Download Chapter One - Indiana University

Chapter Six
IS Network
and
Telecommunications Risks
1
Topics

Network and Telecommunication Technologies

Risks to IT Network and Telecommunication
Systems

IT Network and Telecommunication Security

Auditing Network Security
2
Network Types

By Scale
– Local Area Network (LAN)
– Backbone Networks (BN)
» for linking together organizational LANs at various locations.
– Metropolitan Area Network (MAN)
» connects LANs and BNs across different locations (usually leased lines)
– Wide Area Network (WAN)

By Ownership
– Internet, intranet, extranet
– Virtual private networks (VPN)
3
Network Types

By Topology
–
–
–
–

Star-shaped – centralized
Ring – decentralized
Bus – decentralized
Mesh
By Distribution of Functionality
– Client Server, Thin Client, Fat Client
4
Network Components
(Users and Applications)
Computers and terminals
 Network Operating System
 Telecommunications processors (network
interface cards and modems)
Clients/Servers

Telecommunications channels – physical and
wireless (media)
 Devices (Routers, switching, hubs, etc.)

5
Network Infrastructure
Network Protocols and Software

Network and telecommunications software
– application software (web browsers, e-mail
software, etc.),
– network OS,
– networks management software,
– middleware
6
Multi-layer Network Models

Network models – standard architecture that
allows different HW and SW to communicate
across networks

Open Systems Interconnection Model (7 layer)
– Created by International Standards Organization (ISO) in 1984

Internet Model (5 layer)
– Created by DARPA originally in early 70’s
– Based on Transmission Control Protocol/ Internet Protocol
(TCP/IP) suite
– Combines the “top” three layers of the OSI model into a single
layer.
7
5-Layer Internet Model

Application Layer
– set of utilities used by application programs

Application Software
Transport Layer
– deals with end-to-end issues such as segmenting the message for
network transport, and maintaining the logical connections
between sender and receiver

Network Layer
– responsible for making routing decisions

System Software
Data Link Layer
– deals with message delineation, error control and network medium
access control

Physical Layer
– defines how individual bits are formatted to be transmitted
through the network
Computer Hardware
8
Data Communication Standards
Layer
Common Standards
5. Application layer
HTTP, HTML (Web)
IMAP, POP (e-mail)
4. Transport layer
TCP (Internet)
SPX (Novell LANs)
3. Network layer
IP (Internet)
IPX (Novell LANs)
2. Data link layer
Ethernet (LAN)
PPP (dial-up via modem for MAN)
1. Physical layer
Category 5 twisted pair (LAN)
Fiber optic cable (WAN)
1-9
Message Transmission Example
10
Message Moving Through Layers
5 - 11
IS Network and
Telecommunications Risks

Social Engineering, Software Vulnerabilities
(Unauthorized Access)

Physical Infrastructure Threats – the elements,
natural disasters, power supply, intentional
human attacks (disaster)

Programmed Threats – viruses, worms, Trojan
horses, hoaxes, blended threats (destruction)

Denial of Service Attacks (disruption)
12
IS Network and
Telecommunications Security

Network security administration

Authentication and Access Control

Encryption – secret key and public key

Firewalls – packet filtering and stateful
inspection

Intrusion Detection Systems

Penetration Testing – war dialing, port
scanning, sniffers, password crackers
13
Internal, Perimeter, and External
Networks
14
Auditing Network Security
Risk assessment and best practices
 Benchmark tools
 IT audit programs for network security

15