet,
xmpp1.originating.tld requests permission to send from sender.tld to
target.tld.
The originating server uses STARTTLS to set up a TLS connection. In
the ClientHello message initiating the connection, the
xmpp1.originating.tld includes a Server Name Indication extension set
to xmpp1.receiving.tld [RFC4366]. The remote server
xmpp1.receiving.tld responds to this request with a certificate for
its own name, xmpp1.receiving.tld and requests a client certificate
from the originating server. The originating server presents a
certificate for its own name, xmpp1.originating.tld.
At this point, the server xmpp1.originating.tld knows that
xmpp1.receiving.tld is authorized to represent either
xmpp1.receiving.tld (via the certificate) or target.tld (via DNSSEC).
The other server, xmpp1.receiving.tld knows only that the other
server repressents xmpp1.originating.tld.
Once the two servers have authenticated their own names over TLS,
they can request permission to send stanzas:
I: <db:result from='sender.tld' to='target.tld' />
Since xmpp1.receiving.tld doesn't yet know whether
xmpp1.originating.tld is authorized to represent sender.tld, it has
to check, using an abbreviated form of dialback. Just as the
Provider A server did earlier for target.tld, the Provider B server
looks up the SRV records for _xmpp-server._tcp.sender.tld and any
associated DNSSEC records. If there are no DNSSEC records or the
signature is not valid, then the server rejects the request to send
stanzas from that domain. If the record is DNSSEC-signed, then the
server checks that the server name in the SRV record is one of the
names authenticated for the remote side.
R: <db:result type='invalid' from='sender.tld' to='target.tld' />
On the other hand, if the DNSSEC signature is valid, then the server
can accept the request to send stanzas, and the two servers can
exchange stanzas for those domains.
R: <db:result type='valid' from'sender.tld' to='target.tld' />
I: <!-- stanza -->
Now that the two servers have established this connection, they can
re-used it for other stanzas and other domains. If either server
finds another domain that is delegated to the other server, it can
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send a <db:result> requesting permission to send stanzas for that
domain, and the other server will grant or deny permission after
checking the delegation.
The following figure summarizes the overal process:
Originating DNS Receiving
Server Server Server
----------- --------- --------
| | |
| Lookup _xmpp-server | |
| DNS SRV record for | |
| target.tld to find | |
| delegation of service | |
| to Receiving Server. | |
| Verify zone signature | |
| -----------------------> | |
| | |
| 'Receiving Server' | |
| <----------------------- | |
| | |
| |
| |
| <stream from='originating.tld' to='receiving.tld'> |
| --------------------------------------------------> |
| |
| <stream from='receiving.tld' to='originating.tld'> |
| <-------------------------------------------------- |
| |
| <features><starttls></features> |
| <-------------------------------------------------- |
| |
| <starttls/> |
| --------------------------------------------------> |
| |
| <proceed/> |
| <-------------------------------------------------- |
| |
| |
| <====================== TLS ======================> |
| |
| |
| <stream from='originating.tld' to='receiving.tld'> |
| --------------------------------------------------> |
| |
| <stream from='receiving.tld' to='originating.tld'> |
| <-------------------------------------------------- |
| |
| <features><bidi></features> |
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| <-------------------------------------------------- |
| |
| <db:result from='sender.tld' to='target.tld'/> |
| --------------------------------------------------> |
| |
| ... |
4. Connection Model
The core challenge for managing inter-server connections is the
multiplexing of stanzas for multiple domains onto a single transport-
layer connection. There are two key pieces of state associated with
this multiplexing: A list of domain names that have been
authenticated for use on a connection, and a table binding pairs of
domains that are authorized for a connection.
First table that a server maintains is a connection table. Each
entry in this table contains a connection and a set of domain names.
The domain names represent the set of names for which the remote
server has been authenticated, according to the procedures described
in Section Section 5. This set of domain names constrains the set of
domain pairs that can be bound to this channel; the remote server
cannot ask to transmit stanzas for an unauthenticated domain name.
+------------+---------------------+------------------------+
| Connection | Server Domain Names | Delegated Domain Names |
+------------+---------------------+------------------------+
| XXX | xmpp1.provider.com | capulet.example |
| YYY | xmpp2.provider.com | capulet.example |
| AAA | paris.example | paris.example |
+------------+---------------------+------------------------+
To determine how to handle incoming and outgoing stanzas, each server
maintains a channel binding table. Each row in the binding table
contains a "local" domain name, a "remote" domain name, and an
ordered list of connections. The identifier for a connection is the
stream ID for the single XMPP stream that it carries.
+------------------+-----------------+---------------+
| Local | Remote | Connections |
+------------------+-----------------+---------------+
| montague.example | capulet.example | XXX, YYY |
| laurence.example | capulet.example | AAA |
| laurence.example | paris.example | YYY, AAA |
+------------------+-----------------+---------------+
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The binding table acts as a routing table for outgoing stanzas and a
filter for incoming stanzas. When the server wishes to send a
stanza, it looks in the binding table for a row that has the 'from'
domain as the local domain and the 'to' domain as the remote domain.
If there is such a in the binding table, then the server MUST
transmit the on the first connection in the connection list. Thus,
in the above example, a stanza from montague.example to
capulet.example would be routed on channel XXX.
In the same way, when a server receives a stanza over a connection
from a remote server, it looks up the relevant entry in the binding
table, this time using the 'to' domain as the local domain and the
'from' domain as the remote domain. If the server finds a binding
table entry and the connection over which the stanza arrived is
listed in the entry, then it accepts the stanza. Otherwise, it MUST
discard the stanza and return a stanza error <invalid-connection/>.
In the above example, a stanza from capulet.example to
escalus.example would be accepted on connections AAA and BBB, but no
others.
When a connection is opened (and at some points thereafter), entries
in the name table are established using the processes in Section
Section 5. Once a connection is open, binding table entries are
added or removed using the processes in Section Section 6. When a
connection is closed, both servers MUST delete its entry in the name
table and remove it from all entries in the binding table.
5. Channel Establishment and Authentication
When a server wants to send a stanza and doesn't have an entry in the
connection table for the destination domain, it sets one up. The
first step is to establish a connection to a server for the
destination domain, and validate that the server is authorized to
represent the destination domain.
The originating server MUST take the following steps to establish a
secure connection to the server for example.com:
1. Retrieve SRV records for XMPP services for example.com
[I-D.ietf-xmpp-3920bis].
2. Verify that the SRV records have been signed using DNSSEC
[RFC4033]. The originating server may either retrieve DNSSEC
records directly or rely on a validating resolver. If the SRV
records are not secured with DNSSEC, then the connection fails.
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3. If there is already a connection in the connection table that has
the target of any SRV record in its "server names" list, then
this process terminates and the server attempts to use that
connection (See Section Section 6)
4. If there is no existing connection that matches, establish a TCP
connection to any of the servers listed in an SRV record and
negotiate an XMPP stream with the following parameters:
* 'from' domain: The originating server's name
* 'to' domain: The receiving server's name from the SRV record
* [[ TODO: Add a stream feature to indicate support for this
extension ]]
5. Upgrade the connection to TLS using STARTTLS, using a cipher
suite that requires the server to present an X.509 certificate.
6. Verify that the certificate is valid and chains to a local trust
anchor. If the certificate is invalid, the connection fails.
7. Construct a list of all names that the certificate presents
[I-D.saintandre-tls-server-id-check].
8. Verify that the target name in the SRV record is one of the names
in the certificate. If the target name is not found in the list
of names from the certificate, then the connection fails.
A server receiving such a connection MUST perform the following
steps:
1. Accept the TCP connection from the remote side and accept the
stream negotiation using server names.
2. In the TLS negotiation, require a client certificate from the
remote side.
3. Verify that the remote server name in the stream matches the
client certificate [I-D.saintandre-tls-server-id-check]. If the
certificate does not match, the TLS negotiation fails, and the
server MAY terminate the TCP connection.
If this process establishes a new connection, then the originating
server knows that it has established a connection to a server that
legitimately represents example.com. It should thus initialize a row
in the connection table for this connection:
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o Server names: The list of names in the server's certificate
o Delegated names: example.com
If the process terminated at Step 3, then the server simply updates
the connection table entry to add example.com to the list of
delegated names. In either case, the row for a connection is removed
from the connection table when the connection is closed.
In order for this process to work, the domain owner and the hosting
provider need to publish information that other XMPP entities can use
to verify the delegation. XMPP services are delegated via SRV
records (see Section 3.2.1 of [I-D.ietf-xmpp-3920bis]), so in order
for the delegation to be secure, the domain owner MUST sign these
records with DNSSEC. In other words, if the delegated domain is
example.com, then the zone _xmpp-server._tcp.example.com MUST be
signed. Each server that acts for a domain MUST be provisioned with
a certificate that contains the target name used by SRV records.
The server on the receiving end of the TLS connection MUST request a
client certificate from the originating server during the TLS
handshake, and the originating server MUST provide a client
certificate. The receiving server can then also initialize an entry
in its connection table to which delegated names can be added later:
o Server names: The list of names from the client certificate (from
the originating server), if present. Otherwise, empty.
o Delgated names: Empty.
Once the two servers have established a TLS connection, they MUST set
up an XMPP stream that will be used for domains that they represent.
This process follows the normal stream initiation procedure
[I-D.ietf-xmpp-3920bis], except that the 'to' and 'from' domains MUST
be set to the names of the servers themselves: The originating server
sends a <stream> stanza with the 'from' domain set to a name for
itself that is contained in its client certificate, and the 'to'
domain set to the server name used in the SRV record for this
connection. If stream negotiation fails, then the connection fails.
If it succeeds, then both sides MUST set the connection identifier in
the connection table to be the stream ID for the negotiated stream.
Since server-to-server connections are by default directional, it is
RECOMMENDED that servers also request the <bidi> stream feature to
enable bidirectional flows on this connection [XEP-0288].
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Originating DNS Receiving
Server Server Server
----------- --------- --------
| | |
| Lookup _xmpp-server | |
| DNS SRV record for | |
| target.tld to find | |
| delegation of service | |
| to Receiving Server. | |
| Verify zone signature | |
| -----------------------> | |
| | |
| 'Receiving Server' | |
| <----------------------- | |
| | |
| |
| |
| <stream from='originating.tld' to='receiving.tld'> |
| --------------------------------------------------> |
| |
| <stream from='receiving.tld' to='originating.tld'> |
| <-------------------------------------------------- |
| |
| <features><starttls></features> |
| <-------------------------------------------------- |
| |
| <starttls/> |
| --------------------------------------------------> |
| |
| <proceed/> |
| <-------------------------------------------------- |
| |
| |
| <====================== TLS ======================> |
| |
| |
| <stream from='originating.tld' to='receiving.tld'> |
| --------------------------------------------------> |
| |
| <stream from='receiving.tld' to='originating.tld'> |
| <-------------------------------------------------- |
| |
| <features><bidi></features> |
| <-------------------------------------------------- |
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6. Authorizing XMPP Stanzas
Before sending traffic from a Sender Domain to a Target Domain using
an established connection, the originating server MUST request
permission to do so, and wait until it has received authorization
from the remote service. A service receiving traffic MUST verify
that the Sender and Target domain pair has been authorized on the
connection being used.
An originating server MUST go through the following steps to reqeust
authorization to send traffic from a Sender Domain to a Target
Domain:
1. Send a <db:result/> [XEP-0220] element with Sender Domain as
'from' and Target Domain as 'to'. The server may also include a
Dialback Key as part of the element's character data, to support
legacy deployments.
2. Wait for remote service to respond with a <db:result> with Target
Domain as 'from', Sender Domain as 'to' and 'type' attribute that
is either 'valid' or 'invalid'. In case of 'invalid', the
originating server SHOULD examine the error cause and take
appropriate action and MAY retry requesting authorization on the
same connection in the future.
3. If response 'type' was 'valid', the originating server updates
its binding table to indicate that Sender Domain (Local) and
Target Domain (Remote) is authorized in the sending direction for
the connection used.
4. Originating server proceeds with sending traffic from Sender
Domain to Target Domain.
Upon receiving a <db:result/> stanza, the receiving server MUST take
following steps:
1. Verify that the receiving direction is supported for this
connection. If not, fail by disconnecting the stream. (By
default, connections are one-way)
2. Verify that domain in to-attribute is hosted by the service. If
not, fail and respond with an <item-not-found/> error.
3. Verify that domain in from-attribute delegates hosting of their
XMPP to the remote Server Domain Name by looking up SRV and
verifying that the zone is signed. If not, fail with a <not-
authorized/> error. Note: a service MAY accept a less secure
delegation mechanism such a SRV records in a non signed zone,
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subject to local policy.
4. Once secure delegation from Sending Domain to remote Server
Domain name has been verified, service adds Sending Domain to
list of Delegated Domain Names in the Connection Table, and
updates the Binding Table indicating that the Sending Domain
(remote) is allowed to send traffic to Target Domain (local) on
the connection.
5. Respond to remote service with a <db:result/> stanza with 'type'
set to 'valid'.
A service may revoke authorization for a domain pair at any time by
sending a <db:result> with 'type' set to invalid. Once authorization
has been revoked, the remote side MUST re-aquire authorization before
sending any futher traffic for the domain pair.
If a server receives a stanza for a to/from pair that it does not
consider authorized, then it MUST return a <not-authorized/> error
and MAY terminate the TCP connection.
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Originating Receiving DNS
Server Server Server
----------- --------- --------
| | |
| <db:result | |
| from='sender.tld' | |
| to='target.tld'/> | |
| -----------------------> | |
| | Lookup _xmpp-server |
| | DNS SRV record for |
| | sender.tld to verify |
| | signed delegation of |
| | delegation of service |
| | to Originating Server |
| | -----------------------> |
| | |
| | Result |
| | <----------------------- |
| |
| <db:result |
| from='target.tld' |
| to='sender.tld' |
| type='valid'/> |
| <----------------------- |
| |
| (Traffic authorized |
| from sender.tld to |
| target.tld, in one |
| direction.) |
| |
| <message |
| from='r@sender.tld' |
| to='j@target.tld'> |
| <body>hi</body> |
| </message> |
| -----------------------> |
7. Backward Compatibility
Using Server Domain Names as to/from attributes in <stream> stanzas
is incompatible with XMPP services that do not support this protocol,
because it was previously assumed that when receiving a connection
the stream to attibute will contains an XMPP domain hosted by the
receiving service. It is RECOMMENDED that if the connection fails,
the service tries again using the Remote Domain as stream to-
attribute.
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Presenting a certificate for the Server Domain Name is incompatible
with XMPP services that do not support this protocol, because those
will expect the Remote Domain in the certificate. It is RECOMMENDED
that if the authorization fails, the service tries again presenting
the certificate for the Remote Domain. A service may also choose to
fall back on a weaker identification mechanism such as Server
Dialback, subject to local policy.
8. Operational Considerations
[[ What names to put in certs for servers in a cluster, i.e., all of
them. ]]
[[ Do TLS clients support multiple names in certs? ]]
[[ How DNSSEC validation is done can vary depending on deployment
scenario. ]]
[[ Since SNI is used to signal support for this extension,
recommended not to serve end users on the same domain as hosting
services. ]]
[[ Load balancing thoughts, since each connection will handle a lot
more traffic? ]]
9. IANA Considerations
[[ Register XML schema for assertions, if necessary ]]
[[ Define invalid-connection error element ]]
10. Security Considerations
[[ This document simplifies authentication and authorization of XMPP
servers in certain scenarios. When used together with DNSSEC-
protected delegations, it does not introduce any new security risks.
]]
[[ If a provider chooses to omit DNSSEC checks or ]]
11. Acknowledgements
Thanks to Joe Hildebrand and Sean Turner for prompting the original
work on this problem, and to Stephen Farrell for his work on initial
Barnes & Lindberg Expires September 15, 2011 [Page 16]
Internet-Draft DNA March 2011
versions of this draft.
12. Normative References
[I-D.ietf-xmpp-3920bis]
Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", draft-ietf-xmpp-3920bis-22 (work
in progress), December 2010.
[I-D.saintandre-tls-server-id-check]
Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", draft-saintandre-tls-server-id-check-14
(work in progress), January 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, March 2005.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, March 2005.
[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
and T. Wright, "Transport Layer Security (TLS)
Extensions", RFC 4366, April 2006.
[XEP-0220]
Miller, J., Saint-Andre, P., and P. Hancke, "Server
Dialback", XSF XEP 0220, March 2010.
[XEP-0288]
Hancke, P. and D. Cridland, "Bidirectional Server-to-
Server Connections", XSF XEP 0288, October 2010.
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Authors' Addresses
Richard L. Barnes
BBN Technologies
Email: rbarnes@bbn.com
Jonas Lindberg
Google
Email: jonasl@google.com
Barnes & Lindberg Expires September 15, 2011 [Page 18]
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