draft-ietf-6man-dns-options-bis-03.txt   draft-ietf-6man-dns-options-bis-04.txt 
Network Working Group J. Jeong Network Working Group J. Jeong
Internet-Draft Brocade/ETRI Internet-Draft Brocade/ETRI
Obsoletes: 5006 (if approved) S. Park Obsoletes: 5006 (if approved) S. Park
Intended status: Standards Track SAMSUNG Electronics Intended status: Standards Track SAMSUNG Electronics
Expires: December 11, 2010 L. Beloeil Expires: December 30, 2010 L. Beloeil
France Telecom R&D France Telecom R&D
S. Madanapalli S. Madanapalli
Ordyn Technologies Ordyn Technologies
June 9, 2010 June 28, 2010
IPv6 Router Advertisement Options for DNS Configuration RFC 5006-bis IPv6 Router Advertisement Options for DNS Configuration RFC 5006-bis
draft-ietf-6man-dns-options-bis-03 draft-ietf-6man-dns-options-bis-04
Abstract Abstract
This document specifies IPv6 Router Advertisement options to allow This document specifies IPv6 Router Advertisement options to allow
IPv6 routers to advertise a list of DNS recursive server addresses IPv6 routers to advertise a list of DNS recursive server addresses
and a DNS search list to IPv6 hosts. and a DNS search list to IPv6 hosts.
Status of This Memo Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
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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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on December 11, 2010. This Internet-Draft will expire on December 30, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Configuration . . . . . . . . . . . . . . . . . . . . . . 4 Configuration . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Neighbor Discovery Extension . . . . . . . . . . . . . . . . . 5 5. Neighbor Discovery Extension . . . . . . . . . . . . . . . . . 5
5.1. Recursive DNS Server Option . . . . . . . . . . . . . . . 5 5.1. Recursive DNS Server Option . . . . . . . . . . . . . . . 5
5.2. DNS Search List Option . . . . . . . . . . . . . . . . . . 7 5.2. DNS Search List Option . . . . . . . . . . . . . . . . . . 7
5.3. Procedure of DNS Configuration . . . . . . . . . . . . . . 8 5.3. Procedure of DNS Configuration . . . . . . . . . . . . . . 8
5.3.1. Procedure in IPv6 Host . . . . . . . . . . . . . . . . 8 5.3.1. Procedure in IPv6 Host . . . . . . . . . . . . . . . . 8
6. Implementation Considerations . . . . . . . . . . . . . . . . 9 6. Implementation Considerations . . . . . . . . . . . . . . . . 9
6.1. DNS Repository Management . . . . . . . . . . . . . . . . 9 6.1. DNS Repository Management . . . . . . . . . . . . . . . . 10
6.2. Synchronization between DNS Server List and Resolver 6.2. Synchronization between DNS Server List and Resolver
Repository . . . . . . . . . . . . . . . . . . . . . . . . 10 Repository . . . . . . . . . . . . . . . . . . . . . . . . 10
6.3. Synchronization between DNS Search List and Resolver 6.3. Synchronization between DNS Search List and Resolver
Repository . . . . . . . . . . . . . . . . . . . . . . . . 11 Repository . . . . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.1. Normative References . . . . . . . . . . . . . . . . . . . 13 10.1. Normative References . . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . . 14 10.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. Changes from RFC 5006 . . . . . . . . . . . . . . . . 15 Appendix A. Changes from RFC 5006 . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
The purpose of this document is to standardize IPv6 Router The purpose of this document is to standardize IPv6 Router
Advertisement (RA) option for DNS configuration in IPv6 hosts Advertisement (RA) option for DNS configuration in IPv6 hosts
specified in an earlier experimental specification [RFC5006] and also specified in an earlier experimental specification [RFC5006] and also
to define a new RA option for Domain Name Search lists. to define a new RA option for Domain Name Search lists.
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first data structure is the DNS Server List for RDNSS addresses first data structure is the DNS Server List for RDNSS addresses
and the second is the DNS Search List for DNS search domain names. and the second is the DNS Search List for DNS search domain names.
o Resolver Repository: Configuration repository with RDNSS addresses o Resolver Repository: Configuration repository with RDNSS addresses
and a DNS search list that a DNS resolver on the host uses for DNS and a DNS search list that a DNS resolver on the host uses for DNS
name resolution; for example, the Unix resolver file (i.e., /etc/ name resolution; for example, the Unix resolver file (i.e., /etc/
resolv.conf) and Windows registry. resolv.conf) and Windows registry.
4. Overview 4. Overview
This document standardizes the ND option called RDNSS option defined This document standardizes the ND option called the RDNSS option
in [RFC5006] that contains the addresses of recursive DNS servers. defined in [RFC5006] that contains the addresses of recursive DNS
This document also defines a new ND option called DNSSL option for servers. This document also defines a new ND option called the DNSSL
Domain Search List. This is to maintain parity with the DHCPv6 option for Domain Search List. This is to maintain parity with the
options and to ensure that there is necessary functionality to DHCPv6 options and to ensure that there is necessary functionality to
determine the search domains. determine the search domains.
Existing ND message (i.e., Router Advertisement) is used to carry The existing ND message (i.e., Router Advertisement) is used to carry
this information. An IPv6 host can configure the IPv6 addresses of this information. An IPv6 host can configure the IPv6 addresses of
one or more RDNSSes via RA messages. Through the RDNSS and DNSSL one or more RDNSSes via RA messages. Through the RDNSS and DNSSL
options, along with the prefix information option based on the ND options, along with the prefix information option based on the ND
protocol ([RFC4861] and [RFC4862]), an IPv6 host can perform the protocol ([RFC4861] and [RFC4862]), an IPv6 host can perform the
network configuration of its IPv6 address and the DNS information network configuration of its IPv6 address and the DNS information
simultaneously without needing DHCPv6 for the DNS configuration. The simultaneously without needing DHCPv6 for the DNS configuration. The
RA options for RDNSS and DNSSL can be used on any network that RA options for RDNSS and DNSSL can be used on any network that
supports the use of ND. supports the use of ND.
This approach requires the manual configuration or other automatic This approach requires the manual configuration or other automatic
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IPv6 addresses in the option. IPv6 addresses in the option.
Lifetime 32-bit unsigned integer. The maximum time, in Lifetime 32-bit unsigned integer. The maximum time, in
seconds (relative to the time the packet is sent), seconds (relative to the time the packet is sent),
over which this RDNSS address MAY be used for name over which this RDNSS address MAY be used for name
resolution. Hosts MAY send a Router Solicitation to resolution. Hosts MAY send a Router Solicitation to
ensure the RDNSS information is fresh before the ensure the RDNSS information is fresh before the
interval expires. In order to provide fixed hosts interval expires. In order to provide fixed hosts
with stable DNS service and allow mobile hosts to with stable DNS service and allow mobile hosts to
prefer local RDNSSes to remote RDNSSes, the value of prefer local RDNSSes to remote RDNSSes, the value of
Lifetime should be at least as long as the Maximum RA Lifetime SHOULD be bounded as MaxRtrAdvInterval <=
Interval (MaxRtrAdvInterval) in [RFC4861], and be at Lifetime <= 2*MaxRtrAdvInterval where
most as long as two times MaxRtrAdvInterval; Lifetime MaxRtrAdvInterval is the Maximum RA Interval defined
SHOULD be bounded as follows: MaxRtrAdvInterval <= in [RFC4861]. A value of all one bits (0xffffffff)
Lifetime <= 2*MaxRtrAdvInterval. A value of all one represents infinity. A value of zero means that
bits (0xffffffff) represents infinity. A value of the RDNSS address MUST no longer be used.
zero means that the RDNSS address MUST no longer be
used.
Addresses of IPv6 Recursive DNS Servers Addresses of IPv6 Recursive DNS Servers
One or more 128-bit IPv6 addresses of the recursive One or more 128-bit IPv6 addresses of the recursive
DNS servers. The number of addresses is determined DNS servers. The number of addresses is determined
by the Length field. That is, the number of by the Length field. That is, the number of
addresses is equal to (Length - 1) / 2. addresses is equal to (Length - 1) / 2.
5.2. DNS Search List Option 5.2. DNS Search List Option
The DNSSL option contains one or more domain names of DNS suffixes. The DNSSL option contains one or more domain names of DNS suffixes.
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| Lifetime | | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
: Domain Names of DNS Search List : : Domain Names of DNS Search List :
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: DNS Search List (DNSSL) Option Format Figure 2: DNS Search List (DNSSL) Option Format
Fields: Fields:
Type 8-bit identifier of the RDNSS option type as assigned Type 8-bit identifier of the DNSSL option type as assigned
by the IANA: (TBD) by the IANA: (TBD)
Length 8-bit unsigned integer. The length of the option Length 8-bit unsigned integer. The length of the option
(including the Type and Length fields) is in units of (including the Type and Length fields) is in units of
8 octets. The minimum value is 2 if at least one 8 octets. The minimum value is 2 if at least one
domain name is contained in the option. The Length domain name is contained in the option. The Length
field is set to a multiple of 8 octets to accommodate field is set to a multiple of 8 octets to accommodate
all the domain names in the field of Domain Names of all the domain names in the field of Domain Names of
DNS Search List. DNS Search List.
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are. Note that for the simple decoding, the domain are. Note that for the simple decoding, the domain
names MUST NOT be encoded in a compressed form, as names MUST NOT be encoded in a compressed form, as
described in Section 4.1.4 of [RFC1035]. Because the described in Section 4.1.4 of [RFC1035]. Because the
size of this field MUST be a multiple of 8 octets, size of this field MUST be a multiple of 8 octets,
for the minimum multiple including the domain name for the minimum multiple including the domain name
representations, the remaining octets other than the representations, the remaining octets other than the
encoding parts of the domain name representations encoding parts of the domain name representations
MUST be padded with zeros. MUST be padded with zeros.
Note: An RDNSS address or a DNSSL domain name MUST be used only as Note: An RDNSS address or a DNSSL domain name MUST be used only as
long as both the RA router lifetime and the option lifetime have long as both the RA router lifetime (advertised by a Router
not expired. The reason is that in the current network to which Advertisement message [RFC4861]) and the corresponding option
an IPv6 host is connected, the RDNSS may not be currently lifetime have not expired. The reason is that in the current
reachable, that the DNSSL domain name is not valid any more, or network to which an IPv6 host is connected, the RDNSS may not be
that these options do not provide service to the host's current currently reachable, that the DNSSL domain name is not valid any
address (e.g., due to network ingress filtering more, or that these options do not provide service to the host's
current address (e.g., due to network ingress filtering
[RFC2827][RFC5358]). [RFC2827][RFC5358]).
5.3. Procedure of DNS Configuration 5.3. Procedure of DNS Configuration
The procedure of DNS configuration through the RDNSS and DNSSL The procedure of DNS configuration through the RDNSS and DNSSL
options is the same as with any other ND option [RFC4861]. options is the same as with any other ND option [RFC4861].
5.3.1. Procedure in IPv6 Host 5.3.1. Procedure in IPv6 Host
When an IPv6 host receives DNS options (i.e., RDNSS option and DNSSL When an IPv6 host receives DNS options (i.e., RDNSS option and DNSSL
option) through RA messages, it checks whether the options are valid option) through RA messages, it processes the options as follows:
or not as follow:
o The validity of DNS options is checked with the Length field; that
is, the value of the Length field in the RDNSS option is greater
than or equal to the minimum value (3) and also the value of the
Length field in the DNSSL option is greater than or equal to the
minimum value (2).
o If the DNS options are valid, the host SHOULD copy the values of o If the DNS options are valid, the host SHOULD copy the values of
the options into the DNS Repository and the Resolver Repository in the options into the DNS Repository and the Resolver Repository in
order; the value of the Length field in the RDNSS option is order. Otherwise, the host MUST discard the options. Refer to
greater than or equal to the minimum value (3) and also the value Section 6 for the detailed procedure.
of the Length field in the DNSSL option is greater than or equal
to the minimum value (2).
o If the DNS options are invalid, the host MUST discard the options;
for example, the Length field in the RDNSS option has a value less
than 3 or the Length field in the DNSSL option has a value less
than 2.
When the IPv6 host has gathered a sufficient number (e.g., three) of When the IPv6 host has gathered a sufficient number (e.g., three) of
RDNSS addresses (or DNS search domain names), it MAY ignore RDNSS addresses (or DNS search domain names), it SHOULD maintain
additional RDNSS addresses (or DNS search domain names) within an RDNSS addresses (or DNS search domain names) by the sufficient number
RDNSS (or DNSSL) option and/or additional RDNSS (or DNSSL) options such that the latest received RDNSS or DNSSL is more preferred to the
within an RA. old ones; that is, when the number of RDNSS addresses (or DNS search
domain names) is already the sufficient number, the new one replaces
the old one that will expire first in terms of Lifetime. As an
exceptional case, if the received RDNSS addresses (or DNS search
domain names) already exist in the IPv6 host, their Lifetime fields
update their expiration time, that is, when the corresponding DNS
information expires in the IPv6 host; note that when the Lifetime
field has zero, the corresponding RDNSS (or DNS search domain name)
is deleted from the IPv6 host. Except for this update, the IPv6 host
SHOULD ignore other RDNSS addresses (or DNS search domain names)
within an RDNSS (or a DNSSL) option and/or additional RDNSS (or
DNSSL) options within an RA. Refer to Section 6 for the detailed
procedure. Note that the sufficient number is a system parameter, so
it can be determined by a local policy. Also, separate parameters
can be specified for the sufficient number of RDNSS addresses and
that of DNS search domain names, respectively. In this document,
three is RECOMMENDED as a sufficient number considering both the
robust DNS query and the reasonably time-bounded recognition of the
unreachability of DNS servers.
In the case where the DNS options of RDNSS and DNSSL can be obtained In the case where the DNS options of RDNSS and DNSSL can be obtained
from multiple sources, such as RA and DHCP, the IPv6 host can keep from multiple sources, such as RA and DHCP, the IPv6 host SHOULD keep
some DNS options from RA and some from DHCP; for example, two RDNSS some DNS options from all sources. Unless explicitly specified for
addresses (or DNS search domain names) from RA and one RDNSS address the discovery mechanism, the exact number of addresses and domain
(or DNS search domain name) from DHCP. names to keep is a matter of local policy and implementation choice.
However, it is RECOMMENDED that at least three RDNSS addresses (or
DNSSL domain names) can be stored from at least two different
sources. The DNS options from Router Advertisements and DHCP SHOULD
be stored into DNS Repository and Resolver Repository so that
information from DHCP appears there first and therefore takes
precedence.
6. Implementation Considerations 6. Implementation Considerations
Note: This non-normative section gives some hints for implementing Note: This non-normative section gives some hints for implementing
the processing of the RDNSS and DNSSL options in an IPv6 host. the processing of the RDNSS and DNSSL options in an IPv6 host.
For the configuration and management of DNS information, the For the configuration and management of DNS information, the
advertised DNS configuration information can be stored and managed in advertised DNS configuration information can be stored and managed in
both the DNS Repository and the Resolver Repository. both the DNS Repository and the Resolver Repository.
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DNSSL option), this field is updated to have a new expiration DNSSL option), this field is updated to have a new expiration
time. When Expiration-time becomes less than the current system time. When Expiration-time becomes less than the current system
time, this entry is regarded as expired. time, this entry is regarded as expired.
6.2. Synchronization between DNS Server List and Resolver Repository 6.2. Synchronization between DNS Server List and Resolver Repository
When an IPv6 host receives the information of multiple RDNSS When an IPv6 host receives the information of multiple RDNSS
addresses within a network (e.g., campus network and company network) addresses within a network (e.g., campus network and company network)
through an RA message with RDNSS option(s), it stores the RDNSS through an RA message with RDNSS option(s), it stores the RDNSS
addresses (in order) into both the DNS Server List and the Resolver addresses (in order) into both the DNS Server List and the Resolver
Repository. The processing of the RDNSS option(s) included in an RA Repository. The processing of the RDNSS consists of (i) the
message is as follows: processing of RDNSS option(s) included in an RA message and (ii) the
handling of expired RDNSSes. The processing of RDNSS option(s) is as
follows:
Step (a): Receive and parse the RDNSS option(s). For the RDNSS Step (a): Receive and parse the RDNSS option(s). For the RDNSS
addresses in each RDNSS option, perform Step (b) through Step (d). addresses in each RDNSS option, perform Step (b) through Step (d).
Note that Step (e) is performed whenever an entry expires in the
DNS Server List.
Step (b): For each RDNSS address, check the following: If the Step (b): For each RDNSS address, check the following: If the
RDNSS address already exists in the DNS Server List and the RDNSS RDNSS address already exists in the DNS Server List and the RDNSS
option's Lifetime field is set to zero, delete the corresponding option's Lifetime field is set to zero, delete the corresponding
RDNSS entry from both the DNS Server List and the Resolver RDNSS entry from both the DNS Server List and the Resolver
Repository in order to prevent the RDNSS address from being used Repository in order to prevent the RDNSS address from being used
any more for certain reasons in network management, e.g., the any more for certain reasons in network management, e.g., the
termination of the RDNSS or a renumbering situation. The termination of the RDNSS or a renumbering situation. The
processing of this RDNSS address is finished here. Otherwise, go processing of this RDNSS address is finished here. Otherwise, go
to Step (c). to Step (c).
Step (c): For each RDNSS address, if it already exists in the DNS Step (c): For each RDNSS address, if it already exists in the DNS
Server List, then just update the value of the Expiration-time Server List, then just update the value of the Expiration-time
field according to the procedure specified in the second bullet of field according to the procedure specified in the third bullet of
Section 6.1. Otherwise, go to Step (d). Section 6.1. Otherwise, go to Step (d).
Step (d): For each RDNSS address, if it does not exist in the DNS Step (d): For each RDNSS address, if it does not exist in the DNS
Server List, register the RDNSS address and lifetime with the DNS Server List, register the RDNSS address and lifetime with the DNS
Server List and then insert the RDNSS address in front of the Server List and then insert the RDNSS address in front of the
Resolver Repository. In the case where the data structure for the Resolver Repository. In the case where the data structure for the
DNS Server List is full of RDNSS entries, delete from the DNS DNS Server List is full of RDNSS entries (that is, has more
Server List the entry with the shortest expiration time (i.e., the RDNSSes than the sufficient number discussed in Section 5.3.1),
entry that will expire first). The corresponding RDNSS address is delete from the DNS Server List the entry with the shortest
also deleted from the Resolver Repository. In the order in the expiration time (i.e., the entry that will expire first). The
RDNSS option, position the newly added RDNSS addresses in front of corresponding RDNSS address is also deleted from the Resolver
the Resolver Repository so that the new RDNSS addresses may be Repository. For the ordering of RDNSS addresses in an RDNSS
option, position the first RDNSS address in the RDNSS option as
the first one in the Resolver Repository, the second RDNSS address
in the option as the second one in the repository, and so on.
This ordering allows the RDNSS addresses in the RDNSS option to be
preferred according to their order in the RDNSS option for the DNS preferred according to their order in the RDNSS option for the DNS
name resolution. The processing of these RDNSS addresses is name resolution. The processing of these RDNSS addresses is
finished here. Note that, in the case where there are several finished here.
routers advertising RDNSS option(s) in a subnet, the RDNSSes that
have been announced recently are preferred.
Step (e): Delete each expired entry from the DNS Server List, and The handling of expired RDNSSes is as follows: Whenever an entry
delete the RDNSS address corresponding to the entry from the expires in the DNS Server List, the expired entry is deleted from the
Resolver Repository. DNS Server List, and also the RDNSS address corresponding to the
entry is deleted from the Resolver Repository.
6.3. Synchronization between DNS Search List and Resolver Repository 6.3. Synchronization between DNS Search List and Resolver Repository
When an IPv6 host receives the information of multiple DNSSL domain When an IPv6 host receives the information of multiple DNSSL domain
names within a network (e.g., campus network and company network) names within a network (e.g., campus network and company network)
through an RA message with DNSSL option(s), it stores the DNSSL through an RA message with DNSSL option(s), it stores the DNSSL
domain names (in order) into both the DNS Search List and the domain names (in order) into both the DNS Search List and the
Resolver Repository. The processing of the DNSSL option(s) included Resolver Repository. The processing of the DNSSL consists of (i) the
in an RA message is as follows: processing of DNSSL option(s) included in an RA message and (ii) the
handling of expired DNSSLs. The processing of DNSSL option(s) is as
follows:
Step (a): Receive and parse the DNSSL option(s). For the DNSSL Step (a): Receive and parse the DNSSL option(s). For the DNSSL
domain names in each DNSSL option, perform Step (b) through Step domain names in each DNSSL option, perform Step (b) through Step
(d). Note that Step (e) is performed whenever an entry expires in (d).
the DNS Search List.
Step (b): For each DNSSL domain name, check the following: If the Step (b): For each DNSSL domain name, check the following: If the
DNSSL domain name already exists in the DNS Search List and the DNSSL domain name already exists in the DNS Search List and the
DNSSL option's Lifetime field is set to zero, delete the DNSSL option's Lifetime field is set to zero, delete the
corresponding DNSSL entry from both the DNS Search List and the corresponding DNSSL entry from both the DNS Search List and the
Resolver Repository in order to prevent the DNSSL domain name from Resolver Repository in order to prevent the DNSSL domain name from
being used any more for certain reasons in network management, being used any more for certain reasons in network management,
e.g., the termination of the RDNSS or a renaming situation. The e.g., the termination of the RDNSS or a renaming situation. The
processing of this DNSSL domain name is finished here. Otherwise, processing of this DNSSL domain name is finished here. Otherwise,
go to Step (c). go to Step (c).
Step (c): For each DNSSL domain name, if it already exists in the Step (c): For each DNSSL domain name, if it already exists in the
DNS Server List, then just update the value of the Expiration-time DNS Server List, then just update the value of the Expiration-time
field according to the procedure specified in the second bullet of field according to the procedure specified in the third bullet of
Section 6.1. Otherwise, go to Step (d). Section 6.1. Otherwise, go to Step (d).
Step (d): For each DNSSL domain name, if it does not exist in the Step (d): For each DNSSL domain name, if it does not exist in the
DNS Search List, register the DNSSL domain name and lifetime with DNS Search List, register the DNSSL domain name and lifetime with
the DNS Search List and then insert the DNSSL domain name in front the DNS Search List and then insert the DNSSL domain name in front
of the Resolver Repository. In the case where the data structure of the Resolver Repository. In the case where the data structure
for the DNS Search List is full of DNSSL domain name entries, for the DNS Search List is full of DNSSL domain name entries (that
delete from the DNS Server List the entry with the shortest is, has more DNSSL domain names than the sufficient number
expiration time (i.e., the entry that will expire first). The discussed in Section 5.3.1), delete from the DNS Server List the
corresponding DNSSL domain name is also deleted from the Resolver entry with the shortest expiration time (i.e., the entry that will
Repository. In the order in the DNSSL option, position the newly expire first). The corresponding DNSSL domain name is also
added DNSSL domain names in front of the Resolver Repository so deleted from the Resolver Repository. For the ordering of DNSSL
that the new DNSSL domain names may be preferred according to domain names in a DNSSL option, position the first DNSSL domain
their order in the DNSSL option for the DNS domain name used by name in the DNSSL option as the first one in the Resolver
Repository, the second DNSSL domain name in the option as the
second one in the repository, and so on. This ordering allows the
DNSSL domain names in the DNSSL option to be preferred according
to their order in the DNSSL option for the DNS domain name used by
the DNS query. The processing of these DNSSL domain name is the DNS query. The processing of these DNSSL domain name is
finished here. Note that, in the case where there are several finished here.
routers advertising DNSSL option(s) in a subnet, the DNSSL domain
names that have been announced recently are preferred.
Step (e): Delete each expired entry from the DNS Search List, and The handling of expired DNSSLs is as follows: Whenever an entry
delete the DNSSL domain name corresponding to the entry from the expires in the DNS Search List, the expired entry is deleted from
Resolver Repository. the DNS Search List, and also the DNSSL domain name corresponding
to the entry is deleted from the Resolver Repository.
7. Security Considerations 7. Security Considerations
The security of the RA options for DNS configuration does not affect The security of the RA options for DNS configuration does not affect
ND protocol security [RFC4861]. This is because learning DNS ND protocol security [RFC4861]. This is because learning DNS
information via the RA options cannot be worse than learning bad information via the RA options cannot be worse than learning bad
router information via the RA options. It can be claimed that the router information via the RA options. Thus, the vulnerability of ND
vulnerability of ND is not worse and is a subset of the attacks that is not worse and is a subset of the attacks that any node attached to
any node attached to a LAN can do independently of ND. A malicious a LAN can do independently of ND. A malicious node on a LAN can
node on a LAN can promiscuously receive packets for any router's MAC promiscuously receive packets for any router's MAC address and send
address and send packets with the router's MAC address as the source packets with the router's MAC address as the source MAC address in
MAC address in the L2 header. As a result, L2 switches send packets the L2 header. As a result, L2 switches send packets addressed to
addressed to the router to the malicious node. Also, this attack can the router to the malicious node. Also, this attack can send
send redirects that tell the hosts to send their traffic somewhere redirects that tell the hosts to send their traffic somewhere else.
else. The malicious node can send unsolicited RA or Neighbor The malicious node can send unsolicited RA or Neighbor Advertisement
Advertisement (NA) replies, answer RS or Neighbor Solicitation (NS) (NA) replies, answer RS or Neighbor Solicitation (NS) requests, etc.
requests, etc. Also, an attacker could configure a host to send out Also, an attacker could send an RA with a fraudulent RDNSS address,
an RA with a fraudulent RDNSS address, which is presumably an easier which is presumably an easier avenue of attack than becoming a rogue
avenue of attack than becoming a rogue router and having to process router and having to process all traffic for the subnet. This attack
all traffic for the subnet. It is necessary to disable the RA RDNSS is similar to Neighbor Discovery attacks that use Redirect or
option or DNSSL option in both routers and clients administratively Neighbor Advertisement messages to redirect traffic to individual
to avoid this problem. All of this can be done independently of addresses to malicious parties. In general, the attacks related to
implementing ND. Therefore, it can be claimed that the RA options RDNSS and DNSSL are similar to both Neighbor Discovery attacks and
for RDNSS and DNSSL has vulnerabilities similar to those existing in attacks against unauthenticated DHCP, as both can be used for both
unauthenticated DHCPv6. "wholesale" traffic redirection and more specific attacks.
It is common for network devices such as switches to include It is common for network devices such as switches to include
mechanisms to block unauthorized ports from running a DHCPv6 server mechanisms to block unauthorized ports from running a DHCPv6 server
to provide protection from rogue DHCP servers. That means that an to provide protection from rogue DHCP servers. That means that an
attacker on other ports cannot insert bogus DNS servers using DHCPv6. attacker on other ports cannot insert bogus DNS servers using DHCPv6.
The corresponding technique for network devices is recommended to The corresponding technique for network devices is recommended to
block rogue Router Advertisement messages including the RDNSS and block rogue Router Advertisement messages including the RDNSS and
DNSSL options from unauthorized nodes. DNSSL options from unauthorized nodes.
An attacker may provide a bogus DNS Search List option in order to An attacker may provide a bogus DNS Search List option in order to
skipping to change at page 15, line 46 skipping to change at page 16, line 31
Discovery Option type for DNSSL option. Discovery Option type for DNSSL option.
Authors' Addresses Authors' Addresses
Jaehoon Paul Jeong Jaehoon Paul Jeong
Brocade Communications Systems/ETRI Brocade Communications Systems/ETRI
6000 Nathan Ln N 6000 Nathan Ln N
Plymouth, MN 55442 Plymouth, MN 55442
USA USA
Phone: +1 763 268 7173 begin_of_the_skype_highlighting +1 763 268 7173 end_of_the_skype_highlighting Phone: +1 763 268 7173 +1 763 268 7173
Fax: +1 763 268 6800 Fax: +1 763 268 6800
EMail: pjeong@brocade.com EMail: pjeong@brocade.com
URI: http://www.cs.umn.edu/~jjeong/ URI: http://www.cs.umn.edu/~jjeong/
Soohong Daniel Park Soohong Daniel Park
Mobile Platform Laboratory Mobile Platform Laboratory
SAMSUNG Electronics SAMSUNG Electronics
416 Maetan-3dong, Yeongtong-Gu 416 Maetan-3dong, Yeongtong-Gu
Suwon, Gyeonggi-Do 443-742 Suwon, Gyeonggi-Do 443-742
Korea Korea
Phone: +82 31 200 4508 begin_of_the_skype_highlighting +82 31 200 4508 end_of_the_skype_highlighting Phone: +82 31 200 4508 +82 31 200 4508
EMail: soohong.park@samsung.com EMail: soohong.park@samsung.com
Luc Beloeil Luc Beloeil
France Telecom R&D France Telecom R&D
42, rue des coutures 42, rue des coutures
BP 6243 BP 6243
14066 CAEN Cedex 4 14066 CAEN Cedex 4
France France
Phone: +33 02 3175 9391 begin_of_the_skype_highlighting +33 02 3175 9391 end_of_the_skype_highlighting Phone: +33 2 40 44 97 40 +33 2 40 44 97 40
EMail: luc.beloeil@orange-ftgroup.com EMail: luc.beloeil@orange-ftgroup.com
Syam Madanapalli Syam Madanapalli
Ordyn Technologies Ordyn Technologies
1st Floor, Creator Building, ITPL 1st Floor, Creator Building, ITPL
Bangalore - 560066 Bangalore - 560066
India India
Phone: +91-80-40383000 begin_of_the_skype_highlighting +91-80-40383000 end_of_the_skype_highlighting Phone: +91-80-40383000 +91-80-40383000
EMail: smadanapalli@gmail.com EMail: smadanapalli@gmail.com
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