Technology In Action © 2006 Prentice-Hall, Inc.1 Networking and Security Connecting Computers and Protecting Them from Intruders

Technology In Action © 2006 Prentice-Hall, Inc.2 Networking Advantages and Disadvantages Advantages – –Increased productivity – –More communication options – –Enable the sharing of resources – –Facilitate Internet connectivity Disadvantages – –Complexity – –Cost Materials Personnel Advantages – –Increased productivity – –More communication options – –Enable the sharing of resources – –Facilitate Internet connectivity Disadvantages – –Complexity – –Cost Materials Personnel

Technology In Action © 2006 Prentice-Hall, Inc.3 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

Technology In Action © 2006 Prentice-Hall, Inc.4 Network 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

Technology In Action © 2006 Prentice-Hall, Inc.5 Peer-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

Technology In Action © 2006 Prentice-Hall, Inc.6 Client/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

Technology In Action © 2006 Prentice-Hall, Inc.7 ServersServers Depending on the network size and work load servers can perform a single or multiple roles

Technology In Action © 2006 Prentice-Hall, Inc.8 Dedicated Server Types Application Authentication File Database Web Print

Technology In Action © 2006 Prentice-Hall, Inc.9 Classifications of Client/Server Networks 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

Technology In Action © 2006 Prentice-Hall, Inc.10 Network Topology Physical layout of networks componentsPhysical layout of networks components –Bus –Ring –Star Physical layout of networks componentsPhysical layout of networks components –Bus –Ring –Star

Technology In Action © 2006 Prentice-Hall, Inc.11 Bus Topology All nodes are connected in sequence on a single cableAll nodes are connected in sequence on a single cable Used most often on peer-to-peer networksUsed most often on peer-to-peer networks Networked computers communicate with each otherNetworked computers communicate with each other One computer transmits data at a time:One computer transmits data at a time: –Access methods avoid data collisions –Data is transmitted in “packets” All nodes are connected in sequence on a single cableAll nodes are connected in sequence on a single cable Used most often on peer-to-peer networksUsed most often on peer-to-peer networks Networked computers communicate with each otherNetworked computers communicate with each other One computer transmits data at a time:One computer transmits data at a time: –Access methods avoid data collisions –Data is transmitted in “packets”

Technology In Action © 2006 Prentice-Hall, Inc.12 Ring Topology Nodes are laid out in a ringNodes are laid out in a ring Token (data packet) flows in one direction from device to deviceToken (data packet) flows in one direction from device to device Nodes are laid out in a ringNodes are laid out in a ring Token (data packet) flows in one direction from device to deviceToken (data packet) flows in one direction from device to device

Technology In Action © 2006 Prentice-Hall, Inc.13 Star Topology Nodes connect to a central communications device (hub/switch)Nodes connect to a central communications device (hub/switch) A node sends a signal to the hub which retransmits it to the other nodesA node sends a signal to the hub which retransmits it to the other nodes A node accepts the signal addressed to itA node accepts the signal addressed to it Nodes connect to a central communications device (hub/switch)Nodes connect to a central communications device (hub/switch) A node sends a signal to the hub which retransmits it to the other nodesA node sends a signal to the hub which retransmits it to the other nodes A node accepts the signal addressed to itA node accepts the signal addressed to it

Technology In Action © 2006 Prentice-Hall, Inc.14 Network Operating Systems (NOS) Provide the protocol that controls the communication between devices on the networkProvide the protocol that controls the communication between devices on the network Major network operating systems:Major network operating systems: –Windows Server 2003 –UNIX –Novell NetWare Provide the protocol that controls the communication between devices on the networkProvide the protocol that controls the communication between devices on the network Major network operating systems:Major network operating systems: –Windows Server 2003 –UNIX –Novell NetWare

Technology In Action © 2006 Prentice-Hall, Inc.15 Network 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 NIC External adapter

Technology In Action © 2006 Prentice-Hall, Inc.16 Wireless 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

Technology In Action © 2006 Prentice-Hall, Inc.17 Transmission 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)

Technology In Action © 2006 Prentice-Hall, Inc.18 Choosing a Cable Maximum run lengthMaximum run length BandwidthBandwidth Bend radiusBend radius Cable costCable cost Installation costsInstallation costs Susceptibility to interferenceSusceptibility to interference Signal transmission methodsSignal transmission methods Maximum run lengthMaximum run length BandwidthBandwidth Bend radiusBend radius Cable costCable cost Installation costsInstallation costs Susceptibility to interferenceSusceptibility to interference Signal transmission methodsSignal transmission methods

Technology In Action © 2006 Prentice-Hall, Inc.19 Twisted 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

Technology In Action © 2006 Prentice-Hall, Inc.20 Coaxial Cable Four components:Four components: –Copper core –Nonconductive insulating material –Braided metal –Plastic cover Four components:Four components: –Copper core –Nonconductive insulating material –Braided metal –Plastic cover

Technology In Action © 2006 Prentice-Hall, Inc.21 Fiber-Optic Cable Components include:Components include: –Glass or plastic fibers –Cladding –Outer jacket Uses light impulses to transmit dataUses light impulses to transmit data Immune to interferenceImmune to interference Components include:Components include: –Glass or plastic fibers –Cladding –Outer jacket Uses light impulses to transmit dataUses light impulses to transmit data Immune to interferenceImmune to interference

Technology In Action © 2006 Prentice-Hall, Inc.22 Network Navigation Devices Devices that help make data flow possibleDevices that help make data flow possible – –Repeaters – –Hubs – –Switches – –Routers Devices that help make data flow possibleDevices that help make data flow possible – –Repeaters – –Hubs – –Switches – –Routers

Technology In Action © 2006 Prentice-Hall, Inc.23 Ethernet Repeater and Hubs Repeaters – Amplifies the signal Hubs – Amplifies the signal – Simultaneous broadcasting – Acts like a cable splitter

Technology In Action © 2006 Prentice-Hall, Inc.24 Ethernet 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

Technology In Action © 2006 Prentice-Hall, Inc.25 Data 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 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

Technology In Action © 2006 Prentice-Hall, Inc.26 Circuit Switching Dedicated connection between two pointsDedicated connection between two points Remains active until the transmission is terminatedRemains active until the transmission is terminated Telephone communicationsTelephone communications Dedicated connection between two pointsDedicated connection between two points Remains active until the transmission is terminatedRemains active until the transmission is terminated Telephone communicationsTelephone communications

Technology In Action © 2006 Prentice-Hall, Inc.27 Packet Switching Data is broken into small units called packetsData is broken into small units called packets Packets are sent over various routes to their destinationPackets are sent over various routes to their destination Packets are reassembled by the receiving computerPackets are reassembled by the receiving computer Packets contain:Packets contain: –Destination/source addresses –Reassembling instructions –Data Data is broken into small units called packetsData is broken into small units called packets Packets are sent over various routes to their destinationPackets are sent over various routes to their destination Packets are reassembled by the receiving computerPackets are reassembled by the receiving computer Packets contain:Packets contain: –Destination/source addresses –Reassembling instructions –Data

Technology In Action © 2006 Prentice-Hall, Inc.28 PortsPorts 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 – –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 – –Port 80 HTTP

Technology In Action © 2006 Prentice-Hall, Inc.29 HeadersHeaders 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

Technology In Action © 2006 Prentice-Hall, Inc.30 TCP, IP, UDP TCP- Transmission Control Protocol – –Reliable Will resend lost packets Error 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 packets Error checking – –Send in an orderly fashion UDP - User Datagram Protocol – –Faster – –Less reliable – –Streaming Internet Protocol - specifies the format of packets

Technology In Action © 2006 Prentice-Hall, Inc.31 MAC 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

Technology In Action © 2006 Prentice-Hall, Inc.32 IP Addresses Unique number that identifies NOS/devices connected to the Internet Example: 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: Static address: – –Address never changes: Enter it manually Dynamic address: – –Temporary address: Automatically assigned

Technology In Action © 2006 Prentice-Hall, Inc.33 Anatomy of a Data Packet

Technology In Action © 2006 Prentice-Hall, Inc.34 OSI (Open Systems Interconnection) Model

Technology In Action © 2006 Prentice-Hall, Inc.35

Technology In Action © 2006 Prentice-Hall, Inc.36 Questions?Questions?

Technology In Action © 2006 Prentice-Hall, Inc.37 Network 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

Technology In Action © 2006 Prentice-Hall, Inc.38 Networking Attack Methods Sniffing Spoofing DoS – Denial of Service Port Scanning Sniffing Spoofing DoS – Denial of Service Port Scanning

Technology In Action © 2006 Prentice-Hall, Inc.39 Ethereal- Packet Sniffer

Technology In Action © 2006 Prentice-Hall, Inc.40 Netstumbler - Wireless Network Scanner

Technology In Action © 2006 Prentice-Hall, Inc.41 NetScan- Port Scanner

Technology In Action © 2006 Prentice-Hall, Inc.42 Wireless Security or Lack Thereof Lack of user awarenessLack of user awareness No authenticationNo authentication PervasivenessPervasiveness Tools are easily availableTools are easily available Poor security designPoor security design – –Weak encryption – –Enabled defaults Admin PW Broncast on SSID Lack of user awarenessLack of user awareness No authenticationNo authentication PervasivenessPervasiveness Tools are easily availableTools are easily available Poor security designPoor security design – –Weak encryption – –Enabled defaults Admin PW Broncast on SSID

Technology In Action © 2006 Prentice-Hall, Inc ft = 6 Houses, 1 street

Technology In Action © 2006 Prentice-Hall, Inc ft = 40 houses, 4 streets

Technology In Action © 2006 Prentice-Hall, Inc.45 WWWD 2004 Stats APs found APs found No WEP (60+%) No WEP (60+%) –Wired Equivalent Privacy Default SSID (30+%)71850 Default SSID (30+%) –Service Set IDentifier Default SSID and No WEP (27+%)62859 Default SSID and No WEP (27+%) APs found APs found No WEP (60+%) No WEP (60+%) –Wired Equivalent Privacy Default SSID (30+%)71850 Default SSID (30+%) –Service Set IDentifier Default SSID and No WEP (27+%)62859 Default SSID and No WEP (27+%)

Technology In Action © 2006 Prentice-Hall, Inc.46 Wireless Math Open wireless + Netstumbler = War Driving + GPS + Internet = Open wireless + Netstumbler = War Driving + GPS + Internet =

Technology In Action © 2006 Prentice-Hall, Inc.47 Wireless Security Best Practices Change default settings – –Admin password – –SSID – Service Set identifier Rename Choose wisely Turn on WEP encryption Disable SSID Broadcast Create a VPN and use encryption Change default settings – –Admin password – –SSID – Service Set identifier Rename Choose wisely Turn on WEP encryption Disable SSID Broadcast Create a VPN and use encryption

Technology In Action © 2006 Prentice-Hall, Inc.48 Wireless Security Paradoxs and Myths MAC filtering Disable SSID Broadcast Disable DHCP Antenna placement WEP Enabled MAC filtering Disable SSID Broadcast Disable DHCP Antenna placement WEP Enabled

Technology In Action © 2006 Prentice-Hall, Inc.49 Network 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

Technology In Action © 2006 Prentice-Hall, Inc.50 LinksLinks tml _7-0.html tml _7-0.html