draft-ietf-mext-firewall-admin-01.txt   draft-ietf-mext-firewall-admin-02.txt 
Network Working Group S. Krishnan Network Working Group S. Krishnan
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Informational N. Steinleitner Intended status: Informational N. Steinleitner
Expires: November 20, 2009 University of Goettingen Expires: April 30, 2010 University of Goettingen
Y. Qiu Y. Qiu
Institute for Infocomm Research Institute for Infocomm Research
G. Bajko G. Bajko
Nokia Nokia
May 19, 2009 October 27, 2009
Guidelines for firewall administrators regarding MIPv6 traffic Guidelines for firewall administrators regarding MIPv6 traffic
draft-ietf-mext-firewall-admin-01 draft-ietf-mext-firewall-admin-02
Status of this Memo Status of this Memo
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Abstract Abstract
This document presents some recommendations for firewall This document presents some recommendations for firewall
administrators to help them configure their existing firewalls in a administrators to help them configure their existing firewalls in a
way that allows in certain deployment scenarios the Mobile IPv6 way that allows in certain deployment scenarios the Mobile IPv6 and
signaling and data messages to pass through. For other scenarios, DSMIPv6 signaling and data messages to pass through. For other
the support of additional mechanisms to create pinholes required for scenarios, the support of additional mechanisms to create pinholes
MIPv6 will be necessary. This document assumes that the firewalls in required for MIPv6 will be necessary. This document assumes that the
question include some kind of stateful packet filtering capability. firewalls in question include some kind of stateful packet filtering
capability.
Table of Contents Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 4 4. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 4
4.1. Signaling between the MN and the HA . . . . . . . . . . . 5 4.1. Signaling between the MN and the HA . . . . . . . . . . . 5
4.2. IKEv2 signaling between MN and HA for establishing SAs . . 5 4.2. IKEv2 signaling between MN and HA for establishing SAs . . 5
5. Correspondent Node behind a firewall . . . . . . . . . . . . . 5 5. Correspondent Node behind a firewall . . . . . . . . . . . . . 6
5.1. Route optimization signaling between MN and CN through 5.1. Route optimization signaling between MN and CN through
HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Route optimization signaling between MN and CN . . . . . . 6 5.2. Route optimization signaling between MN and CN . . . . . . 7
5.3. Binding Update from MN to CN . . . . . . . . . . . . . . . 7 5.3. Binding Update from MN to CN . . . . . . . . . . . . . . . 7
5.4. Route Optimization data traffic from MN . . . . . . . . . 7 5.4. Route Optimization data traffic from MN . . . . . . . . . 7
6. Mobile Node behind a firewall . . . . . . . . . . . . . . . . 7 6. Mobile Node behind a firewall . . . . . . . . . . . . . . . . 8
6.1. Signaling between MN and HA . . . . . . . . . . . . . . . 8 6.1. Signaling between MN and HA . . . . . . . . . . . . . . . 8
6.2. Signaling between MN and CN . . . . . . . . . . . . . . . 9 6.2. Data packets between DSMIPv6 . . . . . . . . . . . . . . . 9
6.3. IKEv2 signaling between MN and HA for establishing SAs . . 9 6.3. Signaling between MN and CN . . . . . . . . . . . . . . . 9
7. Related documents . . . . . . . . . . . . . . . . . . . . . . 9 6.4. IKEv2 signaling between MN and HA for establishing SAs . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 7. Related documents . . . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
10. Security Considerations . . . . . . . . . . . . . . . . . . . 10 10. Security Considerations . . . . . . . . . . . . . . . . . . . 10
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . . 10 11.1. Normative References . . . . . . . . . . . . . . . . . . . 11
11.2. Informative References . . . . . . . . . . . . . . . . . . 10 11.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . . . 12
1. Requirements notation 1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Introduction 2. Introduction
Network elements such as firewalls are an integral aspect of a Network elements such as firewalls are an integral aspect of a
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administrators to help them configure their firewalls in a way that administrators to help them configure their firewalls in a way that
allows the Mobile IPv6 signaling and data messages to pass through. allows the Mobile IPv6 signaling and data messages to pass through.
This document assumes that the firewalls in question include some This document assumes that the firewalls in question include some
kind of stateful packet filtering capability. The static rules that kind of stateful packet filtering capability. The static rules that
need to be configured are described in this document. In some need to be configured are described in this document. In some
scenarios, the support of additional mechanisms to create pinholes scenarios, the support of additional mechanisms to create pinholes
required for MIPv6 signalling and data traffic to pass through will required for MIPv6 signalling and data traffic to pass through will
be necessary. A possible solution, describing the dynamic be necessary. A possible solution, describing the dynamic
capabilities needed for the firewalls to create pinholes based on capabilities needed for the firewalls to create pinholes based on
MIPv6 signalling traffic is described in a companion document MIPv6 signalling traffic is described in a companion document
[I-D.ietf-mext-firewall-vendor]. Other solutions may also be [MIP6FWVENDOR]. Other solutions may also be possible.
possible.
Some Mobile IPv6 signalling messages require the use of encryption to Some Mobile IPv6 signalling messages require the use of encryption to
protect the confidentiality of the payload (e.g. the HoTI and HoT protect the confidentiality of the payload (e.g. the HoTI and HoT
messages between the MN and the HA). The other signalling messages messages between the MN and the HA). The other signalling messages
allow the use of encryption. If encryption is being used, it is not allow the use of encryption. If encryption is being used, it is not
possible to inspect the contents of the signalling packets. For possible to inspect the contents of the signalling packets. For
these messages to get through, a generic rule needs to be added in these messages to get through, a generic rule needs to be added in
the firewall to let ESP packets through without further inspection. the firewall to let ESP packets through without further inspection.
3. Abbreviations 3. Abbreviations
This document uses the following abbreviations: This document uses the following abbreviations:
o CN: Correspondent Node o CN: Correspondent Node
o CoA: Care of Address
o CoA: Care of Address
o CoTI: Care of Test Init o CoTI: Care of Test Init
o HA: Home Agent o HA: Home Agent
o HoA: Home Address o HoA: Home Address
o HoTI: Home Test Init o HoTI: Home Test Init
o HoT: Home Test o HoT: Home Test
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work. In order to permit these messages through, the firewall has to work. In order to permit these messages through, the firewall has to
detect the messages using the following patterns. detect the messages using the following patterns.
Destination Address: Address of HA Destination Address: Address of HA
Next Header: 50 (ESP) Next Header: 50 (ESP)
Mobility Header Type: 5 (BU) Mobility Header Type: 5 (BU)
This pattern will allow the BU messages from MNs to HA to pass This pattern will allow the BU messages from MNs to HA to pass
through. through.
When an HA supporting DSMIPv6 clients is behind firewall, in order
for DSMIPv6 signalling to reach the HA, the firewall has to allow
signaling packets sent to HA's UDP port 4191 to pass through:
Destination Address: IPv4 address of HA
Protocol: 17 (UDP)
Port: 4191
The firewall may also have a rule allowing IP-in-IP encapsulated
traffic to pass through to the HA:
Destination Address: IPv4 address of HA
Protocol: 4 (IP-in-IP)
If the above rule is not created by the firewall, IP encapsulated
DSMIPv6 signalling will not reach the HA. A client compliant with ,
when it does not get a response to the BU, is supposed to resend the
BU encapsulated into UDP, with destination port 4191. Thus, even if
the above rule is not created the signaling may pass through with the
(IPv4 HA, UDP 4191) rule.
4.2. IKEv2 signaling between MN and HA for establishing SAs 4.2. IKEv2 signaling between MN and HA for establishing SAs
The MN and HA exchange IKEv2 signaling in order to establish the The MN and HA exchange IKEv2 signaling in order to establish the
security associations. The security associations so established will security associations. The security associations so established will
later be used for securing the mobility signaling messages. Hence later be used for securing the mobility signaling messages. Hence
these messages need to be permitted to pass through the firewalls. these messages need to be permitted to pass through the firewalls.
The following pattern will detect these messages. The following pattern will detect these messages.
Destination Address: Address of HA Destination Address: Address of HA
Transport Protocol: UDP Transport Protocol: UDP
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where CN Address describes the address(es) of the priviledged where CN Address describes the address(es) of the priviledged
node(s).This allows the BU to traverse the firewall and the BA can node(s).This allows the BU to traverse the firewall and the BA can
pass the firewall without any assistance. Therefore, the Binding pass the firewall without any assistance. Therefore, the Binding
Update sequence can be performed successfully. Update sequence can be performed successfully.
5.4. Route Optimization data traffic from MN 5.4. Route Optimization data traffic from MN
Also the Route Optimization data traffic from MN directly to the CN Also the Route Optimization data traffic from MN directly to the CN
can not traverse the firewall without assistance. A dynamically can not traverse the firewall without assistance. A dynamically
created pinhole such as the one specified in created pinhole such as the one specified in [MIP6FWVENDOR] will
[I-D.ietf-mext-firewall-vendor] will allow this traffic to pass. allow this traffic to pass.
6. Mobile Node behind a firewall 6. Mobile Node behind a firewall
This section presents the recommendations for configuring a firewall This section presents the recommendations for configuring a firewall
that protects the network a mobile node visiting. that protects the network a mobile node visiting.
+----------------+ +----+ +----------------+ +----+
| | | HA | | | | HA |
| | +----+ | | +----+
| | Home Agent | | Home Agent
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configured to block the incoming ESP packets. Moreover, from the configured to block the incoming ESP packets. Moreover, from the
view of the firewall, both source and destination addresses of these view of the firewall, both source and destination addresses of these
messages from/to mobile node are variable. Fortunately, for a messages from/to mobile node are variable. Fortunately, for a
stateful firewall, if the initial traffic is allowed through the stateful firewall, if the initial traffic is allowed through the
firewall, then the return traffic is also allowed. A mobile node is firewall, then the return traffic is also allowed. A mobile node is
always the initiator for the BU. Since MN's CoA is not able to be always the initiator for the BU. Since MN's CoA is not able to be
known in advance, the firewall can use following patterns to permit known in advance, the firewall can use following patterns to permit
these messages through. these messages through.
Source Address: Visited subnet prefix Source Address: Visited subnet prefix
Destination Address: Address of HA Destination Address: Address of HA
Next Header: 50 (ESP) Next Header: 50 (ESP)
Mobility Header Type: 5 (BU) Mobility Header Type: 5 (BU)
This pattern will allow the Binding Update packets to pass through This pattern will allow the Binding Update packets to pass through
the firewall. Then the return packets (BA from HA to MN) will also the firewall. Then the return packets (BA from HA to MN) will also
able to pass through accordingly. able to pass through accordingly.
6.2. Signaling between MN and CN 6.2. Data packets between DSMIPv6
In case of a DSMIPv6 client with only a v4 CoA, the dynamic rules set
by the firewall to allow DSMIPv6 signalling packets pass through
between the MN and the HA, may time out and be closed. If that
happens, data packets sent by a CN to the MN through the HA will not
reach the MN. Therefore, the firewall will need to set a static rule
to allow data packets sent from the HA's IPv4 address to the MN's
IPv4 CoA using either protocol number 4 (IP-in-IP encapsulation) or
17 (UDP), depending on the value of the F bit, to pass through. The
UDP port numbers for the rule are to be read from the BU/BA message
exchange [RFC5555]. When the firewall chooses to create static rules
(without traffic based timeout) for allowing DSMIPv6 signalling pass
between the MN and HA, then no further rules need to be created by
the firewall, as data packets follow the same tunnel as the
signaling.
6.3. Signaling between MN and CN
Route Optimization allows direct communication of data packets Route Optimization allows direct communication of data packets
between the MN and a CN without tunneling it back through the HA. It between the MN and a CN without tunneling it back through the HA. It
includes 3 pairs of messages: HoTI/HoT, CoTI/CoT and BU/BA. The includes 3 pairs of messages: HoTI/HoT, CoTI/CoT and BU/BA. The
first pair can pass through the firewall using the pattern described first pair can pass through the firewall using the pattern described
in section 5.1. Here we discuss CoTI/CoT and BU/BA messages. in section 5.1. Here we discuss CoTI/CoT and BU/BA messages.
Following pattern permits these messages through the firewall. Following pattern permits these messages through the firewall.
Source Address: Visited subnet prefix Source Address: Visited subnet prefix
Mobility Header Type: 2 (CoTI) Mobility Header Type: 2 (CoTI)
Source Address: Visited subnet prefix Source Address: Visited subnet prefix
Mobility Header Type: 5 (BU) Mobility Header Type: 5 (BU)
This pattern allows the initial messages (CoTI and BU) from the MN to This pattern allows the initial messages (CoTI and BU) from the MN to
the CN pass through the firewall. The return messages (CoT and BA) the CN pass through the firewall. The return messages (CoT and BA)
from the CN to the MN can also passes through the firewall from the CN to the MN can also passes through the firewall
accordingly. accordingly.
6.3. IKEv2 signaling between MN and HA for establishing SAs 6.4. IKEv2 signaling between MN and HA for establishing SAs
The MN and HA exchange IKEv2 signaling in order to establish the The MN and HA exchange IKEv2 signaling in order to establish the
security associations. The security associations so established will security associations. The security associations so established will
later be used for securing the mobility signaling messages. Due to later be used for securing the mobility signaling messages. Due to
variable source/destination IP addresses and MN always as initiator, variable source/destination IP addresses and MN always as initiator,
the following pattern will let the negotiation pass. the following pattern will let the negotiation pass.
Source Address: Visited subnet prefix Source Address: Visited subnet prefix
Transport Protocol: UDP Transport Protocol: UDP
Destination UDP Port: 500 Destination UDP Port: 500
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discern whether it is safe or not. This document recommends a discern whether it is safe or not. This document recommends a
liberal setting so that all legitimate traffic can pass. This means liberal setting so that all legitimate traffic can pass. This means
that some malicious traffic may be permitted by these rules. These that some malicious traffic may be permitted by these rules. These
rules may allow the initiation of Denial of Service attacks against rules may allow the initiation of Denial of Service attacks against
Mobile IPv6 capable nodes (the MNs, CNs and the HAs). Mobile IPv6 capable nodes (the MNs, CNs and the HAs).
11. References 11. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-mext-firewall-vendor] [MIP6FWVENDOR]
Krishnan, S., Sheffer, Y., Steinleitner, N., and G. Bajko, Krishnan, S., Sheffer, Y., Steinleitner, N., and G. Bajko,
"Guidelines for firewall vendors regarding MIPv6 traffic", "Guidelines for firewall vendors regarding MIPv6 traffic",
draft-ietf-mext-firewall-vendor-00 (work in progress), draft-ietf-mext-firewall-vendor-0 (work in progress),
October 2008. October 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004. in IPv6", RFC 3775, June 2004.
[RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile [RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile
IPv6 and Firewalls: Problem Statement", RFC 4487, IPv6 and Firewalls: Problem Statement", RFC 4487,
May 2006. May 2006.
[RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
Routers", RFC 5555, June 2009.
11.2. Informative References 11.2. Informative References
[RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering [RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering
ICMPv6 Messages in Firewalls", RFC 4890, May 2007. ICMPv6 Messages in Firewalls", RFC 4890, May 2007.
[RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/ [RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/
Co-existence Security Considerations", RFC 4942, Co-existence Security Considerations", RFC 4942,
September 2007. September 2007.
Authors' Addresses Authors' Addresses
skipping to change at page 12, line 4 skipping to change at line 522
21 Heng Mui Keng Terrace 21 Heng Mui Keng Terrace
Singapore Singapore
Phone: +65-6874-6742 Phone: +65-6874-6742
Email: qiuying@i2r.a-star.edu.sg Email: qiuying@i2r.a-star.edu.sg
Gabor Bajko Gabor Bajko
Nokia Nokia
Email: gabor.bajko@nokia.com Email: gabor.bajko@nokia.com
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