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