Cybersecurity chapter 1-6

Network

Two or more devices connected to share data or resources

Client-server network

A server provides services or resources to client devices

Peer-to-peer network

Devices share resources directly with one another

NIC

Network interface card that lets a device connect to a network

Switch

Connects devices on a local network and forwards frames using MAC addresses

Router

Connects different networks and forwards packets using IP addresses

Hub

Repeats incoming bits to all other ports

Server

Computer that provides services or resources

Client

Device that requests services or resources

Star topology

Devices connect to a central switch or hub

Bus topology

Devices share one main cable

Mesh topology

Devices have multiple connections for redundancy

OSI model

Seven-layer model used to understand network communication

Layer 1 Physical

Transmits bits as electrical, light, or radio signals

Layer 2 Data Link

Handles frames and MAC addresses on the local link

Layer 3 Network

Handles packets and IP addressing and routing

Layer 4 Transport

Handles TCP/UDP communication and ports

Layer 5 Session

Manages communication sessions

Layer 6 Presentation

Handles data formatting, encryption, and compression

Layer 7 Application

Provides network services used by applications

Troubleshooting process

Identify the problem, form a theory, test it, plan, implement, verify, and document

ESD

Electrostatic discharge that can damage electronic components

Patch panel

Organizes network cable connections

Demarcation point

Boundary between the provider's network and the customer's network

Equipment rack

Holds network devices and equipment

ANSI/TIA-568

Standards for telecommunications cabling

Horizontal cabling

Connects a telecommunications room to work-area outlets

Backbone cabling

Connects major rooms or network areas

TR

Telecommunications room

ER

Equipment room

Network diagram

Shows how network devices and connections are arranged

Asset inventory

List of equipment owned or managed by an organization

Barcode

Uses an optical scan to identify an asset

RFID

Uses radio waves to identify or track an asset

IPAM

IP Address Management

tracks and manages IP addresses

Change management

Process for planning, approving, and tracking network changes

Rollback plan

Steps to undo a change if it fails

Configuration backup

Saved settings used to restore a device

Change log

Record of changes made to a system

Asset lifecycle

Planning, purchasing, receiving, deploying, maintaining, and retiring equipment

MAC address

Address used to identify a network interface on a local link

IP address

Logical address used to identify a device on an IP network

IPv4

32-bit IP addressing system

IPv6

128-bit IP addressing system

Subnet mask

Identifies the network and host portions of an IPv4 address

Default gateway

Router a device uses to reach other networks

Static IP

IP address configured manually

DHCP

Automatically assigns IP configuration to devices

DNS

Translates domain names into IP addresses

Port number

Identifies a specific service or application connection

169.254.x.x address

Often indicates that a device failed to obtain an IPv4 address through DHCP

MAC vs. IP

Switches use MAC addresses for local frame forwarding

routers use IP addresses to route packets

ipconfig

Displays basic Windows IP configuration

ipconfig /all

Displays detailed Windows network configuration

ping

Tests connectivity using ICMP echo messages

tracert

Shows the route packets take toward a destination

nslookup

Queries DNS information

FTP ports

20 and 21

SSH port

22

Telnet port

23

SMTP port

25

DNS port

53

DHCP ports

67 and 68

HTTP port

80

POP3 port

110

IMAP port

143

HTTPS port

443

Protocol

Rules that devices follow to communicate

HTTP

Protocol used to transfer web content

HTTPS

HTTP secured with encryption using TLS

TCP

Transport protocol that provides reliable, ordered delivery

UDP

Transport protocol with low overhead but no built-in guarantee of delivery or order

TCP acknowledgment (ACK)

Confirms that data has been received

Retransmission

Sending data again when needed

Encapsulation

Adding protocol information as data moves down the sender's network layers

Decapsulation

Removing protocol information as data moves up the receiver's layers

Encapsulation order

Data

TCP segment

Transport-layer data unit associated with TCP

UDP datagram

Transport-layer data unit associated with UDP

Packet

Network-layer data unit

Frame

Data Link-layer data unit

Bits

Ones and zeros transmitted at the Physical layer

Port

Identifies the destination service or application

Remote network traffic

The local Ethernet frame is sent to the gateway's MAC address while the IP packet keeps the remote destination IP

Physical layer

Layer 1

transmits bits using physical signals

Bandwidth

Maximum capacity or available range, depending on context

Throughput

Actual amount of data transferred per second

Goodput

Useful application data transferred per second, excluding overhead and retransmitted data

Latency

Time it takes data to travel from source to destination

Jitter

Variation in packet delay

Frequency

Number of cycles per second, measured in hertz (Hz)

Attenuation

Signal strength decreases as it travels

Dispersion

Signal components spread out and distort the signal

EMI

Electromagnetic interference

RFI

Radio-frequency interference

NEXT

Near-end crosstalk, measured at the same end as the transmitter

FEXT

Far-end crosstalk, measured at the opposite end from the transmitter