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What is Wi-Fi , the answer to many questions

I think this question is given by everyone here I found an article about Wi-Fi , hope for your understanding admins...

What is wifi and how to use it

(2.4 GHz and 5 GHz.)

Wi-Fi (pronounced [Wi-Fi], abbr. Wireless Fidelity — the standard equipment for broadband wireless communication intended for the organization of local wireless networks Wireless LAN. The installation of such networks is recommended where the deployment of the cable system is impossible or economically impractical. Thanks handover users can move between access points throughout the network coverage Wi-Fi without disconnection. Developed by a consortium Wi-Fi Alliance based on IEEE 802.11 standards.


Mobile devices (PDAs and laptops), equipped with a client Wi-Fi receiver-transmitter can connect to a local network and access the Internet via so-called access points or hotspots.

The first Wi-fi

Wi-Fi was created in 1991 NCR Corporation/AT&T (later Lucent and Agere Systems) in Nieuwegein, the Netherlands. Products, initially for systems and cash services, was brought to market under the name WaveLAN and provided data transfer rate of 1 to 2 Mbit/s. Vic Hayes (Vic Hayes) — the Creator of the Wi-Fi was named "father of Wi-Fi" and was in the team involved in the development of standards such as IEEE 802.11 b, 802.11 a and 802.11 g. In 2003, Vic retired from Agere Systems. Agere Systems are unable to compete on equal terms in difficult market conditions, despite the fact that its products have occupied the niche of cheap Wi-Fi solutions. 802.11 abg all-in-one chipset from Agere (code named: WARP) didn't sell well, and Agere Systems decided to quit the Wi-Fi market in late 2004.

Wireless-Fidelity -literally "Wireless Reliability".

Wi-Fi: How it works
Usually a scheme Wi-Fi network contains one access point (AP). access point) and at least one client. Access point is broadcasting its SSID (eng. Service Set IDentifier, Network name — network identifier, network name) via a special packet, called signaling packets transmitted every 100 MS. Signaling packets are transmitted at the speed of 1 Mbps and have a small size, so they do not affect network performance. Since 1 Mbit/s minimum data transfer rate for Wi-Fi, the client, receive the signal packet, can be sure that I will be able to connect at a speed no less than 1 Mbps. Knowing the parameters of the network (i.e. the SSID), the client can figure out if you can connect to this access point. The program, built-in Wi-Fi card of the client, may also affect the connection. When getting within range of two access points with identical SSID, the software can select between them on the basis of the signal level. Standard Wi-Fi gives the customer complete freedom in the choice of criteria for connection and roaming. This is the advantage of Wi-Fi, although it means that one of the adapters can perform these actions much better than the other. The latest versions of operating systems contain a feature called zero configuration which shows the user all available networks and allows you to switch between them on the fly. This means that roaming is fully controlled by the operating system. Wi-Fi transmits data in the ether, so it has properties similar to non-switched ethernet network, and it can cause the same problems as with a non-switched ethernet networks.

Wi-Fi and mobile phones

Some believe that Wi-Fi and similar technologies may eventually replace cellular networks such as GSM. Barriers to such developments in the near future are the lack of roaming and authentication features (see 802.1 x, SIM cards and RADIUS), limited frequency range and very limited radius of action Wi-Fi. Looks more correct comparison of Wi-Fi with other networks, such as GSM, UMTS or CDMA. However, the Wi-Fi is ideal for VoIP in corporate networks or in a SOHO environment. The first equipment was available in the early 90s, but had not entered commercial operation until 2005. Then the company Zyxel, UT Starcomm, Samsung, Hitachi and many others introduced on the market VoIP Wi-Fi phones at "reasonable" prices. In 2005 ADSL ISP providers started to offer VoIP services to your customers (for example German ISP XS4All). When calls using VoIP are very cheap and often even free, providers are able to provide VoIP services, had the opportunity to open up a new market of VoIP services. GSM phones with integrated support for Wi-Fi and VoIP have begun to appear on the market, and potentially they can replace phones. At the moment, a direct comparison of the Wi-Fi and cellular networks is impractical. Phones using Wi-Fi only have a very limited range, so deployment of such networks is very expensive. However, the deployment of such networks may be the best solution for local use, for example, in corporate networks. However, devices that support multiple standards can take a significant market share.

Commercial use of Wi-Fi

Commercial access services based on Wi-Fi is available in places such as Internet cafes, airports, and cafes around the world (normally called Wi-Fi-cafés), but their coverage can be regarded as a point compared with the cellular networks:
• Ozone and OzoneParis In France. In September 2003, Ozone started deploying the OzoneParis network across The City of Lights. The ultimate goal is the creation of a centralized Wi-Fi network that can cover your Paris. The basic principle of Ozone Pervasive Network is that this network on a national scale. 
• WiSE Technologies provides commercial access in airports, universities, and independent cafes in the U.S.; 
• T-Mobile provides hotspots for Starbucks in the US and the UK, as well as more than 7500 hotspots in Germany; 
• Pacific Century Cyberworks provides access to the Pacific Coffee stores in Hong Kong;
• Columbia Rural Electric Association is trying to deploy a network of 2.4 GHz Wi-Fi on an area of 9,500 km?, located between counties Walla-Walla and the Columbia in Washington state and Umatilla, Oregon; To the list of other major networks in the US are: Boingo, Wayport and iPass; • Sify, an Indian Internet service provider, has installed 120 access points in Bangalore, in hotels, galleries and government institutions. 
• Vex has a large network of hotspots located throughout Brazil. Telefónica Speedy Wi-Fi began providing its services in a new growing network that has spread to the territory of the state of Sao Paulo.
• BT Openzone owns many hotspots in the UK, working in McDonald's, and has a roaming agreement with T-Mobile UK and ReadyToSurf. Their clients also have access to The Cloud hotspots.
• Netstop provides access to New Zealand. 
• The company Golden Telecom provides support for municipal Wi-Fi network in Moscow, and also provides communication channels for the project Yandex.Wi-Fi ([2]). 
• EarthLink plans in the third quarter of 2007 to fully connect Philadelphia (USA) to the wireless Internet. This will be the first city-metropolis in the USA which is fully covered by Wi-Fi. The cost will be around 20-22 dollars a month at connection speed of 1 Mbit/sec. For low-income residents of Philadelphia cost would be 12-15 dollars a month. Currently, the city centre and surrounding areas are already connected. Connect the other regions will be made as the installation of transmitters.

Wireless technology in industry

For use in industry Wi-Fi technology are available while a limited number of suppliers. So Siemens Automation & Drives offers Wi-Fi solutions for their controllers SIMATIC in accordance with the IEEE 802.11 b standard in the free ISM-band 2.4-GHz and providing a maximum transmission speed of 11 Mbit/s. these technologies are mainly used to control moving objects and in warehouse logistics, as well as in cases when for any reason it is impossible to lay a wired Ethernet network.

International projects

Another business model is to connect existing networks to the new one. The idea is that users will share your frequency response using personal wireless routers completed. For example, FON is a young Spanish company created in November 2005. She intends to become the largest network of hotspots worldwide by the end of 2006 with 30,000 access points. Users are divided into three categories: linus, allocating free access to the Internet; bills, selling your frequency range; and aliens that use access via bills. Thus, the system is similar to peer-to-peer services. Despite the fact that the FON receives financial support from such companies as Google and Skype, only with time it will be clear, will this idea really work. Now this service has three main problems. The first is that for transition of project from initial stage to bulk requires more attention from the public and the media. You also need to consider the fact that the provision of access to your Internet channel to others may be limited by your contract with the ISP. Therefore, the Internet providers will try to protect their interests. The same is likely to come from record companies opposed to the free distribution MP3. And third, the FON software is still in beta stage, and it remains only to wait when will be solved the problem of security.

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Free Wi-Fi

While commercial services are trying to use existing business models to wifi, many groups, communities, cities, and individuals to build free Wi-Fi network, often using a common peering agreement in order that networks can freely communicate with each other. Free wireless networks are usually represented the future of the Internet. Many municipalities together with local communities to expand free Wi-Fi network. Some groups are building their own Wi-Fi network based entirely on voluntary help and donations. For more information, see joint wireless & networks, where you can also find a list of available Wi-Fi networks located around the world (see also Free Wi-Fi access in Moscow). OLSR is one of the protocols used for the creation of free networks. Some networks use static routing, while others rely completely on OSPF. In Wireless Leiden developed their own software for routing called LVrouteD to combine Wi-Fi networks, is built on a fully wireless basis. Bo?most networks based on open source software, or publish the scheme under an open license. Some smaller countries and municipalities already provide free access to Wi-Fi hotspots and Internet access via Wi-Fi at the place of residence for all. For example, the Kingdom of Tonga or Estonia, which have a large number of free wifi hotspots throughout the country. In Paris, OzoneParis offers free Internet access is unlimited to everyone who contributes to the development of Pervasive Network, providing the roof of his house for the installation of Wi-Fi network. Unwire Jerusalem is a project of the installation of free access points Wi-Fi in the major shopping centers of Jerusalem. Many universities provide free access to the Internet via Wi-Fi for its students, visitors and all who are on campus. Some commercial entities such as Panera Bread, offer free access to Wi-Fi for regular customers. McDonald's Corporation also provide access to Wi-Fi under the brand 'McInternet'. This service was launched at the restaurant in oak brook, Illinois; it is also available in many restaurants in London. However, there is a third subcategory of networks communities and organizations, such as universities, where free access is granted to members of the community, and those who had not included, access is granted on a paid basis. An example of such a service — Sparknet in Finland. Sparknet also supports OpenSparknet project, in which people can make their own access point part of Sparknet, gain some benefit. Recently commercial Wi-Fi providers have built free Wi-Fi hotspots and hotzone. They believe that free Wi-Fi will attract new customers and investment returns.

The Advantages Of Wi-Fi

• Allows you to deploy a network without laying cable, can reduce the cost of deployment and network expansion. Places where you cannot lay cable, for example, outdoors and in buildings of historical value, may be served by wireless networks. • Wi-Fi devices are widely available on the market. And devices from different manufacturers can interoperate at a basic level of services. • Wi-Fi networks support roaming, so the client station can move in space, moving from one access point to another. • Wi-Fi is a set of global standards. Unlike cell phones, Wi-Fi equipment can work in different countries around the world.

Disadvantages Of Wi-Fi

•Frequency range and operational constraints vary across countries; in many European countries, you are allowed two additional channels, which are banned in the US; Japan has one more channel in the upper part of the range, and other countries like Spain, prohibit use of low-frequency channels. Moreover, some countries, such as Italy, require the registration of all Wi-Fi networks operating out of the premises, or require registration of the Wi-Fi operator. • Quite high compared to other standards the energy consumption that reduces battery life and increases the temperature of the device. • The most popular encryption standard, Wired Equivalent Privacy, or WEP, can be cracked relatively easily even with the correct configuration (because of the weak strength of the key). Despite the fact that the new devices support more advanced Protocol Wi-Fi Protected Access (WPA), many older access points don't support it and require replacement. The adoption of the 802.11 i standard (WPA2) in June 2004 makes available a more secure scheme, which is available in new equipment. Both schemes require stronger password than those typically assigned by the user. Many organizations use additional encryption (e.g. VPN) to protect from invasion. • Wi-Fi have limited range. A typical home Wi-Fi router with 802.11 b or 802.11 g has a range of 45 m indoors and 90 meters outdoors. Distance also depends on the frequency.Wi-Fi in the 2.4 GHz range is more than Wi-Fi in the 5 GHz band, and has a radius smaller than Wi-Fi and pre-Wi-Fi) at the frequency of 900 MHz. • Signal interference of a closed or using encryption access points and outdoor access points operating on the same or adjacent channels may interfere with access to an open access point. This problem may occur with a high density of access points, for example, in large apartment buildings where many residents put their access point Wi-Fi. • Incomplete compatibility between devices from different manufacturers or incomplete compliance may lead to limited connectivity or slow.

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By activating this feature you can deny access to your access point via Wi-fi network, but it will not protect you against sniffing or intrusion into your network.

Remember that wrong hardware configuration that supports even the most modern security technology, will not provide the proper level of security to your network. Each standard has additional technologies and settings to maximize security. We therefore recommend to entrust the setup of Wi-Fi equipment only to professionals.

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Games through Wi-Fi

• Wi-Fi is compatible with gaming consoles and PDAs, and allows network play via any access point. • Iwata, President of Nintendo announced the Nintendo Wii, compatible with Wi-Fi, also saying that games like Super Smash Brothers will be available. Nintendo DS is also compatible with Wi-Fi. • Sony PSP has wireless support, which is activated by pressing one button for connecting to Wi-Fi hotspots or other wireless connections.

Wi-Fi and free

• OS family BSD (FreeBSD, NetBSD, OpenBSD) can work with most adapters since 1998. Drivers for chips from Atheros, Prism, Harris/Intersil and Aironet (from the respective manufacturers Wi-Fi devices) is usually included in BSD since version 3. Darwin and Mac OS X, despite the overlap with FreeBSD, have their own unique implementation. In OpenBSD 3.7, it was included more drivers for wireless chips, including RealTek RTL8180L, Ralink RT25x0, Atmel AT76C50x, and Intel 2100 and 2200BG/2225BG/2915ABG. Thanks partly managed to solve the problem of lack of open drivers for wireless chips for OpenBSD. Perhaps some drivers that are implemented on other BSD systems may be transferred if they have not yet been created. Ndiswrapper is also available for FreeBSD. • Linux: Starting from version 2.6, some Wi-Fi devices appeared directly in the Linux kernel. Support for chips Orinoco, Prism, Aironet and Atmel are included in the main kernel, chips ADMtek and Realtek RTL8180L are both supported closed drivers, manufacturers and public, written by the community. Intel Calexico supported open drivers available on Sourceforge. Atheros and Ralink RT2x00 supported through open-source projects. Support for other wireless devices are available using the open source driver ndiswrapper, which allows Linux systems running on computers with Intel x86 architecture to "wrap" the driver manufacturer for Windows for the direct use. Known at least one commercial implementation of this idea. The FSF has created a list of recommended adapters, more information can be found on the Linux wireless site.

Wireless networking standards

There are currently four major Wi-Fi standard is 802.11 a, 802.11 b, 802.11 g and 802.11 i.  there are two of them: 802.11 b and 802.11 g. In 2006, and 802.11 i. By 2007 it is planned to start implementation of another standard – 802.11 n.

802.11 b

 The transmission speed is quite low, and the safety to be on a fairly low level. If desired, the attacker could take less than an hour to decrypt the network key and entering your local network. For protection is used the WEP Protocol, which described itself not with the best hand and was hacked a few years ago. We recommend not to use the data standard is not at home nor even in corporate computer networks. The exception may be those cases where the hardware does not support other, more secure standard.

- Speed: 11 Mbps
- Effective range: 50 m
- Security protocols: WEP
- Security level: low
802.11 g

This is a more advanced standard that has replaced 802.11 b. Was increased data transfer rate nearly 5 times and now she is 54 Mbps. When using equipment which supports superG* or True MIMO* limit the maximum achievable speed is 125 Mpbs. Increased the level of protection: subject to all necessary conditions when properly configured, it can be assessed as high. This standard is compatible with the new WPA and WPA2*. They provide a higher level of protection than WEP. Cases of hacking WPA2* is not yet known.

*- Not supported by all hardware

- 54 Mbps, up to 125* Mbps
- Effective range: 50 m
- Security protocols: WEP, WPA, WPA2*
- Security level: high
802.11 i

This new standard, the implementation of which is just beginning. In this case, directly into the standard built-in support for most modern technologies, such as True MIMO WPA2. Therefore, the need for a more careful selection of equipment is eliminated. It is expected that this standard will replace the 802.11 g and will bring to nothing all attempts of hacking.

- Speed: 125 Mbps?
- Effective range: 50 m
- Security protocols: WEP, WPA, WPA2
- Security level: High
802.11 n

The future standard, development of which is underway at the moment. This standard needs to provide long distance coverage wireless networks and higher speed, up to 540 Mbit/sec.

- Speed: 540 Mbps?
- Radius of action: unknown m
- Security protocols: WEP, WPA, WPA2
- Security level: High

However, remember that improper setup of equipment to support even the most modern security technology, will not provide the proper level of security to your network. Each standard has additional technologies and settings to maximize security. We therefore recommend to entrust the setup of Wi-Fi equipment only to professionals.

Wireless security

Wireless security should be given special attention. Because wi-fi is a wireless network and, moreover, with a large radius of action. Accordingly, the attacker can intercept information, or to attack Your network, from a safe distance. Fortunately currently there are many different ways to protect and with proper setup you can be confident in providing the necessary level of security.


Encryption Protocol that uses a fairly strong algorithm RC4 with static key. There are 64-, 128-, 256 - and 512-bit wep encryption. The more bits used to store the key, the more possible key combinations, and a correspondingly higher resistance of the network to hacking. Part of the wep key is static (40-bit in a 64-bit encryption) and the other part (24-bit) – dinamica (initialization vector), that is, changing in the process network. The main vulnerability in wep is that the initialization vector is repeated after a certain period of time and the attacker only need to collect these repetitions and calculate thereon the static part of the key. To increase the level of security in addition to wep encryption use 802.1 x or VPN.
Stronger encryption Protocol than wep, although it uses the same RC4 algorithm. A higher level of security is achieved through the use of protocols TKIP and MIC. 

- TKIP (Temporal Key Integrity Protocol). Protocol for dynamic key of a network, which change quite often. In this case, each device is also assigned a key that is also changing.
- MIC (Message Integrity Check). The Protocol for checking the integrity of packages. Protects against packet sniffing and redirecting.
It is also possible and the use of 802.1 x and VPN, as in the case of wep.

There are two types of WPA:

- WPA-PSK (Pre-shared key). For key generation networks and to enter network passphrase. Best option for a home or small office network.
- WPA-802.1 x. Logging on to the network through the authentication server. Optimal for the network of a large company.
Improvement of WPA. In contrast, WPA uses stronger AES encryption algorithm. By analogy with WPA, WPA2 is also divided into two types: WPA2-PSK, and WPA2-802.1 x.
802.1 X
Security standard that includes many protocols:

- Extensible Authentication Protocol (EAP). Protocol extended authentication. Used in conjunction with a RADIUS server in large networks.
- TLS (Transport Layer Security). The Protocol that ensures the integrity and encryption of transmitted data between server and client mutual authentication, preventing interception and substitution messages.
- RADIUS (Remote Authentication Dial-In User Server). Server authenticate user by login and password.

VPN (Virtual Private Network) a Virtual private network. This Protocol was originally created to securely connect clients to the network via a public Internet channels. The principle of operation of VPN – creating a secure "tunnel" from the user to the access node or server. Although VPNs were originally created not for WI-Fi, it can be used in any type of networks. To encrypt traffic in a VPN is most often used IPSec. It provides almost one hundred percent security. Instances of hacking VPN is currently unknown. We recommend you to use this technology for corporate networks.
Additional methods of protection

- Filtering by MAC address.

MAC address is a unique identifier for the device (network adapter), "hardwired" into it by the manufacturer. On some equipment it is possible to use this function and allow access to the necessary network addresses. It will create an additional barrier to the attacker, although not very serious – the MAC address can be spoofed.
- Hide the SSID.

The SSID is the ID of your wireless network. Most of the equipment allows it to hide, so when scanning wi-fi networks your network will not be seen. But then again, it's not a serious obstacle if an attacker uses a more advanced scanner networks than a standard utility in Windows.
- Restrict access to the settings of the access point or router through a wireless network.

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