IST 233 Class Notes For Semester PDF

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Jeff Girard...

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8/30 Class on Nerds 2.0 ● President Johnson ○ ARPA/DARPA→ 1958 scientific research on the space program ■ Charter of this organization was the advancement of technology and research originally, later became to be used by the military ○ Kennedy was elected→ “We chose to go to the moon,” ● Responsibility of space program was chopped out of ARPA and went into a different organization→ NASA (so, ARPA was technology, NASA was space) ● Early to mid-60’s, what were computers like? ○ HUGE ○ How were they programmed? → punch cards ○ Could not be simultaneous, but consumed a lot of electricity ■ Not efficient ○ University’s had computers for RESEARCH in this time frame ○ Very expensive, so they were focused on what was important ● Nerds 2.0.1 ○ Bob Taylor ■ Director of ARPA ■ Thought the internet wasn’t about technology, but communication ■ Wanted the different computers to connect to each other ■ Led to the first thought of joining computers together to share information ○ Lenny Kleinrock ■ Professor at UCLA, dissertation was on packet switching ■ Connected the packet from the Behind the development of packet switching, packet switching computer IMP connected to became the first node on ARPANET ○ Circuit switching→ telephones, the process of establishing a dedicated pathway between the phone in your hand through the phone company and then a wire to another switchboard which then eventually gets to the person you’re trying to call ■ That pathway is built and dedicated to only your phone call, no one else can use those wires while you are so this leads circuit switching to be INEFFICIENT. ● Point A-points in between-Point B all dedicated to you, but all those points in between could be useful to someone else who needs to use it ○ Packet switching→ not permanent, breaks up message into little pieces called packets and then let those packets find the best way to get to their destination ■ Makes the process more efficient ○ Bob Khan ■ Built the first hardware by using the theory ● IMP→ Interface Message Processing Unit to form the first networks ■ Began work with DARPA, he demonstrated the ARPANET by connecting 20 different computers at the International Computer

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Communication Conference which helped people to realize that packet switching was a real technology ■ While working on a packet network project, he came up with ideas for TCP which was a replacement for NCP used by ARPANET ● Created an open-architecture networking which would allow for computers to connect with each other all over the world ● Joined up with Vint Cerf to develop TCP/IP ■ TCP/IP ● Controls communications across a shared network ● Transmission Control Protocol and the Internet Protocol ○ Protocols→ rules for how you act/react in a certain situation ● Each sequence number to ensure they had right order ● Acknowledgements ● Retransmitted, timeouts What transferred ARPANET into Internet??? ○ EMAIL→ Ray Tomlinson created by accident, it was a “hack” because they were having a problem with their TCP/IP ALOHAnet ○ In Hawaii, wanted to create a network to link computers at campuses that were far from each other ○ World’s First Wireless LAN ○ Used radio frequencies to transmit data Department of Defense→ Military was very interested in this because it would give them advantages over Russia helped them to maintain command and control and nuclear capability in the advent of nuclear strikes ○ Pentagon dumped tons of money into it to develop it

Moore’s Law ● Smaller computers, stronger processing power, less expensive, more networks Reading Chapter 1- “Welcome to the Cloud” ● Hosts ○ Any computer attached to a network is a host ○ Include large servers that work with hundreds of users ■ Internet of Things→ devices will talk to each other ● Application programs on different hosts communicate by sending messages to one another ● Dotted Decimal Notation (DDN)--> when an IP address is expressed as four numbers separated by periods ○ A crutch for humans, but computers do not use DDN ● 32 bit IP address is IPv4 address ○ Dominant IP protocol on the internet today is IPv4 ● Internet ○ A collection of thousands of single networks and smaller internets ■ Linking internets is called “internet service providers” or ISPs→ internet backbone

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● To use the internet, must connect to an ISP Internet Engineering Task Force (IETF) ○ Creates standards, and network owners decide which standards to adopt Amazon Web Services (AWS) ○ Helped netflix become more reliable because it transformed netflix into a cloud service and used huge server farms Content Delivery Network (CDN) ○ Network created its own webserver appliances→ Open connect ○ Open Connect is a network on the internet that can connect to the ISP of a customer Virtual Machines (VMs) → each VM is a software process running on the physical server ○ hypervisor→ sits between physical hardware and create virtual machines ○ Acts like a real server in its connections with the outside world, has its own IP address and its own data ○ Using VMs gives an organization agility (the ability to make changes quickly) ■ You can make different copies in order to experiment with different things ■ VM instances → specific virtual machines ● A company can spawn many copies of the same virtual machine at once Infrastructure as a Service (IaaS) ○ Amazon is a cloud service provider (CSP) ○ AWS service that Amazon provides is IaaS, because AWS provides the computing infrastructure which consists of server operation, database management systems ○ Netflix creates and manages its own applications for user ordering, transcoding, personalized viewing suggestions and other matters By outsourcing server operation to AWS, Netflix can focus its efforts more fully in developing and extending its applications ■ Software as a Service (SaaS) ○ Application software, “salesforce.com” Product versus Service ○ Cloud services are sold like electrical service, pay for the service as you go ■ Allows customers to avoid the capital expense of purchasing servers and avoids the risk of buying too much capacity IaaS appears as an operating expense, but SaaS changes application programs from products to services Client hosts ○ Used by individual people to receive service Virtual client ○ There is a virtual client host in the cloud, complete with application software and a virtual hard drive Service Level Agreements (SLAs) → speed ○ Guarantees that the CSP will meet specified service parameters or pay a

penalty Most basic parameter: SPEED ■ Measured in bits/second Application Messages ○ Hypertext Transfer Protocol (HTTP) ■ Standard to standardize message exchange between browsers and webserver programs ■ The HTTP request message asks for a file, the subsequent HTTP response message delivers the file or error message. ● This exchange is called an HTTP request/response cycle Message Fragmentation, Frames, and Packets ○ Fragmentation ■ Hosts also have network software which handles network transmission for the operating systems→ does three things with application messages ■ 1. If the application message is large, the network software fragments the long application message into many smaller message segments ■ 2. The network software places each segment in an electronic envelope→ set of added bits after the segment and contain delivery information, like the address of the receiving host ■ 3. The network software on the source host transmits each segment plus envelope over the network Why fragment????? ○ Error Correction ■ Without fragmentation, the sender must retransmit the entire message which adds too much traffic ■ With fragmentation, the sender only needs to retransmit the single damaged frame or packet which makes the error time less ○ Multiplexing ■ In networking, packets share the cost of multiplexed transmission lines ● Reduces transmission costs Single Networks ○ Networks that have three defining characteristics: ■ A single network uses a single technology for transmission. All devices must comply with that technology’s standards ■ There is a controlled address space such that each host address is unique, like a telephone number ● Most widely used type of host address is the EUI-48 address→ 48 bits long + “Extended Unique Identifier” aka MAC address ■ Messages in single networks are called frames, not packets Point-to-Point Networks, Physical Links, and Data Links ○ Point-to-Point Network ■ Connection between two hosts ○ Data Link Layer ■ Frame organization ■ Also allows us to introduce the concept of DLL standards ■ DLL standards also govern addresses ○

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■ Most common data link layer is the Point-to-Point Protocol (PPP) Physical Layer Link ■ Transmission media, connectors, signals ■ Physical layer standards govern transmission media such as wires, connectors, and signaling ■ Both hosts must connect to the network using the proper plug and send signants in appropriate ways

Layers ○ Each layer supporting the next higher layer ○ Layers 1 and 2 (L1 and L2) ■ The physical layer is the lowest layer, L1. ■ The data link layer is the next-lowest layer, L2 ○ All single-network technologies require standards at both L1 and L2. Wireless Single Networks ○ 802.11 wireless network→ collective name for the standards that govern wireless local area networks ○ Source and destination hosts normally do not communicate directly ○ There is always a single data in between the source and destination host in a single network, regardless of how many physical links are involved Switched Single Networks ○ A larger single network, where the frame is forwarded over a number of transmission links connected by forwarding devices called switches ■ Physical links→ hosts and switches are connected by physical links ● These physical links use copper wire or optical fiber ■ Data links→ the path that the frame takes all the way through the switched network is the frame’s data link ■ Switch operation→ when source host X transmits a frame, the frame goes to switch A. Switch must decide whether to switch the frame to Switch B or Switch C (which is a switching decision) ■ Switching table Hybrid Switched/Wireless Single Networks ○ Most common exception to a single network using the same technology ○ Ethernet Internet Transmission ○ Hosts on Different Single Networks→ 3 problems to overcome ■ 1. Single networks may have different standards, each has its own frame organization and can’t make sense of each others ■ 2. Even if the two networks follow the same standard, this does not mean that they can interoperate. A host on one network may have the same DLL address as a host on the other network. ■ 3. How would you link the two networks together? Creating the Internet ○ Routers→ do the work of connecting networks together, they pretend to be hosts IP addresses

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Data link layer addresses are not necessarily unique across different single networks IP Packets ○ Travel all the way from the source host to the destination hosts, delivers an application segment from the source host to the destination host ○ IP packet pretends to be an application segment and the frame simply carries that ○ Encapsulated in a frame Route→ the path that a packet takes from the source host to the destination host across an Internet, there is always a single route for a packet through an internet and that the number of data links is the number of single network separating the source and destination host L3→ internet layer

● RA #1 ● What kind of address do hosts have on the internet ? ○ IP addresses ● Which layer’s standards govern delivering frames? ○ 2 ● Which layer’s standards govern signaling? ○ 1 ● When the source host transmits a packet, the packet is addressed to the ______ ○ Destination host ● Data link layer standards govern ________ ○ Frame organization ● What layer number is the Internet layer? ○ 3 ● A ______ may have multiple ______ ○ Physical server, virtual machines ● Which of the following is NOT a standards organization? ○ ISO, OSI, IETF all of these standards or ● Packets are ____ ○ Both switched and routed ● For Netflix, Google is a ○ SaaS 8/10

RA #1 try 2 ● The second-lowest standards layer is the ________ layer. (Read the question and answers carefully.) ○ Data link ● If two hosts are separated by seven networks, how many packets will there be along the way when a host transmits a packet to another host? ○ 1 ● In the Five General Layers Standard, which layer's standards govern application message fragmentation? ○ 4 ● Cloud customers are concerned that ________.

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○ both their data might be hacked and the government may access their data secretly Which layer's standards govern router operation? ○ 3 Netflix uses the most VMs ________. ○ Evenings ________ collectively form the core of the Internet service. ○ ISPs What layer number is the physical layer? ○ 1 Application programs on ________ communicate by sending messages between each other. ○ Different hosts The most widely used single network address is the ________. ○ EUI-48 addresses

Class Notes on 9/4 about the Cloud

● What two things have to exist in order for the cloud evolution to take place? ○ Network, network infrastructure, and network capabilities ■

Need a network to share information

● Virtualization ○ Smaller rack but more processing; ● Speed ○ Bandwidth→ theoretical maximum of how fast measured fast data can be transferred along the database, defined by the electrical and mechanical specifications across that interface ■ Will never achieve the fastest rate because of overhead ■ Static, never changes ○ Throughput→ measurement of what’s actually transmitted and received ○ Latency ○ Jitter→ measurement of the variability of latency ■ Buffering ■

Jitter is the difference between the latency from packet to packet. Obviously, the speed of light isn't subject to change, and fibers tend to remain the same length. So latency is typically caused by buffering of packets in routers and switches terminating highly utilized links

● Protocols vs ○ TCP/IP→ protocol that says how to communicate across a shared network ○ Hypertext Transfer Protocol (HTTP) → Standard to standardize message exchange between browsers and webserver programs

○ DHCP→ automatically assigns IP addresses ○ DNS(Domain Name Services)→ takes a website and translates it into an IP address, it’s a lookup service. We feed it a domain name and it

comes back with an IP address

● Encapsulation→ a process in which one layer of the network structure is going to add information before it passes that packet to another layer of the model ● How does information find its way onto the network? ○ IP addresses→ how we get information from source to destination across network ○ Mac address→ local ● TCP Model (model→ representation of something) ○ 5 layer model, representation of how networks function ○ Each layer has a responsibility Layer Number

Name

Role

5

Application

Standardize communication between two application programs of a certain type

4

Transport

Fragmentation and other functions

3

Internet

Transmit a packet across an internet. Packet org, router operation, and other things needed to transmit a packet across a route in an internet

Routers work here IP addresses work here 2

Data Link What types of devices work here→ switches MAC addresses work here

1

physical

Transmit a frame across a single network. Frame organization, switch and access point operation and other things needed to transmit a frame across a data link in a single network Transmission media, plugs and connectors, signaling

9/11 Class Notes→ Network Standards ● What model are we going to use as a framework for the remainder of the semester? ○ 5 Layer Network Model ● What’s important about using a model architecture?

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A model establishes standards and helps to show how they relate to each other 1→ Physical layer PURPOSE: to take the message/data and converts it to bits and bytes Copper cables, represented by voltage wireless/fiber optic cable Layer

Name

Function

Standards/Protocol

5

Application

Application to application Putting information in front of an individual user that can be understood

Http, spmt

4

Transport

Governs end to end communications between two hosts Creates a virtual connection (session) between the two end hosts → breaks up into segments and some things might not get delivered to the end station but because we have this virtual session that has been open

TCP (reliable, can identify and fix errors) UDP(unreliable, there is no mechanism to correct if there is error in UDP) → used for any sort of streaming/based upon real time

3

Internet

Governs the transmission of packets across the internet→ different from layer 2 because very large scale *source to destination across network

IPv4, IPv6, Novell, IPX/SPX

2

Data link

Governs the communications to the next hop device (small scale)

802.15 (Bluetooth), 802.11 (wireless), 802.3 (ethernet)

1

Physical

Convert payload to 1,0

Copper, fiber, wifi, Bluetooth

Used at Layer 2: ○ MAC: a unique identifier to an individual device that uses a network interface card (NC card) ○ EUI-48 Address/aka MAC

Layers and Header Content ● Application → hands it off to transport layer ● Encapsulation→ taking data and attaching header information ● Protocol Data Unit(PDU) → ● What is the name of the data transport layer? → segment

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What is contained in that header? ■ Source and destination port numbers→ how does a port number relate to an application? ● The transport layer adds in the header a source port and a destination port. There are two types of ports called ephemeral ports. These are standardized, and there are well known ports for each application ● Port 25- SMTP ● Port 80- HTTP Transport→ network layer ○ Source and Destination IP address are added ○ Network layer creates packets Network to Data link→ ○ SRC→ Source and Destination EUI-48 ○ Frames are created by this layer ○ What is different about this layer? → It has a trailer ○ What is contained in this layer? → CRC, cyclic redundancy check, air detection capability at layer 2 ○ (only layer that has air correction is layer 4) What is the TCP 3 way handshake? ○ The first message that is sent from A to B is a SYN ○ B sends back an ACK (acknowledgement) ○ A sends back a SYN-ACK (i got your message that says you wanted to talk, let’s start talking) ○ This is the start of all communications Decimal/binary ○ Figure out how to convert back and forth

Chapter 3 ● Target breach→ thieves had stolen data from 40 million credit cards, downloaded malware to capture the POS systems in American Target ○ The theft did not begin with a direct attack on target, however it began with an attack on Fazio Mechanical Services (who worked for target) ○ Attackers probably sent out a phishing email to get access ○ Once they were inside, they uploaded a POS malware they had purchased from an online crimeware shop. ■ There is a suspicion that the thieves actually took over Target’s internal server that downloaded uploaded the malware ○ It collected magnetic stripe data from every card swiped at the terminal, this occured before it was encrypted and sent over the target network ■ Malware=Ram scraper→ sent everything to...