NATFW NSLP Intrarealm communications and Migration considerations

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NATFW NSLP Intra-realm communications and
Migration considerations

• Cedric Aoun, Marcus Brunner, Miquel Martin
• Martin Stiemerling, Hannes Tschofenig
• IETF 58 Minneapolis

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Agenda

• NSIS NATFW NSLP role with NSIS unaware NATs
• NSIS protocol traversal of NSIS un-aware NATs and
  Firewalls
• Unilateral signaling - No NR on the far end host
• Open issues

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NSIS NATFW NSLP role with NSIS un-aware NATs

• An NSIS NATFW NSLP MUST be able to discover that
  an NSIS un-aware NAT is deployed on the data path
  
• Once an NSIS un-aware NAT is discovered on the
  data path then either 2 options would be
  available
• STUN
• Create a STUN like capability within the NATFW
  NSLP

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NSIS NATFW NSLP role with NSIS unaware NATs
Net x
Alice
a.b.c.1/24
k.l.m.n/30
Phil
The net
a.b.c.e
Bob
e.f.g.h
a.b.c.d
STUN-like capability
NSIS NATFW NSLP un-aware NAT
NSIS NATFW NSLP signaling
Data Flow
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NSIS NATFW NSLP role with NSIS unaware NATs
Net x
Alternate path issues
Alice
a.b.c.129/25
k.l.m.n/30
Phil
The net
a.b.c.e
a.b.c.1/25
Bob
e.f.g.h
a.b.c.d
STUN-like capability
NSIS NATFW NSLP un-aware NAT
NSIS NATFW NSLP signaling
Data Flow
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NSIS protocol traversal of NSIS unaware NATs and
Firewalls

• NSIS un-aware NAT traversal
• QoS NSLP flow specification need to be taken from
  STUN or STUN like approach
• Qos NSLP responder could only receive messages if
  the responder is listening on the same address
  and port as the data flows (not practical)
• NSIS messages traversing NSIS un-aware NATs would
  require that NSIS is transported on top of widely
  deployed transport protocols (de-multiplexing
  requirement)
• Example of troublesome transport approaches
• Raw IP
• SCTP (very rare NAT implementations support it)

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NSIS protocol traversal of NSIS unaware NATs and
Firewalls

• NSIS un-aware Firewall traversal
• NSIS signaling MUST be allowed to bypass (proper
  identification of NSIS messages is required)
• Data flows would need to use existing ACL
  capabilities

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Unilateral Signaling
Net x
Alice
a.b.c.1/24
NSIS aware NAT/FW Qos NSLP
k.l.m.n/30
The net
a.b.c.e
NSIS aware NAT/FW Qos NSLP
e.f.g.h/30
a.b.c.1/24
Bob
a.b.c.d
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Migration NTLP requirements

• NSIS un-aware NAT
• NTLP to run in datagram mode with NTLP sent from
  the source address and port on which the data
  will be sent and received

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Open issues

• Are there known issues with RAO and existing
  Firewall implementations?
• Packets could be dropped because of the IP
  option?
• Unilateral signaling introduces a DoS attack,
  there is no means to determine if the targeted NR
  cant be reached because of lack of protocol
  support or because the destination is not valid

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Open issues

• How to deal with NATFW NEs that dont have a
  trust relation with the NI in the case of
  uni-lateral signaling?
• Unilateral operations require that last NATFW
  NSLP in the path respond back on behalf on the
  un-available NATFW NR
• Does the NTLP play a role in this?

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Backup
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Intra-realm communications
Net x
Alice wants to talk to Bob
Alice
k.l.m.n/30
a.b.c.1/24
a.b.c.e
The net
Bob
NSIS aware NAT/FW
a.b.c.d
How to avoid useless resource spending on NAT and
Firewalls (potentially event Qos gates)? Let Bob
provide to Alice both his locally scoped and
global scoped addresses
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Intra-realm communications
Net x
Alice
Alice wants to talk Phil
a.b.c.1/24
NSIS aware NAT/FW Qos NSLP
k.l.m.n/30
The net
a.b.c.e
Bob
NSIS aware NAT/FW Qos NSLP
e.f.g.h/30
a.b.c.1/24
a.b.c.d
Local scoped address could obviously overlap, a
solution needs to be provided to handle that case
Phil
a.b.c.d
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Intra-realm communications

• Proposed solution
• Communicate several NR addresses to the NI
• The first response received from an NR will hint
  the NR address to use for the rest of the
  messages
• NSIS messages need to be sent simultaneously and
  not sequentially (I.e. dont wait for responses).
• User application impacts
• Several NR addresses need to be provided
• NTLP impacts
• Although a messaging association was already
  linked to a destination address, it needs to be
  re-checked if applicable or not to avoid the
  confusion of overlapped local scoped addresses