Network Working Group D. von Hugo
Internet-Draft Deutsche Telekom
Intended status: Standards Track B. Sarikaya
Expires: December 9, 2018 Denpel Informatique
T. Herbert
Quantonium
L. Iannone
Telecom ParisTech
June 7, 2018
Gap and Solution Space Analysis for End to End Privacy Enabled Mapping
System
draft-xyzy-atick-gaps-01.txt
Abstract
This document presents a gap and solution analysis for end-to-end
privacy enabled mapping systems. Each of the identifier locator
separation system has its own approach to mapping identifiers to the
locators. We analyse all these approaches and identify the gaps in
each of them and do a solution space analysis in an attempt to
identify a mapping system that can be end to end privacy enabled.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
3. Gap and Solution Space Analysis . . . . . . . . . . . . . . . 3
3.1. ILA . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. LISP . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. General Recommendations . . . . . . . . . . . . . . . . . . . 5
4.1. Security In the Data Path . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Identifier Locator Systems like ILA [I-D.herbert-intarea-ila], LISP
[I-D.ietf-lisp-rfc6830bis] [I-D.ietf-lisp-rfc6833bis] and others are
proposed as alternative approaches to enabling direct routing in the
upcoming converged communication networks such as 5G core network
(5GC) rather than using tunneling with GTP-U, GRE, (P)MIPv6 or
similar ones. In addition to increasing packet overhead due to
encapsulation that may cause fragmentation and all related issues
typical disadvantages of (especially static end-to-end) tunneling
comprise inflexibility to properly react to dynamic changes of end
points and potential on-path anchors. Added complexity in case of
multicast traffic and increased signaling for tunnel management are
further drawbacks. Tunnels may introduce vulnerabilities or add to
the potential for receiver overload and thus DOS attacks [draft-ietf-
intarea-tunnels-08]. Finally without other measures such as deep
packet inspection optimization of paths according to network
resources and application needs becomes complex.
With the Id-Loc systems a mapping system needs to be established so
that 5GC nodes or functions can access the identifier and locator
values of the destination given the source identifier and locator
values to enable them to route the packet towards the destination.
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For mapping systems there will be a trade-off between scalability and
rapid processing versus privacy and security of data.
A public distributed database such as the DNS is used by end hosts
for host name (or FQDN) to identifier mapping usually to start the
communication. DNS can be used to publicly access identifiers.
However, using DNS for locator access brings the issue that any node
in the internet can query and track the location of the roaming UEs
in 5G network which is not desirable. A separate database called a
mapping system needs to be used for identifier to locator mapping.
Such a mapping system need not be public in order to avoid that any
node can write new mapping pairs or ID-Loc bindings in such a
database.
2. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
See the definitions in [I-D.xyz-atick-ps].
3. Gap and Solution Space Analysis
3.1. ILA
ILA is currently using a distributed key value (KV) store for
identifier locator mapping [I-D.herbert-ila-ilamp]. The key value
NoSQL database also supports publish/subscribe where the senders or
publishers send the messages while the receivers or subscribers
receive them and the link by which the messages are transferred is
called channel. Such an approach avoids developing a request
response protocol in order to update the mapping database with new
identifier locator values or to access locator values for a given
identifier and also leverages all the recent developments for
security, availability, reliability, replication, etc. ILA
forwarding nodes (ILA-N) maintain caches of identifier locator values
learned so far but these values are UE specific. The ILA Mapping
Protocol (ILAMP) [I-D.herbert-ila-ilamp] is used between ILA
forwarding nodes and ILA mapping routers (ILA-R). The purpose of the
protocol is to populate and maintain the ILA mapping cache in
forwarding nodes. ILA-N sends Map Request message to ILA-R with a
list of identifiers and ILA-R replies with Map Information message
with identifier to locator mappings. ILA-R contains a horizontal
partition of the whole identifier locator database called a shard.
LISP style request/response protocol based mapping system can also be
used by ILA as defined in [I-D.rodrigueznatal-ila-lisp].
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Privacy is addressed in the data plane by way of UE simultaneously
using different addresses for different connections chosen from a
block of addresses. It is observed that NAT can also provide address
privacy but the use of NAT is discouraged in IETF. UE needs to
reestablish connections every time it changes its address so address
changing incurs delays which could be significant in case of real-
time communication unless connections can be made simultaneously
('make before break').
3.2. LISP
In LISP, FQDN to identifier or EID mappings are stored in DNS. The
LISP control-plane interface to the identifier-locator or EID-RLOC
mapping system is defined in [I-D.ietf-lisp-rfc6833bis]. The LISP
mapping transport system exists in three flavors: LISP-ALT RFC 6836
[RFC6836] LISP NERD RFC 6837 [RFC6837] and LISP-DDT RFC 8111
[RFC8111], respectively. LISP data plane nodes, Ingress/Egress
Tunnel Routers (ITR/ETR or xTR) registers mappings to the mapping
system by sending Map-Register messages to the Map-Server(s). The
Map Servers then publish these identifier locator values in the
mapping system. There is Map-Resolver which accepts Map-Request
messages from an ITR for the EID and returns the corresponding EID-
to-RLOC-set mappings by consulting mapping database system in a Map-
Reply message. All messages defined in the control plane are UDP
messages. All read and write operations to the mapping system are
authenticated with shared-keys using sha256 as well as ECDSA similar
to DNSSEC as well as origin authentication, integrity and anti-replay
protection [I-D.ietf-lisp-sec].
Note that ITRs keep a small scale identifier locator map of all
values learned so far called a cache. In LISP mapping system, the
lack of privacy support in the control plane for a given identifier
value exists. On the data plane, LISP allows to encrypt identifiers
[RFC8061]. Since ITR uses request/response exchange in getting the
locator values, until a resolution response is received, packets for
a flow may be blocked (like any other cache based solution),
depending on the implementation policy. This means a Denial of
Service attack on the ITR or cache has the worst case effect of
indefinitely blocking a legitimate flow. Also the cache in ITR may
raise privacy issue if EID-RLOC values for one UE is used for another
UE. However, there are proposals for LISP to use a Publish/Subscribe
approach [I-D.rodrigueznatal-lisp-pubsub]. While not yet explored,
in the current LISP specification nothing prevents from using privacy
addressing by way of UE simultaneously using different addresses for
different connections chosen from a block of addresses in the data
plane.
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4. General Recommendations
The use of new type of databases known as NoSQL databases organized
as Key-value stores or mapping systems is recommended. Such
databases will provide very efficient read and writes unlike DNS.
NoSQL mapping systems mostly support a message-oriented middleware
system called publish-subscribe or PubSub. In PubSub, publishers are
loosely coupled to subscribers and offer better scalability than
traditional client-server systems because of parallel operation,
message caching and network based message routing. Such systems
support sharding based on a shard key across different database
servers. Publish/subscribe mechanism takes cares of the request/
response mechanism commonly used in DNS or other mapping systems and
have better DDOS protection. Although a proposal exists as in
[I-D.herbert-ila-ilamp], how such a Key-value store will be
architectured in 5GC is not defined. Some guidelines for sharding
need to be developed. How the mapping database will be sharded based
on its identifier values as the key differently for each Id-Loc
system can be defined.
What is stored in the mapping system is limited to the identifier and
locator values and no considerations to provide privacy of the stored
data.
There are many privacy improving mechanisms defined like locator/
identifier privacy of frequent address changing of ILA, establishing
and managing security associations between participating entities
etc. Each of these techniques can be used by any Id-loc system.
There is a need to standardize these privacy techniques in order to
enable wide scale use by the end nodes.
4.1. Security In the Data Path
We address privacy problem for mapping systems: First we state the
Atick privacy model which can be summarized as privacy at every
levels. At the mapping system, the map data will be designed with
privacy considerations so that the access will be enabled only for
the allowed entities and disabled for any others. 5GC nodes/
functions that are ingress/egress nodes may have caches and a
protocol may be needed to communicate with other 5GC nodes that are
part of the mapping servers and contains a shard. 5GC nodes/functions
that are not ingress/egress nodes are considered part of the mapping
servers and they provide secure access to the mapping data and may
contain part of the mapping database. Privacy will be enabled in all
5GC nodes/functions that deal with the mapping database. Such
considerations will be implemented by way of the privacy additions to
the data stored in the mapping database. End hosts or UEs will be
able to have control over their own mapping records stored in the
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mapping database. End nodes or UEs that are unauthorized will not be
able to have access to the location data of another UE. The same
applies to the unauthorized entities or servers/functions in what 5G
architecture calls outside data network (DN).
5. IANA Considerations
TBD.
6. Security Considerations
7. Acknowledgements
8. References
8.1. Normative References
[I-D.ietf-lisp-rfc6830bis]
Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos-Aparicio, "The Locator/ID Separation Protocol
(LISP)", draft-ietf-lisp-rfc6830bis-12 (work in progress),
March 2018.
[I-D.ietf-lisp-rfc6833bis]
Fuller, V., Farinacci, D., and A. Cabellos-Aparicio,
"Locator/ID Separation Protocol (LISP) Control-Plane",
draft-ietf-lisp-rfc6833bis-10 (work in progress), March
2018.
[I-D.ietf-lisp-sec]
Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D.
Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-15
(work in progress), April 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<https://www.rfc-editor.org/info/rfc4941>.
[RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol Alternative Logical
Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836,
January 2013, <https://www.rfc-editor.org/info/rfc6836>.
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[RFC6837] Lear, E., "NERD: A Not-so-novel Endpoint ID (EID) to
Routing Locator (RLOC) Database", RFC 6837,
DOI 10.17487/RFC6837, January 2013,
<https://www.rfc-editor.org/info/rfc6837>.
[RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol
(LISP) Data-Plane Confidentiality", RFC 8061,
DOI 10.17487/RFC8061, February 2017,
<https://www.rfc-editor.org/info/rfc8061>.
[RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu,
"Recommendation on Stable IPv6 Interface Identifiers",
RFC 8064, DOI 10.17487/RFC8064, February 2017,
<https://www.rfc-editor.org/info/rfc8064>.
[RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A.
Smirnov, "Locator/ID Separation Protocol Delegated
Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111,
May 2017, <https://www.rfc-editor.org/info/rfc8111>.
8.2. Informative References
[I-D.herbert-ila-ilamp]
Herbert, T., "Identifier Locator Addressing Mapping
Protocol", draft-herbert-ila-ilamp-00 (work in progress),
December 2017.
[I-D.herbert-intarea-ila]
Herbert, T. and P. Lapukhov, "Identifier-locator
addressing for IPv6", draft-herbert-intarea-ila-01 (work
in progress), March 2018.
[I-D.ietf-intarea-tunnels]
Touch, J. and M. Townsley, "IP Tunnels in the Internet
Architecture", draft-ietf-intarea-tunnels-08 (work in
progress), January 2018.
[I-D.rodrigueznatal-ila-lisp]
Rodriguez-Natal, A., Ermagan, V., Maino, F., and A.
Cabellos-Aparicio, "LISP control-plane for Identifier
Locator Addressing (ILA)", draft-rodrigueznatal-ila-
lisp-01 (work in progress), April 2018.
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[I-D.rodrigueznatal-lisp-pubsub]
Rodriguez-Natal, A., Ermagan, V., Leong, J., Maino, F.,
Cabellos-Aparicio, A., Barkai, S., Farinacci, D.,
Boucadair, M., Jacquenet, C., and S. Secci, "Publish/
Subscribe Functionality for LISP", draft-rodrigueznatal-
lisp-pubsub-02 (work in progress), March 2018.
[I-D.xyz-atick-ps]
Hugo, D., Sarikaya, B., Iannone, L., and T. Herbert,
"Problem Statement for Secure End to End Privacy Enabled
Mapping System", draft-xyz-atick-ps-00 (work in progress),
May 2018.
[I-D.xyz-ideas-gap-analysis]
Qu, Y., Cabellos-Aparicio, A., Moskowitz, R., Liu, B., and
A. Stockmayer, "Gap Analysis for Identity Enabled
Networks", draft-xyz-ideas-gap-analysis-00 (work in
progress), July 2017.
Authors' Addresses
Dirk von Hugo
Deutsche Telekom
Deutsche-Telekom-Allee 7
D-64295 Darmstadt
Germany
Email: Dirk.von-Hugo@telekom.de
Behcet Sarikaya
Denpel Informatique
Email: sarikaya@ieee.org
Tom Herbert
Quantonium
Email: tom@quantonium.net
Luigi Iannone
Telecom ParisTech
Email: ggx@gigix.net
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