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Wireless Technology

Wireless Technology

Wireless networks come in many different forms, cover various distances, and provide a range of low to high bandwidth depending on the type installed. Wireless LAN – Wireless LAN enable Laptop users to access the Network of a company.

Basic Wireless Devices

  • Wireless Access Points
  • Wireless Network Interface Card (WNIC)
  • Wireless Antennas

Wireless Access Points

In the wireless networks, you’ll find a central component such as a switch that’s there to connect hosts together and allow them to communicate with each other.

Only that device is known as a wireless access point (AP) instead.

Wireless Network Interface Card (WNIC)

Every host you want to connect to a wireless network needs a wireless network interface card (WNIC) to do so. Basically, a wireless NIC does the same job as a traditional Ethernet NIC, only instead of having a socket/port to plug a cable into; the wireless NIC has a radio antenna. It would be difficult to buy a laptop today without a wireless card already built in.

Wireless Antennas

Wireless antennas work with both transmitters and receivers. There are two broad classes of antennas on the market today: omnidirectional (or). Wireless access points have at least one antenna. Usually there’s two for better reception (referred to as diversity) and an Ethernet port to connect them to a wired network.

Wireless Standards (The 802.11 Standards)

Standard Speed Frequency (GHZ) Segment Length
802.11b 11 Mbps 2.4 150 to 350 m
802.11a 54 Mbps 5 75 to 175 m
802.11g 54 Mbps 2.4 100 to 300 m
802.11n 74 Mbps 2.4/5 250 to 300 m

Wireless Topologies

Now that I’ve discussed the very basics of wireless devices used in today’s simple networks, I want to describe the different types of networks you’ll run across or design and implement as your wireless networks grow.

These include the following:

  • IBSS
  • BSS
  • ESS

Independent Basic Service Set (Ad Hoc) (IBSS)

Using an ad hoc network is the easiest way to install wireless 802.11 devices. In this mode, the wireless NICs (or other devices) can communicate directly without the need for an AP.

Independent Basic Service Set (Ad Hoc) (IBSS)
Independent Basic Service Set (Ad Hoc) (IBSS)

Basic Service Set (BSS)

A basic service set (BSS) is the area, or cell, defined by the wireless signal served by the AP. It can also be called a basic service area (BSA) and the two terms, BSS and BSA, can be interchangeable. Even so, BSS is the term most commonly used to define the cell area.

Basic Service Set (BSS)
Basic Service Set (BSS)

Extended Service Set (ESS)

A good thing to know is that if you set all your access points to the same SSID, mobile wireless clients can roam around freely within the same network. This is the most common wireless network design you’ll find in today’s corporate settings.

Doing this creates something called an extended service set (ESS), which provides more coverage than a single access point and allows users to roam from one AP to another without having their host disconnected from the network. This design creates the ability to move more or less seamlessly from one AP to another. APs configured with the same SSIDs in an office, thereby creating the ESS network.

Extended Service Set (ESS)
Extended Service Set (ESS)

(NOTE: SSID is a basic name that defines the BSA transmitted from the AP. You’ve probably seen that name pop up on your host when looking for a wireless network. The SSID can be up to 32 characters long. It normally consists of human readable ASCII characters, but the standard doesn’t require this. The SSID is defined as a sequence of 1 to 32 octets, each of which may take any value.)

Wireless Security

Open Access

All Wi-Fi Certified wireless LAN products are shipped in “open-access” mode, with their security features turned off. While open access or no security may be appropriate and acceptable for public hot spots such as coffee shops, college campuses, and maybe airports, it’s definitely not an option for an enterprise organization, and likely not even adequate for your private home network.

SSIDs, WEP, and MAC Address Authentication

  • SSID Authentication: Two types of authentication were specified by the IEEE 802.11 committee: open authentication and shared-key authentication. Open authentication involves little more than supplying the correct SSID—but it’s the most common method in use today.
  • WEP Authentication: WEP is a type of shared-key authentication With shared-key authentication, the access point sends the client device a challenge-text packet that the client must then encrypt with the correct Wired Equivalency Privacy (WEP) key and return to the access point. Without the correct key, authentication will fail and the client won’t be allowed to associate with the access point.
  • MAC Address Authentication: Last, client MAC addresses can be statically typed into each access point, and any of them that show up without that MAC addresses in the filter table would be denied access. Sounds good, but of course all MAC layer information must be sent in the clear—anyone equipped with a free wireless sniffer can just read the client packets sent to the access point and spoof their MAC address.
Encryption Methods

There are two basic types of encryption methods used in most wireless networks today: TKIP and AES.

  • Temporal Key Integrity Protocol (TKIP): Temporal Key Integrity Protocol (TKIP) which is based on the RC4 encryption algorithm. TKIP first gained respect in the WLAN world due to the protections it affords the authentication process, but it is also used after that completes to encrypt the data traffic thereafter.
  • Advanced Encryption Standard (AES): Both WPA/2 and the 802.11i standard call for the use of 128-bit Advanced Encryption Standard (AES) for data encryption. It’s widely considered the best encryption available today and has been approved by the National Institute of Standards and Technology (NIST). It’s also referred to as AES-CCMP, or AES Counter Mode with CBC-MAC authentication.

Wi-Fi Protected Access (WPA)

Wi-Fi Protected Access (WPA) is a standard testing specification developed in 2003 by the Wi-Fi Alliance, formerly known as the Wireless Ethernet Compatibility Alliance (WECA). WPA provides a standard for authentication and encryption of WLANs that’s intended to solve known security problems existing up to and including the year 2003. WPA is a step toward the IEEE 802.11i standard and uses many of the same components, with the exception of encryption—802.11i uses AES encryption.

  • WPA or WPA2 Pre-Shared Key: WPA or WPA2Pre-Shared Key (PSK) is a better form of wireless security than any other basic wireless security method mentioned so far.
  • WPA or WPA2 Enterprise: WPA and WPA2 support an enterprise authentication method. This is called Extensible Authentication Protocol (EAP). Understand that EAP isn’t a single method, but a framework that enhances the existing 802.1x framework.

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