Internet Overview


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  • Internet Overview

    1. 1. Introduction to the Internet May 18, 2000 Sandy Bacik, CISSP Senior Security Consultant Breakwater Security Associates email:
    2. 2. Agenda <ul><li>History </li></ul><ul><li>Definitions </li></ul><ul><li>IP addresses and classes </li></ul><ul><li>Protocols </li></ul><ul><li>Tracking information </li></ul>
    3. 3. History <ul><li>Sometimes call “the Net” </li></ul><ul><li>U.S. Defense Department - ARPAnet </li></ul><ul><li>A system of linked computer networks, international in scope, that facilitates data communication services </li></ul>
    4. 4. Definitions Internet backbone This superfast network spanning the world from one major metropolitan area to another is provided by a handful of national Internet service providers (ISPs). Local ISPs connect to this backbone through routers so that data can be carried though the backbone to its destination.
    5. 5. Definitions Internet Network Information Center A repository of information about the Internet. It is divided into two parts: 1) directory services, run by AT&T in New Jersey, and 2) registration services, run by Network Solutions in Virginia.
    6. 6. Definitions IP (Internet Protocol) address <ul><li>A numeric address that is given to servers and users connected to the Internet. </li></ul><ul><li>For servers it is translated into a domain name by a Domain Name Server aka the DNS. </li></ul>
    7. 7. Definitions TCP/IP <ul><li>Transmission Control Protocol/Internet Protocol </li></ul><ul><li>A suite of protocols </li></ul><ul><li>A 2 layer program </li></ul>
    8. 8. Definitions Protocol An agreed upon formatting for transmitting data between two devices IP Internet Protocol. IP specifies the format of packets, also called datagrams, and the addressing scheme
    9. 9. Definitions TCP Transmission control protocol enables 2 hosts to establish a connection and exchange streams of data. UDP User Datagram Protocol, a connectionless protocol that, like TCP, runs on top of IP networks.
    10. 10. IP Addresses 192 . 168 . 124 . 123 An identifier for a computer or device on a TCP/IP network.
    11. 11. Definitions DNS Domain Name Service WINS Windows Internet Naming Service DHCP Dynamic Host Configuration Protocol
    12. 12. Port Number <ul><li>The port numbers are divided into three ranges: </li></ul><ul><ul><li>the Well Known Ports </li></ul></ul><ul><ul><li>the Registered Ports </li></ul></ul><ul><ul><li>the Dynamic and/or Private Ports </li></ul></ul><ul><li> </li></ul>
    13. 13. Protocols with Well-Known Ports <ul><li>telnet </li></ul><ul><li>news </li></ul><ul><li>echo </li></ul><ul><li>ping </li></ul><ul><li>chat </li></ul><ul><li>irc </li></ul><ul><li>http </li></ul><ul><li>smtp </li></ul><ul><li>pop3 </li></ul><ul><li>imap </li></ul><ul><li>netbios </li></ul><ul><li>ftp </li></ul><ul><li>print </li></ul>
    14. 14. Protocols with Registered Ports <ul><li>Network blackjack </li></ul><ul><li>Tripwire </li></ul><ul><li>HP WebAdmin </li></ul><ul><li>Lotus Notes </li></ul><ul><li>screen cast </li></ul><ul><li>timbuktu </li></ul><ul><li>MS SQL </li></ul><ul><li>IBM wireless LAN </li></ul><ul><li>Shiva </li></ul><ul><li>laplink </li></ul><ul><li>prodigy internet </li></ul>
    15. 15. TCP Session Setup Session setup using 3-way handshake
    16. 16. TCP Session Termination Aborting a connection (reset)
    17. 17. Reference Model
    18. 18. TCP/IP related to OSI stack
    19. 19. IPX/SPX related to OSI stack
    20. 20. NetBEUI related to OSI stack
    21. 21. UDP Packet Header information <ul><li>Source Port </li></ul><ul><li>Destination Port </li></ul><ul><li>Datagram Length </li></ul><ul><li>Checksum </li></ul>
    22. 22. TCP Packet Header information <ul><li>Source Port </li></ul><ul><li>Destination Port </li></ul><ul><li>Sequence Number </li></ul><ul><li>Acknowledgement Number </li></ul><ul><li>Header Length </li></ul><ul><li>Flags </li></ul><ul><li>Window Advertisement </li></ul><ul><li>Checksum </li></ul><ul><li>Urgent Pointer </li></ul>
    23. 23. Ping <ul><li>Information gathering </li></ul><ul><li>Selected hosts </li></ul><ul><li>See if hosts are alive and responding on a network </li></ul>
    24. 24. Ping Sample
    25. 25. Port Scanning <ul><li>Information gathering </li></ul><ul><li>Can be custom built or 3rd party software </li></ul><ul><li>Selected hosts </li></ul><ul><li>Ports are tested </li></ul>
    26. 26. Traceroute <ul><li>Utility to record the route to a specific computer </li></ul><ul><li>Information gathering </li></ul><ul><li>Usually 3rd party software </li></ul><ul><li>UDP protocol using ports 33000 > < 35000 </li></ul>
    27. 27. Traceroute Sample
    28. 28. Thank you