1. Intro to Wireless Networking Flashcards
Summarise how wireless communication works
Wireless communication is an UNGUIDED signal via radio waves.
Wireless communications like this are sent & recieved via ANTENNAE.
ANTENNAE take an ELECTRICAL signal & convert it to a RADIO signal in the form of ELECTROMAGNETIC WAVES (and vice versa)
What are electromagnetic (EM) waves?
Electromagnetic waves are invisible sinusoidal waves that travel through space and carry energy.
They are created by the movement of electrically charged particles and consist of oscillating electric and magnetic fields.
The waves travel at the speed of light in a vacuum.
Wavelength and Frequency: have a wide range of wavelengths and frequencies. The wavelength is the distance between successive peaks of the wave, and frequency is the number of cycles per second, measured in Hertz (Hz).
Spectrum: The electromagnetic spectrum includes various types of electromagnetic waves, each with different wavelengths and frequencies. The spectrum ranges from radio waves (longest wavelength) to gamma rays (shortest wavelength). Other types are Ultra violet, visible light, x-rays, microwaves & infra red
What are sinusoidal (‘sine’) waves?
A sinusoidal wave (or sine wave) is a smooth, repetitive oscillation that looks like the shape of a wave when you draw it. It’s one of the most fundamental waveforms in mathematics and physics, and it can be described by the sine function
What are the advantages of using wireless communication in the form of EM waves?
- Cost
- Mobility
- Ease of Installation
- Reliability (can be more resiliant that wired comms, e.g in times of disaster)
What are the disadvantages of wireless communications using EM waves?
- Interference (with unguided signals there is always the possibility of interference between multiple signals. e.g cross talk.)
- Signal Strength (repeaters are often required to maintain sufficient signal strength to communicate)
- Security
Man-in-the-middle (MITM) Attack
Wireshark - Health & Welfare (EM radiation can cause health problems - US embassy staff in Cuba and China microwave bombardment)
List some Wireless Technologies
- RFID (Radio Frequency Identification).
A technology used to identify and track objects wirelessly using radio waves. It consists of two main components: RFID tags and RFID readers - NFC (Near Field Communication).
Similar to RFID, can be found in mobile devices - phone ‘bumping’ to transfer data via NFC - WiFi (Wireless Fidelity)
Used in point to point communications. Small wave lengths so antennae can be smaller. bandwidth 30 x times that of all the rest of radio spectrum below it but line of sight restrictions means limited use where there are geographical / physical boundaries. - Microwave
- GSM (Global System for Mobile Communications)
- Infrared
Infrared can also be used to transmit data and is found in some cell phones. An infra red port allows data transfer where there is a clear line of siight.to connect using a beam of infrared light. Can only operate within a range of about 1 metre. - Bluetooth.
short distance communication - GPS (Global Positioning System)
- RF (Radio Frequency).
uses a wireless electromagnetic signal for communication. uses radio frequencies in the range of 3 khz to 300 ghz.
ALL THESES TECHNOLOGIES OPERATE ON DEIFFERENT FREQUENCIES
Summarise how Wireless Access Points (‘routers’) transmit.
A wireless access point (WAP) will typically transmit data at either 2.4 ghz or 5 ghz.
The reciever for communication is called the NIC (network interface card).
How many channels operate at 2.4 GHz?
24 channels oeprate at 2.4 GHz.
Summaries the channels that operate at 2.4 GHz
- Channels 1-14
Operate 2.412 to 2.484 GHz - Each Channel is 5 MHz apart
- Some Channels Overlap
means there can be Interference - to avoid this interference, routers in the US generally operate on channels 1, 6 and 11, so there is little or no overlap in channels. Interference can still occur e.g from a neighbour’s access point or baby monitor or microwave, etc
- Channel 1 (2.412 GHz), Channel 6 (2.437 GHz), Channel 11 (2.462 GHz)
How manay channels operate on 5 GHz frequency?
200.
Summarise the 5 GHz Frequency Channels
A router that operates on the 5 GHz frequencies has access to 200 channels.
- Numerous Non-overlapping Channels
- Some Channels are Restricted
- US Routers Commonly Use 36, 40, 44, 48… etc (every 4)
What is an SSID?
Service Set Identifier (SSID) = text-based Identifier for a Wireless Network
SSID is the name associated with the network.
Can be CLOAKED or UNCLOAKED
An access point (router) can be associated with the SSID.
What is the BSSID?
Basic Service Set Identifier (BSSID) = 6-byte number that each access point needs (even if they all connect to one SSID)
In a Wi-Fi network, especially in infrastructure mode, there can be multiple wireless access points (WAP) serving the same SSID (network name). The BSSID helps devices identify and connect to the right access point.
The BSSID is typically represented as a 48-bit address (like 00:14:22:01:23:45).
Each access point in a network will have a unique BSSID, even if they all broadcast the same SSID.
Think of the SSID as the name of the coffee shop, and the BSSID as the specific table you want to sit at
What is a MAC address?
Media Access Control (MAC) Address = 6-byte Numerical Address
Every station must have one and it must be unique.
What is the standard protocol that all Wireless LAN (Local Area Network) technologies are based on?
802.11
List the evolution of Wireless LAN Technologies
- 802.11a. 1999. used regulated band in US so little interference. Better than b but more expensive so most usually used by businesses.
5 GHz / 54 Mbps - 802.11b. 1999. Used unregulated range was more suseptable to interference. Gained more acceptance in homes because it’s implementation was more affordable.
2.4 GHz / 11 Mbps - 802.11g . 2003.
2.4 GHz / 54 Mbps - 802.11n. 2009. First to implement MIMO
2.4 GHz or 5 GHz / 600 Mbps - 802.11ac (WiFi 5). 2014. Alot faster. Supports video streaming. Supports a large number of MIMO radios and antenna which allow for simultaneous tranmission
5 GHz / 2.6 Gbps - 802.11ax (WiFi 6 / high efficency Wireless). 2019. Backward compatable with ac and n.
Summmarise the key features of WiFi 6
- 802.11ax. 2019
- Goal was to attempt to keep up with demand in busy areas and explosion of IoT devices.
- Goal – 4x throughput of 802.11ac
1148 Mbps on 2.4GHz
4804 Mbps on 5GHz - Peak total bandwidth ~ 6000Mbps
- Creation of WiFi Alliance to ensure wifi can handle increase in devices and increase in tech
- 4K Video (double the bit rate of HD)
- 2020 – 12.3 billion Mobile Devices & 21 billion IoT devices = Pressure on Public Networks. More than 70% of global population have mobile devices 2020
- Wifi 6 gave 30% Increase in Speed in reality. The only real limitation is if WiFi SP don’t support it.
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Summarise the key features that make WiFi 6 faster
- QAM. Quadrature Amplitude Modulation 1024.
QAM is a modulation scheme in telecommunication systems. Transmitting data wirelessly is achieved by modulating radio waves. wifi 6 is 1024 QAM which can transmit 10 bits at a time (2 bits more than wifi 5). Improves throughput because more data is tranmitted per packet. - Orthogonal frequency-division multiple access (OFDMA).
OFDMA enables an ax router to send and recieve data to multiple devices simultaneously by splitting a transmission channel into multiple channels. Devices can have clear path to access point - Multi-User, Multi-Input, Multiple Output (MU-MIMO). allows access points to send up to 8 streams simultaneously.
- Beamforming Technology.
To direct streams more accurately to an access point’s antennae
List 3 WLAN Topologies
- Ad-hoc
- Access point
- Bridge mode
What is Ad-Hoc Mode?
1 computer has wifi access, one doesn’t (e.g ‘hotspot’)
- Computer to computer Wi-Fi
- No Access Point (less risk of failure)
- Wireless ad hoc network (WANET)
- Share files directly
- Proximity – 100 metres
- Share your wireless connection
- Limitations include distance and scalability because no. of devices is limited.
List some types of Ad-Hoc Networks
Mobile ad hoc network (MANET)
Vehicular ad hoc network (VANET)
Smartphone ad hoc network (SPAN)
Wireless mesh network
Army tactical MENT
Wireless sensor network
Disaster rescue ad hoc network
What is Infrastructure Mode?
Think of a standard LAN. Where multiple devices can connect via a centralised accress point (‘router’).
Centralised access point means security features exist such as:
- MAC address verification
- SSID checking
- Encryption
Describe in more detail the security features on an Infrastructure mode WLAN.
- MAC Address Verification.
MAC address verification simply checks that the mac address of the device trying to connect to the network, is allowed to connect to it. - SSID Checking.
SSID Verification: The network checks if the SSID provided by the connecting device matches the SSID of the authorized network. Only devices with the correct SSID can access the network, preventing unauthorized devices from connecting - Encryption. Two types WPA and WEP.
WEP. WEP = Wired Equivalent Privacy.
Means access point is encrypted with encryption key. Device can only connect if it possesses the encryption key. HOWEVER various security weaknesses assoc so no prefered now.
WPA. WPA is the preferred encryption protocol for routers. Created to address weaknesses in WEP. WPA = Wireless Protected Access.
WPA uses a stronger encryption method called TKIP (Temporal Key Integrity Protocol) to protect data transmitted over Wi-Fi networks.
It provides improved user authentication, ensuring that only authorized users can access the network.
Dynamic Key Management: WPA regularly changes the encryption keys, making it more difficult for attackers to decipher the keys
However. Broadband routers often contain a WLAN access point which can possess unsecured access to the internet (public wifi)
What is Bridge Mode?
Can connect two different parts of a network wirelessly. No physical cable between the two so low cost and has scalability
Can be used in homes or small offices.
Allows two routers to work together seamlessly. When you enable bridge mode on one router, it stops performing certain functions like Network Address Translation (NAT) and lets the main router handle those tasks1. This helps to avoid issues like IP address conflicts and double NAT, which can cause connectivity problems
Bridge mode is particularly useful if you’re using a second router to extend your Wi-Fi coverage or if you want to create a separate network for guests while keeping your main network secure
List some WLAN security Issues
- Rogue / hacker access point to sniff traffic on your network or to intercept it.
- Employee can setup their own access point (to access banned websites)
- WEP vs WPA
- Hack5 website
Devices beliwve they are connecting to strongest signal so pineapples can be effective.
What is Wifi Scanning?
WiFi scanning modes are the way in which wireless enabled devices discover wireless networks that are within range of the wireless adapter.
They define the device and determine the info about the network (can include the channel, signal strength, security configuration,). This info is used to determine what network the device may connect to.
What are the two types of WiFi Scanning Mode?
ACTIVE or
PASSIVE
Describe ACTIVE scanning mode
In ACTIVE scanning mode the device transmits probes.
Can BROADCAST to all devices or DIRECT to a specific SSID
With a BROADCAST probe request the request by the client will include SSID = Null, the access point will respond with its SSID.
Direct probe requests will include the SSID that the network adapter wants to connect to. The response indicates the configuration and capability of the wireless network managed by the network.
Describe PASSIVE scanning mode
With PASSIVE mode the client device or application listens for BEACONS that are specific frames transmitted by the access point. While scanning, the device or application can identify the SSID.
List some security concerns re Wifi scanning
Packets Can be Intercepted
Traffic can be decrypted
Beacons & Probes can be monitored by hackers when gathering info about a network.
Mitigated by:
Encryption Keys
Hiding (Cloaked) SSID can mitigate risk
802.11 Encryption Protocols
MAC Address Filtering