W3 CyberSecurity

Question 1

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OSI: Layer 7

Answer 1

The Application Layer.

Where humans process data and information.

Question 2

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OSI: Layer 6

Answer 2

The Presentation Layer.
Ensures data is in a usable format.

Question 3

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OSI: Layer 5

Answer 3

The Session Layer.
Capable of maintaining connections.

Question 4

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OSI: Layer 4

Answer 4

The Transport Layer.
Data is forwarded to a service capable of handling requests.

Question 5

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OSI: Layer 3

Answer 5

The Network Layer.
Responsible for which path packets should travel on a network.

Question 6

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OSI: Layer 2

Answer 6

The Data Link Layer.
Responsible for which physical devices packets should go to.

Question 7

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OSI: Layer 1

Answer 7

The Physical Layer.
The pysical infrastructure to transport data.

Question 8

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Layer 7, 6, and 5 are typically implemented how?

Answer 8

Through software.

Question 9

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Layers 3, 2, and 1 are typically implemented how?

Answer 9

Through hardware.

Question 9

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Layer 4 is implemented how?

Answer 9

Layer 4 acts as the bridge between software and hardware.

Question 10

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SDN

Answer 10

SDN, Software Defined Networking, allows more layers of the hardware to be implemented via software.

Question 11

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HTTP

Answer 11

Hypertext Transfer Protocol
A layer 7 protocol that allows web access.

Question 12

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FTP

Answer 12

File Transfer Protocol
A layer 7 protocol which allows users to transfer files.

Question 13

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SNMP

Answer 13

Simple Network Management Protocol
A layer 7 protocol used to read and update network device configurations.

Question 14

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Application Layer

Layer 7

Answer 14

The business logic and functionality of the application lies here. This is what the users use to interact with services across a network. Most developers create applications on the Application Layer.

Most of the applications you use are on the Application Layer, with the complexity of the other layers hidden.

Question 15

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Presentation Layer

Layer 6

Answer 15

Typically an unseen layer, but is responsible of adapting, transforming and translating data. This is to ensure the application and layers beneath can understand one another.

Encoding Schemes used to represent text and data, for example ASCII(American Standard Code for Information Interchange) and UTF(Unicode Transformation Format).
Encryption for services, for example SSL (“Secure Sockets Layer”) and TLS (“Transport Security Layer”)
Compression, for example GZip in use in many implementations of HTTP.

Question 16

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Session Layer

Layer 5

Answer 16

This layer’s responsibility is handling connections between the application and the layers below. It involves establishing, maintaining and terminating connections, otherwise referred to as sessions.

Question 17

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Common protocols which represent the Session Layer well are:

Answer 17

• SOCKS - A protocol for sending packets through a proxy server.
• NetBIOS - An older Windows protocol for establishing sessions and resolving names.
• SIP (“Session Initiation Protocol”) - For engaging in VOIP (“Voice Over IP”) communications

Question 18

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Transport

Layer 4

Answer 18

The layer which allows applications to be represented on the network.

Question 19

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Some well known applications on layer 4:

Answer 19

• TCP (“Transmission Control Protocol”) - Used for many applications, ensuring stability, control of how much data can be sent at any given time, reliability and more.
• UDP (“User Datagram Protocol”) - Lightweight and quick protocol use for many services.
• QUIC (“Quick UDP Internet Connections”) - A protocol designed for faster connections and goes hand-in-hand with the version 2 of the HTTP protocol.

Question 20

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Network

Layer 3

Answer 20

A layer responsible of routing packets between networks via routers.

Question 21

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On the network layer, the following protocols reside:

Answer 21

• IP (“Internet Protocol”) - Used everyday when accessing the Internet. Comes in two versions, IP version 4 and 6.
• ICMP (“Internet Control Message Protocol”) - Used by network devices and network operators, to diagnose network connections or for devices to send and respond to error conditions and more.
• IPSec (“Internet Protocol Security”) - Allows encrypted and secure connections between two network devices.

Question 22

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Data Link

Layer 2

Answer 22

Link networks, as the name implies, consist of protocols designed to send packets through the actual links (physical connections) that network nodes are connected to. A simpler way of thinking of it is that the Link Layer is responsible for moving data from physical over to logical (to the network layer).

Question 23

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Protocols on the data link layer include:

Answer 23

• Ethernet - An essential protocol used by most operating systems when connecting to networks using a physical cable.
• Wi-Fi (“Wireless Fidelity”) - For accessing networks via radio signals. It uses a family of protocols called IEEE 802.11.xx
• NDP (“Neighbor Discovery Protocol”) - IP version 6(IPv6) uses this protocol on the Link Layer to gather information required to communicate via IPv6

Question 24

# cy Physical | Layer 1

Answer 24

Physical layer represents the signaling which allows bits and bytes to transfer between a physical medium. It can be transferred via radio or signals over a cable, using electrical signals or light, for example fiber.

Question 25

# cy Examples of the Physical Layer protocols includes:

Answer 25

* CAN Bus ("Controller Area Network") - Used in microcontrollers and other devices to communicate to other similar devices, not involving a computer. Often used in ICS ("Industrial Control Systems"). * Ethernet Physical Layer - Used by Ethernet on the physical layer to send signals with speeds up to many gigabits of traffic per second. * Bluetooth Physical Layer - Bluetooth also has its own specifications on how radio signals should be sent and received.

Question 26

# cy IP

Answer 26

Internet Protocol Allows communication across networks. It exists in two versions IPv4 and IPv6.

Question 27

# cy netmask

Answer 27

Dictates how large a network is and which packet is routed within the ntwork and which should be routed outside of the network.

Question 28

# cy broadcasting

Answer 28

sending data to everyone on the network.

Question 29

# cy broadcast address

Answer 29

is always the last IP address in the network.

Question 30

# cy what is the windows command to check ip address?

Answer 30

ipconfig

Question 31

# cy what is the linux/mac command to show ip address

Answer 31

ifconfig or ip addr show

Question 32

# cy NAT

Answer 32

Network Address Translation Allows a system accepting connections on a public IP to map requests to an internal RFC 1918 IP or vice versa. These are typically firewalls or routers.

Question 33

# cy RFC 1918 IPs

Answer 33

IP addresses that are reserved for certain kinds of traffic.

Question 34

# cy IPv6

Answer 34

128 bits broken into 8 groups of 4 hex numbers.