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December 27th > Wireless networks > Flashcards

Wireless networks Flashcards

1
Q

Spread Spectrum Wireless Transmission Methods

A
  • DSSS (Direct Sequence Spread Spectrum):
  • FHSS (Frequency Hopping Spread Spectrum):
  • OFDM (Orthogonal Frequency Division Multiplexing):
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2
Q

DSSS (Direct Sequence Spread Spectrum):

A

Uses the entire frequency range to transmit signals.
Susceptible to interference and slower bandwidth.
Channels 1, 6, and 11 are non-overlapping; other channels are wasted.
Not commonly used due to inefficiency.

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3
Q

FHSS (Frequency Hopping Spread Spectrum):

A

Devices hop between predetermined frequencies.
Provides better security but reduces bandwidth and speed.
Rarely used in commercial-grade wireless networks.

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4
Q

OFDM (Orthogonal Frequency Division Multiplexing):

A

Uses slow modulation with simultaneous transmissions over 52 data streams.
Resists interference and provides higher data rates.
Common in Wireless-G (22 MHz channels), Wireless-N (40 MHz in 5 GHz), Wireless-AC, and Wireless-AX.

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5
Q

2.4 GHz Spectrum:

A

Bandwidth: 2.4 GHz to 2.5 GHz (or up to 2.495 GHz in Japan).
Channel width: 22 MHz.
Channels:
U.S.: 11 channels (2401 MHz to 2473 MHz).
Worldwide (except Japan): 13 channels.
Japan: 14 channels.
Only 3 non-overlapping channels: 1, 6, 11.
Supports B, G, N, and AX.

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6
Q

5 GHz Spectrum:

A

Bandwidth: 5.725 GHz to 5.875 GHz.
Channel width: 20 MHz standard.
24 non-overlapping channels.
Channel bonding:
Combines channels to create wider channels (40 MHz, 80 MHz, 160 MHz).
Increases speed and bandwidth but risks interference.
Supports A, N, AC, and AX.

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7
Q

6 GHz:

A

Introduced with Wi-Fi 6E.
Higher speeds and less interference.

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8
Q

Channel Bonding:

A

Merging neighboring channels to increase throughput.
Can combine up to 8 channels (160 MHz wide).
Leads to faster speeds but increases interference risks.

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9
Q

Interference Prevention:

A

In the 2.4 GHz band, use channels 1, 6, and 11 for non-overlapping channels

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10
Q

Wireless Standards

A

802.11a (Wireless A):
802.11b (Wireless B):
802.11g (Wireless G):
802.11n (Wireless N or Wi-Fi 4):
802.11ac (Wireless AC or Wi-Fi 5):
802.11ax (Wireless AX or Wi-Fi 6):

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11
Q

802.11a (Wireless A):

A

Early 5 GHz Wi-Fi standard with 54 Mbps max speed.

Frequency: 5 GHz.
Max Speed: 54 Mbps.
Expensive; used mainly in business settings.

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12
Q

802.11b (Wireless B):

A

Affordable 2.4 GHz standard with 11 Mbps max speed.

Frequency: 2.4 GHz.
Max Speed: 11 Mbps.
Affordable and widely adopted but crowded frequency.

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13
Q

802.11g (Wireless G):

A

Improved 2.4 GHz standard with 54 Mbps max speed.

Frequency: 2.4 GHz.
Max Speed: 54 Mbps.
Faster than B but still interferes with other devices in 2.4 GHz.

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14
Q

802.11n (Wireless N or Wi-Fi 4):

A

Frequency: 2.4 GHz and 5 GHz.
Max Speed: 300–600 Mbps.
Introduced MIMO (Multiple Input, Multiple Output) for better throughput.

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15
Q

802.11ac (Wireless AC or Wi-Fi 5):

A

Frequency: 5 GHz.
Max Speed: Up to 6.9 Gbps.
Introduced MU-MIMO (Multiple User, Multiple Input, Multiple Output).

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16
Q

802.11ax (Wireless AX or Wi-Fi 6):

A

Frequency: 2.4 GHz, 5 GHz, and optionally 6 GHz (Wi-Fi 6E).
Max Speed: Up to 9.6 Gbps.
Fully backward compatible with previous standards.

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17
Q

Interference Types

A

Radio Frequency Interference (RFI): Caused by devices like microwaves, baby monitors, and cordless phones, especially in 2.4 GHz.
Physical Interference: Obstacles like concrete walls, refrigerators, or cabinets that weaken signals.
Attenuation: Signal weakening due to distance or obstacles.

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18
Q

Wireless Technologies

A

MIMO (Multiple Input, Multiple Output)

MU-MIMO (Multiple User, Multiple Input, Multiple Output)

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19
Q

MIMO (Multiple Input, Multiple Output):

A

Uses multiple antennas to increase data transfer rates.

Introduced with 802.11n.

20
Q

MU-MIMO (Multiple User, Multiple Input, Multiple Output):

A

Supports multiple users simultaneously.

Introduced with 802.11ac.

21
Q

Wireless Security Protocols

A
  1. WEP (Wired Equivalent Privacy):
  2. WPA (Wi-Fi Protected Access):
  3. WPA2 (Wi-Fi Protected Access 2):
22
Q

Wireless Network Security Basics

A
  1. Wireless networks are convenient but vulnerable to security threats.
  2. Key goals for wireless security:
    - Prevent unauthorized access.
    - Encrypt data transmissions.
  3. Pre-Shared Key (PSK):
    - Both access point and client share the same password for encryption.
    - Suitable for small environments, but not scalable.
23
Q

WEP (Wired Equivalent Privacy):

A

Early wireless encryption
Introduced with 802.11.
Uses a 40-bit or 128-bit static key and a 24-bit Initialization Vector (IV).
IV is transmitted in clear text, making it highly insecure.
Easily cracked using tools like AircrackNG.

24
Q

WPA (Wi-Fi Protected Access):

A

Replaced WEP due to IV vulnerability.
Introduced TKIP (Temporal Key Integrity Protocol) and RC4 encryption.
Added MIC (Message Integrity Check) to prevent tampering.
Weak by today’s standards.

25
Q

WPA2 (Wi-Fi Protected Access 2):

A

Current standard.

Replaces RC4 with AES (Advanced Encryption Standard).

Uses CCMP (Counter Mode with Cipher Block Chaining Message Authentication Code Protocol) for integrity checks.

Two modes:
- Personal Mode: Uses a shared key for small networks.
- Enterprise Mode: Uses unique credentials for each user with a central authentication server.

26
Q

Additional Security Measures

A
  1. MAC Address Filtering:
  2. SSID (Service Set Identifier) Broadcasting:
  3. Strong Passwords:
27
Q

MAC Address Filtering:

A

Access points permit or deny specific devices based on their MAC addresses.
Easy to bypass by spoofing MAC addresses.

28
Q

SSID (Service Set Identifier) Broadcasting:

A

Disabling SSID broadcast hides the network name.
Users must manually enter the network name.
Easy to detect using penetration testing tools.

29
Q

Strong Passwords:

A

Prevent brute force and dictionary attacks.
Essential for WPA2 security.

30
Q

“open” in reference to a wireless network

A

If you see the word “open” on the exam, it means:
No security.
No encryption or password protection.
Open networks are not recommended for secure environments and should be avoided unless absolutely necessary.

31
Q

Fixed wireless

A

refers to wireless communication between fixed locations, commonly used for point-to-point connectivity.

32
Q

Four main types of fixed wireless networks:

A
  1. 802.11 Wi-Fi:.
  2. Cellular:
  3. Microwave:
  4. Satellite
33
Q

802.11 Wi-Fi:

A

Speed: Comparable to regular Wi-Fi speeds.
Uses: Short-range building-to-building connections.
Technology: Directional antennas to reduce interference and increase speed.
Regulation: Unlicensed spectrum (2.4 GHz and 5 GHz).

34
Q

Cellular

A

Speed: Varies; 5G can provide gigabit speeds.
Uses: Fixed cellular devices (e.g., 5G hotspots) Internet access via fixed hotspots in homes or offices.
Technology: Larger fixed antennas for better performance.
Regulation: Licensed spectrum (regulated by FCC).
Provided by carriers like AT&T, T-Mobile, and Verizon.

35
Q

Microwave

A

Speed: High-speed connections over long distances.
Uses: Point-to-point links over distances up to 40 miles.
Technology: Requires clear line of sight.
Regulation: Licensed spectrum.

36
Q

Satellite:

A

Speed: Depends on orbit type; generally slower than terrestrial connections.
Uses: Internet access in remote areas or global communication.
Technology:
LEO (e.g., Starlink): Lower latency, requires more satellites.
Geosynchronous: Higher latency, fewer satellites needed.
Regulation: Licensed spectrum.

37
Q

Unlicensed Spectrum

A

Frequencies (e.g., 2.4 GHz and 5 GHz) that do not require a license for use.

38
Q

Licensed Spectrum

A

Frequencies regulated by authorities (e.g., FCC) and used by cellular, microwave, and satellite providers.

39
Q

NFC (Near Field Communication):

A

Use: Short-range data transmission (2–4 inches even up to 8). Used for payments (e.g., Apple Pay) and tap-to-transfer data. Also can be used to instantly connect devices like airrpods.
Vulnerabilities:
Eavesdropping: High-gain antennas can pick up signals beyond the designed range.
Skimming: Attackers use RF skimmers to capture transaction data.

40
Q

RFID (Radio Frequency Identification):

A

Use: Inventory tracking and authentication systems.
Components: Tags (embedded in objects) and readers (capture signal).
Vulnerabilities: Signals can be captured and retransmitted; should be paired with two-factor authentication for security.

41
Q

Infrared (IRDA):

A

Use: Line-of-sight communication for older wireless devices like mice, keyboards, and some data transfers.
Limitations: Requires direct line of sight, low data rates.

42
Q

Bluetooth:

A
  • Use: Wireless communication between devices (e.g., peripherals, headphones) over a 2.4 GHz personal area network.
    Vulnerabilities:
    Bluejacking
    Bluesnarfing
    Blueborn
43
Q

Tethering

A

Sharing a smartphone’s internet connection with other devices via Wi-Fi, Bluetooth, or USB.

44
Q

Bluejacking

A

Sending unsolicited messages via Bluetooth.

45
Q

Bluesnarfing

A

Unauthorized access to data through Bluetooth.

46
Q

Blueborn

A

Exploit targeting Bluetooth protocol vulnerabilities for device control.

47
Q

Wireless Router Configuration Steps

A

Wireless Security:

Use WPA2 with AES encryption for secure connections.
Set a strong, complex pre-shared key (8–63 characters).

SSID Broadcast:

Disable SSID broadcast to hide the network name and require manual entry for connections.
Note: Hidden SSIDs can still be detected with advanced tools.

Wireless Isolation:

Enables isolation of devices on the wireless network, making the router act like a switch rather than a hub.

Channel Selection:

Use Channels 1, 6, or 11 for 2.4 GHz networks to avoid overlap.
Allow auto-selection for convenience or manually choose a less congested channel.

Modes:

Choose a mixed mode (e.g., G and N) to support older devices if necessary.
For newer networks, use N or AC modes for faster speeds.

Guest Network:

Enable a separate guest network with internet-only access to isolate guests from the main LAN.

MAC Filtering:

Allows only specific MAC addresses to connect.
Easily bypassed by attackers and not highly secure.

WPS (Wi-Fi Protected Setup):

Disable WPS for better security since it is vulnerable to hacking.

Remote Management:

Disable remote management unless needed for specific cases.
If enabled, restrict access to specific IP addresses for added security.

December 27th (20 decks)

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