Transcript Introduction (Pres.)

COEN 350 Network Security
Introduction
Computer Networks
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OSI Reference Model
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Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
OSI Reference Model
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Useful to establish terminology
Not implemented
Upper layer implemented in terms of
lower layer.
OSI Reference Model
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Application Layer
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Locus of applications that use networking
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P2P
HTTP
ftp
Presentation Layer
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Encodes application data into a canonical form
Decodes it into system-dependent format at the
receiving end.
OSI Reference Model
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Session Layer
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Extra functions over reliable one-to-one
connection
RPC
Transport Layer
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Reliable communication stream between a
pair of systems.
IP, UDP, TCP, ICMP
OSI Reference Model
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Network Layer
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Computes paths across an interconnected
mesh of links and packet switches
Forwards packets over multiple links from
source to destination
OSI Reference Model
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Data Link Layer
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Organizes physical layer’s bits into packets
and controls who on a shared link gets
each packet.
Physical Layer
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Delivers an unstructured stream of bits
across a single link of some sort.
TCP/IP Suite
Protocol Layers and Security
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Security measures often layer network
protocols.
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Protect contents of packages is protection
at layer 2.
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Still allows traffic analysis.
IPSec protects (encrypts) packages at layer
4
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Does not work with NAT.
Goals
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Authentication
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Authorization
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Are you allowed to do that?
Integrity
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Who are you?
Is this the real message?
Privacy
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Does anyone else know about it?
Zone of Control
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The zone that needs to be secured in
order to prevent eavesdropping.
Physical access needs to be prevented.
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Tempest program (US military)
Legal Issues
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Patent Law
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First inventor has the right to invention.
Patents issued based on what inventors present
regarding
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Novelty (  Prior Art)
Importance (“Aha” effect)
Patent process flawed since Reagan underfunding,
but slowly getting better
Many cryptography algorithms are moving into the
public domain.
Legal Issues
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Export Control
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Cryptographic algorithms and tools were
considered to be restricted technology.
Treated like ammunition.
Taking a laptop to Mexico for a week-end
could be a violation of export control.
Government gave up after PGP fiasco
Legal Issues
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Key Escrow
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Cryptography algorithms became
unbreakable in the nineties.
Prevent wiretaps, computer forensics, etc.
National security efforts sponsored Clipper:
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Encryption chip
Two different agencies needed to cooperate to
recover secret key.
Government gave up.