Chapter6 The Internet1 In search box, enter command prompt At c:\ prompt enter ping alpha.fdu.edu –Are you connected to the Internet? –Is the destination host alive on the Internet –How many packets were sent? (4 in windows), lost, received –The average latency in milli-sec; min. max. avg –IP address translation for the destination given The Internet

History of Internet Impetus of Cold War –Sputnik showed Russia’s advanced technology –Russia had detonated an atom bomb Desire for a decentralized, robust, alternative communications network Decision for a packet switching network –AT&T’s telecommunications monopoly had a circuit switching network Chapter6 The Internet2

ARPA sponsored ARPANet 1969 Four universities linked together –Gradually expanded to other sites Linked LANs and WANs together (internet) –1990 – FDU connected through dial-up to Rutgers Initially command line interface “Archie” became a command line search tool for anonymous ftp sites Chapter6 The Internet3

Commercializing the Internet The Internet was “given” to NSFNet and eventually to Network Service Providers – Each NSP maintains its own infrastructure –High speed fiber-optic links; high capacity routers for directing traffic –NSPs are connected at network access points –AT&T, British Telecom, Deutsche Telekom, Verizon Chapter6 The Internet4

NSPs and ISPs NSPs may also be ISPs – lease lines to public NSPs may lease internet connections to Internet Service Providers –Internet connections are leased to public on monthly basis or by time consumed –Typically ISPs are AT&T, Verizon, MSN, Comcast, British Telcom Chapter6 The Internet5

ISP services Internet connection server (possibly with virus protection) Perhaps server for subscriber web sites –Maintains web pages Perhaps server for chat groups, instant messaging, FTP, music file sharing, etc. News, Ads Chapter6 The Internet6

Public connection to the Internet Computer connected to (perhaps internal) modem and/or router. –Computer may be connected to a LAN which is then connected to the Internet –Connects to the ISP’s (edge) router –ISP is connected to NSP –NSPs are connected through the Internet backbone infrastructure Chapter6 The Internet7

Internet Protocols Communication protocol is a set of rules for defining network services –TCP/IP is the main protocol suite for Internet communication Search window: View Network connections/ click on any icon that shows a connection properties Chapter6 The Internet8

TCP/IP attributes TCP/IP is in public domain, free, extensible Handles addressing packets (using IP) on the Internet Handles addressing services (using TCP ports) on your system TCP breaks message unit into packets IP and TCP add headers for error detection, sequencing, addressing Chapter6 The Internet9

IP IPv4 provides 32 bits for IP addresses –About 4.3 billion –This is not enough, partially because there is a class structure imposed on the addresses European and Asian countries spearheaded the development of IPv6 –128 bits provided  enough even if every device in your house has a static IP address Chapter6 The Internet10

Static and Dynamic Addresses On FDU’s system, our desktop IP addresses are “leased” – may be periodically changed Web servers must have static IP addresses. These are registered in a central database (DNS) There are security advantages of leased, non-static addresses Chapter6 The Internet11

Network Connection Details In search bar, write “view network connections” Click on the icon that shows a connection –General/ details –IP address(es) –DHCP –DHCP server –DNS server Chapter6 The Internet12

Some Other Internet Protocols UDP (User Datagram Protocol) –less reliable, less complex alternative to TCP HTTP (Hypertext Transfer Protocol) –Web GUI for information sharing and linking FTP (File Transfer Protocol) SMTP (Simple Mail Transfer Protocol –and POP (Post Office Protocol) - mail transport VoIP – (Voice over IP) BitTorrent (distributed file sharing) Chapter6 The Internet13

Every address and web site has a top-level domain fdu.edu –FDU’s top-level domain is edu Top level domains of edu, gov, mil restricted in US Unrestricted domains include com, org, biz –In most countries, country code is top-level –DNS for each top-level domain translates the words into IP addresses –Fdu domain information is stored at DNS Who.is/whois Chapter6 The Internet14

Port addresses Each computer (system) on the Internet has an IP address Each service has a port –In command prompt, type netstat (or netstat –a for UDP and TCP) (netstat –n for ports on both ends) –80 is a well-known port for web services –User processes are assigned ports dynamically Chapter6 The Internet15

Setting up a web site Get your own domain name (Internet Corporation for Assigned Names and Numbers - ICANN) –Or get a domain name from a regional registry –Fees range from $10 to $100 with perhaps other services includes “parking” is reserving a name for later use Internet Assigned Numbers Authority (IANA) delegated the last 5 blocks of IPv4 address space to regional registries on 2/11 Chapter6 The Internet16

Try Tracert on Windows Go to command prompt Tracert google.com –returns number of “hops”; path taken Compare to ping (latencies don’t match) To identify IP owners try –who.is/whois or nslookup –You may not be successful Chapter6 The Internet17

Connection speed Dial-up lines provide top speeds of 56 kbps –Upstream speed is slower than downstream –Asymmetric Internet connection –Yet, servers need high upstream speed DSL, cable, FIOS, WiMAX, cellular phones –FIOS advertises up to 50/25Mbps –WiMAX from Sprint advertises up to 40Mbps Chapter6 The Internet18

Different types of connectivity Fixed internet access –Desktop is connected through wall socket to roof-mounted antenna or wire to ISP Portable Internet access –Wireless router in your house links your laptops to Internet, for example Mobile Internet access – cell-phone or laptop that connects to base station Chapter6 The Internet19

Fixed Internet Access Dial-up RJ-11 port on computer connected to telephone line through telephone wall jack –Internal or external modem –Modem (modulator/demodulator) converts digital signals (pulses) to analog signals (continuous electromagnetic waves) –Modem and ISP negotiate (handshake) Chapter6 The Internet20

Fixed Internet Access DSL, ISDN, T1 lines –More expensive, faster than dial-up –DSL is provided by the local telephone company, linked to the ISP Not available in all areas – depends on the distance from the switching station (5km max) Phone and computer can share connection Uses existing phone lines Chapter6 The Internet21

Fixed Internet Access Cable Internet Service (Comcast, Cox) –Connected through LAN port (or USB port) Coaxial cable installed (or used from cable TV) –Local customers are all connected to the same bus, perhaps via a metro ethernet (MAN) Download speed decreases with more users Potential for users to access each other’s data –Always-on connection Chapter6 The Internet22

Satellite Internet Service Geosynchronous satellites are 22,000 m above the equator Latency can be 1 second or more Teledesic, Iridium-low orbit satellite ISPs –Require a satellite dish and a modem –Satellites may offer a type of fixed wireless service –Use microwave frequencies – line-of-sight Chapter6 The Internet23

WiMax fixed wireless service IEEE / Ethernet-compatible Microwave towers sending signals to dishes –Line of sight –Either a roof antenna is hard wired to clients in the house –or customers may be able to communicate with tower through wireless – must be line of sight Chapter6 The Internet24

Downstream speeds Dial-up 56Kbps ISDN 128Kbps DSL 384K to 8Mbps Cable 5-30 Mbps Satellite Mbps WiMAX 70 Mbps (advertises 40 Mbps) FIOS – up to 50 Mbps Chapter6 The Internet25

Portable & mobile Internet access Wi-Fi equipped computers can connect to any “hotspot” –Some ISPs offer hotspot service plans Not interchangeable –Local hotspots may be free or usable by-fee –Wi-Fi is not really portable in that you cannot easily move from one hotspot to another –Mobile Wi-Fi would provide for hand-offs Security is always an issue Chapter6 The Internet26

Wi-MAX If you are within the area of your transmitting tower, your access to the internet, perhaps by a laptop, is portable Mobile Wi-MAX is being worked on to provide handoffs for users Chapter6 The Internet27

Smartphone Internet access Portable and mobile; transparent handoffs 4G cellular technology advertises speed of perhaps 6Mbps –PCWorld tested devices – only Verizon reached this speed for download (5 Mbps for upload) –Issues of Size of display, Security/ confidentiality, Coverage, Cost Chapter6 The Internet28

Internet Services Vo/IP (such as phone service through a cable company) –Download Skype for Windows 7 for free Includes free computer to computer calls Cost for connecting to land lines Real-time messaging is also available –Concern about security of Skype (always on unless you pull the plug out) –Ekiga – open source alternative Chapter6 The Internet29

VoIP Transmits voice with IP/packet switching Quality can vary –Packets can be lost or delayed –Most VoIP connections need power Land lines do not require power connection as long as their handsets are not cordless –911 systems cannot automatically identify caller Chapter6 The Internet30

Cellular Data Service HSUPA (3 rd generation cellular networking) –High-Speed Uplink Packet Access –Voice and data – Mbps uplink data rate –WAP (wireless application protocol) to access Internet through cellular phones, PDAs, etc. Simplified versions of web sites Low-resolution screens Chapter6 The Internet31

FTP, the Web and BitTorrent ftp –open ftp://ftp.swfwmd.state.fl.us/pub/ –Login anonymous; password: address Web download (restricted upload) BitTorrent –Swarm of computers sharing in distributing packets of a large file using peer-to-peer Computer is freed as soon as it sends all of its packets off Chapter6 The Internet32

Internet Security An Oxymoron? Attackers are constantly attempting to “hack” your machines Always on computers are always at risk Chapter6 The Internet33

Connecting through open ports Port probe (port scan) – i.e. nmap – free, open source software –Port scanning software can probe 30,000 computers/minute –Sends connection requests to all TCP ports Does it get any response? Use netstat –a to find a list of open ports “listening” services (ftp, http) typically do respond Chapter6 The Internet34

What to do against port attacks? Close any services (and their ports) that you are not using Turn off your computer when you are not using it Get good protection software (firewalls, virus protection) Patch/ update your OS and security software Chapter6 The Internet35

Other measures Turn off guest account Turn off file sharing, if possible Use a router with NAT addresses Use VPNs if possible –Place VPN client in windows search bar for FDU VPN service Encrypt your files Chapter6 The Internet36

Other Internet issues Corrupted web sites Infected mail Downloading infected files Chapter6 The Internet37

Societal concerns Pornographic sites Violent computer games Gambling Cyber bullying Posted knowledge of bomb making, etc. This behavior was available before the Internet, but the Internet makes it easier Chapter6 The Internet38

Free Speech as a positive force “Should governments be allowed to block access to web sites [and the web] based on local religions, politics, and customs?” p.347 Chapter6 The Internet39