CS372 - Week 2

Application layer responsibilities

- Determine destination IP address - Support network applications - Decide which data transits internet

5 layers of the internet protocol stack in order

- Layer 5: Application layer - Layer 4: Transport Layer - Layer 3: Network Layer - Layer 2: Data Link Layer - Layer 1: Physical Layer

7 layers of OSI layering model

- Layer 7: Application layer - Layer 6: Presentation Layer - Layer 5: session layer - Layer 4: Transport Layer - Layer 3: Network Layer - Layer 2: Data Link Layer - Layer 1: Physical Layer

In the internet protocol stack, the ______ layer is responsible for assembling user data to be sent

Application Layer

At the transport layer, what is the payload?

Application data

In the internet protocol stack, the _____ Layer is responsible for finding the destination IP address

Application layer

- Types of messages exchanged - Message syntax - Message semantics - Rules for when and how processes send/respond

Application layer protocol defines:

attack sends a deluge of packets to target host, access link becomes clogged, preventing legitatmate packets from reaching server

Bandwidth flooding

Uses a small part of the wave spectrum and sends only one signal at a time

Baseband

if your computer becomes infected, you may be enrolled in a _______ and used in _______ against other hosts without your knowledge

Botnet(s), DDoS attack(s)

In a _____ architecture, one host is always on, and other hosts may connect and be continually serviced by the first host

Client-Server

A socket pair consisting of 4 tuples. client IP, client Port, Server IP, Server Port

Connection

Attacker establishes a large number of half open or fully open TCP connections at target host. Boggs down host, prevents from accepting real connections

Connection flooding

Renders a network, host, or other piece of infrastructure unusable

Denial of service (DoS)

Reflection, Obstruction from objects, interference

Effects of propagation unguided media

When a packet is passed down to the next lower layer, it is ______ into the lower layer packet

Encapsulated

Twisted pair copper wire, coaxial cable, fiber optic cable

Guided Media

Signal attenuation is less of an issue in _____ media than it is in _____ media

Guided, Unguided

in a ___________ architecture, one host is always on, and other hosts may connect and be handed off amongst themselves by their first host

Hybrid client-server/P2P

Send packet with false source address

IP spoofing

Protocol _______ allows multiple protocols to work together

Interoperability

Merging multiple communication streams into the same media is called ______

Multiplexing

A third party intercepting a packet and downloading its information before it is sent onward toward its destination is called ______

Packet Sniffer

In a ________ architecture, no one host is always on, but hosts may connect amongst themselves in an on-demand fashion

Peer-to-Peer

Provides required link between sender and receiver, propagates bits between sender/receiver

Physical Media

A program running within a host

Process

The minimum necessary information for identifying a process on a remote host would be:

Remote Port Number, Remote Host IP

Waits to be contacted

Server process

supporting network applications (FTP, HTTP, SMTP)

Service - Application layer

Data transfer between neighboring network elements (PPP, Ethernet)

Service - Link layer

Routing of datagrams from source to destination (IP, Routing protocols)

Service - Network layer

Carries actual signals between devices (cable, wireless)

Service - Physical layer

process to process data transfer (TCP, UDP)

Service - Transport layer

- Data integrity - reliability of data transfer - Timing - Bandwidth - certain amount of bandwidth - Security

Services of application layer

A paired IP address and port number is called a _____

Socket

Software interface in a network that sends and receives messages. between application layer and transport layer within a host

Socket (job)

If i were to send information into the internet with your IP address listed as the sender IP, I would be _____

Spoofing IP address

On the internet, an application level protocol implementing email service would most likely utilize ______ as its transport layer protocol

TCP

On the internet, an application level protocol implementing web browsing would most likely utilize _____ as its transport layer protocol

TCP

Application layer protocols?

Telnet, POP3, FTP, SSH, DNS

In the internet, an application level protocol implementing live-streaming video would most likely utilize _____ as its transport layer protocol

UDP

Wireless radio - wifi, terrestrial microwave, wide area (cellular), satellite. Signal is carried in the electromagnetic spectrum.

Unguided Media

Malware that requires some form of user interaction to infect a user's device. Self replicating

Virus

Sending malicious message to a vulnerable application or OS

Vulnerability Attack

Applying FDM to optical transmission, receiver separates frequencies using a prism

Wave-length division

Complex systems. Modularization eases maintenance and updating of system.

Why Layering?

Malware that can enter a device without any interaction

Worms

Uses larger part of wave spectrum and uses frequency division multiplexing to send multiple signals simultaneously

broadband

process that initiates contact

client process

network layer packet

datagram

Link Layer packet

frames

Application layer packet

message

Merging multiple communication streams onto the same medium

multiplexing

a passive receiver that records a copy of every packet that flies

packet sniffer

Transport layer packet

segment