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wifi

WIRELESS NETWORKING

Wireless Network Modes
The simplest wireless network consists of two or more PCs communicating directly with each other sans cabling or any other intermediary hardware. More complicated wireless networks use a WAP to centralize wireless communication and bridge wireless network segments to wired network segments. These two different methods are called ad-hoc mode and infrastructure mode.

wireless NIC wireless access point


Ad-hoc Mode
Ad-Hoc mode is sometimes called peer to peer mode, which each wireless node in direct contact with each other node in a decentralized free for all. This is suited for wireless networks use in small groups also known as Independent basic Service Set (IBSS)


Ad Hoc Mode


Infrastructure Mode
Wireless networks running in infrastructure mode use one or more WAPs to connect the wireless network nodes to a wired network segment, as shown above. A single WAP servicing a given area is called a Basic Service Set (BSS). This service area can be extended by adding more WAPs. This is called, appropriately, an Extended basic Service Set (EBSS).

Infrastructure Mode

Wireless Networking Security
One of the major complaints against wireless networking is that it offers weak security. In many cases, the only thing you need to do to access a wireless network is walk into a WAP’s coverage area and turn on your wireless device! Further, data packets are floating through the air instead of safely wrapped up inside network cabling. What’s to stop an unscrupulous PC tech with the right equipment from grabbing those packets out of the air and reading that data himself?

Wireless networks use three methods to secure access to the network itself and secure the data that’s’ being transferred. The SSID (network name) parameter ensures that only wireless network devices configured with the same SSID are permitted access to the network. You can tighten security even further by employing MAC filtering, a way of creating a list of machines that are permitted to access the network. Enabling wireless encryption through either Wireless Equivalency Privacy (WEP) or Wi-Fi Protected Access (WPA) ensures that the data packets themselves are secure while in transit

Wireless Networking Security (War Chalking, War Driving and Hot Spots)
Wireless Antennas (Omni Directional vs. Yagi Directional Antennas)
Wireless Channels (mostly use 1, 6 and 11) Beacon advertise wireless presence

SSID
The service set identification (SSID), sometimes called a network name, is a 32bit identification string that's inserted into the header of each data packet processed by a wireless access point. This provides the basic unit of wireless security.

MAC Filtering
MAC filtering, a method that enables you to limit access to your wireless network based on the physical, hard wired addresses of the wireless network adapters you support

WEP
Wireless Equivalency Privacy (WEP) uses a 64bit-128bit encryption algorithm to scramble data packets as sent in a wireless transmission

wep

WPA
WPA addresses the weaknesses of WEP, and acts as a sort of security protocol upgrade to WEP-enabled devices. WPA offers security enhancement such as an encryption key integrity-checking feature and user authentication through the industry-standard Extensible Authentication Protocol (EAP). The use of EAP is a huge security improvement over WEP’s MAC address authentication scheme. After all, MAC addresses are fairly easy to “sniff” out, since they’re transmitted in unencrypted, clear-text format. User names and passwords are encrypted, and therefore much more secure.
Even with these enhancements, WPA is only intended as an interim security solution until the IEEE 802.11i security standard is finalized and implemented.

wpa

WPA2
WPA2 supports the IEEE 802.11i standard which also offers AES advance encryption system support

wpa2

EAP – Extensible Authentication Protocol is an authentication framework used inwireless networks and point to point connections.

Types of EAP

LEAP, TLS, MD5, PSK, TTLS, IKEv2, FAST, SIM, AKA, GTC and EKE

Encapsulation – IEEE 802.1x, PEAP, RADIUS, Diameter, PANA and PPP

Wireless Networking Standards
To gain better understanding of wireless network technology, let’s take a brief look at the standards they use.

IEEE 802.11-Based Wireless Networking
The IEEE 802.11 wireless Ethernet standard defines methods by which devices may communicate using spread-spectrum radio waves. Spread-spectrum broadcast data in small, discrete chunks over different frequencies available within a certain frequency range. All of the 802.11-based wireless technologies broadcast and receive at 2.4 GHz (with the exception of 802.11a, which uses 5 GHz). The original 802.11 standard has been extended to 802.11a, 802.11b, and 802.11g variations used in Wi-Fi wireless networks, and also hybridized (combined with another wireless communication technology) to form the Shared Wireless Access Protocol (SWAP) used in Home RF networks.

Spread-Spectrum Broadcasting

Spread spectrum refers to the manner in which data signals travel through a radio frequency.  The 2 types of spread spectrum are direct-sequence spread-spectrum (DSSS) and frequency-hopping spread-spectrum (FHSS). DSSS sends data out on different frequencies at the same time, while FHSS sends data on one frequency at a time, constantly shifting (or hopping) frequencies. DSSS uses considerably more bandwidth than FHSS.
DSSS is capable of greater data throughput, but DSSS is also more prone to interference than FHSS.
(OFDM) Orthogonal Frequency Division Multiplexing is a method of encoding digital data on multiple carrier frequencies.

The 802.11 Standard
Devices that use the original 802.11 (with no letter) standard are a rarity these days. You’re most likely to find them in service on some brave early adopter’s network.
The original 802.11 standard was hampered by both slow speeds (2 Mbps maximum) and limited range (about 150 feet). However, 802.11 employed some of the same features that are in use in the current wireless standards. 802.11 uses the same 2.4 GHz broadcast range, and security is provided by the use of industry-standard WEP and WAP encryption.

802.11 Chart

Standard 802.11 802.11a 802.11b 802.11g 802.11n
Speed 1-2Mbps 54Mbps 11Mbps 54 up to (108)Mbps 100 up to (600)Mbps
Range 75ft 150ft 300ft 300ft 300ft
Frequency 2.4GHz 5GHz 2.4GHz 2.4GHz 2.4-5GHz
Security SSID, MAC filtering, WEP, WPA (TKIP) WPA2 (AES)
Compatibility 802.11 802.11a 802.11b 802.11g/b 802.11n/g/b/a
Spread Spectrum method DSSS DSSS DSSS OFDM OFDM
Mode Ad Hoc or Infrastructure Mode

802.11n (MIMO) Multiple Input/Multiple Output (Found on some wireless networks today)

802.11ac the newest wireless standard which will support 1Gpbs speed

Infrared Wireless Networking
Wireless networking using infrared technology is largely overlooked these days, probably due to explosion of interest in the newer and faster wireless standards. This is a shame, because infrared provides an easy way to transfer data, often without the need to purchase or install any additional hardware or software on your PCs.


Infrared Data Association Standard
Communication through infrared devices is enabled via the Infrared Data Association (IrDA) protocol. The IrDA protocol stack is widely supported industry standard, and has been included in all versions of Windows since Windows 95.
Speed-and range wise, infrared isn’t very impressive. Infrared devices are capable of transferring data up to 4 Mbps. Not too shabby, but hardly stellar. The maximum distance between infrared devices is 1 meter.

Infrared links are direct line-of-sight, and are susceptible to interference.
Infrared devices operate at half-duplex, meaning that while one is talking, the other is listening-they can’t talk and listen at the same time. IrDA has a mode that emulates full-duplex communication, but it’s really half-duplex.

Security-wise, the IrDA protocol offers exactly nothing in the way of encryption or authentication. Infrared’s main security feature is the fact that you have to be literally within arm’s reach to establish a link.
Clearly, infrared is not the best solution for a dedicated network connection, but for a quick file transfer or print job without getting your hands dirty, it’ll do in a pinch.

Standard Infrared (IRDA)
Speed 4Mbps
Range 1 Meter
Security None
Compatibility Infrared Devices
Mode Ad Hoc
Description Infrared is best suited for quick, small transfers, such as transferring files from one PDA to another PDA and sending print jobs to an Infrared capable printer



Bluetooth
Bluetooth wireless technology (named for 9th century Danish king Harald Bluetooth) is designed to create small wireless Personal Area Networks (PANs) that link PCs to peripheral devices such as PDAs and printers, scanners, web cams, input devices like keyboards, joystick and mice, and even consumer electronics like cell phones, head sets, home stereos, televisions, home security systems, and so on.


Bluetooth Operation Modes

Master/Slave Scheme in which one master device can control up to seven active slave devices

Bluetooth Communication

Bluetooth devices go to four stages to find each other and start talking.


Discovery Service – Broadcast it’s MAC address as well as what type of device it is
Name Discovery – Device identifies itself by a friendly name such as Motorola headsets
Association – Bonding, Pairing or Joining the device officially joins your Bluetooth network
Service Discovery – Device tells what kind of service or profile it provides

Bluetooth services

Bluetooth is not designed to be a full-function networking solution, nor is it meant to compete with either Wi-Fi or HomeRF. If anything, Bluetooth is poised to replace infrared as a means to connect PCs to peripherals.

The IEEE organization has made Bluetooth the basis for its forthcoming 802.15 standard for wireless PANs. Bluetooth uses the FHSS spread-spectrum broadcasting method, switching between any of the 79 frequencies available in the 2.45 GHz range. Bluetooth hops frequencies some 1,600 times per second, making it highly resistant to interference. Some high-powered Bluetooth devices have throughput speed of a whopping 2 Mbps and a maximum range of up to 300 feet, but these are uncommon.


Standard Bluetooth
Speed 1-2Mbps
Range 33-300 feet
Frequency 2.4GHz
Security PPTP or SSL
Compatibility Bluetooth Devices
Spread Spectrum FHSS
Mode Master and Slave (up to 7 devices)
Description Popular with peripheral devices



 

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