1. Introduction to Networking

2. Key Terms packet  envelope of data sent between computers server  provides services to the network client  requests actions from a server (i.e. makes requests to a server)

3. Local Area Network (LAN) computers and peripherals directly linked together in a single area  room, office, or building enables sharing of peripherals (e.g. printer) commonly uses client-server model  one machine acts as the central node (server)  all others are clients LANs may connect to other LANs or to the outside using a “gateway”

4. Wide Area Network (WAN) a really, really big network  your house  ISP  Internet  Washington-Lee  Yorktown  etc. allows a computer to connect to other computers over a wide geographic area

5. Hardware network cable Network Interface Card (NIC) hub  connects together multiple computers or segments  any incoming data will be broadcasted out to all ports switch  connects together multiple computers or segments  analyzes network traffic and learns which machines are connected to particular ports  incoming data is forwarded through proper port router  forwards traffic to proper destination  programmable (e.g. filter traffic) gateway  a computer that connects users of a LAN to another network

6. Types of Network Cables Modes of communication  Telephone lines ~ dialup  Coaxial cable ~ cable internet  Twisted pair ~ ethernet  Fiber-optic ~ FIOS  Microwave (high frequency radio) ~ wifi  Satellite

7. Topologies network layout in what configuration are the computers connected together Example configurations:  star  bus  hybrid

8. Bus topology single cable used to link all computer together all computers can “see” all traffic, but only grab their respective data

9. Star Topology computers are connected to a switch or hub if any client machine fails, the network keeps on truckin’

10. Hybrid Topology a combination of two or more topologies Example: star-bus topology

11. More Key Terms data integrity  making sure that what is received is what was transmitted  how does data integrity compromised? noise / interference on a line  error in message hacking (hax0ring) data security  preventing unauthorized access to data  examples: required user logins data encryption permissions (one user cannot access another user’s data)

12. Packets an envelope of data sent between computers typically contains:  source (origin) address  destination address  sequence numbers (for packets that combine into one larger piece of data)  timestamp (i.e. postmark)

13. Packet-switched vs. Circuit-switched Networks http://vimeo.com/10347883

14. Packet Switching Break data up into packets & transmit Individual packets are not all necessarily transmitted through the same links Each packet travels over the best available link at the time Packets may arrive at destination out of order  must be re-ordered and reassembled (protocol!)

15. Protocols technical word for “agreed set of rules”  “Jack Bauer breaks protocol” networking protocols define how two computers exchange information initiating a message (multiple packets!) acknowledging that a message has been received error checking compression

16. Internet Protocol source (origin) address destination address Activity:  Each person receives an address on a card  One person in each row will be a switch The switch will write down on his/her card that he/she is a switch The switch will write down the range of addresses on their card  Rules: NO TALKING Switches can move cards  As a class, we will send several messages

17. IP Problems What happens when we send large data? Let’s try to send lots of messages now Problems?

18. Transmission Control Protocol Messages now contain  sequence numbers (for packets that combine into one larger piece of data)  timestamp (i.e. postmark) Now let’s try to send bigger messages

19. Network Security User logins  Must be an authenticated user to login  Password, smartcard, fingerprint, iris, etc. Layered access via permissions  Different levels of user access Firewall  Inspect and filter incoming traffic Encryption  Encrypt data so that it is unreadable by outsiders