1
Q
WIRELESS NETWORKING: Wireless Communications Techniques
A
Wireless communication involves transmitting information via radio waves that move through free space.
Terms:
- Frequency (Hz): of signal indicates how many radio waves travel through a fixed place each second.
- Amplitude (Watts): of a radio signal indicates its power, which in turns dictates how far it can go.
- Wireless Lan (WLAN): uses CSMA/CA (Collision Avoidance)
2
Q
WIRELESS NETWORKING: Wireless Communications Techniques: Spread Spectrum:
A
- Spread Spectrum means that something is distributing individual signals across the allocated frequencies in some fashion.
- The challenge is how to dynamically allocate individual frequencies to specific sets of transmitters and receivers without them stepping all over each other. This is where Spread Spectrum becomes handy.
- Use case: Communications are used primarily to reduce the effects of adverse conditions such as crowded radio bands, interference, and eavesdropping
3
Q
WIRELESS NETWORKING: Wireless Communications Techniques: Spread Spectrum: Frequency Hopping Spread Spectrum (FHSS)
A
- Takes the total amount of spectrum and splits it into smaller subchannels.
- The sender and receiver work at one of these subchannels for a specific amount of time and then move to another subchannel.
- The sender puts the first piece of data on one frequency, the second on different frequency, and so on. The FHHS algorithm determines the individual frequencies that will be used and it what order. This referred to as “hop sequence”
4
Q
WIRELESS NETWORKING: Wireless Communications Techniques: Spread Spectrum: Direct Sequence Spread Spectrum (DSSS)
A
- Takes different approach by applying sub-bits to a message.
- The sub-bits are used by the sending system to generate a different format of the data before the data is transmitted.
- The Receiving end uses these sub-bits to reassemble the signal into the original format.
- Sub-bits are called “Chips”
- Sequence of application is referred as “chipping code” (Pseudo-noise sequence)
5
Q
WIRELESS NETWORKING: Wireless Communications Techniques: Spread Spectrum: FHSS vs DSSS
A
FHSS:
- Uses only a portion of the total spectrum available at any one time.
- Spread signals over a wider frequency band
DSSS:
- Uses all of the available spectrum continuously
- Whereas FHSS uses narrowband carrier that changes frequency across a wide band.
- DSSS has higher data rates than FHSS
6
Q
WIRELESS NETWORKING: Wireless Communications Techniques: Orthogonal Frequency Division Multiplexing (OFDM)
A
- This is a multiplexing Technology
- Move even more data than spread-spectrum
- OFDM is a digital multicarrier modulation scheme that compacts multiple modulated carriers tightly together, reducing the required spectrum
- OFDM uses a composite of narrow channel bands to enhance its performance in high-frequency bands.
7
Q
WIRELESS NETWORKING: Wireless Networking Fundamentals -Topologies
A
- Fundamentally, there are three topologies: Star, Mesh and Point to point.
8
Q
WIRELESS NETWORKING: Wireless Networking Fundamentals: Star Topology
A
- Star topology is by far the most prevalent because it is used both WLAN and cellular networks. (Layer 3 forward or Layer 2 routing)
9
Q
WIRELESS NETWORKING: Wireless Networking Fundamentals: Mesh Topology:
A
- Mesh topology is common for low-power devices in close proximity to each other, such as those used in smart homes, as well as in devices that span a large area, such as environmental sensors in wildlife refuges.
10
Q
WIRELESS NETWORKING: Wireless Networking Fundamentals: Point-to-Point Topology
A
- Point-to-Point wireless topologies are common when connecting buildings as part of MAN.
11
Q
WIRELESS NETWORKING: Wireless Networking Fundamentals: WLAN Components
A
- Access Point (AP - a transceiver, aka Wireless Access Point (WAP). Connects the wired and the wireless worlds.
- When APs are used to connect wireless and wired networks, this is referred to as an infrastructure WLAN.
- When there is one AP and it is not connected to a wired network, it is considered to be in standalone mode (just act as a wireless hub)
- An Ad-hoc WLAN has no APs, connected via wireless NICs
12
Q
WIRELESS NETWORKING: Wireless Networking Fundamentals: Ad-hoc WLANs vs. Infrastructure WLANs
A
Ad-hoc WLANs are inherently less secure than Infrastructure WLANs
13
Q
WIRELESS NETWORKING: Wireless Networking Fundamentals: WLAN Components : Service Set ID (SSID)
A
Any hosts that whish to participate within a particular WLAN must be configured with the proper Service Set ID (SSID)
14
Q
WIRELESS NETWORKING: WLAN Standards:
A
- Standards are developed s that may different vendors can create various products that will work together seamlessly.
- IEEE develop standards, wireless being one of them.
15
Q
WIRELESS NETWORKING: WLAN Standards:
A
- 802.11b - WiFi 1 - 11 Mbps - 2.4GHz - DSSS
- 802.11a - WiFi 2 - 54 Mbps - 5.0GHz - OFDM - 25 feet
- 802.11g - WiFi 3 - 54 Mbps -
- 802.11n - WiFi 4 - 100 Mbps - 5.0Ghz - Multiple Input, Multiple Output (MIMO)
- 802.11ac - WiFi 5 - 1.3 Gbps - 5.0Ghz - Multi-User MIMO - Beamforming
- 802.11ax - WiFi 6 - Multi-User OFDM (Doubles the number of streams)
16
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Li-Fi
A
- Li-Fi is a wireless networking technology that uses light rather than radio waves to transmit and receive data.
- Speed, ubiquity (every where, very common), restricted to an area
17
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: 802.16
A
- IEEE standard 802.16 is a MAN wireless standard that allows for wireless traffic to cover a much wider geographic area.
- 70 Km part
- 2.4 Ghz and 5 Ghz uses up to 256
- based on WiMAX, replacement for (2G)
18
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: 802.15.4
A
- The IEEE 802.15.4 standard deals with a much smaller geographical network, which is referred to as a wireless personal area network (WPAN)
- This standards defines they Physical layer and Media Access Control (MAC) sublayer of the data link layer.
- Intended to support embedded devices in close proximity to each other
- Industrial (IoT)
- 10m range, 250 Mbps (lower rates 100, 20 10 Kbps)
19
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: 802.15.4: Despite of low rates…
A
- Able to support real-time applications through the use of Guaranteed Time Slot (GTS) reservations.
- Note that when GTS is used, the channel access technique used has to be time division multiple access (TDMA)
- TDMA is a technique that divides each communications channels into multiple time slots to increase the data rates by taking advantage of the fact that not every station will be transmitting all the time.
20
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: ZigBee assumes an Open Trust Model - All applications within a device trust each other, which indirectly extends to all devices in a network as well.
A
- ZigBee is one of the most popular standards based on IEEE 802.15.4.
- It sits rights on top of the layer 2 services provided by 802.15.4 and adds networking and application layer support.
- ZigBee is intended to be simpler and cheaper than most WPAN protocols and is very popular in the embedded device market.
- e.g.: home automation, industrial control, medical, and sensor network applications.
21
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: ZigBee standard defines three different 128-bit Symmetric Key:
A
- Network Key: Shared by all nodes to support broadcasts
- Link Key: Unique for each pair of connected devices and used for unicasts
- Master Key: Unique for each pair of connected devices and used for the symmetric-key key establishment (SKKE) protocol from which the other keys are derived.
22
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: ZigBee, When is it most trusted?
A
ZigBee is most secure when a coordinator node acts as a Trust Center.
23
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Bluetooth:
A
- This has a 1-3 Mbps transfer rate and works in a range of approximately 1, 10, or 100 meters
24
Q
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Bluetooth: Bluesnarfing
A
- Which is the unauthorized access from a wireless device through a Bluetooth connection .
- This allows attacker to read, modify, or delete calendar events, contacts, emails, text messages, and so on.
25
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Bluetooth: Bluejacking:
- In this attack, someone sends an unsolicited message to a device that is Bluetooth-enabled.
- Bluejackers look for a receiving device (phone, tablet, laptop) and hen send a message to it.
26
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Other Important Standards:
These include Quality of Service (QoS), roaming, and spectrum management issues.
27
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Other Important Standards: 802.11e series
- 802.11e: This provides QoS and support of multimedia traffic in wireless transmissions.
- Original 802.11 protocol treats Video, email transmission etc equally
- To address the issue, 802.11e standard defines four access categories: Background, Best Effort, Video and voice.
- Prioritize traffic and guaranteed delivery
28
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Other Important Standards: 802.11f series
- Roaming: The conveying of this information between different Access Categories (APs) during roaming is what 802.11f, do the device does not lose the continuity when changing zones.
29
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Other Important Standards: 802.11h
- Deals with Interference from other devices
- 2 Specific Technology used:
i. Dynamic Frequency Selection (DFS): Automatically select channels that have less interference
ii. Transmit Power Control (TPC): Causes device to automatically reduce its power output when it detects interference from other networks.
30
WIRELESS NETWORKING: WLAN - Other Wireless Network Standards: Other Important Standards: 802.11j
- Japan has its own radio spectrum differently.
- Devices to connect with Japan, the IEEE developed the 802.11j standard.
31
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.11
- Beginning of Wired Equivalent Privacy (WEP). RC4 Algorithm. Tremendous number of security flaws
- 2 Main ways:
i. Open System Authentication (OSA) - Used clear text without encryption
ii. Shared key Authentication (SKA)
- 3 issues:
i. Static encryption keys
ii. Ineffective use of initialization vectors
iii. lack of packet integrity assurance
32
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.11i
- aka Wi-Fi Protected Access 2 (WPA2).
- WPA - 256 bit - first protocol is Temporal Key Integrity Protocol (TKIP)
- WPA Enterprise - Extensible Authentication Protocol (EAP)
33
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.11i: 2 WEP Hacking tools:
- AirSnort
- WEPCrack
34
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.11i: WPA2
- Use of the AES algorithm in couter mode with CBC-MAC (CCM) aka Counter Mode Cipher Block Chaining Message Authentication Code Protocol (CCMP)
- Can switch down to TKIP
35
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.11w
- Though WPA2 was a huge step forward for WLAN Security, there are certain frames that cannot be encrypted because every station must be able to receive. These are called management frames, but prone to DoS attacks.
- This solves 802.11w
36
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: WPA3
- Two flavors: Personal and Enterprise
- Protect Management frames
- Users can choose passwords
- This is done through Simultaneous Authentication of Equals (SAE).
- SAE uses the Diffie-Hellman key exchange method
- 192-bit keys
37
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.1X, Access control protocol that can be implemented on both wired and wireless networks.
- 3 Main component in 2 specific layers.
- Lower Layer: Contains the improved encryption algorithms and techniques.
(TKIP and CCMP)
- Top layer: contains 802.1X
- Both work together to provide more layers of protection
- 3 Entities:
i. Supplicant (wireless device)
ii. Authenticator (AP)
iii. Authentication server (usually a RADIUS server)
38
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.1X: The use of EAP, however allows different protocols to be used by different vendors... for example (CISCO etc.)
- Cisco uses a purely password-based authentication framework called Lightweight Extensible Authentication Protocol (LEAP).
- Other Vendors including Microsoft, use EAP and Transport Layer Security (EAP-TLS), which carries out authentication through digital certificates.
- Protected EAP (PEAP), where only the server uses a digital certificate.
39
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: 802.1X: What was the reason TKIP created?
- TKIP was created as a quick fix to WEP's overwhelming problems.
- It does not provide overhaul for the wireless standard itself because WEP and TKIP are still based on the RC4 algorithm, which is not the best fit for this type of technology.
40
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: Multiple Access Technologies (4):
- Frequency Division Multiple Access (FDMA)
- Time Division Multiple Access (TDMA)
- Code Division Multiple Access (CDMA)
- Orthogonal Frequency Division Multiple Access (OFDMA)
41
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: Multiple Access Technologies: Frequency Division Multiple Access (FDMA): Used in 1G Cellular Networks
- This was the earliest multiple access technology put into practice
- The available frequency range is divided into sub-bands (channels) and one channel is assigned to each subscriber (cell phone)
- Used by:
Advanced Mobile Phone System (AMPS)
Total Access Communication System (TACS)
42
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: Multiple Access Technologies: Time Division Multiple Access (TDMA)
- This increases the speed and efficiency of the cellular network by taking the radio frequency spectrum channels and dividing them into timeslots.
- Time is divided into Frames, Each frame is divided into slots.
- TDMA requires that each slot's start and end time are known to both the source and destinations.
- Used by:
Global System for Mobile Communication
(GSM)
Digital AMPS, Personal Digital Cellular (PDC)
43
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: Code Division Multiple Access (CDMA)
- This was developed after FDMA, and as the term "code" implies, CDMA assigns a unique code to each voice call or data transmission to uniquely identify it from all other transmissions sent over the cellular network.
- In a CDMA spectrum networks, calls are spread throughout the entire radio frequency band.
- Simultaneously interact with multiple other cells.
- 1:M
44
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: Orthogonal Frequency Division Multiple Access (OFDMA)
- This is derived from combination of FDMA and TDMA
- Each of the channels is subdivided into a set of closely spaced orthogonal frequencies with narrow subchannels.
- Each of the different subchannels can be transmitted and received simultaneously in a Multiple Input, Multiple Output (MIMO) manner.
- Reduce interference
- Need 4G and 5G
45
WIRELESS NETWORKING: WLAN: Evolution of WLAN Security: Generations of Mobile Wireless:
- 1G: Dealt with analog transmissions of voice-only data over circuit-switched networks
- 2G: Allows for digitally encoded voice and data to be transmitted between wireless devices, such as cell phones, and content providers. TDMA, CDMA, GSM and PCS falls under 2G
- 3G: This has the flexibility to support a great variety of applications and services. This replaced "circuit-switching" with "packet switching" Speed enhanced.
CISSP
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