The Internet

1. The Internet 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 Chapter6 The Internet

2. 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 Internet

3. 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 Internet

4. 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 Internet

5. 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 Internet

6. ISP services • Internet connection • E-mail 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 Internet

7. 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 Internet

8. 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 Internet

9. 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 Internet

10. 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 Internet

11. 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 Internet

12. 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 Internet

13. 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 Internet

14. Every email 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 Internet

15. 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 Internet

16. 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 Internet

17. 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 Internet

18. 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 Internet

19. 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 Internet

20. 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 Internet

21. 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 Internet

22. 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 Internet

23. 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 Internet

24. WiMax fixed wireless service • IEEE 802.16 / 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 Internet

25. Downstream speeds • Dial-up 56Kbps • ISDN 128Kbps • DSL 384K to 8Mbps • Cable 5-30 Mbps • Satellite 1-1.5 Mbps • WiMAX 70 Mbps (advertises 40 Mbps) • FIOS – up to 50 Mbps Chapter6 The Internet

26. 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 Internet

27. 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 Internet

28. 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 Internet

29. 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 Internet

30. 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 Internet

31. Cellular Data Service • HSUPA (3rd generation cellular networking) • High-Speed Uplink Packet Access • Voice and data • 2-5.75 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 Internet

32. FTP, the Web and BitTorrent • ftp • open ftp://ftp.swfwmd.state.fl.us/pub/ • Login anonymous; password: email 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 Internet

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

34. 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 Internet

35. 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 Internet

36. 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 Internet

37. Other Internet issues • Corrupted web sites • Infected mail • Downloading infected files Chapter6 The Internet

38. 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 Internet

39. 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 Internet