Networking and Security

Technology In Action

© 2006 Prentice-Hall, Inc. 1

Networking and SecurityNetworking and SecurityNetworking and SecurityNetworking and Security

Connecting Computers and Protecting Them Connecting Computers and Protecting Them from Intrudersfrom Intruders

Connecting Computers and Protecting Them Connecting Computers and Protecting Them from Intrudersfrom Intruders



Networking Advantages and Networking Advantages and DisadvantagesDisadvantages

Networking Advantages and Networking Advantages and DisadvantagesDisadvantages

• Advantages– Increased productivity– More communication options– Enable the sharing of resources– Facilitate Internet connectivity

• Disadvantages– Complexity– Cost

MaterialsPersonnel

• Advantages– Increased productivity– More communication options– Enable the sharing of resources– Facilitate Internet connectivity

• Disadvantages– Complexity– Cost

MaterialsPersonnel



What is a Network?What is a Network?What is a Network?What is a Network?

• Computer network:– Two or more computers connected together– Nodes: Any device connected to a network

• Computer network:– Two or more computers connected together– Nodes: Any device connected to a network



Network ArchitectureNetwork ArchitectureNetwork ArchitectureNetwork Architecture

• Network designs:– Locally controlled:

Peer-to-peer (P2P)

– Centrally controlled:Client/server

• Network designs:– Locally controlled:

Peer-to-peer (P2P)

– Centrally controlled:Client/server

Peer-to-peer

Client/server



Peer-to-Peer NetworksPeer-to-Peer NetworksPeer-to-Peer NetworksPeer-to-Peer Networks

• Nodes communicate with each other:– Peers

• Share peripheral devices:– Printers

• Home and small office networks

• Nodes communicate with each other:– Peers

• Share peripheral devices:– Printers

• Home and small office networks



Client/Server NetworksClient/Server NetworksClient/Server NetworksClient/Server Networks

• Client computers:– Users

• Server computers:– Provide resources to clients– Central control unit

• Data flows efficiently• Servers respond to requests from clients• Scalable network

• Client computers:– Users

• Server computers:– Provide resources to clients– Central control unit

• Data flows efficiently• Servers respond to requests from clients• Scalable network



ServersServersServersServers

• Depending on the network size and work load servers can perform a single or multiple roles

• Depending on the network size and work load servers can perform a single or multiple roles



Dedicated Server TypesDedicated Server TypesDedicated Server TypesDedicated Server Types

• Application• Authentication• File• Database• Email• Web• Print

• Application• Authentication• File• Database• Email• Web• Print



Classifications of Client/Server Classifications of Client/Server NetworksNetworks

Classifications of Client/Server Classifications of Client/Server NetworksNetworks

• LAN: local area network– Computers linked together over a small geographic

region

• WAN: wide area network– Computers linked together over large diverse

geographic locations

• MAN: metropolitan area network– Computers linked together within a city or county

• PAN: personal area network– Wireless devices connected in close proximity to each

other

• LAN: local area network– Computers linked together over a small geographic

region

• WAN: wide area network– Computers linked together over large diverse

geographic locations

• MAN: metropolitan area network– Computers linked together within a city or county

• PAN: personal area network– Wireless devices connected in close proximity to each

other



Network TopologyNetwork TopologyNetwork TopologyNetwork Topology

• Physical layout of Physical layout of networks networks componentscomponents– BusBus– RingRing– StarStar

• Physical layout of Physical layout of networks networks componentscomponents– BusBus– RingRing– StarStar



Bus TopologyBus TopologyBus TopologyBus Topology• All nodes are connected All nodes are connected

in sequence on a single in sequence on a single cablecable

• Used most often on Used most often on peer-to-peer networkspeer-to-peer networks

• Networked computers Networked computers communicate with each communicate with each otherother

• One computer transmits One computer transmits data at a time:data at a time:– Access methods avoid data Access methods avoid data

collisionscollisions– Data is transmitted in Data is transmitted in

“packets”“packets”

• All nodes are connected All nodes are connected in sequence on a single in sequence on a single cablecable

• Used most often on Used most often on peer-to-peer networkspeer-to-peer networks

• Networked computers Networked computers communicate with each communicate with each otherother

• One computer transmits One computer transmits data at a time:data at a time:– Access methods avoid data Access methods avoid data

collisionscollisions– Data is transmitted in Data is transmitted in

“packets”“packets”



Ring TopologyRing TopologyRing TopologyRing Topology

• Nodes are laid out in Nodes are laid out in a ringa ring

• Token (data packet) Token (data packet) flows in one direction flows in one direction from device to devicefrom device to device

• Nodes are laid out in Nodes are laid out in a ringa ring

• Token (data packet) Token (data packet) flows in one direction flows in one direction from device to devicefrom device to device



Star TopologyStar TopologyStar TopologyStar Topology

• Nodes connect to a Nodes connect to a central communications central communications device (hub/switch)device (hub/switch)

• A node sends a signal to A node sends a signal to the hub which the hub which retransmits it to the retransmits it to the other nodesother nodes

• A node accepts the A node accepts the signal addressed to itsignal addressed to it

• Nodes connect to a Nodes connect to a central communications central communications device (hub/switch)device (hub/switch)

• A node sends a signal to A node sends a signal to the hub which the hub which retransmits it to the retransmits it to the other nodesother nodes

• A node accepts the A node accepts the signal addressed to itsignal addressed to it



Network Operating Systems (NOS)Network Operating Systems (NOS)Network Operating Systems (NOS)Network Operating Systems (NOS)

• Provide the protocol that controls the Provide the protocol that controls the communication between devices on the communication between devices on the networknetwork

• Major network operating systems:Major network operating systems:– Windows Server 2003Windows Server 2003– UNIXUNIX– Novell NetWareNovell NetWare

• Provide the protocol that controls the Provide the protocol that controls the communication between devices on the communication between devices on the networknetwork

• Major network operating systems:Major network operating systems:– Windows Server 2003Windows Server 2003– UNIXUNIX– Novell NetWareNovell NetWare



Network AdaptersNetwork AdaptersNetwork AdaptersNetwork Adapters

• Devices connected to or installed in nodes:– Network interface cards (NIC)– External network adapter

• Enable communication between nodes

• Devices connected to or installed in nodes:– Network interface cards (NIC)– External network adapter

• Enable communication between nodes

NICExternal adapter



Wireless AdaptersWireless AdaptersWireless AdaptersWireless Adapters

• Uses radio waves to connect nodes (2.4GHz)

• Each node requires a wireless network adapter

• Uses radio waves to connect nodes (2.4GHz)

• Each node requires a wireless network adapter



Transmission MediaTransmission MediaTransmission MediaTransmission Media

• Provides communications channel between nodes• Forms of media:

– Telephone wire: Twisted pair

– Coaxial cable– Fiber-optic cable– Radio waves:

Wireless

• Bandwidth:– Data transfer rate– Throughput– Measured in megabits per second (Mbps)

• Provides communications channel between nodes• Forms of media:

– Telephone wire: Twisted pair

– Coaxial cable– Fiber-optic cable– Radio waves:

Wireless

• Bandwidth:– Data transfer rate– Throughput– Measured in megabits per second (Mbps)



Choosing a CableChoosing a CableChoosing a CableChoosing a Cable

• Maximum run lengthMaximum run length• Bandwidth Bandwidth • Bend radiusBend radius• Cable costCable cost• Installation costsInstallation costs• Susceptibility to interferenceSusceptibility to interference• Signal transmission methodsSignal transmission methods

• Maximum run lengthMaximum run length• Bandwidth Bandwidth • Bend radiusBend radius• Cable costCable cost• Installation costsInstallation costs• Susceptibility to interferenceSusceptibility to interference• Signal transmission methodsSignal transmission methods



Twisted Pair CableTwisted Pair CableTwisted Pair CableTwisted Pair Cable

• Copper wire twisted around each other to reduce interference

• STP- Shielded• UTP- Unshielded

– Cat 5– Cat 6

• Copper wire twisted around each other to reduce interference

• STP- Shielded• UTP- Unshielded

– Cat 5– Cat 6



Coaxial CableCoaxial CableCoaxial CableCoaxial Cable

• Four components:Four components:– Copper coreCopper core– Nonconductive insulating materialNonconductive insulating material– Braided metalBraided metal– Plastic coverPlastic cover

• Four components:Four components:– Copper coreCopper core– Nonconductive insulating materialNonconductive insulating material– Braided metalBraided metal– Plastic coverPlastic cover



Fiber-Optic CableFiber-Optic CableFiber-Optic CableFiber-Optic Cable

• Components include:Components include:– Glass or plastic fibersGlass or plastic fibers– CladdingCladding– Outer jacketOuter jacket

• Uses light impulses to transmit dataUses light impulses to transmit data• Immune to interferenceImmune to interference

• Components include:Components include:– Glass or plastic fibersGlass or plastic fibers– CladdingCladding– Outer jacketOuter jacket

• Uses light impulses to transmit dataUses light impulses to transmit data• Immune to interferenceImmune to interference



Network Navigation DevicesNetwork Navigation DevicesNetwork Navigation DevicesNetwork Navigation Devices

• Devices that help make Devices that help make data flow possibledata flow possible– Repeaters– Hubs– Switches– Routers

• Devices that help make Devices that help make data flow possibledata flow possible– Repeaters– Hubs– Switches– Routers



Ethernet Repeater and HubsEthernet Repeater and HubsEthernet Repeater and HubsEthernet Repeater and Hubs

• Repeaters– Amplifies the signal

• Hubs– Amplifies the signal– Simultaneous

broadcasting– Acts like a cable

splitter

• Repeaters– Amplifies the signal

• Hubs– Amplifies the signal– Simultaneous

broadcasting– Acts like a cable

splitter



Ethernet Switches and RoutersEthernet Switches and RoutersEthernet Switches and RoutersEthernet Switches and Routers

• SwitchesSwitches– Send data to specific

nodes on the network

• RoutersRouters– Communicates data

between different networks

• SwitchesSwitches– Send data to specific

nodes on the network

• RoutersRouters– Communicates data

between different networks



Data Transmission and ProtocolsData Transmission and ProtocolsData Transmission and ProtocolsData Transmission and Protocols

• Computer protocols are rules for electronic information exchange

• Open system protocols:– Any computer can communicate with other computers

using the same protocols

• Circuit switching• Packet switching



Circuit SwitchingCircuit SwitchingCircuit SwitchingCircuit Switching

• Dedicated connection between two pointsDedicated connection between two points• Remains active until the transmission is Remains active until the transmission is

terminatedterminated• Telephone communicationsTelephone communications

• Dedicated connection between two pointsDedicated connection between two points• Remains active until the transmission is Remains active until the transmission is

terminatedterminated• Telephone communicationsTelephone communications



Packet SwitchingPacket SwitchingPacket SwitchingPacket Switching

• Data is broken into small units called Data is broken into small units called packetspackets

• Packets are sent over various routes to Packets are sent over various routes to their destinationtheir destination

• Packets are reassembled by the Packets are reassembled by the receiving computerreceiving computer

• Packets contain:Packets contain:– Destination/source addressesDestination/source addresses– Reassembling instructionsReassembling instructions– Data Data

• Data is broken into small units called Data is broken into small units called packetspackets

• Packets are sent over various routes to Packets are sent over various routes to their destinationtheir destination

• Packets are reassembled by the Packets are reassembled by the receiving computerreceiving computer

• Packets contain:Packets contain:– Destination/source addressesDestination/source addresses– Reassembling instructionsReassembling instructions– Data Data



PortsPortsPortsPorts

• Source Ports - is assigned to the client and is used to keep track of user sessions.

• Destination Ports - are used to route packets to the appropriate application.

• Listening Ports - software that responds to a port number is said to be "listening" for its packets.

• 65,535 ports• Well known ports are 0-1023.

– Port 80 HTTP

• Source Ports - is assigned to the client and is used to keep track of user sessions.

• Destination Ports - are used to route packets to the appropriate application.

• Listening Ports - software that responds to a port number is said to be "listening" for its packets.

• 65,535 ports• Well known ports are 0-1023.

– Port 80 HTTP



HeadersHeadersHeadersHeaders

• Encapsulation- layering of instructions onto the data

• Headers are like mailing addresses and handling instructions

• Contains information for the handling of the data block

• Encapsulation- layering of instructions onto the data

• Headers are like mailing addresses and handling instructions

• Contains information for the handling of the data block



TCP, IP, UDPTCP, IP, UDPTCP, IP, UDPTCP, IP, UDP

• TCP- Transmission Control Protocol– Reliable

Will resend lost packetsError checking

– Send in an orderly fashion• UDP - User Datagram Protocol

– Faster– Less reliable– Streaming

• Internet Protocol - specifies the format of packets

• TCP- Transmission Control Protocol– Reliable

Will resend lost packetsError checking

– Send in an orderly fashion• UDP - User Datagram Protocol

– Faster– Less reliable– Streaming

• Internet Protocol - specifies the format of packets



MAC AddressMAC AddressMAC AddressMAC Address

• Media Access Control address: hardware address that uniquely identifies each node of a network.

• Example: 07-a1-34-ff-b5-df

• Media Access Control address: hardware address that uniquely identifies each node of a network.

• Example: 07-a1-34-ff-b5-df



IP AddressesIP AddressesIP AddressesIP Addresses

• Unique number that identifies NOS/devices connected to the Internet

• Example: 134.68.76.100• Static address:

– Address never changes: Enter it manually

• Dynamic address:– Temporary address: Automatically assigned

• Unique number that identifies NOS/devices connected to the Internet

• Example: 134.68.76.100• Static address:

– Address never changes: Enter it manually

• Dynamic address:– Temporary address: Automatically assigned



Anatomy of a Data PacketAnatomy of a Data PacketAnatomy of a Data PacketAnatomy of a Data Packet



OSI (Open Systems Interconnection) ModelOSI (Open Systems Interconnection) ModelOSI (Open Systems Interconnection) ModelOSI (Open Systems Interconnection) Model





Questions?Questions?Questions?Questions?



Network SecurityNetwork SecurityNetwork SecurityNetwork Security

• Why attack a network rather than the computers on the network?– Lower risk of getting

caught– Less work– Availability of tools– Numerous methods

• Why attack a network rather than the computers on the network?– Lower risk of getting

caught– Less work– Availability of tools– Numerous methods



Networking Attack MethodsNetworking Attack MethodsNetworking Attack MethodsNetworking Attack Methods

• Sniffing• Spoofing• DoS – Denial of Service• Port Scanning

• Sniffing• Spoofing• DoS – Denial of Service• Port Scanning



Ethereal- Packet SnifferEthereal- Packet SnifferEthereal- Packet SnifferEthereal- Packet Sniffer



Netstumbler - Wireless Network Netstumbler - Wireless Network ScannerScanner

Netstumbler - Wireless Network Netstumbler - Wireless Network ScannerScanner



NetScan- Port ScannerNetScan- Port ScannerNetScan- Port ScannerNetScan- Port Scanner



Wireless Security or Lack ThereofWireless Security or Lack ThereofWireless Security or Lack ThereofWireless Security or Lack Thereof

• Lack of user Lack of user awarenessawareness

• No authenticationNo authentication• PervasivenessPervasiveness• Tools are easily Tools are easily

availableavailable• Poor security designPoor security design

– Weak encryption– Enabled defaults

Admin PW Broncast on SSID

• Lack of user Lack of user awarenessawareness

• No authenticationNo authentication• PervasivenessPervasiveness• Tools are easily Tools are easily

availableavailable• Poor security designPoor security design

– Weak encryption– Enabled defaults

Admin PW Broncast on SSID



150ft = 6 Houses, 1 street



450ft = 40 houses, 4 streets



WWWD 2004 StatsWWWD 2004 StatsWWWD 2004 StatsWWWD 2004 Stats

• 228537 APs found228537 APs found• 140890 No WEP (60+%)140890 No WEP (60+%)

– Wired Equivalent PrivacyWired Equivalent Privacy

• 71850 Default SSID (30+%)71850 Default SSID (30+%)– Service Set IDentifierService Set IDentifier

• 62859 Default SSID and No WEP (27+%)62859 Default SSID and No WEP (27+%)

• 228537 APs found228537 APs found• 140890 No WEP (60+%)140890 No WEP (60+%)

– Wired Equivalent PrivacyWired Equivalent Privacy

• 71850 Default SSID (30+%)71850 Default SSID (30+%)– Service Set IDentifierService Set IDentifier

• 62859 Default SSID and No WEP (27+%)62859 Default SSID and No WEP (27+%)



Wireless MathWireless MathWireless MathWireless Math

Open wireless + Netstumbler =Open wireless + Netstumbler =

War Driving + GPS + Internet =War Driving + GPS + Internet =

http://www.wifimaps.com/http://www.wifimaps.com/

Open wireless + Netstumbler =Open wireless + Netstumbler =

War Driving + GPS + Internet =War Driving + GPS + Internet =

http://www.wifimaps.com/http://www.wifimaps.com/



Wireless Security Best Practices Wireless Security Best Practices Wireless Security Best Practices Wireless Security Best Practices

• Change default settings– Admin password– SSID – Service Set identifier

RenameChoose wisely

• Turn on WEP encryption• Disable SSID Broadcast• Create a VPN and use encryption

• Change default settings– Admin password– SSID – Service Set identifier

RenameChoose wisely

• Turn on WEP encryption• Disable SSID Broadcast• Create a VPN and use encryption



Wireless Security Paradoxs and Wireless Security Paradoxs and MythsMyths

Wireless Security Paradoxs and Wireless Security Paradoxs and MythsMyths

• MAC filtering• Disable SSID Broadcast• Disable DHCP• Antenna placement• WEP Enabled

• MAC filtering• Disable SSID Broadcast• Disable DHCP• Antenna placement• WEP Enabled



Network SecurityNetwork SecurityNetwork SecurityNetwork Security

• Firewalls: Block unused ports– Protects against port scanning

• Authentication:– User ID and password used to access the network

• Access privileges:– Close access to unused network systems– Use encryption and VPNs

• Monitor your network– Fake APs– Watch traffic– Scan detectors

• Firewalls: Block unused ports– Protects against port scanning

• Authentication:– User ID and password used to access the network

• Access privileges:– Close access to unused network systems– Use encryption and VPNs

• Monitor your network– Fake APs– Watch traffic– Scan detectors



LinksLinksLinksLinks

http://netstats.indiana.edu/wanmap/index.html

http://reviews.cnet.com/Bandwidth_meter/7004-7254_7-0.html

http://netstats.indiana.edu/wanmap/index.html

http://reviews.cnet.com/Bandwidth_meter/7004-7254_7-0.html

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Networking and Security