UDLR WG 52nd IETF

1
UDLR WG 52nd IETF
ltdraft-ietf-udlr-security-00.txtgt December 11th,
2001 Salt Lake City US Emmanuel Duros UDcast
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Identifying Security Implications

• Abstract
• The purpose of this document is to attempt to
  identify any potential security implications
  related to this mechanism in order to help
  operators set up adequate securing mechanisms.
• 1 Introduction
• Presentation of the document
• 2 Terminology
• Mostly taken from RFC 3077

3
Generic Topology using LLTM

• 3 General overview
• Unidirectional Link
• ----gt------------------------------gt------
  
  fuip r1u r2u
• -------- --------
  -------- ---------- Feed
  Recv 1 Recv 2---subnet A --------
  -------- -------- ----------
  fbip r1b r2b
  
  ----------------------------------------
  ------------ Internet
  ----------------------------
  ------------------------ Figure 1
  Typical topology using LLTM
• Description on how packets flow

4
DTCP protocol

• 4 DTCP protocol
• Feeds periodically announce their tunnel
  end-point addresses over the unidirectional link.
• it may be fairly easy for unauthorised receivers
  to listen to HELLO packets and discover the feed
  tunnel end-point(s).
• link-layer security mechanisms may be used to
  prevent unauthorised receivers from obtaining
  this information.

5
Tunnelling Mechanism

• 5 Tunneling Mechanism
• -------------------------------------
  ---
• IP delivery destination addr fbip
  
• header source addr r1b or r2b
  
• IP proto GRE (47)
  
• -------------------------------------
  ---
• GRE header type MAC type of the UDL
  
• -------------------------------------
  ---
• GRE payload
  
• MAC packet
  
• -------------------------------------
  ---
• Stateless IP tunnels are not secure
• Unauthorized receiver may tunnel packets to the
  feed and gain access to the service
• setup a firewall near the feed with IP-src-addr
  based filtering
• Not efficient against IP spoofing
• Use of authentication in the delivery protocol
  (RFC 2402) or within the tunneling mechanism

6
Routing Protocols

• 6 Routing Protocol
• we consider receivers which are routers
• routers may implement various routing protocols
  (e.g. BGP, OSPF, PIM, etc.)
• some of them may not be authorized to announce
  routing information
• routing protocols should use authentication
  mechanisms when available