OSI and TCP/IP Models Flashcards
4.1.1 Study Guide
What are the OSI Layers
Physical
Data Link
Network
Transport
Session
Presentation
Application
What happens at the physical layer
Converts a frame into bits for transmission/receiving over the physical connection medium.
Network hardware devices that function at layer 1 include NICs, hubs, repeaters, concentrators, amplifiers.
What are physical layer protocol data unit (PDU)
Bits
What are common physical layer protocols
Electrical signal (copper wire)
Light Signal (optical fibre)
Radio Signal (air)
What are some physical network topologies
Ring
Bus
Star
Mesh
What are physical layer attack vectors
Passive sniffing
Excessive Electrical Interference
Cutting a cable
What happens at the Data Link Layer
Responsible for formatting a packet for transmission
Adds the source and destination hardware address to the frame
Address Resolution Protocol (ARP) operates at layer 2
Switches and Bridges function at this layer
What sublayers of Data Link Layer
Logical Link Control (LLC)
Media Access Control (MAC)
What does the Logical Link Control do?
Controls packet synchronization, flow control, and error checking
What does the Media Access Control do?
It controls how devices on a network gain permission to transmit data.
What are common Data Link Layer protocols
MAC, ARP, Ethernet 802.3 (Wired)
LLDP, HDLC, PPP, DSL, IEEE 802.11(Wireless), SONET/SDH, VLANs
What are Data Link Attack Vectors
Address Resolution Protocol spoofing
Man in the Middle Attack
Session Hijacking
What happens at the Network Layer
Responsible for logical addressing Providing routing or delivery guidance (not necessarily verifying guaranteed delivery)
Manages error detection and traffic control
What are common Network Layers protocols
IPv4
IPv6
IPSec
OSPF
EIGRP
ICMP
RIP
NAT
What are Network Layer Attack Vectors
Man in the Middle Attack
Denial of Service
Spoofing IP address
What happens at the Transport Layer
Responsible for managing the integrity of a connection and controlling the session. Providing transparent data transport and end to end transmission control
Defines session rules like how much data each segment can contain, how to verify message integrity, and how to determine whether data has been lost
Segmentation, sequencing, and error checking happen on this layer
What are common Transport layer protocols
TCP
UDP
SSL
TLS
What are Transport layer attack vectors
SYN Flood Attack
Trojans and other malware tend to target specific TCP and UDP ports
Session Hijacking
What happens at the Session Layer
Responsible for establishing, maintaining, and terminating communication sessions between two computers
Uses data streams
What are the 3 communications session phases
Connection establishment
Data Transfer
Connection release
What are common Session layer implemenations
RPC
NFS
SMB
NetBIOS
What are Session Layer attack vectors
Protocols such as NFS and NetBIOS may be vulnerable to DoS and root privilege attacks
What happens at the Presentation Layer
Responsible for transforming data into format that any system following the OSI model can understand
Uses data streams
What are Presentation Layer tasks
data representation
character conversion
data compression
data encryption
What are common Presentation layer implementations
Encryption protocols and Format types like
ASCII
EBCDICM
TIFF
JPEG,
MPEG
MIDI
What are Presentation Layer Attack Vectors
Crytanalytic Attacks such as
Brute Force
Ciphertext Only
Know Plaintext
Frequency Analysis
What happens at the Application Layer
Interfacing user applications, network services, or the Operating system with protocol stack
Identifying and establishing availabilty of communication partners
Determining resources availability
Synchronizing communication
Uses data streams
What are common Application Layer implementations
HTTP
FTP
LDAP
Telnet
What are the TCP/IP Layers
Link Layer (Physical and Data Link)
Internet Layer (Network)
Transport Layer (Transport)
Application Layer (Session, Presentation, and Application)
What is the Protocol Data Unit (PDU) at the Data Link Layer
Frames
Routing Protocols
Move routed protocol messages across a network.
Defined at the Network Layer and specify how routers communicate
Can be static or dynamic and categorized as interior or exterior
Include Internetwork Packet Exchange (IPX) and Internet Protocol (IP)
Static Routing Protocol
Requires an admin to create/update routes on the router
Dynamic Routing Protocol
Can discover routers and determine best route to a given destination
Routing table is periodically updated
Distance Vector Router Protocol
An interior router protocol that makes routing decisions based on distance (hop count), and vector (router egress interface)
Examples of Distance Vector routing protocol
Routing Information Protocol (RIP): uses hop count as it routing metric
Interior Gateway Routing Protocol (IGRP)
Enhanced Interior Gateway Routing Protocol (EIGRP)
Link State Routing Protocol
An interior routing protocol that uses router characteristics(e.g. speed, latency, error rates) to make next hop routing decisions
Examples of Link State routing protocols
Open Shortest Path First(OSPF) an interior gateway routing protocol developed for IP networks based on shortest path first or link state algorithm.
Intermediate System to Intermediate System (IS-IS)
Interior Routing Protocol
As called “myopic” make next hop decisions based only on info related to the next immediate hop
Exterior Router Protocols
As called “far-sighted” makes hop decisions based on the entire remaining path (i.e.) vector
Border Gateway Protocol (BGP)
an exterior/path vector protocol
Transmission Control Protocol (TCP)
Major transport protocol in the internet suite of protocols. Provides reliable, connection oriented, full duplex streams.
Use 3 way handshake: Synchronize (SYN), synchronize-acknowledge (SYN-ACK), and acknowledge(ACK)
User Datagram Protocol (UDP)
Connectionless protocol that provides fast, best effort delivery of datagrams(self-container unit of data)
What is the Protocol Data Unit (PDU) at the Transport Layer
Segments
What is the Protocol Data Unit (PDU) at the Network Layer
Packets
Simplex
A one way connection establishment in the session layer
Half Duplex
A connection establishment in the session layer where both communication devices can transmit/receive but not at the same time
Full Duplex
A connection establishment in the session layer where both communication devices can transmit/receive at the same time
What is the Protocol Data Unit (PDU) at the Session Layer
Data
What is the Protocol Data Unit (PDU) at the Session Layer
Data
What is the Protocol Data Unit (PDU) at the Application Layer
Data
