Network Working Group S. Krishnan
Internet-Draft Ericsson
Intended status: Informational June 28, 2007
Expires: December 30, 2007
Firewall Recommendations for MIPv6
draft-krishnan-mip6-firewall-00
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Copyright (C) The IETF Trust (2007).
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Abstract
This document presents some recommendations for firewall
administrators to help them configure their firewalls in a way that
allows Mobile IPv6 signaling and data messags to pass through. This
document assumes that the firewalls in question include some kind of
stateful packet filtering capability.
Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 5
3.1. Signaling between the MN and the HA . . . . . . . . . . . 5
3.2. Route optimization signaling between MN and CN through
HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.3. IKEv2 signaling between MN and HA for establishing SAs . . 6
3.4. Data traffic from and to MN passing through the HA . . . . 6
4. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . . . 11
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1. Requirements notation
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 [RFC2119].
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2. Introduction
Network elements such as firewalls are an integral aspect of a
majority of IP networks today, given the state of security in the
Internet, threats, and vulnerabilities to data networks. MIPv6
[RFC3775] defines mobility support for IPv6 nodes. Since firewalls
are not aware of MIPv6 protocol details, they will probably interfere
with the smooth operation of the protocol. The problems caused by
firewalls to Mobile IPv6 are documented in [RFC4487]
This document presents some recommendations for firewall
administrators to help them configure their firewalls in a way that
allows Mobile IPv6 signaling and data messags to pass through. This
document assumes that the firewalls in question include some kind of
stateful packet filtering capability.
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3. Home Agent behind a firewall
This section presents the recommendations for configuring a firewall
that is protects a home agent. For each type of traffic that needs
to pass through this firewall, recommendations are presented on how
to identify that traffic. The following types of traffic are
considered
o Signaling between the MN and the HA
o Route optimization signaling between MN and CN through HA
o IKEv2 signaling between MN and HA for establishing SAs
o Data traffic from and to MN passing through the HA
3.1. Signaling between the MN and the HA
The signaling between the MN and HA is protected using IPSec ESP.
These messages are encrypted and hence are not inspectable by
firewalls. So the firewall either has to either permit all these
messages or discard all of them. But if these messages are
discarded, Mobile IPv6 as specified today will cease to work. In
order to permit these messages through, the firewall has to detect
the messages using the following pattern.
Destination Address: Address of HA
IP payload protocol number: 50 (ESP)
This pattern will allow the BU messages from MNs to HA and BA
messages from the HA to the MNs to pass through. It will also allow
the HoTI and HoT messages (related to route optimization) between the
MN and the HA to pass through.
3.2. Route optimization signaling between MN and CN through HA
Route Optimization allows direct communication of data packets
between the MN and a CN without tunneling it back through the HA. In
order for route optimization to work, part of the initial signaling
has to pass through the HA. The following pattern will allow these
messages to pass through.
Destination Address: HoA of MN
Mobility Header Type: 3
This pattern allows the HoT message from the CN to the MN's HoA to
pass through the firewall. The HoTI message from the MN to the CN
through the HA usually passes through the firewall without any
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problems. Hence no specific pattern is recommended.
3.3. IKEv2 signaling between MN and HA for establishing SAs
The MN and HA exchange IKEv2 signaling in order to establish the
security associations. The security associations so established will
later be used for securing the mobility signaling messages. Hence
these messages need to be permitted to pass through the firewalls.
The following pattern will detect these messages.
Destination Address: Address of HA
Transport Protocol: UDP
Destination UDP Port: 500
3.4. Data traffic from and to MN passing through the HA
If a CN tries to initiate traffic to an MN, a stateful firewall would
prevent these connection requests to pass through as there is no
established state on the firewall. Since MNs do not usually provide
services, this is not usually a problem. But if this is necessary to
do, the pattern to look for is
Destination Address: MN HoA
Allowing this traffic might allow any kind of traffic, including
malicious traffic, to pass through unfiltered to the MN. This might
cause a Denial of Service at the MN.
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4. Contributors
This document is one of the deliverables of the MIPv6 firewall
design. The following members of the team were involved in the
creation of this document.
Hannes Tschofenig Hannes.Tschofenig@gmx.net
Gabor Bajko Gabor.Bajko@nokia.com
Suresh Krishnan suresh.krishnan@ericsson.com
Hesham Soliman solimanhs@gmail.com
Yaron Sheffer yaronf@checkpoint.com
Qiu Ying qiuying@i2r.a-star.edu.sg
Ram Vishnu vishnu@motorola.com
Niklas Steinleitner steinleitner@cs.uni-goettingen.de
Vijay Devarapalli vijay.devarapalli@AzaireNet.com
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5. Security Considerations
This document specifies recommendations for firewall administrators
to allow Mobile IPv6 traffic to pass through unhindered. Since some
of this traffic is encrypted it is not possible for firewalls to
discern whether it is safe or not. This document recommends a
liberal setting so that all legitimate traffic can pass. This means
that some malicious traffic may be permitted by these rules. These
rules may allow the initiation of Denial of Service attacks against
Mobile IPv6 capable nodes such as a home agent.
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6. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile
IPv6 and Firewalls: Problem Statement", RFC 4487,
May 2006.
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Author's Address
Suresh Krishnan
Ericsson
8400 Decarie Blvd.
Town of Mount Royal, QC
Canada
Phone: +1 514 345 7900 x42871
Email: suresh.krishnan@ericsson.com
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