Securing WLAN Technologies Secure Configuration Advice on Wireless Network Setup

The Growth of Wireless LAN

In recent years, there have been a number of substantial developments in the acceptance and functionality of wireless networks. Contemporary organisations are finding their workforce increasingly more mobile, often equipped with notebook computers and spend more of their productive time working away from the standard office-desk or personal-computer environment. Wireless networks support mobile workers by providing the required freedom in their network access. Workers can thus access networked resources from any point within range of a wireless access point. For IT managers, the combination of lowering wireless hardware costs and the ease of implementation in to diverse office environments means that wireless deployment is actively promoted, for it provides the combination of wired network throughput with mobile access and configuration flexibility.
A wireless LAN (WLAN) provides location-independent network access over radio waves rather than traditional cable infrastructures (e.g. 10BaseT, Token Ring, etc.). For most organisations, the WLAN is implemented as the final link between the wired network and the mobile (or inaccessible) wireless devices, thus providing access to all resources and services normally accessible through the wired network.
Previously, WLAN’s were largely implemented in environments (such as warehouses, manufacturing facilities and retail environments) where flexibility of network access took precedence over costly vendor specific wireless implementations. Already, due to the lowering price of components and development of the IEEE 802.11 standards, there has been a large increase in the application of WLAN technology to the corporate enterprise and home environment. Future development areas are likely to include Healthcare equipment and street-wide home Internet access (along the lines of Cable and DSL).
Security often plays second-fiddle to ease-of-use and if security is not transparent to the application and easy to use, it will not be used. However, given the wireless medium, certain security considerations must be applied to protect both the transmitted data and connected hosts. This page aims to explain the current suite of security issues for the most popular WLAN standards and provide advice on the secure configuration of a wireless network.

Inherent Weaknesses in Wireless Networks

Wireless networks typically utilise radio frequency (RF) signals that are capable of passing through barriers such as cubicle partitions, glass and standard walls. Cement walls and metal tend to act as solid barriers, however due to the reflective nature of the RF signal, they can be received (bounced) around corners when a barrier cannot be penetrated. The signal range, and corresponding power, is thus dependant on intermediary barriers and signal reflections. An interesting exercise is to measure signal strength throughout a building and locating “sweet-spots” (where signal strength is greater than expected given the range from the wireless node). Conducting such an exercise outside of the building can also be highly enlightening.
It is important to understand that many of the security risks and issues associated with WLAN’s also apply to the wired LAN. The real difference between a wired LAN and a wireless LAN is at the physical layer. All other network services and vulnerabilities remain; these include:

• Threats to the physical security of the network
• Attacks from within by “authorised” users
• Unauthorized access and eavesdropping

Often, organisations do not realise that wired LANs also have an unintended wireless component. Almost all types of LAN cabling radiate energy, particularly unshielded twisted pair; this radiation can be significant and detectable. Thus, with sufficient motivation and the right radio equipment, it is possible to intercept wired Ethernet data packets from a point external to most buildings, provided they were equipped with an appropriate antenna.
However, the fact remains that WLAN’s are designed to broadcast network traffic, and devices are readily available to receive and decode this traffic. As such, the current wireless standards were designed to include various methods of encryption and authentication from conception. Unfortunately, many of these security features have suffered from design or implementation flaws. It is important to note that the greater the level of security, the more complex the implementation can be. If network and security managers wish to implement a strong security policy, they will need to possess a reasonable knowledge of the security mechanisms inherent to the technology.

Current Wireless Standards

There are of course numerous standards in the world of wireless networking and it often appears that every vendor has their own. The WLAN market is comprised of many competing technologies, each with different operational characteristics. The most common WLAN standards include:

• HomeRF and HomeRF 2.0 (Wide-band Frequency Hopping (WBFH))
• IEEE 802.11 FH/DS
• Wi-Fi (IEEE 802.11b)
• IEEE 802.11gOFDM & 802.11gPBCC (Wi-Fi speed extension proposal)
• MMAC (HiSWANa)
• HiperLAN/2
• IEEE 802.11a
• Bluetooth

Of these WLAN standards, the most prevalent (and are commonly available at most High Street retailers) will adhere to one of following three standards:

• Bluetooth
• Home RF
• Wi-Fi (Institute of Electrical and Electronics Engineers (IEEE) 802.11b)

Although each standard offers different technological advantages or disadvantages, all three mentioned above operate in the 2.4 GHz Industrial, Scientific & Medical (ISM) band. This band offers 83 MHz of spectrum for all wireless traffic and is currently shared with cordless phones, building-to-building transmissions, and microwave ovens.
An emerging fourth wireless standard is the IEEE 802.11a, operating at the higher 5 GHz U-NII band and offering 300 MHz of spectrum, is not currently certified in Europe although negotiations between IEEE and the European Telecommunications Standards Institute (ETSI) is currently underway.

Band	WLAN Systems	Other Communication Systems	Non-Communication Systems
2.4 GHz 2.4000-2.4835 US 2.4000-2.4835 EU 2.471-2.497 Japan 2.4465-2.4835 France 2.445-2.475 Spain	HomeRF HomeRF 2.0 (WBFH) Wi-Fi (802.11b) Bluetooth	Proprietary cordless phones 802.11 FHSS (1997) 802.11 DSSS (1997) Proprietary vertical applications WLL (shared Internet access)	Microwave ovens Microwave lighting Marine weather radar
5 GHz 5.150-5.390	802.11a (US) HiperLAN1 (Europe) HiperLAN2 (Europe) HiSWAN (Japan)	Mobile satellite systems (MSS) Earth exploration satellite systems (ESSS) Short range wireless systems Radio Location Electronic News Gathering Proprietary vertical applications WLL (shared Internet access)	Radar systems Microwave ovens (future – upper band)
5.470-5.725	HiperLAN1 (Europe) HiperLAN2 (Europe)
5.725-5.875	802.11a (US)

Table 1: Wireless Standards by Frequency Band
It is important to note that both Wi-Fi (802.11b) and 802.11a are service sub definitions of the overall IEEE 802.11 standard. The IEEE 802.11 defines a standard on wireless communications and is not limited to RF communications, but also supports methods such as diffused infrared (IR). IR wireless LANs are inherently more secure and are immune from electromagnetic radiation that can interfere with RF and cable based systems. IR based WLAN’s are often used in high-security applications because the signals are line-of-sight only and will not penetrate solid objects like walls.
The key difference between the Bluetooth and Wi-Fi standards is the expected operational range. Bluetooth’s native 1 Mbps data rate is designed to connect devices that are in close proximity, such as notebook computers to printers and PDA’s to mobile phones. This short-range network is often referred to as a Personal Area Network (PAN). Wi-Fi is designed to offer full LAN connectivity and support the full suite of networking protocols (i.e. TCP/IP).
Bluetooth was never originally designed for truly sensitive data transmission. It is not a true competitor of Wi-Fi, but rather Bluetooth was intended to form PANs, where security is desirable but not absolutely essential, as shown by Bluetooth's goal to facilitate for cordless applications instead of being used for networking purposes.
The Home RF and Wi-Fi technologies both provide very similar services to home users. In the highly competitive wireless market, only one of these standards is expected to survive longterm. Given the wider support from the development community, the greater uptake in the business environment, higher transmission rates, and the greater choice of vendor compatible products – the Wi-Fi standard is expected to win this battle.

Technology: Bluetooth

Developed by the Bluetooth Special Interest Group in May 1998, it was designed to provide short-range, low-cost, low-power wireless communications. The key uses for this technology were seen to be data synchronization between computers, hand-held devices, mobile phones and pagers. Bluetooth is ideally suited to devices that travel in and out of a home network, as opposed to remaining connected to a network for extended periods.
Version 1.0 of the Bluetooth specification was approved in the summer of 1999. The IEEE standards body is currently reviewing a faster successor to Bluetooth (IEEE 802.15.3), which will offer data transfer rates of 20 Mbps, while maintaining backward compatibility.
Key Features of Bluetooth:

• Supports data rates of 1 Mbps to distances of up to 10 meters (Up to 20 Mbps if IEEE 802.15.3 is ratified).
• Can support either one asynchronous data channel and up to three simultaneous synchronous speech channels, or one channel that transfers asynchronous data and synchronous speech simultaneously.
• Supports up to eight wireless devices.
• Frequency hopping to be implemented with Gaussian Frequency Shift Keying (GFSK).
• Uses the Link Manager Protocol (LMP) to configure, authenticate and handle the connections between Bluetooth devices.
• Supported by over 1,300 telecommunications, computing, and networking companies globally.

Technology: Home RF

Developed by the Home RF Working Group, it was designed as a lower-cost wireless network technology for use in the home.
Key Features of Home RF:

• Supports data rates of up to 2 Mbps at distances of up to 130 meters. An FCC ruling last August let the group finish spec 2.0 which brought its speed from 2 Mbps up to 10 Mbps distances of up to 15 meters.
• Supports up to three simultaneous voice channels.
• Supports up to 128 network devices.
• Security features include Blowfish encryption (up to 56 bit).
• Supported by several large home computer/network manufacturers.

Technology: Wi-Fi

Wi-Fi is the friendlier name for devices adhering to the IEEE 802.11b High Rate wireless technology standard. It is hoped that IEEE 802.11b will become known as “Wi-Fi” just as IEEE 802.3 is currently known as “Ethernet”. Due to the current prevalence of the Wi-Fi standard and the large installed base of WLAN devices, this standard will be discussed in greater detail in a following section.
Key Features of Wi-Fi:

• Supports data rates of up to 11 Mbps at distances of up to 150 meters. Although some vendors claim to have successfully operated their products to ranges of excess of 500 meters. This range is using an omnidirectional antenna. Using a 21 dB Yagi directional antenna, other people have built links as long as 14 kilometres. Interestingly, this sort of standards “hacking” does not appear to break any laws because the Effective Radiated Power of the Yagi is still under the maximum set by many country authorities.
• Supports up to 128 network devices.
• Security features include authentication and encryption.
• Supports voice over IP (VoIP) data and voice networking capabilities.
• Has widespread industry support.

The IEEE 802.11 Standard and Evolution of 802.11b

Proposed and ratified by the IEEE as 802.11 in 1997, the standard defines the specifications and services for wireless network communications such as:

• Asynchronous and time-critical delivery service support
• Service continuity in extended areas via a distributed system (e.g. Ethernet)
• Network management services
• Registration and authentication services
• Support for standard applications and protocols (e.g. TCP/IP)

It allows for two different (and incompatible) methods of encoding RF signals, FHSS and DSSS. FHSS (Frequency Hopping Spread Spectrum) spreads the communications across 75 sub channels, each consisting of 1 MHz, and continually skipping between them. DSSS (Direct Sequence Spread Spectrum) divides the band into 14 overlapping 22 MHz channels which are utilised one at a time.
FHSS frequency-hopping cards were the first to arrive to the marketplace, as they were cheaper to produce and easier to implement than DSSS. However, as the technology matured and faster processors became available, it became cheaper to implement DSSS. DSSS was the preferred encoding scheme due to US government constraints on broadcasting in the ISM band.
In September 1999, the IEEE 802 committee extended the specification (802.11b) and decided to standardise on DSSS and utilised better encoding techniques. This in turn extended the data throughput from 1-2 Mbps to 5.5-11 Mbps, while allowing backwards compatibility with the older, slower, DSSS standard.
Due to speed and security considerations, various alternatives and extensions to 802.11b are currently under review or have been ratified by the IEEE.

WLAN Topologies

The 802.11 standard defines three basic topologies to be supported by the MAC layer implementation:

• Independent Basic Service Set (IBSS)
• Basic Service Set (BSS)
• Extended Service Set (ESS)

The 802.11 standard further defines the following two modes:

• Ad hoc
• Infrastructure

Mode: Ad-Hoc

The Ad-hoc (sometimes referred to as IBSS topology) mode is analogous to a standard peer-to-peer office network in which no dedicated system is required to assume the role of a server. In WLAN terms, a number of wireless nodes or computers will communicate directly with one another in a mesh or partial-mesh topology (i.e. free-for-all). Typical instances of such an ad-hoc implementation would not connect to a larger network and cover only a limited area. If a client in an ah-hoc network wishes to communicate outside of the peer-to-peer cell, a member MUST operate as a gateway and perform routing.
Bluetooth devices can also form an ad-hoc network. In these networks, one Bluetooth device will act as a master and the others as slaves. The master defines the frequency-hopping behaviour of the network, and it is possible to connect up to 10 of these networks together.

Mode: Infrastructure

Utilising the Infrastructure mode of 802.11 devices requires the installation of at least one wireless Access Point (AP, but also often referred to as a base station) connected to the wired network infrastructure, and a set of wireless nodes or computers. This most basic configuration is referred to as a BSS topology in the 802.11 standard. Communication between wireless nodes, wireless computers and the wired network will be via the AP. Wireless computers conduct all communications through the AP, unlike the Ad hoc peer-to-peer communications.
Before being able to communicate data, wireless clients and AP’s must establish a relationship, or an association. Only after an association is established can the two wireless stations exchange data.
All AP’s transmit a beacon management frame at fixed intervals. To associate with an access point and join a BSS, a client listens for beacon messages to identify the access points within range. The client selection of which BSS to join is carried out in a vendor independent manner. A client may also send a probe request management frame to find an access point associated with the desired SSID (service set identifier).
It is possible to combine multiple wireless access points into a single sub network; this is referred to as an ESS topology. It is thus possible to expand the wireless network with multiple AP’s utilising the same channel or utilise different channels to boost aggregate throughput.
An Access Point acts as a bridge between the wired and wireless networks. The device consists of a radio, a wired network interface and bridging software. It thus acts as the base station for the wireless network, aggregating access for multiple wireless stations onto the wired network.

Roaming Techniques

Although the Wi-Fi standard defines how a wireless computer communicates with an AP, it does not define how roaming should be conducted and supported within an ESS topology network, in particular when a roaming user crosses a router boundary between subnets. Roaming between AP’s is largely reliant on vendor-specific implementations and management. Organisations should carefully evaluate vendors support for roaming and evaluate the ease of operation.
In theory it is possible to implement DHCP across the network and force users to release and renew their IP address as migrate from one subnet to another. However, this is not seen as a practical solution for non-technical staff or where continuous communications are required while roaming.
For environments where DCHP is not in use, Cisco offers a solution referred to as local-area mobility (LAM). Cisco’s LAM enables computers with static addresses to move from one subnet to another while maintaining transparent connectivity without software changes on the roaming host.

Compatibility between Wireless Networks

There has been a lot of talk about interoperation, backwards compatibility and interference between the various WLAN technologies.
The most prevalent WLAN technology, Wi-Fi, has several potential speed increases and security modifications in store from the IEEE 802.11 Task Force g. This yet to be ratified standard (IEEE 802.11g) is proposed to be backwardly compatible with Wi-Fi. It is likely that, in the very near future, wireless products adhering to this standard will replace current Wi-Fi equipment and will be produced by the same companies currently producing Wi-Fi chipsets.
Although sharing the 802.11 nomenclature, Wi-Fi (802.11b) and the faster 802.11a standard are incompatible. Companies with an existing Wi-Fi network cannot simply deploy a new 802.11a network on the Wi-Fi access points and expect to suddenly jump from 11 Mbps to 54 Mbps. The physics and operational characteristics simply do not work that way, and an 802.11a AP will only cover approximately a fourth of the area covered by a Wi-Fi AP. Thus, to cover a similarly sized area and all factors being equal, four 802.11a AP’s are required for every Wi-Fi AP. This is not to say that the two cannot be deployed together. In the near future, it is likely that WLAN access points will support both standards within a single device. Thus Wi-Fi’s range and sustainable 11 Mbps data rate could be complemented with 802.11a’s concentrated 54 Mbps.
Within the crowded 2.4 GHz ISM band, interference between devices can cause concern. Of primary concern has been the interference between Wi-Fi and Bluetooth. However, multiple companies have researched this interference issue and have concluded that, when separated by 2 metres or more, there is no significant interference. With separation distances less than 2 metres, the two technologies can interfere with each other and this can be severe when collocated within a single device (i.e. a combination PCMCIA card). Several solutions have already been proposed; ranging from modifications and extensions to the existing standards, through to recommended best practices and technological advances.

Security within the Standards

Wi-Fi

By default, Wi-Fi utilises open system authentication, and authenticates anyone who requests authentication. Wireless nodes perform a mutual authentication using this method when joining a network. In many cases the management authentication frames are sent in the clear even when WEP is enabled.
Until very recently, the law used to be that a manufacturer could only export up to 56-bit encryption. The Wi-Fi standard specified up to only 40-bit for export reasons. It is important to note that, with the 40-bit encryption option, a 24-bit initialisation vector is appended and all encryption is conducted with a 64-bit key length. While not officially part of the Wi-Fi standard, many vendors now implement 128-bit key lengths for encrypting data. This 128-bit key consists of the 24-bit initialisation vector and a 104-bit pseudo-random key.
Although the IEEE 802.11 standards body is currently working to improve the security of the standard, it is too late for deployed networks and those networks about to be deployed. Nether the less, Wi-Fi vendors have provided numerous mechanisms to help secure both communications and the operating environment:

Security Feature	Details
Wi-Fi WEP	The Wired Equivalent Privacy (WEP) protocol is used to protect wireless communication from eavesdropping and prevent unauthorised access to the WLAN. WEP relies on a secret key that is shared between an AP and wireless node (e.g. notebook computer). The secret key is used to encrypt packets before they are transmitted, and an integrity check is used to ensure that packets are not modified in transit. WEP utilises the established RC4 stream cipher to encrypt data. The stream cipher operates by expanding a short key into an infinite pseudo-random key stream. Although stream ciphers are commonly vulnerable to several attack methods, WEP was designed to overcome these failings. In particular, WEP uses an Integrity Check (IC) field within the data packet to ensure that it has not been modified in transit, and an Initialisation Vector (IV) is used to augment the shared secret key and produce a different RC4 key for each packet; thus avoiding encrypting two cipher texts with the same key. However, both of these security measures have been found to be implemented incorrectly: The integrity check (which forms part of the encrypted payload of the packet) is implemented as a linear 32-bit checksum. Thus, it is possible to alter individual bits within the encrypted message and correctly adjust the checksum so that the resulting message appears valid. If an attacker has partial knowledge of the contents of the packet, it is possible to intercept and perform selective modification on it. The attacker could thus modify interactions with a file server. If the attacker is able to guess the headers of the data packet, it may be possible to alter the destination IP address and port. By resending this modified packet from a rogue wireless node, the AP will decrypt the packet and forward it on unencrypted to the modified destination. If the destination is Internet based, the attacker could remotely retrieve the plain test data. The initialisation vector in WEP is a 24-bit field, and is sent in the clear text part of the message. Utilising such a small space of initialisation vectors guarantees the reuse of the same key string at a busy access point. This allows an attacker to collect two cipher texts that are encrypted with the same key stream and perform statistical attacks to recover the plain text. Once it is possible to recover the entire plain text for one of the messages, the plain text for all other messages with the same IV follows directly. The 802.11 standard specifies that changing the IV with each packet is optional; some wireless card vendors increment the IV by 1 each packet while others leave this value blank. The result of these flaws in the Wi-Fi implementation of RC4 is that the encryption of data can be broken within 15 minutes. And, more importantly, the time to break the encryption scales linearly with the key length - thus a 128-bit key could be broken within 30 minutes.
Wi-Fi Shared Key Authentication	Shared key authentication uses a standard challenge and response along with a shared secret key to provide authentication. The challenge-response sequence utilises WEP to encrypt the data. Thus this authentication sequence is subject to the weaknesses of WEP.
Wi-Fi Closed Network Access	In a closed network, only clients with knowledge of the network name, or SSID, can join. Essentially, the network name acts as a shared secret. However, the SSID is often transmitted in clear text within the management frames (even if WEP is enabled). Thus simple sniffing will rapidly enumerate the SSID
Wi-Fi Access Control Lists (ACL)	Access to the wireless network can be controlled by limiting access to nodes defined in a central (or shared) list based upon the Ethernet MAC address. There are two problems with this method of control: Loss of flexibility – The Network Administrator needs to maintain an up to date list of valid MAC addresses for every wireless node. Roaming or multi-site users would require changes to the ACL to access the network. MAC Impersonation – Many wireless cards currently available allow the MAC address to be manually changed. MAC addresses are easily sniffed by an attacker as they must appear in the clear even if WEP is enabled.
Wi-Fi Key Management	Wi-Fi defines two methods for using WEP keys: 4 Key Window – A wireless node or AP can decrypt packets enciphered with any of the four defined keys. However, transmission is limited to one of the four manually entered keys (a default key). MAC Unique Key – Each MAC address may have a separate key. The standard recognises that the key mappings table should hold at least 10 entries. As with the standard WEP failings, enforcing a reasonable key period remains a problem, as the keys need to be changed manually. Only a few major Wi-Fi vendors have implemented any form of key management or key agreement in their wireless products.
Future Development of the Standard	The IEEE is currently working on a new standard to address many of these security issues with 802.1x, for port-based authentication on wireless networks. This standard is likely to include: An Extended Encapsulation Protocol (EEP) that allows various authentication protocols. Enable WEP keys to be dynamically generated and sent out. Including multicast support for large organisations. Centralised AP authentication, thus making roaming transparent. Users will receive a logon dialog when roaming between VPN servers on a network, or when resuming from standby mode, if an AP requires alternate identification.

Table 2: 802.11b security measures

Bluetooth

Bluetooth technology provides three security attributes (authorisation, authentication and encryption), and three modes of security:

• Security Mode 1 (non secure) – A device does not initiate any security procedure such as encryption or authentication.
• Security Mode 2 (service-level enforcement security) – A device does not initiate security procedures before channel establishment at the service level.
• Security Mode 3 (link-level enforced security) – A device allows only authenticated connections. The difference between Security Mode 2 and Security Mode 3 is that in Security Mode 3 the Bluetooth device initiates security procedures before the channel is established.

As there are numerous services that a Bluetooth device may have, a sizable database of services the device has authorisation to use is required. The user can choose to “auto” trust devices or “manually” trust devices.

Security Feature	Details
Key Management	The link key (a 128-bit random number) handles all security transactions between two or more parties. It is used in the authentication process and as a parameter when deriving the encryption key. The lifetime of a link key depends on whether it is a semi-permanent or a temporary key. A semi-permanent key can be used after the current session is over to authenticate Bluetooth units that share it. A temporary key lasts only until the current session is terminated and it cannot be reused. Temporary keys are commonly used in point-to-multipoint connections, where the same information is transmitted to several recipients. There are several different types of keys defined in Bluetooth. Link keys can be combination keys, unit keys, master keys or initialization keys, depending on the type of application. In addition to link keys, there is the encryption key. The length of the Personal Identification Number (PIN) code used in Bluetooth devices can vary between 1 and 16 octets. The regular 4-digit code is sufficient for some applications, but higher security applications may need longer codes. The PIN code of the device can be fixed, so that it needs to be entered only to the device wishing to connect. Another possibility is that the PIN code must be entered to the both devices during the initialization. The major problem is likely to be a partial user one. The atypical 4-digit PIN code, is used in combination with other variables to generate the Link Key and Encryption Key. In fact it is the only truly secret key generation variable, the only one (a random number) is transmitted over the air. When using 4 digit PIN codes there are only 10,000 different possibilities. As the process of supplying PIN codes to devices often has to be repeated each time, it is common to set the value to "0000".
Encryption	The Bluetooth encryption system encrypts the payloads of the packets. This is done with a stream cipher E0, which is re-synchronized for every payload. The E0 stream cipher consists of the payload key generator, the key stream generator and the encryption/decryption part. Depending on whether a device uses a semi-permanent link key or a master key, there are several encryption modes available. If a unit key or a combination key is used, broadcast traffic is not encrypted. Individually addressed traffic can be either encrypted or not. If a master key is used, there are three possible modes. Encryption mode 1 - nothing is encrypted. Encryption mode 2 - broadcast traffic is not encrypted, but the individually addressed traffic is encrypted with the master key. Encryption mode 3 - all traffic is encrypted with the master key.
Authentication	The Bluetooth authentication scheme uses a challenge-response strategy, where a 2-move protocol is used to check whether the other party knows the secret key. The protocol uses symmetric keys, so a successful authentication is based on the fact that both participants share the same key. As a side product, the Authenticated Ciphering Offset (ACO) is computed and stored in both devices and is used for cipher key generation later on. If the authentication fails, there is a period of time that must pass until a new attempt at authentication can be made. The period of time doubles for each subsequent failed attempt from the same address, until the maximum waiting time is reached. The waiting time decreases exponentially to a minimum when no failed authentication attempts are made during a time period. Another problem arises with the use of the Link key. Authentication and encryption are based on the assumption that the link key is the participants' shared secret. All other information used in the procedures is generally public. However this can lead to fundamental problems: Assume that devices 1 and 2 use 1's unit key as their link key. Later on, or at the same time, device 3 may communicate with device 1 and use 1's unit key as the link key. 2 uses 1's Link key to decrypt the communication between 1 & 3 Device 2, having obtained 1's unit key earlier, can use the unit key with a faked Bluetooth Device Address to calculate the encryption key and therefore listen to the traffic. It can also authenticate itself to device 1 as device 3 and to device 3 as device 1.   The Bluetooth Device Address is unique to each and every Bluetooth device. However due to its uniqueness it introduces another problem. Once this ID is associated with a person, individuals can be traced and their activities easily logged, thus privacy is violated.

Table 3: Bluetooth security measures

Signals and Data Throughput

Although each of the technologies and standards specify maximum data rates for wireless communications, it is important to realise that these rates differ greatly from what an organisation can expect to achieve using real data in a live environment. Just as wired Ethernet is touted as 10 or 100 Mbps, the actual throughput maximum is roughly 85% of these values due to overheads inherent to the technology. For instance, with Ethernet, once the network traffic load reaches beyond 60%, the probability of network collisions is very high – at levels beyond, this collisions and retransmissions of data can cause the network to stall.
When securing the wireless network by utilising either the native encryption mechanisms or third-party products, actual data throughput can drop even further. Organisations should carefully review not only the strength of the encryption mechanism, but also the overhead to throughput. For instance, Wi-Fi’s highest data rate is 11 Mbps – this corresponds to approximately 7 Mbps actual throughput. Buy utilising WEP, it is not untypical for this rate to drop to 6 Mbps.

Technology	Data Rate	Actual Throughput	Shared Among Users	Estimated Time to Download a 100 MB file (actual throughput)
56.6 Kbps Modem	56.6 Kbps	56.6 Kbps	No	4 hours
Dual channel ISDN	128 Kbps	128 Kbps	No	1 hour 45 minutes
10/100 Ethernet	100 Mbps	85 Mbps	Yes	10 seconds
2Mb Leased Line	2 Mbps	2 Mbps	Yes	6 minutes 40 seconds
Wi-Fi	11 Mbps	5-7 Mbps	Yes	2 minutes 13 seconds
802.11gOFDM	24 Mbps	10-11 Mbps	Yes	1 minute 16 seconds
802.11gPBCC	22 Mbps	10-11 Mbps	Yes	1 minute 16 seconds
802.11a	54 Mbps	31 Mbps	Yes	26 seconds

Table 4: Transmission speed comparisons
Another important consideration is range. Due to the physics of wireless wave propagation, signal strength is inversely proportional to the range between devices. Thus, in real terms, range corresponds to maximum data rates. The maximum rate for Wi-Fi (11 Mbps) can only be achieved within a certain range of the transmitter. Moving further away from the transmitter causes the data rate to “step down” to 5.5 Mbps, 2 Mbps, 1 Mbps and finally no-signal. This range is dependant on the transmitter design and type of receiving antenna.
IEEE 802.11a provides a higher data transfer rate than Wi-Fi (36-54 Mbps versus 11 Mbps) when close to the WLAN access point (within 10-15 metres), making it more attractive for dense user environments that also require high throughput, but the data rate is closer to 9-12 Mbps at ranges over 30 metres.
A typical maximum range (at the lowest data rate of 1 Mbps) for standard Wi-Fi devices is 500 metres. However, utilising improved or specially designed receiving antennas, ranges in excess of 14 km have been achieved. The ranges achieved with standard external PCMCIA Wi-Fi cards are generally poor due to the antenna being in the worst possible orientation: sideways, and very close to the laptop (the radiation pattern is thus almost straight up and down). To address this, and offer greater ranges, many laptop vendors now build the Wi-Fi antennas into and around the screen.

WLAN Security Solutions

The omni directional broadcasting of WLAN traffic is of a primary security concern. Although various mechanisms for securing the data have been included within each of the established wireless standards, the nature of the media ensures that an anonymous attacker or interloper can easily monitor or collect traffic. Given the current range of security flaws within these security mechanisms, it is inevitable that the data content will be decoded or decrypted by those who have the time and tools to do so. Unfortunately, the tools required to sniff, decrypt and gain access to most wireless networks are freely available through numerous sites on the Internet.
While many of the security systems built into the various wireless standards have been proven to be flawed or open to abuse, there are numerous options that an organization may undertake to help deploy these technologies in a secure manner. These options may range from common-sense practices, to physical implementation, through to proven third-party products. Those members of a Corporation for the management of security and system integrity should review the following suggestions to aid their deployment of WLAN technologies

Default Settings

Almost all WLAN products come preconfigured with a suite of default settings, services and passwords. These defaults are well known and various lists exist on the Internet for ready inclusion in to tools designed expressly for compromising the security of your WLAN.
Always review the literature that comes with the WLAN components and be wary of all default settings. In particular, take note of the default security permissions for Bluetooth devices, and the default SSID and WEP keys for Wi-Fi. For AP’s, review the services utilized for remote management of the device (i.e. web admin and SNMP), decide whether these services can be made secure (through appropriate passwords and access controls or limitations), and whether such mechanisms are compatible or consistent with your corporations existing security management procedures.

The Value of the Data

Consider the value of the data that could be transmitted over the WLAN. The data will be broadcast and may be collected by an anonymous observer. Depending on the security settings and encryption levels used for the WLAN traffic, the difficulty in decoding or decrypting the data may range from trivial through to almost impossible. Beware though, if an observer is able to collect a sizable amount of data and is willing to invest the time and effort, almost all encrypted data can be decrypted.
Organizations should review the value of the data being broadcast and ascertain how important it is that an outsider should not be able to render it readable. For some organizations the value of the data may be best measured in time – consider competitive tender document that may have a life of a couple of months, a sensitive financial data that may have a life of several years, or private banking details that must be kept secret for decades. For some organizations the value of the data may be measured in reputation.
Even using the best commercial encryption algorithms, given the advances in computer processing power, it is unlikely that such confidential data will remain secret in several years should an observer choose to decrypt the data.

Treat as Untrusted

Do not inherently trust connections from the WLAN. Wireless AP’s should be handled similarly to Internet and Dial-in (e.g. RAS) connections. Best practices dictate that all AP’s should be located with separate firewall zones (i.e. DMZ) and similar access controls or filtering rules should be configured as for Internet access into the organization. This is not to say that the AP’s should be located outside the corporate firewall on the same network as the Internet, but on a separate untrusted segment controlled with appropriate rules and policies.
Just as external users may access an organizations LAN through the Internet or RAS services using technologies such as Radius, Kerberos, Secure Sockets Layer (SSL) encryption and virtual private networks (VPN’s) - an organization should extend these authentication and encryption techniques through to the WLAN and carefully examine all access procedures.
The most widely used mechanism for securing VPN traffic is the Internet Protocol Security (IPSec) specification, as defined by the IEEE. IPSec can use keyed hash algorithms (MD5, SHA, HMAC) for authenticating packets, DES, 3DES and other bulk algorithms for encrypting data, and digital certificates for validating public keys.
By employing this solution, WEP is no longer required (as all encryption is handled by the VPN channel) and should be disabled. The VPN server(s) provide the necessary authentication and full encryption over the WLAN. Utilising digital certificates at each wireless node helps ensure strong authentication.
As a more general policy, all organizations should be using secure communication methods all the time to transfer data, even internally. Consider utilizing SSL encryption for internal applications and Intranet components.

Fault Tolerance

Deploying multiple access points on the same frequency can increase the fault tolerance and adds range to a wireless segment, but won't increase your overall bandwidth. When one access point in a segment fails, the wireless clients seamlessly roam to the other access points without interrupting service, provided the appropriate roaming technologies have been configured. Not all vendor WLAN products may support seamless network roaming – choose carefully.

Be Capable of Monitoring the WLAN

Invest in appropriate network technologies to readily identify wireless AP’s or PC Card’s that may be misbehaving and cause a degradation of service. It is important to note that even a single PC Card can saturate a wireless segment. Whether an organization has just one user or 50 on a segment, each user will contend for the same amount of bandwidth. After all, a Wi-Fi network utilizes CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance), and like shared Ethernet, have a finite capacity and a certain amount of overhead associated with it. This is especially important given the threat from attackers who may purposefully seek to disrupt the WLAN services. Such an attack may cost less than £400 to an attacker (i.e. Palm computer and Wi-Fi PCMCIA card) and could be performed anywhere within range of the WLAN.

Be Capable of Detecting and Responding to Intruders

It is important not only to be able to monitor the WLAN, but also record and identify attacks. Modern Intrusion Detection Systems (IDS) are capable of identifying and responding to many of the most popular and dangerous attacks in an automated manner. Where possible, network IDS sensors should be placed on the WLAN DMZ segment, and the organizations wired LAN. Key hosts, particularly authentication servers on the wired LAN used to authorize access from the WLAN should utilize host based IDS sensors.
Having protected the organizations LAN and key authentication servers, ensure that the client WLAN devices (e.g. laptops, printers and access points) on the “dirty” side of the DMZ are also properly secured. As these devices are now likely to be primary targets of an attacker - ensure that each device has been hardened to appropriate security standards, have current anti-virus detection agents, and utilize updated personal IDS monitors.

Security Education

Ensure that both the WLAN end users and administrative staff understand the security limitations of the technology. It is vital that users be aware of the vulnerabilities of the data they may access or share over the WLAN to other users, and understand the secure access methods available to them. For administrative staff, it is equally important they understand the security configuration of the environment and have the skills to readily maintain and monitor the integrity of the WLAN.
All staff with access to WLAN components of an organisations infrastructure must understand and use good password policies. Almost all security mechanisms used by any organisation can be compromised or thwarted by poor passwords.

Be Aware of Country Specific Laws

Regulation of radio frequency bands is often country specific, and various laws exist controlling their usage. Additionally, many countries have specific laws relating to the monitoring of radio frequency data and the protection of personal data that may be observed and recorded.
Consider the following two wireless standards, 802.11b and 802.11a. 802.11b operates in the 2.4 GHz ISM band and defines a total of 14 frequency channels. Channels 1 through 11 are approved for use within the U.S.; whereas most of Europe can use channels 1 through 13, with the notable exception of France, where only channels 10 through 13 are available. 802.11a operates in the 5 GHz U-NII and, although approved for use in the U.S., is not currently approved for European.
Both suppliers and implementers of all WLAN technologies must carefully review the legal implications of installing and using such wireless technologies. Use of devices operating outside the approved radio frequency bands may interfere with 3rd-party devices, and is likely to lead to legal prosecution in most countries. Additionally, local laws relating to maximum encryption key length, radio broadcast power and range, reception and observation of unintended radio frequency data (e.g. the WLAN from across the road), and data protection regulations must also be carefully reviewed.

Understand the Operational Characteristics of the Technology

Focusing on 802.11b, an important concept to note regarding channel assignments is that the channel actually represents the centre frequency that the transceiver within the radio and access point uses (e.g., 2.412 GHz for channel 1 and 2.417 GHz for channel 2). There is only 5 MHz separation between the centre frequencies, and an 802.11b signal occupies approximately 30 MHz of the frequency spectrum. The signal falls within about 15 MHz of each side of the centre frequency.
As a result, an 802.11b signal overlaps with several adjacent channel frequencies. This leaves only three channels (channels 1, 6, and 11 for the U.S.) that can be used without causing interference between access points. For WLAN’s with only one access point, it is possible to set the access point to any one of the channels. Often, the default setting shipped by the vendor will be adequate. If there are two or three access points, assign any combination of channels 1, 6, and 11. Doing so will keep the signals far enough apart in the RF spectrum to avoid problems.

Channel Number	Frequency (GHz) – Channels are 22MHz wide
1*	2.412 (US FCC, Europe ETSI, Japan)
2	2.417 (US FCC, Europe ETSI, Japan)
3	2.422 (US FCC, Europe ETSI, Japan)
4	2.427 (US FCC, Europe ETSI, Japan)
5	2.432 (US FCC, Europe ETSI, Japan)
6*	2.437 (US FCC, Europe ETSI, Japan)
7	2.442 (US FCC, Europe ETSI, Japan)
8	2.447 (US FCC, Europe ETSI, Japan)
9	2.452 (US FCC, Europe ETSI, Japan)
10	2.457 (US FCC, Europe ETSI, Japan, France)
11*	2.462 (US FCC, Europe ETSI, Japan, France)
12	2.467 (Europe ETSI, Japan, France)
13	2.472 (Europe ETSI, Japan, France)
14	2.484 (Japan)

 Table 4: 802.11b channel median frequencies (* indicates non-overlapping channels)

What is a Wireless LAN?

A Wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still be connected to the network.

For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. For the business, public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service. Large wireless network projects are being put up in many major cities. Google is providing a free service to Mountain View, California and has entered a bid to do the same for San Francisco. New York City has also begun a pilot program to cover all five boroughs of the city with wireless Internet access.

IEEE 802.11, also known by the brand Wi-Fi, denotes a set of Wireless LAN (WLAN) standards developed by working group 11 of the IEEE LAN/MAN Standards Committee (IEEE 802). The term 802.11x is also used to denote this set of standards and is not to be mistaken for any one of its elements. There is no single 802.11x standard. The term IEEE 802.11 is also used to refer to the original 802.11, which is now sometimes called "802.11 legacy".

The 802.11 family currently includes six over-the-air modulation techniques that all use the same protocol. The most popular techniques are those defined by the b, a, and g amendments to the original standard; security was originally included and was later enhanced via the 802.11i amendment. 802.11n is another modulation technique that has recently been developed; the standard is still under development, although products designed based on draft versions of the standard are being sold. Other standards in the family (c-f, h, j) are service enhancements and extensions or corrections to previous specifications. 802.11b was the first widely accepted wireless networking standard, followed (somewhat counterintuitively) by 802.11a and 802.11g.

802.11b and 802.11g standards use the 2.40 GHz (gigahertz) band, operating (in the United States) under Part 15 of the FCC Rules and Regulations. Because of this choice of frequency band, 802.11b and 802.11g equipment can incur interference from microwave ovens, cordless telephones, Bluetooth devices, and other appliances using this same band. The 802.11a standard uses the 5 GHz band, and is therefore not affected by products operating on the 2.4 GHz band.

The segment of the radio frequency spectrum used varies between countries, with the strictest limitations in the United States. While it is true that in the U.S. 802.11a and g devices may be legally operated without a licence, it is not true that 802.11a and g operate in an unlicensed portion of the radio frequency spectrum. Unlicensed (legal) operation of 802.11 a & g is covered under Part 15 of the FCC Rules and Regulations. Frequencies used by channels one (1) through six (6) (802.11b) fall within the range of the 2.4 gigahertz amateur radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC Rules and Regulations, allowing increased power output but not allowing any commercial content.

History of Wireless LAN

In 1970 University of Hawaii, under the leadership of Norman Abramson, developed the world's first computer communications network using low-cost ham-like radios, named ALOHAnet. The bi-directional star topology of the system included seven computers deployed over four islands to communicate with the central computer on the Oahu Island without using phone lines.

Originally WLAN hardware was so expensive that it was only used as an alternative to cabled LAN in places where cabling was difficult or impossible. Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by standards, primarily the various versions of IEEE 802.11 (Wi-Fi). An alternative ATM-like 5 GHz standardized technology, HIPERLAN, has so far not succeeded in the market, and with the release of the faster 54 Mbit/s 802.11a (5 GHz) and 802.11g (2.4 GHz) standards, almost certainly never will.

In November 2006, the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) won a legal battle in the US federal court of Texas against Buffalo Technology which found the US manufacturer had failed to pay royalties on a US WLAN patent CSIRO had filed in 1996. CSIRO are currently engaged in legal cases with computer companies including Microsoft, Intel, Dell, HP and Netgear which argue that the patent is invalid and should negate any royalties paid to CSIRO for WLAN-based products.

Benefits of Wireless LAN

The popularity of wireless LANs is a testament primarily to their convenience, cost efficiency, and ease of integration with other networks and network components. The majority of computers sold to consumers today come pre-equipped with all necessary wireless LAN technology.

The benefits of wireless LANs include:

• Convenience - The wireless nature of such networks allows users to access network resources from nearly any convenient location within their primary networking environment (home or office). With the increasing saturation of laptop-style computers, this is particularly relevant.
• Mobility - With the emergence of public wireless networks, users can access the internet even outside their normal work environment. Most chain coffee shops, for example, offer their customers a wireless connection to the internet at little or no cost.
• Productivity - Users connected to a wireless network can maintain a nearly constant affiliation with their desired network as they move from place to place. For a business, this implies that an employee can potentially be more productive as his or her work can be accomplished from any convenient location.
• Deployment - Initial setup of an infrastructure-based wireless network requires little more than a single access point. Wired networks, on the other hand, have the additional cost and complexity of actual physical cables being run to numerous locations (which can even be impossible for hard-to-reach locations within a building).
• Expandability - Wireless networks can serve a suddenly-increased number of clients with the existing equipment. In a wired network, additional clients would require additional wiring.
• Cost - Wireless networking hardware is at worst a modest increase from wired counterparts. This potentially increased cost is almost always more than outweighed by the savings in cost and labor associated to running physical cables. Wi-Fi chipset pricing continues to come down, making Wi-Fi a very economical networking option and driving inclusion of Wi-Fi in an ever-widening array of devices.

Disadvantages of Wireless LAN

Wireless LAN technology, while replete with the conveniences and advantages described above, has its share of downfalls. For a given networking situation, wireless LANs may not be desirable for a number of reasons. Most of these have to do with the inherent limitations of the technology.

• Security - Wireless LAN transceivers are designed to serve computers throughout a structure with uninterrupted service using radio frequencies. Because of space and cost, the "antennas" typically present on wireless networking cards in the end computers are generally relatively poor. In order to properly receive signals using such limited antennas throughout even a modest area, the wireless LAN transceiver utilizes a fairly considerable amount of power. What this means is that not only can the wireless packets be intercepted by a nearby adversary's poorly-equipped computer, but more importantly, a user willing to spend a small amount of money on a good quality antenna can pick up packets at a remarkable distance; perhaps hundreds of times the radius as the typical user. In fact, there are even computer users dedicated to locating and sometimes even hacking into wireless networks, known as wardrivers. On a wired network, any adversary would first have to overcome the physical limitation of tapping into the actual wires, but this is not an issue with wireless packets. To combat this consideration, wireless network users usually choose to utilize various encryption technologies available such as WPA. Some of the older encryption methods, such as WEP, are known to have weaknesses that a dedicated adversary can compromise.
• Range - The typical range of a common 802.11g network with standard equipment is on the order of tens of meters. While sufficient for a typical home, it will be insufficient in a larger structure. Range varies with frequency band, as Wi-Fi is no exception to the physics of radio wave propagation. To obtain additional range, repeaters or additional access points will have to be purchased. Costs for these items can add up quickly. Other technologies are in the development phase, however, which feature increased range, hoping to render this disadvantage irrelevant.
• Reliability - Like any radio frequency transmission, wireless networking signals are subject to a wide variety of interference, as well as complex propagation effects (such as multipath, or especially in this case Rician fading) that are beyond the control of the network administrator. In the case of typical networks, modulation is achieved by complicated forms of phase-shift keying (PSK) or quadrature amplitude modulation (QAM), making interference and propagation effects all the more disturbing. As a result, important network resources such as servers are rarely connected wirelessly. Also, many 2.4 GHz 802.11b and 802.11g Access points default to the same channel, contributing to congestion on certain channels.
• Speed - The speed on most wireless networks (typically 1-108 Mbps) is reasonably slow compared to the slowest common wired networks (100Mbit/s up to several Gbit/s). There are also performance issues caused by TCP and its built-in congestion avoidance. For most users, however, this observation is irrelevant since the speed bottleneck is not in the wireless routing but rather in the outside network connectivity itself. For example, the maximum ADSL throughput (usually 8Mbit/s or less) offered by telecommunications companies to general-purpose customers is already far slower than the slowest wireless network to which it is typically connected. That is to say, in most environments, a wireless network running at its slowest speed is still faster than the internet connection serving it in the first place. However, in specialized environments, the throughput of a wired network might be necessary. Newer standards such as 802.11n are addressing this limitation and will support peak throughputs in the range of 100-200 Mbit/s.
• Energy - Power consumption is fairly high compared to some other standards, making battery life and heat a concern.

Important WLAN Standards

802.11 Legacy

The original version of the standard IEEE 802.11 released in 1997 specifies two raw data rates of 1 and 2 megabits per second (Mbit/s) to be transmitted via infrared (IR) signals or by either Frequency hopping or Direct-sequence spread spectrum in the Industrial, Scientific and Medical frequency band (ISM) at 2.4 GHz. IR remains a part of the standard but has no actual implementations.

The original standard also defines Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) as the medium access method. A significant percentage of the available raw channel capacity is sacrificed (via the CSMA/CA mechanisms) in order to improve the reliability of data transmissions under diverse and adverse environmental conditions.

At least six different, somewhat-interoperable, commercial products appeared using the original specification, from companies like Alvarion (PRO.11 and BreezeAccess-II), BreezeCom, Lucent, Netwave Technologies (AirSurfer Plus and AirSurfer Pro), Symbol Technologies (Spectrum24), and Proxim (OpenAir). A weakness of this original specification was that it offered so many choices that interoperability was sometimes challenging to realize. It is really more of a "beta-specification" than a rigid specification, allowing individual product vendors the flexibility to differentiate their products. Legacy 802.11 was rapidly supplemented (and popularized) by 802.11b. Widespread adoption of 802.11 networks only occurred after 802.11b was ratified and as a result few networks ran on the 802.11-1997 standard.

The 802.11a Amendment

The 802.11a amendment to the original standard was ratified in 1999. The 802.11a standard uses the same core protocol as the original standard, operates in 5 GHz band, and uses a 52-subcarrier orthogonal frequency-division multiplexing (OFDM) with a maximum raw data rate of 54 Mbit/s, which yields realistic net achievable throughput in the mid-20 Mbit/s. The data rate is reduced to 48, 36, 24, 18, 12, 9 then 6 Mbit/s if required. 802.11a has 12 non-overlapping channels, 8 dedicated to indoor and 4 to point to point. It is not interoperable with 802.11b, except if using equipment that implements both standards.

Since the 2.4 GHz band is heavily used, using the 5 GHz band gives 802.11a the advantage of less interference. However, this high carrier frequency also brings disadvantages. It restricts the use of 802.11a to almost line of sight, necessitating the use of more access points; it also means that 802.11a cannot penetrate as far as 802.11b since it is absorbed more readily, other things (such as power) being equal.

Different countries have different regulatory support, although a 2003 World Radiotelecommunications Conference made it easier for use worldwide. 802.11a is now approved by regulations in the United States and Japan, but in other areas, such as the European Union, it had to wait longer for approval. European regulators were considering the use of the European HIPERLAN standard, but in mid-2002 cleared 802.11a for use in Europe. In the U.S., a mid-2003 FCC decision may open more spectrum to 802.11a channels.

Of the 52 OFDM subcarriers, 48 are for data and 4 are pilot subcarriers with a carrier separation of 0.3125 MHz (20 MHz/64). Each of these subcarriers can be a BPSK, QPSK, 16-QAM or 64-QAM. The total bandwidth is 20 MHz with an occupied bandwidth of 16.6 MHz. Symbol duration is 4 microseconds with a guard interval of 0.8 microseconds. The actual generation and decoding of orthogonal components is done in baseband using DSP which is then upconverted to 5 GHz at the transmitter. Each of the subcarriers could be represented as a complex number. The time domain signal is generated by taking an Inverse Fast Fourier transform (IFFT). Correspondingly the receiver downconverts, samples at 20 MHz and does an FFT to retrieve the original coefficients. The advantages of using OFDM include reduced multipath effects in reception and increased spectral efficiency.

802.11a products started shipping in 2001, lagging 802.11b products due to the slow availability of the 5 GHz components needed to implement products. 802.11a was not widely adopted overall primarily because the less-expensive 802.11b was already widely adopted, but also because of 802.11a's range disadvantage, some poor initial product implementations that further reduced its range, and in some cases the regulations. Manufacturers of 802.11a equipment responded to the lack of market success by improving the implementations (current-generation 802.11a technology has range characteristics much closer to those of 802.11b), and by making technology that can use more than one 802.11 standard. There are dual-band, or dual-mode or tri-mode cards that can automatically handle 802.11a and b, or a, b and g, as available. Similarly, there are mobile adapters and access points which can support all these standards simultaneously.

The 802.11b Amendment

The 802.11b amendment to the original standard was ratified in 1999. 802.11b has a maximum raw data rate of 11 Mbit/s and uses the same CSMA/CA media access method defined in the original standard. Due to the CSMA/CA protocol overhead, in practice the maximum 802.11b throughput that an application can achieve is about 5.9 Mbit/s using TCP and 7.1 Mbit/s using UDP.

802.11b products appeared on the market very quickly, since 802.11b is a direct extension of the DSSS (Direct-sequence spread spectrum) modulation technique defined in the original standard. Technically, the 802.11b standard uses Complementary code keying (CCK) as its modulation technique, which is a variation on CDMA. Hence, chipsets and products were easily upgraded to support the 802.11b enhancements. The dramatic increase in throughput of 802.11b (compared to the original standard) along with substantial price reductions led to the rapid acceptance of 802.11b as the definitive Wireless LAN technology.

802.11b is usually used in a point-to-multipoint configuration, wherein an access point communicates via an omni-directional antenna with one or more clients that are located in a coverage area around the access point. Typical indoor range is 30 m (100 ft) at 11 Mbit/s and 90 m (300 ft) at 1 Mbit/s. With high-gain external antennas, the protocol can also be used in fixed point-to-point arrangements, typically at ranges up to 8 kilometers (5 miles) although some report success at ranges up to 80-120 km (50-75 miles) where line of sight can be established. This is usually done in place of costly leased lines or very cumbersome microwave communications equipment. Designers of such installations who wish to remain within the law must however be careful about legal limitations on effective radiated power (ERP).

802.11b cards can operate at 11 Mbit/s, but will scale back to 5.5, then 2, then 1 Mbit/s (also known as Adaptive Rate Selection), if signal quality becomes an issue. Since the lower data rates use less complex and more redundant methods of encoding the data, they are less susceptible to corruption due to interference and signal attenuation. Extensions have been made to the 802.11b protocol (for example, channel bonding and burst transmission techniques) in order to increase speed to 22, 33, and 44 Mbit/s, but the extensions are proprietary and have not been endorsed by the IEEE. Many companies call enhanced versions "802.11b+". These extensions have been largely obviated by the development of 802.11g, which has data rates up to 54 Mbit/s and is backwards-compatible with 802.11b.

The 802.11g Amendment

In June 2003, a third modulation standard was ratified: 802.11g. This flavor works in the 2.4 GHz band (like 802.11b) but operates at a maximum raw data rate of 54 Mbit/s, or about 24.7 Mbit/s net throughput (like 802.11a). 802.11g hardware is compatible with 802.11b hardware. Details of making b and g work well together occupied much of the lingering technical process. In older networks, however, the presence of an 802.11b participant significantly reduces the speed of an 802.11g network.

The modulation scheme used in 802.11g is orthogonal frequency-division multiplexing (OFDM) for the data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbit/s, and reverts to (like the 802.11b standard) CCK for 5.5 and 11 Mbit/s and DBPSK/DQPSK+DSSS for 1 and 2 Mbit/s. Even though 802.11g operates in the same frequency band as 802.11b, it can achieve higher data rates because of its similarities to 802.11a. The maximum range of 802.11g devices is slightly greater than that of 802.11b devices, but the range in which a client can achieve the full 54 Mbit/s data rate is much shorter than that of which a 802.11b client can reach 11 Mbit/s.

The 802.11g standard swept the consumer world of early adopters starting in January 2003, well before ratification. Corporate users held back - Cisco and other big equipment makers waited until ratification. By summer 2003, announcements were flourishing. Most of the dual-band 802.11a/b products became dual-band/tri-mode, supporting a, b, and g in a single mobile adapter card or access point. Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include microwave ovens, Bluetooth devices, and cordless telephones.

The 802.11n Amendment (MIMO)

802.11n builds upon previous 802.11 standards by adding MIMO (multiple-input multiple-output). MIMO uses multiple transmitter and receiver antennas to allow for increased data throughput through spatial multiplexing and increased range by exploiting the spatial diversity, perhaps through coding schemes like Alamouti coding.

The Enhanced Wireless Consortium (EWC) was formed to help accelerate the IEEE 802.11n development process and promote a technology specification for interoperability of next-generation wireless local area networking (WLAN) products.

Standard or Amendment?

Both the terms "standard" and "amendment" are used when referring to the different variants of IEEE 802.11. Which is correct?

As far as the IEEE is concerned there is only one standard - IEEE 802.11. This standard is continuously updated by means of amendments such as IEEE 802.11a, IEEE 802.11b etc. Periodically a new version of the IEEE 802.11 standard is produced combining the previous version of the standard and all amendments published up to that date. For example, there is a 2003 edition of the standard available for purchase that incorporates the IEEE 802.11a, IEEE 802.11b, and IEEE 802.11d amendments. It is possible that at some point, only this version will be made available for free download replacing the six year old version of the base standard and the first three amendments.

So the correct term for the base standard called "802.11 legacy" on this page would in fact be 802.11-1999. But outside the working group that produces IEEE 802.11 such accuracy is probably unnecessary.

Examples of Standard Wi-Fi Devices

Wireless Access Point (WAP)

A wireless access point (AP) connects a group of wireless stations to an adjacent wired local area network (LAN). An access point is similar to an ethernet hub, but instead of relaying LAN data only to other LAN stations, an access point can relay wireless data to all other compatible wireless devices as well as to a single (usually) connected LAN device, in most cases an ethernet hub or switch, allowing wireless devices to communicate with any other device on the LAN.

Wireless Router

A wireless router integrates a wireless access point with an IP router and an ethernet switch. The integrated switch connects the integrated access point and the integrated ethernet router internally, and allows for external wired ethernet LAN devices to be connected as well as a (usually) single WAN device such as cable modem or DSL modem. A wireless router advantageously allows all three devices (mainly the access point and router) to be configured through one central configuration utility, usually through an integrated web server.

Wireless Network Interface Card

A wireless network interface controller (WNIC) is a network card which connects to a radio-based computer network, unlike a regular network interface controller (NIC) which connects to a wire-based network such as token ring or ethernet. A WNIC, just like a NIC, works on the Layer 1 and Layer 2 of the OSI Model.
A WNIC is an essential component for wireless desktop computer. This card uses an antenna to communicate through microwaves. A WNIC in a desktop computer is mostly located in the PCI slot. Other options are USB WNIC, PCMCIA WNIC and integrated WNIC (typically in Mini PCI/PCI Express Mini Card form).

A WNIC can operate in two modes known as infrastructure mode and ad hoc mode.

In an infrastructure mode network the WNIC needs an access point: all data is transferred using the access point as the central hub. All wireless nodes in an infrastructure mode network connect to an access point. All nodes connecting to the access point must have the same service set identifier (SSID) as the access point, and if the access point is enabled with WEP they must have the same WEP key or other authentication parameters.

In an ad-hoc mode network the WNIC doesn't require an access point, but rather can directly interface with all other wireless nodes directly. All the peer nodes in an ad-hoc network must have the same channel and SSID.

WNICs are designed around the IEEE 802.11 standard which sets out low-level specifications for how all Wireless Networks operate. Earlier Interface Controllers are usually only compatible with earlier variants of the standard, while newer cards support both current and old standards.

Wireless Ethernet Bridge

A wireless Ethernet bridge connects a wired network to a wireless network. This is different from an access point in the sense that an access point connects wireless devices to a wired network at the data link layer. Two wireless bridges may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes.

Range Extender

A wireless range extender (or wireless repeater) can increase the range of an existing wireless network by being strategically placed in locations where a wireless signal is sufficiently strong and nearby locations that have poor to no signal strength.

An example location would be at the corner of an L-shaped corridor, where the access point is at the end of one leg and a strong signal is desired at the end of the other leg. Another example would be 75% of the way between the access point and the edge of its usable signal. This would effectively increase the range by 75%.

There are several stand-alone 802.11 wireless repeaters on the market today. In addition, some access points and routers have a built-in repeater mode. The advantage of the stand alone repeaters is that they are generally less expensive. One downside of wireless repeaters, though, is that they reduce throughput on the WLAN. A repeater must receive and retransmit each frame on the same RF channel, which effectively doubles the number of frames that are sent. This problem compounds when using multiple repeaters because each repeater will duplicate the number of frames sent.

WPA vs WPA2 (802.11i): How your Choice Affects your Wireless Network SecurityWPA vs WPA2 (802.11i): How your Choice Affects your Wireless Network Security

A discussion of why 802.11i (WPA2) provides stronger wireless security than WiFi Protected Access (WPA) and WEP, why there is a need for a new standard and why you should use it.
We’ve already looked at why WPA is better than WEP, so why have a new 802.11i security standard? Isn’t WPA good enough?
WPA has, rightly, been admired as a masterpiece of retro engineering. It addresses the weaknesses of WEP and the result is a very secure security system that is backwardly compatible with most existing WiFi compliant equipment. WPA is a practical solution that will provide more than adequate security for most wireless network applications.
However WPA is in the end a compromise solution. It still relies on the RC4 encryption algorithm and TKIP (Temporary Key Integrity Protocol). Although unlikely, the possibility of new weaknesses being discovered still exists.
A completely new security system, avoiding the design flaws of WEP entirely, represents the best long term, scalable solution to wireless LAN security. To this end the standards committee decided to design a new security system from the ground up. This is the new 802.11i standard, also known as WPA2 by the WiFi Alliance.

What is 802.11i?

802.11i uses the concept of a Robust Security Network (RSN). In RSN wireless devices need to support additional capabilities. This requires new hardware and software drivers making a fully compliant RSN network incompatible with existing WEP equipment. In the transitional period both RSN and WEP equipment will be supported, (in fact WPA/TKIP was a solution designed to make use of older equipment) but in the longer term WEP devices will be phased out.
802.11i allows for various network implementations and can use TKIP, but by default RSN uses AES (Advanced Encryption Standard) and CCMP (Counter Mode CBC MAC Protocol) and it is this which provides for a stronger, scalable solution.

What is AES/CCMP?

Advanced Encryption Standard (AES) is the cipher system used by RSN. It is the equivalent of the RC4 algorithm used by WPA. However the encryption mechanism is much more complex and does not suffer from the problems associated with WEP. AES is a block cipher, operating on blocks of data 128bits long.
CCMP is the security protocol used by AES. It is the equivalent of TKIP in WPA. CCMP computes a Message Integrity Check (MIC) using the well known, and proven, Cipher Block Chaining Message Authentication Code (CBC-MAC) method. Changing even one bit in a message produces a totally different result.
One of the worst aspects of WEP was the management of the secret keys. Many administrators found it impractical to manage keys in larger networks. As a result WEP keys were often not changed making it easier for hackers.
RSN defines a hierarchy of limited life keys, similar to TKIP. AES/CCMP requires 512bits to accommodate all the keys, less than TKIP.
Also like TKIP master keys are not used directly, but are used to derive other keys. Fortunately the administrator only needs to provide a single master key.
Messages are encrypted using a secret key (128bits) and a 128bit block of data. The encryption process is complex, but again the administrator does not need to be aware of the intricacies of the computations. The end result is encryption that is much harder to break than even WPA.

Conclusion

802.11i is by far the strongest security system for wireless networks. The purist would argue that anything less is the equivalent of no security at all.
When the 802.11i standard is ratified RSN (WPA2) compatible equipment will begin to appear. 802.11i (WPA2) will be the most robust, scalable, and secure solution and will appeal particularly to enterprise users where key management and administration has been a major headache.
802.11i has been designed using proven technologies. Security has been designed from scratch in full consultation with the best cryptographers and stands every chance of being the solution that wireless networks need. Although no security system can ever be considered totally unbreakable, 802.11i security is a dependable solution and seems unlikely to be breached. It suffers none of the problems of older systems.
802.11i is a wireless security system that you can depend on. You can use WPA to accommodate older equipment and as that reaches the end of its useful life you can upgrade to a fully compliant RSN network.

Wireless Encryption - WEP, WPA, and WPA2.

This a very basic description of the differences between Encryption Security Methods used by Entry Level Wireless Hardware (802.11b/g).

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WEP.
Each packet of the Encryption has 24bits Initialization vector. Which unfortunately done in plaintext.

40bits (encryption)+ 24bits(init. vector)=64bits Encryption.

104bit(encryption)+ 24bits(init. vector)=128bits Encryption.

WEP uses RC4 stream encryption, for a fresh key stream for each packet.

The Init Vector & the key are combined to get per-packet key which is used to generate RC4 keys stream.

The RC4 is one of the major culprits in the security issues.

Part of the weakness of RC4 has to do with the combo of Init. Vector and Plain Text chipper.

24 bit Init vector is finishing a cycle of 2 in the power of 24 in about hour and then repeats.

Repeating Init Vector plus knowledge about the plaintext language, makes guessing the plaintexts simpler.
 

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WPA
It is an interim solution that is used now until 802.11i comes out.

It still using RC4, but the Key was changed to TKIP.

TKIP basically works by generating a sequence of WEP keys based on a master key, and re-keying periodically before enough volume of info. could be captured to allow recovery of the WEP key. TKIP changes the Key every 10,000 packets, which is quick enough to combat statistical methods to analyze the cipher.

TKIP also adds into the picture the Message Integrity Code (MIC). The transmission’s CRC, and ICV (Integrity Check Value) is checked. If the packet was tampered with. WPA will stop using the current keys and re-keys.

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The Future (probably in mid 2005 will come with the release of 802.11i).

The Big Change will be Advance Encryption Standard (AES).

802.11i will change the WPA RC4 usage to employ AES.

Referred to as WPA2 the main difference for regular user would be.

WPA uses (as describe above) TKIP/MIC Encryption.

WPA2 uses AES-CCMP Encryption

AES aka the Rijndael algorithm is a secure, fast symmetric cipher that is easily implemented in hardware.

AES has its own mechanism for dynamic key generation. It's also resistant to statistical analysis of the cipher text.

Counter-Mode/CBC-MAC Protocol (CCMP) called the Advanced Encryption
Standard (AES).

Understanding the updated WPA and WPA2 standards

If the challenge of securing a wireless LAN wasn’t already confusing enough, things have just gotten worse.  The confusion started last month when the Wi-Fi Alliance changed the WPA and WPA2 standards from supporting a single EAP (Extensible Authentication Protocol) standard to five EAP standards.  Although this has broadened the WPA/WPA2 standards to be more inclusive, the decision of the Wi-Fi Alliance to not rename the updated WPA and WPA2 standards is causing mass confusion within the IT industry.  This could have been avoided if the Wi-Fi Alliance had named the updated standards "WPA + Extended EAP" and "WPA2 + Extended EAP" because it would make it easy to differentiate between old WPA/WPA2 certified products from the newer WPA/WPA2 certified products that will support five EAP types instead of one.  In my previous story, where Gartner issued a false alarm on Microsoft’s new WPA2 patch that led to a rash dire warnings from the press, I tried to provide some proper context to the situation.  Because the story touched on the complex topic of EAP (Extended Authentication Protocol) standards, it raised more questions than answers for the average reader who wanted to know what the heck are all these EAP standards in relation to the WPA/WPA2 standard.  This article provides an in-depth look at the WPA/WPA2 standard and the five EAP standards currently certified by the Wi-Fi Alliance.
The WPA and WPA2 standards were created by the Wi-Fi Alliance industry group that promotes interoperability and security for the wireless LAN industry.  The Wi-Fi Alliance WPA and WPA2 standards closely mirrors the official IEEE 802.11i wireless LAN security standards group but incorporates additional IETF EAP standards that the Wi-Fi Alliance considers secure.  The WPA and WPA2 standards have two components (encryption and authentication) that are crucial to a secure wireless LAN.  The encryption piece of WPA and WPA2 mandates the use of TKIP or, because it’s considered to be more secure than TKIP, preferably AES encryption.  From an encryption standpoint, WPA leaves AES optional while WPA2 mandates both TKIP and AES capability.  The authentication piece of WPA and WPA2 before the Extended EAP update called for the use of a PSK (Pre-Shared Key) for personal mode and EAP-TLS for enterprise mode.  After the Extended EAP update, there are now five EAP standards to choose from in WPA and WPA2 enterprise mode.

Note:  Besides the stricter encryption requirements, WPA2 also adds two enhancements to support fast roaming of wireless clients moving between wireless access points.  PMK (Pair-wise Master Key used for each session between an access point and wireless client) caching support in WPA2 allows you to reconnect to an access point that you’ve recently connected to without the need to re-authenticate.  Pre-authentication support in WPA2 allows a client to pre-authenticate with the access point toward which it is moving, while maintaining a connection to the access point it’s moving away from.  This new capability allows the roaming to occur in less than 1/10th of a second while a traditional roam without PMK caching and pre-authentication would take more than one second.  Timing-sensitive applications like Citrix, video, or VoIP will all break without fast roaming.

To give you some historical context on some significant EAP types, EAP-TTLS and PEAP were primarily created because the original EAP-TLS standard was deemed too difficult to deploy because of the need for a server-side x.509 digital certificate on the RADIUS authentication server and a client-side x.509 digital certificate on each and every client computer that needed to connect to the wireless LAN.  While the server-side certificate requirement wasn’t so bad because there are usually only a few RADIUS servers that need certificates, the client-side requirement was cause for major concern due to their sheer numbers.  Because the client-side certificate required a PKI server infrastructure (rare for most organizations) to be in place ahead of time or expensive third-party certificates, it automatically excluded EAP-TLS as a feasible option for most organizations and forced them into using less secure forms of EAP such as Cisco’s proprietary LEAP.  EAP-TTLS and PEAP were created to eliminate the need for client-side certificates but still leverage the server-side certificate to create a secure TLS tunnel to protect the "inner authentication methods" such as EAP-MSCHAPv2 and EAP-GTC from eavesdropping and offline dictionary and brute force attacks.  Conceptually, this works just like e-commerce security with SSL-enabled web sites where a web server’s server-side certificate is leveraged to create a secure SSL tunnel even though the visitors to the secure web site don’t have client-side digital certificates.
The current WPA/WPA2 certified EAP standards are:

• EAP-TLS (originally certified protocol)
• EAP-TTLS/MSCHAPv2
• PEAPv0/EAP-MSCHAPv2
• PEAPv1/EAP-GTC
• EAP-SIM

EAP-TLS is the original wireless LAN EAP authentication protocol.  Although it’s rarely implemented due to a steep deployment curve, it is still considered one of the most secure EAP standards available and is universally supported by all manufacturers of wireless LAN hardware and software including Microsoft.  The requirement for a client-side certificate, however unpopular it may be, is what gives EAP-TLS its authentication strength.  A compromised password is not enough to break into EAP-TLS enabled systems because the hacker still needs to have the client-side certificate.  When the client-side certificates are housed in smartcards, this offers the most secure authentication solution available because there is no way to steal a certificate from a smartcard without stealing the smartcard itself.  Any physical theft of a smartcard would be immediately noticed and revoked and a new smartcard would be issued.  Up until last month, this was the only EAP type vendors needed to certify for a WPA or WPA2 logo.  There are client and server implementations of it in Microsoft, Cisco, Apple, Linux, and open source.  EAP-TLS is natively supported in MAC OS 10.3 and above, Windows 2000 SP4, Windows XP, Windows Mobile 2003 and above, and Windows CE 4.2.

Note:  Although Windows 2000 supports EAP-TLS and PEAPv0/EAP-MSCHAPv2 authentication, it does not support WPA or WPA2 encryption, while all of the other newer operating systems mentioned support WPA.  Windows XP with Service Pack 2 and the new WPA2 patch is currently the only operating system that natively supports WPA2.

EAP-TTLS was created by Funk software and Certicom and is primarily backed by Funk software and is supported by other third-party server and client software.  Although it’s a fine protocol and even better than PEAP in some ways, it isn’t supported natively in Microsoft Windows clients such as Windows 2000, XP, Mobile 2003, or CE.  Support on the server side is also lacking in Microsoft Windows 2003 server and Cisco ACS (Access Control Server).  Where EAP-TTLS shines over PEAP authentication is that the username is not revealed in clear-text, which might avoid some DoS (Denial of Service) attacks where someone can maliciously log-in repeatedly with the right username and wrong password to lock out that user’s account.  PEAP authentication only protects the password portion with a strong TLS tunnel but broadcasts the username in the clear.  I’ve seen tools that have implemented this form of attack, but have never seen it used in the wild since it would mostly just annoy people and bring unwanted attention to a hacker.
PEAPv0/EAP-MSCHAPv2 is the technical term for what people most commonly refer to as "PEAP".  Whenever the word PEAP is used, it almost always refers to this form of PEAP since most people have no idea there are so many flavors of PEAP.  Behind EAP-TLS, PEAPv0/EAP-MSCHAPv2 is the second most widely supported EAP standard in the world.  There are client and server implementations of it in Microsoft, Cisco, Apple, Linux, and open source.  PEAPv0/EAP-MSCHAPv2 is natively supported in MAC OS 10.3 and above, Windows 2000 SP4, Windows XP, Windows Mobile 2003 and above, and Windows CE 4.2.  The server side implementation of PEAPv0/EAP-MSCHAPv2, called IAS (Internet Authentication Service), is also included in Windows 2003 server.  PEAPv0/EAP-MSCHAPv2 enjoys universal support and is known as the PEAP standard.
PEAPv1/EAP-GTC was created by Cisco as an alternative to PEAPv0/EAP-MSCHAPv2.  It allows the use of an inner authentication protocol other than Microsoft’s MSCHAPv2.  Even though Microsoft (along with RSA and Cisco) co-invented the PEAP standard, Microsoft never added support for PEAPv1 in general, which means PEAPv1/EAP-GTC has no native Windows OS support.  Since Cisco has always favored the use of its own less secure proprietary LEAP and EAP-FAST protocols over PEAP and markets them as simpler certificate-less solutions, standardized PEAP is rarely promoted by Cisco.  Cisco stands to gain a monopoly in the access point market if LEAP or EAP-FAST is universally adopted.  As a result, most Cisco customers run the less secure and proprietary LEAP or EAP-FAST authentication protocols because they’ve swallowed the Cisco Kool-Aid.  With no interest from Microsoft to support PEAPv1 and little interest from Cisco to promote PEAP in general, PEAPv1 authentication is rarely used.  There is no native OS support for this EAP protocol.

Note: The PEAP standard was created by Microsoft, Cisco, and RSA after EAP-TTLS already had already come on the market.  Even with its late start, Microsoft’s and Cisco’s size allowed them to quickly overtake EAP-TTLS in the market.  Microsoft and Cisco parted ways when Microsoft only supported the PEAPv0 standard while Cisco supported both PEAPv0 and PEAPv1.  PEAPv0 and PEAPv1 both refer to the outer authentication method and is the mechanism that creates the secure TLS tunnel to protect subsequent authentication transactions while EAP-MSCHAPv2, EAP-GTC, and EAP-SIM refer to the inner authentication method which facilitates user or device authentication.  From Cisco’s perspective, PEAPv0 supports inner EAP methods EAP-MSCHAPv2 and EAP-SIM while PEAPv1 supports inner EAP methods EAP-GTC and EAP-SIM.  Since Microsoft only supports PEAPv0 and doesn’t support PEAPv1, Microsoft simply calls PEAPv0 PEAP without the v0 or v1 designator.  Another difference between Microsoft and Cisco is that Microsoft only supports PEAPv0/EAP-MSCHAPv2 mode but not PEAPv0/EAP-SIM mode.  However, Microsoft supports another form of PEAPv0 (which Microsoft calls PEAP-EAP-TLS) that Cisco and other third-party server and client software don’t support.  PEAP-EAP-TLS does require a client-side digital certificate located on the client’s hard drive or a more secure smartcard.  PEAP-EAP-TLS is very similar in operation to the original EAP-TLS but provides slightly more protection due to the fact that portions of the client certificate that are unencrypted in EAP-TLS are encrypted in PEAP-EAP-TLS.  Since few third-party clients and servers support PEAP-EAP-TLS, users should probably avoid it unless they only intend to use Microsoft desktop clients and servers.  Ultimately, PEAPv0/EAP-MSCHAPv2 is the only form of PEAP that most people will ever know.  PEAP is so successful in the market place that even Funk Software, the inventor and backer of EAP-TTLS, had no choice but to support PEAP in their server and client software for wireless networks.

EAP-SIM was created for the GSM mobile telecom industry, which favors the use of SIM cards for authentication.  The Wi-Fi Alliance is trying to broaden support beyond the conventional wireless LAN, but the typical IT director probably doesn’t care too much about it because it isn’t something they would use.  There is no native OS support for this EAP protocol.
The bottom line is that the current WPA2 standard is now fully mature and provides rock solid wireless LAN security.  WPA2 provides solid military grade encryption and a broad choice of strong to strongest authentication protocols.  EAP-TLS and PEAPv0/EAP-MSCHAPv2 with universal platform support are the de facto EAP standards in wireless LAN authentication.  PEAPv0/EAP-MSCHAPv2 provides strong single-factor security while EAP-TLS provides the strongest two-factor authentication scheme in wireless LAN security.

Amazon Associates - Amazon preview

Amazon Associates - Amazon preview