CompTIA A+ 1101 Unit 2

internet protocol

the “roads” that are designed for the truck to tranfer data the most efficiently

defines how data is packaged, addressed, transmitted, and routed between computers on a network.

data (TCP and UDP)

represented as the boxes inside the truck. Each box contains application information

the two main transport layer protocols used with the Internet Protocol (IP).

IP address

is like the house address the package is going to

port number

is like the room inside of the house that the package belongs in

what application on the server is receiving the data

TCP and UDP

transported inside of the IP and represent 2 different ways to move data for different applications

TCP - Transmission Control Protocol

A connection oriented protocol that is a formal process to set up the flow from one device to another and then another formal process when the connection is over

• reliable delivery because it has a built in system to ensure the data has been sent

• easy to manage out of order messages and retransmissions neede

• can control flow to be faster or slower

  • ex: HTTPS, SSH, etc

UDP - User Diagram Protocol

a connectionless protocol where no formal process is needed, therefore it is used for simple transactions

• unreliable delivery - no error recovery, reordering, or retransmission

• good for real time communication (quick communicaiton)

• DHCP, TFTP

DHCP - Dynamic Host Configuration Protocol

automated configuration of IP address, subnet mask, and other options using a largepool of IP addresses

• DHCP reservations can be assigned by MAC address so that a device has the same IP everytime it is booted up

• UDP/67 orUDP/68

FTP - File Transfer Protocol

generic way to transfer data between systems using authentification by username and password to a remote device

• TCP/20 active mode

• TCP/21 control data transfer

SSH - Secure Shell

Encrypted communication link

• looks and acts the same as Telnet except it is safer because it uses encryption to send and retrieve data

Telnet - telecommunication network protocol

a network protocol that allows a user on one computer to log into another computer that is part of the same network.

• not encrypted so anyone will be able to see the packets that you are sending and receiving, included passwords and confidential information

SMTP - Simple Mail Transfer Protocol

server to server email transfer used only for sending and forwarding emails between mail clients and servers. It does not receive emails — receiving is handled by POP3 or IMAP.

POP3/IMAP

IMAP allows multiple clients to access the same mailbox, while keeping the email messages available on the server for later access via webmail.

POP3 downloads the messages, while removing the messages from the server. The emails are then no longer accessible via webmail or a mail program.

DNS - Domain Name System

turns domain names into IP addresses, which browsers use to load internet pages.

HHTP/HTTPS - Hypertext Transfer Protocol (Secure)

HTTP - communicaiton in the browser and by other application (not encrypted)

HTTPS - communication with encryption

SMB - Server Message Block

a network file-sharing protocol that lets computers share files, printers, and other resources over a network.

Also known as CIFS (Common Internet File System) — a newer version of SMB.

Early SMB used NetBIOS over TCP/IP:

UDP/137 – Name Service (finds devices by name)

TCP/139 – Session Service (sets up data transfer sessions)

SNMP - Simple Network Management Protocol

Used to monitor and manage network devices. It lets management systems query devices for performance data and receive alerts.

• Uses UDP 161 for queries and UDP 162 for traps.

• Versions: v1 – no encryption, v2 – bulk data but still unencrypted, v3 – adds authentication, integrity, and encryption.

LDAP - Lightweight Directory Access Protocol

used to store and retrieve information in a network directory

RDP - Remote Desktop Protocol

used to gain remote access to someone’s desktop

Server communication on IPV4 Sockets

• Server IP address, protocol, server application port number

• The port numbers need to be Non ephemeral ports

• Usually Ports 0 - 1023

• Non temporary ports that are usually the same number every time we use it

• Occasionally uses dynamic port numbers but on rare occasions

Client communication on IPV4 Sockets

• Client IP address, protocol, client port number

• The port numbers are ephemeral ports

• Temporary port numbers that are only used to communicate to the server and then may be different the next time we communicate

• Ports 1025- 65,535

router

a device that forwards routes betwen different IP subnets

• it uses the IP addess that’s within the packet to determine what the next hop might be, on its way to the final destination

switches

detemines where traffic should be forwarded based on the destination MAC address

• may provide additional power over ethernet

unmanaged switch

a switch with very few configuration options besides plug and play

• no management protocols

• no way to query devices fo performance information

• no VLANs

  • very little integration with other devices

managed switch

switches that provides additional capabilities

• VLAN support - allow to interconnect other switches via 802.1

  • has configuration options to configure traffic

  • redundancy support to prevent loops using a spanning tree protocol

  • allows port mirroring to capture packages from one switch to another

Access point

Provides wireless connectivity for the local network (link from wireless network to the wired network like a bridge)

patch panel

a combination of punch down blocks and RJ-45 connectors and are permanently punched down.

firewall

allows or disallows traffic through your network based on IP address and port number

• can encrupt traffic in/out of network to protect traffic between sites

• can act as a proxy to browse for the user and receive the response over the internet to make sure none of the traffic is dangerous before sending it back to the user

power over ethernet (PoE)

a technology that transmits both electrical power and data through a single Ethernet cable to devices like IP cameras and wireless access points.

Hub

A multi port repeater used before switches that was not very intelligent

• any traffic going into one port, goes to every port

• everything is half duplex

• as network traffic increases, it becomes less efficient in connecting devices

cable modem

allows you to communicate over broad bands because there is multiple frequencies going through a single wire

acts as a bridge, converting the signal from your internet service provider (ISP) into a usable digital signal (Ethernet) for your computer or home network, and vice-versa.

DSL Modem

asymmetric digital subscriber line that connects a home or office to the internet by using a telephone line to transmit digital data

• called asymmetrical because the download speed is faster than the upload speed

• there is a distance limitation before the signal gets super week

Optical Network Terminal (ONT)

a device that terminates the fiber optic cable connection and converts the incoming light signals into electrical signals that your devices can use for high-speed internet.

• connected via fiber in the terminal outside your home

• connect the ISP fiber network to the copper network to be used inside your home

• delineates the ISPs netwok from your own internal network (aka demarc point)

network interface card (NIC)

a hardware component that allows a computer or device to connect to a network and communicate with other devices

• often built into the motherboard or added as an expansion card

software defined networking (SDN)

a way to take netwokring platfoms in the real world and convert them to be used in the virtualized cloud based world

Application Layer → Management Plane - this is where administrators and application define network policies and overall behavior (sets what the network should do)

Control Layer → Control Plane - Determines how packets should be routed or forwarded ( translates policies from management plane into specific forwarding rules for devices)

Infrastructure Layer → Data Plane - the devices that forwards packets based on the rules given by the control plane (execute the instructions: forward, drop, mirror, modify, etc)

802.11

• one of the original 1999 standards for wifi

• 5GHz

• 54 Mbps max speeds

• shorter range

802.11b

• one of the original 1999 standards

• operates at 2.4 GHz

• 11 Mbps max speed

• longer range than 802.11a

  • interference from Bluetooth, microwaves, baby monitors, etc

802.11g

• Released June 2003

• operates at 2.4 GHz

• 54 Mbps max speed

• backwards compatible with 802.11b

• same interference issues as 802.11b

802.11n (Wi-Fi 4)

• released October 2009

• operates on 2.4 or 5 GHz

• 40 MHz

• up to 600 Mbps

• uses MIMO (mulitple input multiple output)

• supports multiple antennas for better performance

802.11ac (Wi-Fi 5)

• released 2014

• operates at 5GHz

• up to 160 MHz

• uses MU-MIMO with up to 8 streams

802.11ax

• Operates at 2.4 GHz and 5 GHz

• 20/40/80/160 MHz channel widths

• ~1.2 Gbps per channel

• 8 bi-directional MU-MIMO streams

• Uses OFDMA for efficient multi-user communication in dense areas

long range fixed wireless

a wireless access point in a house with stock antennas

• used to connect 2 buildings via directional antennas

• minimal signal loss/bounce

Radio Frequency Identification (RFID)

• Wireless ID & authentication technology

• Used in access badges, pets, inventory tracking

• Powered by reflected radar signal

• Transfers small data to/from a chip

File Server

A centralized storage of documents, spreadsheets, videos, pictures, and any other files

• allows you to log in from anywhere to have access to your files because it is on the network

print server

A server tat connects a printer to the network and provides printing services for all network devices

Syslog

standard message logging where you send logs to a centralized database that is integrated into a central logging receiver called the SIEM

• Needs a lot of disk space

Web Server

responsible for responding to browser requests using standard browsing protocols like HTTP/HTTPS

Authentication server

responsible for login authentication to resources

spam

responsible for unsolicited messages such as emails, forums, and puts them into a spam folder so you don’t have to read them

• spam gateways can also be used to stop the messages at the gateway from even reaching the user

all in one security appliance

a next generation firewall that combines many security networks into one.

• identify malware

• filter content and URLs

• spam filters

• CSU/DSU capabilities

• acts as a router or switch

• acts as a firewall

• intrusion detection/prevention systems

load balancers

responsible for checking all the servers that are connected to it and distributing the load from multiple servers

Proxy Server

adds additional security to their internet communications by making request to the third party services and then reviewing their response for malicious data

SCADA/ICS

responsible for control and management of industrial machines

• allows us to control industrial machines all in one control system for real time information and requires no access from the outside

Legacy Systems

Devices that may have been installed previously and are too expensive to get rid of because they have a lot of important information on them

Embedded Systems

Systems we dont usually have direct access to but instead is purpose built, meaning it was designed to only have access to the service or application it provides

internet of things (loT)

devices that connect to an applicance on the network using an app

• ex: refrigerator, smart device, air control, smart doorbells

IPV4

the primary protocol for everything we do and included in most configurations

• made up of 4 numbers represented by 8 bits separated by 3 dots

IPV6

A new internet protocol that was created to support the growing number of people who use the internet

• made up of 8 numbers represented as 16 hexadecimal numbers

• are 128 bit addressses meaning that we can have as many as 5 octillion address for each person in the world

bootstrap protocol

protocol used to assign IP numbers and was a process used before DHCP

• did not automatically define eveyrthing and sometimes required manual configuration

• was not able to figure out when an IP address may become available again after it is not used

DORA

A four step process that happens behind the scenes when DHCP is operating

1. Discover - our device ties to locate a DHCP server

2. Offer -  DHCP offers one or more IP addresses to the device

3. Request - Device picks one or more of the IP addresses and requests to use it

4. Acknowledge - the DHCP server confirms the request and provides the configuration we need to use that IP address

How to turn your dynamic IP address to static

1. option 1 - disable DHCP on all devices that you want to have consistent IP’s and manually configure the IP addresses, but all future configuration on this device will have to be manual

2. option 2 - associate a specific MAC address with an IP address (better option)

Automatic Private IP Addressing (APIPA) 

A feature in operating systems that automatically assigns a private IP address to a device when no DHCP sever can be reached

• uses IP range 169.254.0.1 to 169.254.255.254

• the subnet mask is always 255.225.0

• useful fo small temporary networks

DNS hierarchy

helps to create a well defined stucture that works across every fully qualified domain

DNS Records

a database of domain name services

DNS Configuration

defines how a domain’s DNS records are structured and managed

Address records (A)(AAAA)

defines the IP address of a host

Mail Exchanger Record (mx)

determines the host name for the mail server

• 2 separate records in your DNS server, one pointing to the mail and the other pointing to the A record

text records (TxT)

DNS server function to store text information which can then be used for other purposes

Sender Policy Framework (SPF)

a list of all email servers that are authorized to send messages using your fully qualified domain name

• helps to prevent others from spoofing your qualified domain name and sending messages using it

• performs a check to see if a message came from an authorized host

Domain Keys Identified Mail (DKIM)

a digitalized signatue that validates a outgoing mail

The public key is in the DKIM TXT record

Domain Based Message Authentication (DMARC)

A way to determine what we do with the message if the veifcation fails

• prevets spoofing

• allows you to deteming what external email servers should do with the emails that dont validate through SPF or DKIM

satellite networking

using a satellite to connect to networks using another satellite in space

• expesive compared to terrestrial networking

• high latency (250 ms up and down)

• high frequency - 2GHz

fiber connection

high speed connection using the speed of light to transfer data

• supports high data rates

• higher cost

• good for long business

cable broadband

uses the same cable for cable television to provide user with an internet connection

• multiple streams of data using the same cable/wire

• high speed networking 

DSL

uses telephone lines to also provide the user with high speed network connections

• speed of downloads in faster than the speed of upload

• the closer the user is to the central office witht he telephone lines, the faster the speed

tethering

turning your phone into a wireless network

wireless internet service (WISP)

Provides internet access using wireless signals instead of traditional cables.

• commonly used in rural/ remote areas where wired internet is not available

• requires an outdoor antenna to connect to the provider’s nearby ground station/tower

• terrestrial internet via radio waves

local area network (LAN)

connects computers within a small area like buildings or campus

• high speed, low latency

wide area network (WAN)

covers a large geographic area - even worldwide

• slower than LAN due to long distance

Metropolitan Area Network (MAN)

Connects multiple LANs across a city or metro area

• larger than LAN, smaller then WAN

• often government owned

wireless local area network (WLAN)

wireless version of LAN using Wi-Fi

storage area network (SAN)

high speed network connected servers to centralized storage

• uses block level data transfer for fast read/write access

• often isolated and used high fiber or high-bandwidth links

what are cable crimpers used for?

pinches the connectors onto a wire

usually used on the final step of cable installation process

What does a wifi analyzer do?

listens to all of the signals on a network and provides the used with information about which frequencies are in use and which are open

What does a tone generator do?

used to find cables in complex environments by following the tone of the cable

• the inductive probe listens to the wire through a small speaker and provides a tone

what is a punch down tool used for?

used to “punch” a wire into a wiring block permanently (a tedious procedure)

What is a cable tester used for?

helps to identify missing pins or crossed wires by plugging in both ends of the cable into t2 units of he cable tester performing a continuity test

what does Loopback plugs do?

test if the issue is coming from the wire or the interface by looping it onto itself and receiving the information to compare if they match

what does a Tap do?

a hardware decice that passively copies all traffic between 2 network devices and sends it to a monitoring tool for accurate and continuous network analysis

What does a Port Mirror do?

A switch feature that duplicates network traffic from selected ports and send it to another port for monitoring or troubleshooting without disrupting the original network operations

Wireless Personal Area Network (WPAN)

A small scale wireless network designed for short-ranged communication between devices, usually personal devices like phones, laptops, headsets, using bluetooth

NetBIOS (network basic input/output system)

An API that lets applications on different computers within the same local network communicate.

it handles name services, sessions, and data transfers between hosts

NetBT (NetBios over TCP/IP)

NetBIOS running on top of the TCP/IP network stack

Which port enables FTP’s Data Connection for sending file data?

TCP port 20

The FTP Control Connection for administering a session is established through?

TCP port 21

SSH protocol runs on?

TCP port 22

Which of the TCP port is used by Telnet?

TCP port 23

TCP port 25 is used by?

SMTP

Post Office Protocol v3 (POP3) uses?

TCP port 110

Internet Message Access Protocol (IMAP) uses?

TCP port 143