draft-ietf-dnsop-rfc7816bis-02.txt   draft-ietf-dnsop-rfc7816bis-03.txt 
Network Working Group S. Bortzmeyer Network Working Group S. Bortzmeyer
Internet-Draft AFNIC Internet-Draft AFNIC
Obsoletes: 7816 (if approved) P. Hoffman Obsoletes: 7816 (if approved) R. Dolmans
Intended status: Standards Track ICANN Intended status: Standards Track NLnet Labs
Expires: September 25, 2019 March 24, 2019 Expires: September 7, 2020 P. Hoffman
ICANN
March 6, 2020
DNS Query Name Minimisation to Improve Privacy DNS Query Name Minimisation to Improve Privacy
draft-ietf-dnsop-rfc7816bis-02 draft-ietf-dnsop-rfc7816bis-03
Abstract Abstract
This document describes techniques called "QNAME minimisation" to This document describes techniques called "QNAME minimisation" to
improve DNS privacy, where the DNS resolver no longer always sends improve DNS privacy, where the DNS resolver no longer always sends
the full original QNAME to the upstream name server. This document the full original QNAME to the upstream name server. This document
obsoletes RFC 7816. obsoletes RFC 7816.
This document is part of the IETF DNSOP (DNS Operations) Working This document is part of the IETF DNSOP (DNS Operations) Working
Group. The source of the document, as well as a list of open issues, Group. The source of the document, as well as a list of open issues,
skipping to change at page 1, line 44 skipping to change at page 1, line 46
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 25, 2019. This Internet-Draft will expire on September 7, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction and Background . . . . . . . . . . . . . . . . . 2 1. Introduction and Background . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. General Description of QNAME Minimisation . . . . . . . . . . 3 2. Description of QNAME Minimisation . . . . . . . . . . . . . . 3
2.1. Algorithm to Perform Aggressive Method QNAME Minimisation 5 2.1. Algorithm to Perform Aggressive Method QNAME Minimisation 5
3. Operational Considerations . . . . . . . . . . . . . . . . . 6 3. QNAME Minimisation Examples . . . . . . . . . . . . . . . . . 5
4. Performance Considerations . . . . . . . . . . . . . . . . . 8 4. Limit number of queries . . . . . . . . . . . . . . . . . . . 6
5. Alternative Methods for QNAME Minimisation . . . . . . . . . 9 5. Operational Considerations . . . . . . . . . . . . . . . . . 7
6. Results of the Experimentation . . . . . . . . . . . . . . . 9 6. Performance Considerations . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. Alternative Methods for QNAME Minimisation . . . . . . . . . 10
8. Implementation Status . . . . . . . . . . . . . . . . . . . . 10 8. Results of the Experimentation . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 11 10. Implementation Status . . . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 11 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 13 11.1. Normative References . . . . . . . . . . . . . . . . . . 12
Changes from RFC 7816 . . . . . . . . . . . . . . . . . . . . . . 13 11.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 14
Changes from RFC 7816 . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction and Background 1. Introduction and Background
The problem statement for this document and its predecessor [RFC7816] The problem statement for this document and its predecessor [RFC7816]
is described in [I-D.bortzmeyer-dprive-rfc7626-bis]. The terminology is described in [I-D.bortzmeyer-dprive-rfc7626-bis]. The terminology
("QNAME", "resolver", etc.) is defined in ("QNAME", "resolver", etc.) is defined in
[I-D.ietf-dnsop-terminology-bis]. This specific solution is not [I-D.ietf-dnsop-terminology-bis]. This specific solution is not
intended to fully solve the DNS privacy problem; instead, it should intended to fully solve the DNS privacy problem; instead, it should
be viewed as one tool amongst many. be viewed as one tool amongst many.
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A "cold" cache is one that is empty, having literally no entries in A "cold" cache is one that is empty, having literally no entries in
it. A "warm" cache is one that has some entries in it. it. A "warm" cache is one that has some entries in it.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. General Description of QNAME Minimisation 2. Description of QNAME Minimisation
The idea behind QNAME minimisation is to minimise the amount of data The idea behind QNAME minimisation is to minimise the amount of
sent from the DNS resolver to the authoritative name server. This privacy sensitive data sent from the DNS resolver to the
section describes the RECOMMENDED way to do QNAME minimisation -- the authoritative name server. This section describes the RECOMMENDED
way that maximises privacy benefits. That algorithm is summarized in way to do QNAME minimisation -- the way that maximises privacy
Section 2.1. benefits. That algorithm is summarized in Section 2.1.
Instead of sending the full QNAME and the original QTYPE upstream, a When a resolver is not able to answer a query from cache it has to
resolver that implements QNAME minimisation and does not already have send a query to an authoritative nameserver. Traditionally these
the answer in its cache sends a request to the name server queries would contain the full QNAME and the original QTYPE as
authoritative for the closest known ancestor of the original QNAME. received in the client query. The full QNAME and original QTYPE are
The request is done with: only needed at the nameserver that is authoritative for the record
requested by the client. All other nameservers queried while
resolving the query only need to receive enough of the QNAME to be
able to answer with a delegation. The QTYPE in these queries is not
relevant, as the nameserver is not authoritative to answer with the
records the client is looking for. Sending the full QNAME and
original QTYPE to these nameservers therefore exposes more privacy
sensitive data than necessary to resolve the client's request. A
resolver that implements QNAME minimisation changes the QNAME and
QTYPE in queries to authoritative nameserver that are not known to be
responsible for the original QNAME. These request are done with:
o a QTYPE selected by the resolver to hide the original QTYPE
o the QTYPE NS
o the QNAME that is the original QNAME, stripped to just one label o the QNAME that is the original QNAME, stripped to just one label
more than the zone for which the server is authoritative more than the longest matching domain name for which the
nameserver is known to be authoritative
This method is called the "aggressive method" in this document This method is called the "aggressive method" in this document
because the resolver only sends NS queries until it knows the because the resolver won't expose the original QTYPE to nameservers
nameserver responsible for the desired name. This method is the that are not known to be responsible for the desired name. This
safest from a privacy point of view, and is thus the RECOMMENDED method is the safest from a privacy point of view, and is thus the
method for this document. Other methods are described in Section 5. RECOMMENDED method for this document. Other methods are described in
Section 7.
For example, a resolver receives a request to resolve The QTYPE to use while minimising queries can be any possible data
foo.bar.baz.example. Assume that the resolver already knows that TYPE RRTYPE (rfc6895 #3.1) for which the authority always lies below
ns1.nic.example is authoritative for .example, and that the resolver the zone cut (i.e. not DS, NSEC, NSEC3, OPT, TSIG, TKEY, ANY, MAILA,
does not know a more specific authoritative name server. It will MAILB, AXFR, and IXFR), as long as there is no relation between the
send the query QTYPE=NS, QNAME=baz.example to ns1.nic.example. incoming QTYPE and the selection of the QTYPE to use while
minimising. A good candidate is to always use the A QTYPE as this is
the least likely to give issues at DNS software and middleboxes that
do not properly support all QTYPEs. The QTYPE=A queries will also
blend into traffic from non-minimising resolvers, making it in some
cases harder to observe that the resolving has QNAME minimisation
enabled.
The minimising resolver works perfectly when it knows the zone cut The minimising resolver works perfectly when it knows the zone cut
(zone cuts are described in Section 6 of [RFC2181]). But zone cuts (zone cuts are described in Section 6 of [RFC2181]). But zone cuts
do not necessarily exist at every label boundary. In the name do not necessarily exist at every label boundary. In the name
www.foo.bar.example, it is possible that there is a zone cut between www.foo.bar.example, it is possible that there is a zone cut between
"foo" and "bar" but not between "bar" and "example". So, assuming "foo" and "bar" but not between "bar" and "example". So, assuming
that the resolver already knows the name servers of .example, when it that the resolver already knows the name servers of example, when it
receives the query "What is the AAAA record of www.foo.bar.example?", receives the query "What is the AAAA record of www.foo.bar.example?",
it does not always know where the zone cut will be. To find the it does not always know where the zone cut will be. To find the
zone cut, it will query the .example name servers for the NS records zone cut, it will query the example name servers for a record for
for bar.example. It will get a NODATA response, indicating that bar.example. It will get a non-referral answer, it has to query the
there is no zone cut at that point, so it has to query the .example example name servers again with one more label, and so on.
name servers again with one more label, and so on. (Section 2.1 (Section 2.1 describes this algorithm in deeper detail.)
describes this algorithm in deeper detail.)
Here are more detailed examples of queries with the aggressive method
of QNAME minimisation:
Cold cache, aggressive method, request for www.isc.org:
QTYPE QNAME TARGET NOTE
NS org root nameserver
NS isc.org .org nameserver
NS www.isc.org isc.org nameserver "www" may be delegated
A www.isc.org isc.org nameserver
Cold cache, lazy algorithm (for a cold cache, it is the
same algorithm as now), request for www.isc.org:
QTYPE QNAME TARGET NOTE
A www.isc.org root nameserver
A www.isc.org .org nameserver
A www.isc.org isc.org nameserver
Warm cache (all NS RRsets are known), both algorithms, request for
www.isc.org:
QTYPE QNAME TARGET NOTE
A www.isc.org isc.org nameserver
Warm cache with only isc.org, (example.org's NS RRset is not known),
aggressive method, request for www.example.org:
QTYPE QNAME TARGET NOTE
NS example.org .org nameserver
NS www.example.org .example nameserver
A www.example.org .example nameserver
Since the information about the zone cuts will be stored in the
resolver's cache, the performance overhead for using the aggressive
method is probably reasonable. Section 4 discusses this performance
discrepancy further.
Note that DNSSEC-validating resolvers already have access to the zone
cut information because the DNSKEY record set is just below a zone
cut and the DS record set is just above it.
2.1. Algorithm to Perform Aggressive Method QNAME Minimisation 2.1. Algorithm to Perform Aggressive Method QNAME Minimisation
This algorithm performs name resolution with aggressive method QNAME This algorithm performs name resolution with aggressive method QNAME
minimisation in the presence of zone cuts that are not yet known. minimisation in the presence of zone cuts that are not yet known.
Although a validating resolver already has the logic to find the Although a validating resolver already has the logic to find the
zone cuts, implementers of other resolvers may want to use this zone cuts, implementers of other resolvers may want to use this
algorithm to locate the zone cuts. algorithm to locate the zone cuts.
(0) If the query can be answered from the cache, do so; otherwise, (0) If the query can be answered from the cache, do so; otherwise,
iterate as follows: iterate as follows:
(1) Find the closest enclosing NS RRset in your cache. The owner of (1) Get the closest delegation point that can be used for QNAME from
this NS RRset will be a suffix of the QNAME -- the longest suffix the cache. This is the NS RRset with the owner matching the most
of any NS RRset in the cache. Call this ANCESTOR. labels with the QNAME. The QNAME will be equal to or a subdomain
of this NS RRset. Call this ANCESTOR.
(2) Initialise CHILD to the same as ANCESTOR. (2) Initialise CHILD to the same as ANCESTOR.
(3) If CHILD is the same as the QNAME, resolve the original query (3) If CHILD is the same as the QNAME, resolve the original query
using ANCESTOR's name servers, and finish. using ANCESTOR's name servers, and finish.
(4) Otherwise, add a label from the QNAME to the start of CHILD. (4) Otherwise, add a label from the QNAME to the start of CHILD.
(5) If you have a negative cache entry for the NS RRset at CHILD, go (5) Look for a negative cache entry for the NS RRset at CHILD. If
back to step 3. this entry is for an NXDOMAIN and the resolver has support for
RFC8020 the NXDOMAIN can be used in response to the original
query, and stop. If the entry is for a NOERROR/NODATA answer go
back to step 3
(6) Query for CHILD IN NS using ANCESTOR's name servers. The (6) Query for CHILD with the minimised QTYPE using ANCESTOR's
response can be: name servers. The response can be:
(6a) A referral. Cache the NS RRset from the authority section, (6a) A referral. Cache the NS RRset from the authority section,
and go back to step 1. and go back to step 1.
(6b) An authoritative answer. Cache the NS RRset from the (6b) A NOERROR answer. Cache this answer, and go back to step 3.
answer section, and go back to step 1.
(6c) An NXDOMAIN answer. Return an NXDOMAIN answer in response (6c) An NXDOMAIN answer. Return an NXDOMAIN answer in response
to the original query, and stop. to the original query, and stop.
(6d) A NOERROR/NODATA answer. Cache this negative answer, and 3. QNAME Minimisation Examples
go back to step 3.
3. Operational Considerations For example, a resolver receives a request to resolve
foo.bar.baz.example. Assume that the resolver already knows that
ns1.nic.example is authoritative for .example, and that the resolver
does not know a more specific authoritative name server. It will
send the query QTYPE=NS, QNAME=baz.example to ns1.nic.example.
Here are more detailed examples of queries with the aggressive method
of QNAME minimisation:
Cold cache, traditional resolution algorithm without QNAME
minimisation, request for A record of a.b.example.org:
QTYPE QNAME TARGET NOTE
A a.b.example.org root nameserver
A a.b.example.org org nameserver
A a.b.example.org example.org nameserver
Cold cache, aggressive QNAME minimisation method, request for A
record of a.b.example.org, using NS QTYPE to hide the original QTYPE:
QTYPE QNAME TARGET NOTE
NS org root nameserver
NS example.org org nameserver
NS b.example.org example.org nameserver
NS a.b.example.org example.org nameserver "a" may be delegated
A a.b.example.org example.org nameserver
Warm cache with only org delegation known, (example.org's NS RRset is
not known), aggressive QNAME minimisation method, request for A
record of a.b.example.org, using NS QTYPE to hide the original QTYPE:
QTYPE QNAME TARGET NOTE
NS example.org org nameserver
NS b.example.org example.org nameserver
NS a.b.example.org example.org nameserver "a" may be delegated
A a.b.example.org example.org nameserver
4. Limit number of queries
When using QNAME minimisation the number of labels in the received
QNAME can influence the number of queries sent from the resolver.
This opens an attack vector and can decrease performance. Resolvers
supporting QNAME minimisation should implement a mechanism to limit
the number of outgoing queries per user request.
Take for example an incoming QNAME with many labels, like
www.host.group.department.example.com, where
host.group.department.example.com is hosted on example.com's
name servers). Assume a resolver that knows only the name servers of
example.com. Without QNAME minimisation, it would send these
example.com name servers a query for
www.host.group.department.example.com and immediately get a specific
referral or an answer, without the need for more queries to probe for
the zone cut. For such a name, a cold resolver with QNAME
minimisation will, depending on how QNAME minimisation is
implemented, send more queries, one per label. Once the cache is
warm, there will be no difference with a traditional resolver.
Actual testing is described in [Huque-QNAME-Min]. Such deep domains
are especially common under ip6.arpa.
This behaviour can be exploited by sending queries with a large
number of labels in the QNAME that will be answered using a wildcard
record. Take for example a record for *.example.com, hosted on
example.com's name servers. An incoming query containing a QNAME
with more than 100 labels, ending in example.com, will result in a
query per label. By using random labels the attacker can bypass the
caching and always require the resolver to send many queries
upstream. Note that RFC8198 can limit this attack in some cases.
One mechanism to reduce this attack vector is by sending more than
one label per iteration for QNAMEs with a large number of labels. To
do this a maximum number of QNAME minimisation iterations has to be
selected (MAX_MINIMISE_COUNT), a good value is 10. Optionally a
value for the number of queries that should only have one label
appended can be selected (MINIMISE_ONE_LAB), a good value is 4. The
assumption here is that the number of labels on delegations higher in
the hierarchy are rather small, therefore not exposing too may labels
early on has the most privacy benefit.
When a resolver needs to send out a query if will look for the
closest known delegation point in its cache. The number of QNAME
minimisation iterations is the difference between this closest
nameserver and the incoming QNAME. The first MINIMISE_ONE_LAB
iterations will be handles as described in Section 2. The number of
labels that are not exposed yet now need to be divided over the
iterations that are left (MAX_MINIMISE_COUNT - MINIMISE_ONE_LAB).
The remainder of the division should be added to the last iterations.
For example, when resolving a QNAME with 18 labels, the number of
labels added per iteration are: 1,1,1,1,2,2,2,2,3,3.
5. Operational Considerations
TODO may be remove the whole section now that it is no longer TODO may be remove the whole section now that it is no longer
experimental? experimental?
QNAME minimisation is legal, since the original DNS RFCs do not QNAME minimisation is legal, since the original DNS RFCs do not
mandate sending the full QNAME. So, in theory, it should work mandate sending the full QNAME. So, in theory, it should work
without any problems. However, in practice, some problems may occur without any problems. However, in practice, some problems may occur
(see [Huque-QNAME-Min] for an analysis and [Huque-QNAME-Discuss] for (see [Huque-QNAME-Min] for an analysis and [Huque-QNAME-Discuss] for
an interesting discussion on this topic). an interesting discussion on this topic).
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The administrators of the forwarders, and of the authoritative The administrators of the forwarders, and of the authoritative
name servers, will get less data, which will reduce the utility of name servers, will get less data, which will reduce the utility of
the statistics they can produce (such as the percentage of the the statistics they can produce (such as the percentage of the
various QTYPEs). various QTYPEs).
DNS administrators are reminded that the data on DNS requests that DNS administrators are reminded that the data on DNS requests that
they store may have legal consequences, depending on your they store may have legal consequences, depending on your
jurisdiction (check with your local lawyer). jurisdiction (check with your local lawyer).
4. Performance Considerations 6. Performance Considerations
The main goal of QNAME minimisation is to improve privacy by sending The main goal of QNAME minimisation is to improve privacy by sending
less data. However, it may have other advantages. For instance, if less data. However, it may have other advantages. For instance, if
a resolver sends a root name server queries for A.example followed by a resolver sends a root name server queries for A.example followed by
B.example followed by C.example, the result will be three NXDOMAINs, B.example followed by C.example, the result will be three NXDOMAINs,
since .example does not exist in the root zone. When using QNAME since .example does not exist in the root zone. When using QNAME
minimisation, the resolver would send only one question (for .example minimisation, the resolver would send only one question (for .example
itself) to which they could answer NXDOMAIN, thus opening up a itself) to which they could answer NXDOMAIN, thus opening up a
negative caching opportunity in which the full resolver could know a negative caching opportunity in which the full resolver could know a
priori that neither B.example nor C.example could exist. Thus, in priori that neither B.example nor C.example could exist. Thus, in
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minimisation could be counterintuitively less than the number of minimisation could be counterintuitively less than the number of
queries under the traditional iteration (as described in the DNS queries under the traditional iteration (as described in the DNS
standard). TODO mention [RFC8020]? And [RFC8198], the latter standard). TODO mention [RFC8020]? And [RFC8198], the latter
depending on DNSSEC? depending on DNSSEC?
QNAME minimisation may also improve lookup performance for TLD QNAME minimisation may also improve lookup performance for TLD
operators. For a TLD that is delegation-only, a two-label QNAME operators. For a TLD that is delegation-only, a two-label QNAME
query may be optimal for finding the delegation owner name, depending query may be optimal for finding the delegation owner name, depending
on the way domain matching is implemented. on the way domain matching is implemented.
QNAME minimisation can decrease performance in some cases, most QNAME minimisation can increase the number of queries based on the
notably for domain names with many labels (like incoming QNAME. This is described in Section 4.
www.host.group.department.example.com, where
host.group.department.example.com is hosted on example.com's
name servers). Assume a resolver that knows only the name servers of
example.com. Without QNAME minimisation, it would send these
example.com name servers a query for
www.host.group.department.example.com and immediately get a specific
referral or an answer, without the need for more queries to probe for
the zone cut. For such a name, a cold resolver with QNAME
minimisation will, depending on how QNAME minimisation is
implemented, send more queries, one per label. Once the cache is
warm, there will be no difference with a traditional resolver.
Actual testing is described in [Huque-QNAME-Min]. Such deep domains
are especially common under ip6.arpa.
5. Alternative Methods for QNAME Minimisation 7. Alternative Methods for QNAME Minimisation
One useful optimisation may be, in the spirit of the HAMMER idea One useful optimisation may be, in the spirit of the HAMMER idea
[HAMMER], The resolver can probe in advance for the introduction of [HAMMER], The resolver can probe in advance for the introduction of
zone cuts where none previously existed to confirm their continued zone cuts where none previously existed to confirm their continued
absence or to discover them. absence or to discover them.
To reduce the number of queries (an issue described in Section 4), a To reduce the number of queries (an issue described in Section 6), a
resolver could always use full name queries when the cache is cold resolver could always use full name queries when the cache is cold
and then to move to the aggressive method of QNAME minimisation when and then to move to the aggressive method of QNAME minimisation when
the cache is warm. (Precisely defining what is "warm" or "cold" is the cache is warm. (Precisely defining what is "warm" or "cold" is
left to the implementer). This will decrease the privacy for initial left to the implementer). This will decrease the privacy for initial
queries but will guarantee no degradation of performance. queries but will guarantee no degradation of performance.
Another possible algorithm, not fully studied at this time, could be Another possible algorithm, not fully studied at this time, could be
to "piggyback" on the traditional resolution code. At startup, it to "piggyback" on the traditional resolution code. At startup, it
sends traditional full QNAMEs and learns the zone cuts from the sends traditional full QNAMEs and learns the zone cuts from the
referrals received, then switches to NS queries asking only for the referrals received, then switches to NS queries asking only for the
minimum domain name. This leaks more data but could require fewer minimum domain name. This leaks more data but could require fewer
changes in the existing resolver codebase. changes in the existing resolver codebase.
6. Results of the Experimentation 8. Results of the Experimentation
TODO various experiences from actual deployments, problems heard. TODO various experiences from actual deployments, problems heard.
TODO the Knot bug #339 https://gitlab.labs.nic.cz/knot/knot-resolver/ TODO the Knot bug #339 https://gitlab.labs.nic.cz/knot/knot-resolver/
issues/339? TODO Problems with AWS https://forums.aws.amazon.com/ issues/339? TODO Problems with AWS https://forums.aws.amazon.com/
thread.jspa?threadID=269116? thread.jspa?threadID=269116?
7. Security Considerations 9. Security Considerations
QNAME minimisation's benefits are clear in the case where you want to QNAME minimisation's benefits are clear in the case where you want to
decrease exposure to the authoritative name server. But minimising decrease exposure to the authoritative name server. But minimising
the amount of data sent also, in part, addresses the case of a wire the amount of data sent also, in part, addresses the case of a wire
sniffer as well as the case of privacy invasion by the servers. sniffer as well as the case of privacy invasion by the servers.
(Encryption is of course a better defense against wire sniffers, but, (Encryption is of course a better defense against wire sniffers, but,
unlike QNAME minimisation, it changes the protocol and cannot be unlike QNAME minimisation, it changes the protocol and cannot be
deployed unilaterally. Also, the effect of QNAME minimisation on deployed unilaterally. Also, the effect of QNAME minimisation on
wire sniffers depends on whether the sniffer is on the DNS path.) wire sniffers depends on whether the sniffer is on the DNS path.)
QNAME minimisation offers zero protection against the recursive QNAME minimisation offers zero protection against the recursive
resolver, which still sees the full request coming from the stub resolver, which still sees the full request coming from the stub
resolver. resolver.
All the alternatives mentioned in Section 5 decrease privacy in the All the alternatives mentioned in Section 7 decrease privacy in the
hope of improving performance. They must not be used if you want hope of improving performance. They must not be used if you want
maximum privacy. maximum privacy.
8. Implementation Status 10. Implementation Status
\[\[ Note to RFC Editor: Remove this entire section, and the \[\[ Note to RFC Editor: Remove this entire section, and the
reference to RFC 7942, before publication. \]\] reference to RFC 7942, before publication. \]\]
This section records the status of known implementations of the This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942]. Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation RFCs. Please note that the listing of any individual implementation
skipping to change at page 11, line 16 skipping to change at page 12, line 24
% blaeu-resolve --requested 1000 --type TXT qnamemintest.internet.nl % blaeu-resolve --requested 1000 --type TXT qnamemintest.internet.nl
["no - qname minimisation is not enabled on your resolver :("] : 888 occurrences ["no - qname minimisation is not enabled on your resolver :("] : 888 occurrences
["hooray - qname minimisation is enabled on your resolver :)!"] : 105 occurrences ["hooray - qname minimisation is enabled on your resolver :)!"] : 105 occurrences
[ERROR: SERVFAIL] : 3 occurrences [ERROR: SERVFAIL] : 3 occurrences
Test #16113243 done at 2018-09-14T13:01:47Z Test #16113243 done at 2018-09-14T13:01:47Z
10 % of the probes have a resolver with QNAME minimisation (it is not 10 % of the probes have a resolver with QNAME minimisation (it is not
possible to infer the percentage of users having QNAME minimisation). possible to infer the percentage of users having QNAME minimisation).
9. References 11. References
9.1. Normative References 11.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>. <https://www.rfc-editor.org/info/rfc1034>.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>. November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
skipping to change at page 11, line 47 skipping to change at page 13, line 9
<https://www.rfc-editor.org/info/rfc6973>. <https://www.rfc-editor.org/info/rfc6973>.
[RFC7816] Bortzmeyer, S., "DNS Query Name Minimisation to Improve [RFC7816] Bortzmeyer, S., "DNS Query Name Minimisation to Improve
Privacy", RFC 7816, DOI 10.17487/RFC7816, March 2016, Privacy", RFC 7816, DOI 10.17487/RFC7816, March 2016,
<https://www.rfc-editor.org/info/rfc7816>. <https://www.rfc-editor.org/info/rfc7816>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 11.2. Informative References
[atlas-qname-min] [atlas-qname-min]
Bortzmeyer, S., "DNS resolution of Bortzmeyer, S., "DNS resolution of
qnamemintest.internet.nl/TXT on RIPE Atlas probes", qnamemintest.internet.nl/TXT on RIPE Atlas probes",
September 2018, September 2018,
<https://atlas.ripe.net/measurements/16113243/>. <https://atlas.ripe.net/measurements/16113243/>.
[DNS-Res-Improve] [DNS-Res-Improve]
Vixie, P., Joffe, R., and F. Neves, "Improvements to DNS Vixie, P., Joffe, R., and F. Neves, "Improvements to DNS
Resolvers for Resiliency, Robustness, and Responsiveness", Resolvers for Resiliency, Robustness, and Responsiveness",
skipping to change at page 13, line 42 skipping to change at page 14, line 46
Stephane Bortzmeyer Stephane Bortzmeyer
AFNIC AFNIC
1, rue Stephenson 1, rue Stephenson
Montigny-le-Bretonneux 78180 Montigny-le-Bretonneux 78180
France France
Phone: +33 1 39 30 83 46 Phone: +33 1 39 30 83 46
Email: bortzmeyer+ietf@nic.fr Email: bortzmeyer+ietf@nic.fr
URI: https://www.afnic.fr/ URI: https://www.afnic.fr/
Ralph Dolmans
NLnet Labs
Email: ralph@nlnetlabs.nl
Paul Hoffman Paul Hoffman
ICANN ICANN
Email: paul.hoffman@icann.org Email: paul.hoffman@icann.org
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