Introduction (Pres.)

Download Report

Transcript Introduction (Pres.)

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