Peer-To-Peer Networks

Technology 7

Peer-to-Peer Networks Client-Server Networks Nodes

Transmission Media  Existing Wiring  Twisted Pair  Coaxial Cable  Fiber-Optic Cable  Wireless Connections

Data Transfer Rate (Bandwidth) -- Maximum Speed of Data Transfer Throughput – Actual Speed of Data Transfer Data Transfer Rate – Megabits per Second – Mbps (one million bits per second)

Network Adapters – devices that enable nodes to communicate  External Network Adapters  Network Interface Cards (NIC)

Packets

Network Navigation Devices  Router – transfer packets of information between networks  Switches – sends packets to selected nodes on the same network

Peer-to-Peer Networks  Wired Ethernet Networks  Wireless Ethernet Networks  Power-Line Networks

Wired Ethernet Networks – IEEE 802.3 Standard  Efficient Transfer of Data  Complex Data Transfer Algorithms  Fast, Reliable  NIC Cards -- 1,000 Mbps Equipment  Unshielded Twisted Pair (UTP) Cables --  page 319 for details wrt specific UTP features  Network Navigation Devices  Repeaters – devices that amplify data signals o required for cable runs over 328 feet o maximum run limited to 600 feet  Ethernet Switches o sends packets to selected nodes on the same network o sends a specific packet only to the node to which it should be sent o keeps track of the data packets o in conjunction with the NIC cards, guides the data packets to their final destination o keeps the network running efficiently  Hubs – retransmits data signals, ie., data packets to all nodes attached to it

Wireless Ethernet Networks – IEEE 802.11 (WiFi) Standard See www.ieee.org for details wrt IEEE 802.11b, IEEE 802.11g standards  Wireless Network Adapter Cards o Transceiver . converts electronic signals to &/or from radio signals . transmit and receive radio signals  Wireless Router o Transceiver . converts electronic signals to &/or from radio signals . transmit and receive radio signals  Range & Quality of Transmission o Maximum Range 250 feet o 802.11b & 802.11g devices transmit on a bandwidth of 2.4 GHz o cell phones transmit on a bandwidth of 2.4 GHz  Wireless Access Point Device – extends the range of a wireless network o connect directly to the router o connect to a node that is within range of the router

Power-Line Networks HomePlug Power Line Alliance – www.homeplug.org  Data Transfer Rate -- 200 Mbps  Attach a Power-Line Network Adapter to each Node (computer)  Plug the Power-Line Network Adapter into an electrical outlet

Historical Cost Analysis (page 327)

Cybercrime  Hackers – anyone who unlawfully breaks into a computer system  White-Hat Hackers (testing a systems vulnerabilities)  Black-Hat Hackers (malicious intent) o Financial Benefit o Industrial Espionage o International Governmental Espionage . W32/Conficker.worm.gen.d  Script Kiddies – use tools created by hackers to break into systems  Packet Sniffer program that searches all packets traveling through a specific node, looking for vital financial &/or other useful information, e.g., credit card numbers, bank account numbers & passwords, e-commerce login names & passwords, social security numbers, birthdates, etc.  Copier Machines – hard drives – tax returns  Identity Theft (see page 336)  Trojan Horses o Appears to do something useful or desirable o Does something malicious in the background o Installation of Backdoor Programs o Zombie Computers  Denial of Service Attacks (DoS)  Distributed Denial of Service Attacks (DDoS) o Hackers use numerous zombie computers to repeatedly request bogus service from a service provider; the requests overwhelm the service providers computer systems to the point where they shut down

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Logical Ports  Virtual, i.e., software, communication paths that allow a computer to organize requests for information from other networks or computers  Each port is numbered and assigned to a specific service o HTTP – port 80 o Simple Mail Transfer Protocol (SMTP) – port 25

Firewalls  Software Firewalls o Norton Personal Firewall o McAfee Firewall o ZoneAlarm o BlackICE PC Protection  Hardware Firewalls – Network Address Translation (page 338-339) o Linksys Routers Routers without NAT cannot provided o D-Link Routers Firewall Protection o Netgear Routers  Security Test – www.grc.com  Wireless Networks o Firewall o Change the Service Set Identifier, i.e., router name o Disable the SSID Broadcast feature – keeps the router from broadcasting the SSID o Change the router password o Security Protocols – Encryption Key Required for access . Wired Equivalent Privacy (WEP) -- weaker encryption code . Wi-Fi Protected Access (WPA) -- stronger encryption code o Implement the Media Access Control feature . each Network Adapter has a unique number assigned to it by the manufacturer, the Media Access Control Number (MAC Address) . restrict network access to designated MAC Address devices o Apply Firmware Upgrades – router has a read-only memory chip with software, i.e., firmware, written on it; manufacturers issue updates, i.e., “patches”; periodically check the manufacturer’s website and apply the necessary upgrades

Viruses -- program fragments that  attach to other programs  attempt to hide within the host program  replicate itself  attach it’s replicates to other programs  side affects o malicious intent o innocuous intent  types of viruses o Boot-Sector Viruses . Master Boot Record is a program that executes whenever the computer is started; this ensures that the virus is loaded into memory before the virus protection programs become active . Potentially very destructive, e.g., format t hard drive o Logic Bombs -- triggered when certain conditions are met o Time Bombs – triggered by the passage of time or on a certain date o Script Viruses – series of commands embedded in websites . automatically run when you visit the website . Amazon.com scripts allow you to purchase items from the site . E-mail website links – potential source of script viruses o Macro Viruses – . Macros are series of commands which may be attached to any MS Office Product, e.g., MS Word . Opening the infected document triggers the virus which then infects other documents of the same type o Encryption Viruses . Virus searches for common data files, e.g., MS Word documents . Encrypts the files with a complex encryption method . Requests, via e-mail, payment of a fee for the encryption code and key

 Worms – programs that travel between systems via network connections o can run independently of a host program execution o very active in spreading themselves o exploits weaknesses in the Windows Operating System o antivirus software is ineffective against worms o firewalls with up to date patches applied are effective Technology 8

EDGE – Enhanced Data Rate for Global Evolution & EVDO – Evolution Data Optimized  data transfer rate ≥ 700 Kb/sec hence improved multimedia access  wide area coverage  less interference – fewer dropped calls

Music File Formats  MP3  ACC  WMA

Napster – P2P Sharing -- centralized index server  Pre June 2002 – free downloads  Post June 2002 – sells access to music files

Gnutella & Kazaa – P2P Sharing – facilitates connections between interested parties

Podcasting

PDA  faster processors than cell phones  more powerful than cell phones  slightly larger than cell phones  decreased battery life compared to cell phones  synchronization of data files with computer system -- cradle  synchronization of data files with other PDA’s o IrDA wireless -- infrared waves o Bluetooth wireless -- radio waves  WAP – Wireless Application Protocol

Smartphones  Palm Treo 700wz – PDA with the following capabilities added o Cellphone o EVDO o Bluetooth o PMP features – multimedia  T-Mobile SDA – Cellphone with the following capabilities added o Email access o Internet access

New Gadgets www.gizmodo.com Tablet PC  Portable computer  Electronic clipboard – advanced handwriting recognition  Digital Ink o Pressure sensitive screen o Hand drawn images . stored as hand drawn picture images . converted to & stored as rectified graphic images  Software keyboard displayed on the screen  Bluetooth or WiFi connectivity  Docking Station

GPS – Global Positioning System -- 21 satellites

Notebooks  Hot-swappable bays  Battery Life Extension o turn off computer when not in use o install maximize amount of RAM o turn off wireless capabilities when not in use o charge batteries to maximum amount – don’t partially charge system o minimize the use of DVD drives  security lock  portable surge protector  collaboration software o www.colligo.com o Windows Meeting Space