![](media/image1.png){width="5.997222222222222in"
height="6.933333333333334in"}

+-----------------------------------+-----------------------------------+
| ![](media/image2.j                | Alphabet Soup:                    |
| peg){width="2.5479166666666666in" |                                   |
| height="1.7909722222222222in"}    | wireless standards                |
+-----------------------------------+-----------------------------------+

  ---------------------------------------------------- ------------------------------------------------
  ![](media/image3.png){width="1.8486111111111112in"   Networking without cocktails or wires:\
  height="1.3347222222222221in"}                       Wi-Fi, WLANS, PANS, WANS and MANS

  ---------------------------------------------------- ------------------------------------------------

# Wi-Fi 

**Wi-Fi** (sometimes written **Wi-fi**, **WiFi**, **Wifi**, **wifi**) is
a trademark for sets of product compatibility standards for wireless
local area networks (WLANs). Wi-Fi, short for \"Wireless Fidelity\", was
intended to allow mobile devices, such as laptop computers and personal
digital assistants (PDAs) to connect to local area networks, but is now
often used for Internet access and wireless VoIP phones. Desktop
computers can use Wi-Fi too, allowing offices and homes to be networked
without expensive wiring. Many computers are sold today with Wi-Fi
built-in; others require adding a Wi-Fi network card. Other devices,
such as digital cameras, are sometimes equipped with Wi-Fi.

A person with a Wi-Fi-enabled device can connect to a local area network
when near one of the network\'s access points. The connection is made by
radio signals; there is no need to plug the device into the network. If
the local area network is connected to the Internet, the Wi-Fi device
can have Internet access as well. The geographical region covered by one
or several access points is called a hotspot. The range of an access
point varies. The access point built into a typical Wi-Fi home router
might have a range of 45 m (150 ft) indoors and 90 m (300 ft) outdoors.

## Specifications

Wi-Fi is based on the IEEE 802.11 specifications. There are currently
four deployed 802.11 variations: 802.11a, 802.11b, 802.11g, and 802.11n.
The *b* specification was used in the first Wi-Fi products. The *g* and
*n* variants are the ones most often sold as of 2005.

  -------------------- -------------- ----------------- ------------------
  **Wi-Fi                                               
  specifications**                                      

  **Specification**    **Speed**      **Frequency\      **Compatible\
                                      Band**            with**

  802.11b              11 Mb/s        2.4 GHz           b

  802.11a              54 Mb/s        5 GHz             a

  802.11g              54 Mb/s        2.4 GHz           b, g

  802.11n              100 Mb/s       2.4 GHz           b, g, n
  -------------------- -------------- ----------------- ------------------

In most of the world, the frequencies used by Wi-Fi do not require user
licenses from local regulators (eg, the Federal Communications
Commission in the US). 802.11a equipment, using a higher frequency, has
reduced range, all other things being equal.

The most widespread version of Wi-Fi in the US market today (based in
IEEE 802.11b/g) operates in the 2,400 MHz to 2,483.50 MHz. It allows
operation in 11 channels (5 MHz each).

New standards beyond the 802.11 specifications are currently in the
works and offer many enhancements, anywhere from longer range to greater
transfer speeds. One example is 802.16 WiMAX, with a range of several
miles and data rates of up to 70Mbs. 802.16a permits operation between 2
and 11 GHz, so there may eventually be some interoperability between
802.11 units and some 802.16a units.

+-----------+----------------------------------------------------------+
| ***De     | *Mbps is not to be confused with MBps (megabytes per     |
| finition: | second). Also see Kilo, mega, giga, tera, peta, and all  |
| Mbps or   | that.*                                                   |
| Mb/s***   |                                                          |
|           | *Mbps stands for millions of bits per second or megabits |
|           | per second and is a measure of bandwidth (the total      |
|           | information flow over a given time) on a                 |
|           | telecommunications medium. Depending on the medium and   |
|           | the transmission method, bandwidth is also sometimes     |
|           | measured in the Kbps (thousands of bits or kilobits per  |
|           | second) range or the Gbps (billions of bits or gigabits  |
|           | per second) range.*                                      |
+-----------+----------------------------------------------------------+

## Advantages of Wi-Fi

-   Unlike packet radio systems, Wi-Fi uses unlicensed radio spectrum
    and does not require regulatory approval for individual deployers.

-   Allows LANs to be deployed without cabling, potentially reducing the
    costs of network deployment and expansion. Spaces where cables
    cannot be run, such as outdoor areas and historical buildings, can
    host wireless LANs.

-   Wi-Fi products are widely available in the market. Different brands
    of access points and client network interfaces are interoperable at
    a basic level of service.

-   Competition amongst vendors has lowered prices considerably since
    their inception.

-   Many Wi-Fi networks support roaming, in which a mobile client
    station such as a laptop computer can move from one access point to
    another as the user moves around a building or area.

-   Many access points and network interfaces support various degrees of
    encryption to protect traffic from interception.

-   Wi-Fi is a global set of standards. Unlike cellular carriers, the
    same Wi-Fi client works in different countries around the world
    (although may require some software configuration).

## Disadvantages of Wi-Fi

-   ![](media/image4.png){width="1.9479166666666667in"
    height="2.9270833333333335in"}Use of the 2.4 GHz Wi-Fi band does not
    require a license in most of the world provided that one stays below
    the local regulatory limits and provided one accepts interference
    from other sources, including interference that causes your devices
    to no longer function.

-   Legislation/regulation is not consistent worldwide; most of Europe
    allows for an additional 2 channels over those allowed for *b* and
    *g*; Japan has one more on top of that - and some countries, like
    Spain, prohibit use of the lower-numbered channels. Furthermore some
    countries, such as Italy, used to require a \'general
    authorization\' for any WiFi used outside the owned premises; or
    required something akin to operator registration. For Europe;
    consult http://www.ero.dk for an annual report on the additional
    restriction each European country imposes.

-   The 802.11b and 802.11g flavors of Wi-Fi use the 2.4 GHz spectrum,
    which is crowded with other equipment such as Bluetooth devices,
    microwave ovens, cordless phones (900 MHz or 5.8 GHz are, therefore,
    alternative phone frequencies one can use to avoid interference if
    one has a Wi-Fi network), or video sender devices, among many
    others. This may cause a degradation in performance. Other devices
    that use these microwave frequencies can also cause degradation in
    performance.

-   Closed access points can interfere with properly configured open
    access points on the same frequency, preventing use of open access
    points by others.

-   Power consumption is fairly high compared to other standards, making
    battery life and heat a concern.

## Unintended and Intended use by outsiders

The default configuration of most Wi-Fi access points provides no
protection from unauthorized use of the network. Many business and
residential users do not intend to secure their access points by leaving
them open to users in the area. It has become etiquette to leave access
points open for others to use just as one can expect to find open access
points while on the road. Most Wi-Fi community networks are based on
free access and freely sharing bandwith.

Measures to deter unauthorized users include suppressing the AP\'s
service set identifier (SSID) broadcast, only allowing computers with
known MAC addresses to join the network, and various encryption
standards. Older access points frequently do not support adequate
security measures to protect against a determined attacker armed with a
packet sniffer and the ability to switch MAC addresses. Harmless
recreational exploration of other people\'s access points has become
known as wardriving, and the leaving of chalk graffiti describing
available services as warchalking.

It is also common for people to unintentionally use others\' Wi-Fi
networks without specific authorization. Operating systems such as
Windows XP and Mac OS X automatically connect to any nearby wireless
network, depending on the network configuration. A user who happens to
start up a laptop in the vicinity of an access point may find the
computer has joined a network without any visible indication. Moreover,
a user intending to join one network may instead end up on another one
if the latter\'s signal is stronger. In combination with automatic
discovery of other network resources this could theoretically lead
wireless users to send sensitive data to the wrong destination.

## Security

WiFi equipment could be used to steal personal information (passwords,
financial information, identity information, and so on) transmitted from
Wi-Fi users, if sensible protections are not used.

The first and most commonly used wireless encryption standard, Wired
Equivalent Privacy or WEP, has been shown to be easily breakable even
when correctly configured. Most wireless products now on the market
support the Wi-Fi Protected Access (WPA) encryption protocol, which is
considered much stronger, though some older access points have to be
replaced to support it. The adoption of the 802.11i standard (marketed
as WPA2) makes available a rather better security scheme --- when
properly configured. As of mid-2005, both Microsoft Windows XP and Mac
OS X support WPA2, but on newer equipment only. While waiting for better
standards to be available, many enterprises have chosen to deploy
additional layers of encryption (such as VPNs) to protect against
interception.

Some report that interference of a closed or encrypted access point with
other open access points on the same or a neighboring channel can
prevent access to the open access points by others in the area. This can
pose a problem in high-density areas such as large apartment buildings
where many residents are operating Wi-Fi access points.

Large corporations are often concerned about the security risk posed to
a secure company network by an unauthorized wireless access point, also
known as a rogue access point. With the advent of inexpensive wireless
routers available at consumer electronics stores, employees sometimes
connect an unauthorized access point out of ignorance or malice, thereby
exposing the secure corporate network to anyone who may be
\"wardriving\" nearby. To alleviate the potential risk of rogue access
points, some large organizations have begun (as of 2005) to install
wireless intrusion detection systems. These systems are designed to
monitor the premises for wireless signals and immediately report the
presence of any unauthorized access points.

Adapted from http://en.wikipedia.org/wiki/Wi-Fi

Wireless Usage Scenarios by Technology

+-----------+-----------+----------------------------------------------+
| *         | **Ap      | **Usage Scenario**                           |
| *Wireless | plication |                                              |
| S         | C         |                                              |
| tandard** | ategory** |                                              |
+-----------+-----------+----------------------------------------------+
| Bluetooth | Wireless  |  I want to instantly connect my notebook    |
|           | Personal  | computer to another Bluetooth enabled        |
|           | Area      | notebook to transfer a file.                 |
|           | N         |                                              |
|           | etworking |  I want to collaboratively work on a        |
|           | (WPAN)    | document where meeting participants use      |
|           |           | notebooks that are wirelessly connected via  |
|           |           | Bluetooth.                                   |
|           |           |                                              |
|           |           |  Using a Bluetooth enabled, wireless        |
|           |           | headset, I want to listen to a CD playing on |
|           |           | my notebook computer while it is in my       |
|           |           | briefcase.                                   |
|           |           |                                              |
|           |           |  I often travel to a remote site and want   |
|           |           | to walk up to a shared printer, connect and  |
|           |           | print a document without having to           |
|           |           | physically connect using a standard printer  |
|           |           | cable.                                       |
|           |           |                                              |
|           |           |  I want to connect to the Internet via a    |
|           |           | cellular phone without having to take my     |
|           |           | telephone out of my briefcase                |
+-----------+-----------+----------------------------------------------+
| 802.11b   | Wireless  |  I want to always be connected to my        |
|           | Local     | corporate LAN while moving about in my       |
|           | Area      | office building or campus.                   |
|           | N         |                                              |
|           | etworking |  Usage demands that I have access to        |
|           | (WLAN)    | corporate network data at performance levels |
|           |           | equivalent to a wire based LAN connection.   |
+-----------+-----------+----------------------------------------------+
| Cellular  | Wireless  |  I want access to e-mail and web resources  |
| Tec       | Wide Area | while traveling away from the home office.   |
| hnologies | N         |                                              |
| (GSM)     | etworking |                                              |
|           | (WWAN)    |                                              |
+-----------+-----------+----------------------------------------------+

![](media/image5.png){width="3.1354166666666665in"
height="2.9583333333333335in"}Excerpted from Tutorial-Reports.com

+-----------------------------------+-----------------------------------+
| # Wireless LAN (wlan)             | ![](media/image6.j                |
|                                   | peg){width="2.9027777777777777in" |
|                                   | height="2.1805555555555554in"}    |
+-----------------------------------+-----------------------------------+

A **wireless LAN** or **WLAN** is a wireless local area network that
uses radio waves as its carrier: the last link with the users is
wireless, to give a network connection to all users in the surrounding
area. Areas may range from a single room to an entire campus. The
backbone network usually uses cables, with one or more wireless access
points connecting the wireless users to the wired network.

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. Such places could be old protected buildings or classrooms,
although the restricted range of the 802.11b (typically 30ft.) limits
its use to smaller buildings. WLAN components are now cheap enough to be
used in the home, with many being set-up so that one PC (a parent\'s PC,
for example) can be used to share an internet connection with the whole
family (while retaining access control at the parents\' PC).

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) and HomeRF (2
Mbit/s, intended for home use).

The lack of default security of Wireless connections is fast becoming an
issue where many Broadband (ADSL) connections are now offered together
with a Wireless Basestation/ADSL Modem/firewall/Router access point.
Further, many laptop PCs now have Wireless Networking built in (cf.
Intel \'Centrino\' campaign) thus eliminating the need for an additional
plug-in (PCMCIA) card. This might even be enabled, by default, without
the owner ever realizing it, thus \'broadcasting\' the laptop\'s
accessibility to any computer nearby.

The basic security used for a WLAN was originally Wired Equivalent
Privacy (WEP), but this was shown to provide minimal security due to
serious weaknesses. The alternate Wi-Fi Protected Access (WPA) security
protocol was later created to address these problems. Since then
software solutions such as SSL, SSH, and various types of software
encryption have become the preferred methods of securing wireless
information transmission.

Modern operating systems such as Linux, Mac OS, or Microsoft Windows XP
as the \'standard\' in home PCs make it very easy to set up a PC as a
Wireless LAN \'basestation\' and using Internet Connection Sharing
allows all the PCs in the home to access the Internet via the \'base\'
PC. However, lack of expertise in setting up such systems often means
that someone nearby, such as a next-door neighbor, may also share the
internet connection. This is typically without the wireless network
owner\'s knowledge; it may even be without the knowledge of the user
(the neighbor) if his computer automatically selects a nearby wireless
network. Nowadays it has become etiquette to leave wireless access
points open for others to use just as one expects to find open access
points while on the road. This freely sharing of bandwidth is the basis
of free wireless community networks which are often considered the
future of the internet.

The frequency which 802.11b operates at is 2.4GHz, which can lead to
interference with cordless phones on the same frequency. If one wants to
use a cordless telephone on the same premises, one should ensure that
the cordless set uses a different frequency, such as 900Mhz or 5.8 Ghz.
However, any wireless router has the ability to operate in different
channels. Using channel 11 is most often the best situation for a
wireless access point.

+-----------------------------------+-----------------------------------+
| # Personal Area Network (PAN)     | ![](media/image7.                 |
|                                   | png){width="2.0833333333333335in" |
|                                   | height="2.4166666666666665in"}    |
+-----------------------------------+-----------------------------------+

A **personal area network** (**PAN**) is a computer network used for
communication among computer devices (including telephones and personal
digital assistants) close to one person. The devices may or may not
belong to the person in question. The reach of a PAN is typically a few
meters. PANs can be used for communication among the personal devices
themselves (intrapersonal communication), or for connecting to a higher
level network and the Internet (an uplink).

Personal area networks may be wired with computer buses such as USB and
Firewire. A **wireless personal area network** (**WPAN**) can also be
made possible with network technologies such as IrDA and Bluetooth.

## Wireless

A Bluetooth PAN is also called a *piconet*, and is composed of up to 8
active devices in a master-slave relationship (up to 255 devices can be
connected in \'parked\' mode). The first Bluetooth device in the piconet
is the master, and all other devices are slaves that communicate with
the master. A piconet typically has a range of 10 meters, although
ranges of up to 100 meters can be reached under ideal circumstances.

+------------------+---------------------------------------------------+
| # !              | Wide Area Network:\                               |
| [](media/image8. | WAN or WWAN                                       |
| png){width="0.69 |                                                   |
| 44444444444444in |                                                   |
| " height="0.9305 |                                                   |
| 555555555556in"} |                                                   |
+------------------+---------------------------------------------------+

# Wide area network

A **wide area network** or **WAN** is a computer network covering a wide
geographical area, involving a vast array of computers. This is
different from personal area networks (PANs), metropolitan area networks
(MANs) or local area networks (LANs) that are usually limited to a room,
building or campus. The best example of a WAN is the Internet.

Wireless WANs cover a much more extensive area than wireless local area
networks (WLANs). Unlike WLANs, which offer limited user mobility and
instead are generally used to enable the mobility of the entire network,
WWANs facilitate connectivity for mobile users such as the traveling
businessman. In general, WWANs allow users to maintain access to
work-related applications and information while away from their office.

In wireless WANs, communication occurs predominantly through the use of
radio signals over analog, digital cellular, or PCS networks, although
signal transmission through microwaves and other electromagnetic waves
is also possible. Today, most wireless data communication takes place
across 2G cellular systems such as CDMA, PDC and GSM, or through
packet-data technology over old analog systems. Although traditional
analog networks, having been designed for voice rather than data
transfer, have some inherent problems, some 2G (second generation) and
new 3G (third generation) digital cellular networks are fully integrated
for data/voice transmission. With the advent of 3G networks, transfer
speeds should also increase greatly.

WWAN connectivity requires wireless modems and a wireless network
infrastructure, provided as a fee-for service by a wireless service
carrier. Portable devices receive communications as the connected
wireless modems and wireless networks interact via radio waves. The
modem directly interfaces with radio towers, which carry the signal to a
mobile switching center, where the signal is passed on to the
appropriate public or private network link (i.e., telephone, other high
speed line, or the Internet). From here, the signal can be transferred
to an organization\'s existing network.

Similarly, WWANs can communicate with the Internet. For small devices
such as handhelds and mobile phones, a universal specification known as
wireless application protocol (WAP) exists to facilitate the delivery
and presentation of Web content. The request for Web content is sent
through the wireless network to a WAP gateway, where it is processed and
the required information is retrieved and returned. WAP supports most
wireless networks and mobile device operating systems.

As with wireless LANs, wireless WANs have many interference problems
related to their reliance on terrestrial radio networks. Inclement
weather conditions, rugged terrain and other naturally occurring
conditions can cause prolonged latency and other disruptions to a radio
channel. Nevertheless, wireless WANs have many intrinsic benefits,
namely enhancing productivity through real-time information access.

  ---------------------------------------------------- ------------------------------------------------
  ![](media/image9.png){width="1.8465277777777778in"   802.11something
  height="1.8465277777777778in"}                       

  ---------------------------------------------------- ------------------------------------------------

**IEEE 802.11**

IEEE 802.11 or Wi-Fi denotes a set of Wireless LAN standards developed
by working group 11 of the IEEE LAN/MAN Standards Committee (IEEE 802).
The term is also used to refer to the original 802.11, which is now
sometimes called \"802.11legacy.\"

The 802.11 family currently includes six over-the-air modulation
techniques that all use the same protocol, the most popular (and
prolific) techniques are those defined by the a, b, and g amendments to
the original standard; security was originally included, and was later
enhanced via the 802.11i amendment. Other standards in the family (c--f,
h--j, n) are service enhancement 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 unlicensed 2.4 gigahertz (GHz)
band. The 802.11a standard uses the 5 GHz band. Operating in an
unregulated frequency band, 802.11b and 802.11g equipment can incur
interference from microwave ovens, cordless phones, and other appliances
using the same 2.4 GHz band.

**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 in the Industrial Scientific
Medical frequency band 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 media 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 five different, somewhat-interoperable, commercial products
appeared using the original specification, from companies like Alvarion
(PRO.11 and BreezeAccess-II), 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 \"meta-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.

**802.11b**

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 over TCP and 7.1
Mbit/s over 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. 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. With high-gain external antennas, the protocol can also be used
in fixed point-to-point arrangements, typically at ranges up to eight
kilometers (km) although some report success at ranges up to 80--120 km
where line of sight can be established. This is usually done in place of
costly leased lines or very cumbersome microwave communications
equipment.

802.11b cards can operate at 11 Mbit/s, but will scale back to 5.5, then
2, then 1 Mbit/s (a.k.a 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 (e.g., 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.

**802.11a**

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.

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 because 802.11b was
already widely adopted, because of 802.11a\'s disadvantages, because of
poor initial product implementations, making its range even shorter, and
because of 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. Image:Table of phy
rates.jpg

**802.11g**

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. It is fully backwards compatible with b and uses the same
frequencies. 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 802.11g standard swept the consumer world of early adopters starting
in January 2003, well before ratification. The corporate users held back
and 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 adaptor card or access point.

While 802.11g held the promise of higher throughput, actual results were
mitigated by a number of factors: conflict with 802.11b-only devices
(see above), exposure to the same interference sources as 802.11b,
limited channelization (only 3 fully non-overlapping channels like
802.11b) and the fact that the higher data rates of 802.11g are often
more susceptible to interference than 802.11b, causing the 802.11g
device to reduce the data rate to effectively the same rates used by
802.11b. The move to dual-mode/tri-mode products also carries with it
economies of scale (e.g. single chip manufacturing). For the consumer,
dual-band/tri-mode products ensure the best possible throughput in any
given environment.

The first major manufacturer to use 802.11g was Apple, under the
trademark AirPort Extreme. Cisco joined the game by buying up Linksys,
an early adopter, and also offers its own wireless mobile adaptors under
the name Aironet.

**802.11n**

In January 2004 IEEE announced that it had formed a new 802.11 Task
Group (TGn) to develop a new amendment to the 802.11 standard for
local-area wireless networks. The real data throughput is estimated to
reach a theoretical 540 Mbit/s (which may require an even higher raw
data rate at the physical layer), and should be up to 10 times faster
than 802.11a or 802.11g, and near 40 times faster than 802.11b. It is
projected that 802.11n will also offer a better operating distance than
current networks.

**Security**

In 2001, a group from the University of California, Berkeley presented a
paper describing weaknesses in the 802.11 WEP (wired equivalent privacy)
security mechanism defined in the original standard; they were followed
by Fluhrer, Mantin, and Shamir\'s paper entitled \"Weaknesses in the Key
Scheduling Algorithm of RC4\". Not long after, Adam Stubblefield and
AT&T publicly announced the first verification of the attack. In the
attack they were able to intercept transmissions and gain unauthorized
access to wireless networks.

The IEEE set up a dedicated task group to create a replacement security
solution, 802.11i (previously this work was handled as part of a broader
802.11e effort to enhance the MAC layer). The Wi-Fi Alliance announced
an interim specification called Wi-Fi Protected Access (WPA) based on a
subset of the then current IEEE 802.11i draft. These started to appear
in products in mid-2003. 802.11i (aka WPA2) itself was ratified in June
2004, and uses the Advanced Encryption Standard, instead of RC4, which
was used in WEP and WPA.

  ----------------------------------------------------- ------------------------------------------------
  ![](media/image10.wmf){width="1.8479166666666667in"   Bluetooth
  height="1.2215277777777778in"}                        

  ----------------------------------------------------- ------------------------------------------------

*Bluetooth* is an industrial specification for wireless personal area
networks (PANs).

Bluetooth provides a way to connect and exchange information between
devices like personal digital assistants (PDAs), mobile phones, laptops,
PCs, printers and digital cameras via a secure, low-cost, globally
available short range radio frequency.

![](media/image11.png){width="1.8472222222222223in"
height="1.1666666666666667in"}Bluetooth lets these devices talk to each
other when they come in range, even if they are not in the same room, as
long as they are within up to 100 metres (328 feet) of each other,
dependent on the power class of the product. Products are available in
one of three power classes:

-   Class 3 (1 mW) is the rarest and allows transmission of 10
    centimetres (3.9 inches), with a maximum of 1 metre (3.2 feet)

-   Class 2 (2.5 mW) is most common and allows a quoted transmission
    distance of 10 metres (32 ft)

-   Class 1 (100 mW) has the longest range at up to 100 metres. This
    class of product is readily available.

The specification was first developed by Ericsson, and was later
formalized by the Bluetooth Special Interest Group (SIG). The SIG was
formally announced on May 20, 1999. It was established by Sony Ericsson,
IBM, Intel, Toshiba and Nokia, and later joined by many other companies
as Associate or Adopter members. Bluetooth is also IEEE 802.15.1.

## About the name

Contrary to popular belief, the name Bluetooth has nothing to do with
blue teeth.

The system is named after a Danish king Harald Blåtand (Harold Bluetooth
in English), King of Denmark and Norway from 935 and 936 respectively,
to 940 known for his unification of previously warring tribes from
Denmark, Norway and Sweden. Bluetooth likewise was intended to unify
different technologies like computers and mobile phones. The Bluetooth
logo merges the Nordic runes analogous to the modern Latin H and B. This
is the official story; however, the actual Harald Blåtand that was
referred to in naming Bluetooth was most probably the liberal
interpretation given to him in The Long Ships by Frans Gunnar Bengtsson,
a Swedish best-selling Viking-inspired novel.

In April, 1998, Intel and Microsoft formed a consortium between
themselves and IBM, Ericsson, Nokia, Toshiba and Puma Technology and
adopted the code name Bluetooth for their proposed open specification.

## General information

![](media/image12.jpeg){width="2.611111111111111in"
height="1.6944444444444444in"}The latest version currently available to
consumers is 2.0, but few manufacturers have started shipping any
products yet. Apple Computer, Inc. offered the first products supporting
version 2.0 to end customers in January 2005. The core chips have been
available to OEMs (from November 2004), so there will be an influx of
2.0 devices in mid-2005. The previous version, on which all earlier
commercial devices are based, is called 1.2.

Bluetooth is a wireless radio standard primarily designed for low power
consumption, with a short range (up to 400 meters \[1\], ) and with a
low-cost transceiver microchip in each device.

Cell phones with integrated Bluetooth technology have also been sold in
large numbers, and are able to connect to computers, PDAs and,
specifically, to handsfree devices. The standard also includes support
for more powerful, longer-range devices suitable for constructing
wireless LANs.

## Bluetooth applications

-   Wireless Networking between desktops and laptops, or desktops in a
    confined space and where little bandwidth is required

-   Bluetooth peripherals such as printers, mice and keyboards

-   Transfer of files (images, mp3s, etc) between mobile phones, PDA\'s
    and computers via OBEX

-   Certain low-end mp3 players and Digital Cameras to transfer files to
    and from computers

-   Bluetooth headsets for mobile phones & Smartphones

-   Some testing equipment is bluetooth enabled

-   ![](media/image13.jpeg){width="1.875in"
    height="2.1944444444444446in"}Medical applications - Advanced
    Medical Electronics Corporation is working on several devices

-   Certain GPS receivers transfer NMEA data via Bluetooth

-   Bluetooth car kits - Acura was the first motor vehicle manufacturer
    to install handsfree Bluetooth technology in the 2004 Acura TL.
    Later on BMW added it as an option on its 3 Series, 5 Series, 7
    Series and X5 vehicles. Since then, other manufacturers have
    followed suit, with many vehicles, including the 2004 Toyota Prius
    and the 2004 Lexus LS 430. The Bluetooth car kits allow users with
    Bluetooth-equipped cell phones to make use of some of the phone\'s
    features, such as making calls, while the phone itself can be left
    in a suitcase or in the boot/trunk, for instance.

-   Certain data logging equipment transmits data to a computer via
    Bluetooth.

-   For remote controls where infrared was traditionally used.

## Technical information

A Bluetooth device playing the role of the \"master\" can communicate
with up to 7 devices playing the role of the \"slave\". At any given
time, data can be transferred between the master and one slave; but the
master switches rapidly from slave to slave in a round-robin fashion.
(Simultaneous transmission from the master to multiple slaves is
possible, but not used much in practice). These groups of up to 8
devices (1 master and 7 slaves) are called piconets. Either device may
switch the master/slave role at any time.

The Bluetooth specification also allows connecting two or more piconets
together to form a scatternet, with some devices acting as a bridge by
simultaneously playing the master role in one piconet and the slave role
in another piconet. These devices have yet to come, though are supposed
to appear within the next two years.

### ![](media/image14.wmf){width="2.0416666666666665in" height="3.388888888888889in"}Air interface

The protocol operates in the license-free ISM band at 2.45 GHz. In order
to avoid interfering with other protocols which use the 2.45 GHz band,
the Bluetooth protocol divides the band into 79 channels (each 1 MHz
wide) and changes channels up to 1600 times per second. Implementations
with versions 1.1 and 1.2 reach speeds of 723.1 kbit/s. Version 2.0
implementations feature *Bluetooth Enhanced Data Rate (EDR)*, and thus
reach 2.1 Mbit/s. Technically version 2.0 devices have a higher power
consumption, but the three times faster rate reduces the transmission
times, effectively reducing consumption to half that of 1.x devices
(assuming equal traffic load).

Bluetooth differs from Wi-Fi in that the latter provides higher
throughput and covers greater distances but requires more expensive
hardware and higher power consumption. They use the same frequency
range, but employ different multiplexing schemes. While Bluetooth is a
cable replacement for a variety of applications, Wi-Fi is a cable
replacement only for local area network access. A glib summary is that
Bluetooth is wireless USB whereas Wi-Fi is wireless Ethernet, both
operating at much lower bandwidth than the cable systems they are trying
to replace.

Many USB Bluetooth adapters are available, some of which also include an
IrDA adapter.

## Future Bluetooth uses

One of the ways Bluetooth technology may become useful is in Voice over
IP. When VOIP becomes more widespread, companies may find it unnecessary
to employ telephones physically similar to today\'s analogue telephone
hardware. Bluetooth may then end up being used for communication between
a cordless phone and a computer listening for VOIP and with an infrared
PCI card acting as a base for the cordless phone. The cordless phone
would then just require a cradle for charging. Bluetooth would naturally
be used here to allow the cordless phone to remain operational for a
reasonably long period. In May 2005, the Bluetooth Special Interest
Group (SIG) announced its intent to work with UWB manufacturers to
develop a next-generation Bluetooth technology using UWB technology and
delivering UWB speeds. This will enable Bluetooth technology to be used
to deliver high speed network data exchange rates required for wireless
VOIP, music and video applications.

Bluetooth may also be used for remote sales technology, allowing
wireless access to vending machines and other commercial enterprises.

## Security concerns

In November 2003, Ben and Adam Laurie from A.L. Digital Ltd. discovered
that serious flaws in Bluetooth security may lead to disclosure of
personal data (see http://bluestumbler.org). It should be noted however
that the reported security problems concerned some poor implementations
of Bluetooth, rather than the protocol itself.

In a subsequent experiment, Martin Herfurt from the trifinite.group was
able to do a field-trial at the CeBIT fairgrounds showing the importance
of the problem to the world. A new attack called BlueBug was used for
this experiment.

In April 2004, security consultants \@Stake revealed a security flaw
that makes it possible to crack into conversations on Bluetooth based
wireless headsets by reverse engineering the PIN.

This is one of a number of concerns that have been raised over the
security of Bluetooth communications. In 2004 the first purported virus
using Bluetooth to spread itself among mobile phones appeared for the
Symbian OS. The virus was first described by Kaspersky Labs and requires
users to confirm the installation of unknown software before it can
propagate. The virus was written as a proof-of-concept by a group of
virus writers known as 29a and sent to anti-virus groups. Because of
this, it should not be regarded as a security failure of either
Bluetooth or the Symbian OS. It has not propagated \'in the wild\'.

In August 2004, a world-record-setting experiment (see also Bluetooth
sniping) showed that with directional antennas the range of class 2
Bluetooth radios could be extended to one mile. This enables attackers
to access vulnerable Bluetooth-devices from a distance beyond
expectation.(class 1. acessories have maximal distance 100meters.
comunication with this standart (unaltered) device it is not possible
farther than 100meters. so such a concern about \"beyond exeption\" is
not true. receiver and transmiter needs to achive same distance
otherwise conection is not posssible. )

In June 2005 Yaniv Shaked and Avishai Wool published the paper
\"Cracking the Bluetooth PIN1\", which shows both passive and active
methods for obtaining the PIN for a Bluetooth Link. The passive attack
would allow a suitably equipped attacker to eavesdrop on communications
and spoof if they were present at the time of initial pairing. The
active method makes use of a specially constructed message that must be
inserted at a specific point in the protocol, to make the master and
slave repeat the pairing process. After that the first method may be
used to crack the PIN. This attack\'s major weakness is that it requires
the user of the devices under attack to re-enter their PIN during the
attack when their device prompts them to. Also, this active attack will
most likely require custom hardware, as most commercially available
Bluetooth Devices are not capable of the timing necessary.

In August 2005, police in Cambridgeshire, England, issued warnings about
thieves using Bluetooth-enabled phones to track other devices left
within parked cars. Police are advising users to ensure any mobile
networking connections are de-activated if laptops and other devices are
left in this way.

Bluetooth uses the SAFER+ waleed algorithm for authentication and key
generation. The E0 stream cipher is used for encrypting packets.

Adapted from \"http://en.wikipedia.org/wiki/Bluetooth\"

![](media/image15.png){width="6.0in" height="3.9895833333333335in"}

# Faster Than a Speeding Bullet! internet2 

#   {#section-1 .unnumbered}

# 

  --------------------------------------- ------------------------------------------------
  ![](media/image15.png){width="2.25in"   Internet2
  height="1.8840277777777779in"}          

  --------------------------------------- ------------------------------------------------

# 

**Internet2** or **UCAID** is a non-profit consortium that develops and
deploys advanced network applications and technologies, mostly for
high-speed data transfer. It is led by 207 US universities and partners
from the networking and technology industries (such as Comcast, Intel,
Sun Microsystems, and Cisco Systems). Some of the technologies it has
developed include IPv6, IP multicasting and quality of service.

Internet2 members created the Abilene Network and are a major supporter
of the National LambdaRail project.

## Mislabeling of Internet2

In light of a recent series of lawsuits filed by the RIAA against
university students attending several of the major participants in
Abilene, there has been a recent trend in the media to report on a
network called \"Internet2.\" Some sources go so far as to suggest
Internet2 is a network wholly separate from the Internet. This is
misleading since Internet2 is in fact a **consortium** and not a
computer network. It is possible that many news sources have adopted the
term Internet2 because it seems like a logical name for a
next-generation Internet backbone. Articles that reference Internet2 as
a network are in fact referring to the previously mentioned Internet
backbone known as the Abilene Network. This forms a high-speed backbone
by deploying many of the technologies developed by Internet2. Abilene is
not an isolated network and its members are usually accessible in some
way through the public Internet.

Adapted from http://en.wikipedia.org/wiki/internet2

# ![](media/image16.png){width="5.736111111111111in" height="4.944444444444445in"}Let My Software Go: 

# the open source software movement 

#   {#section-4 .unnumbered}

# 

  ---------------------------------------------------- ------------------------------------------------
  ![](media/image17.png){width="4.158333333333333in"   Open Source
  height="2.734027777777778in"}                        

  ---------------------------------------------------- ------------------------------------------------

**Open source software** refers to computer software and the
availability of its source code as open source under an open source
license to study, change, and improve its design.

A group of individuals presented \"open source\" to relabel free
software as open-source software, for such software to become more
mainstream in the corporate world. Software developers may want to
publish their software with an open-source software license, so that
anybody may also develop the same software or understand how it works.
Open-source software generally allows anybody to make a new version of
the software, port it to new operating systems and processor
architectures, share it with others or market it. The advantage of open
source is to let the product be more understandable, modifiable,
duplicatable, or simply accessible, while it is still very marketable.

The Open Source Definition, notably, presents an open-source philosophy,
and further defines a boundary on the usage, modification and
redistribution of open-source software. Software licenses grant rights
to users which would otherwise be prohibited by copyright. These include
rights on usage, modification and redistribution. Several open-source
software licenses have qualified within the boundary of the Open Source
Definition. The most prominent example is the popular GNU General Public
License (GPL). While open source presents a way to broadly make the
sources of a product publicly accessible, the open-source licenses allow
the authors to fine tune such access.

![](media/image17.png){width="6.0in" height="3.9444444444444446in"}

## Terminology

The \"open source\" label came out of a strategy session held in Palo
Alto in reaction to Netscape\'s January 1998 announcement of a source
code release for Navigator (as Mozilla). A group of individuals at the
session included Todd Anderson, Larry Augustin, John Hall, Sam Ockman,
Christine Peterson and Eric S. Raymond. They used the opportunity before
the release of Navigator\'s source code to clarify a potential confusion
caused by the ambiguity of the word \"free\" in English. The \'open
source\' movement is generally thought to have begun with this strategy
session. Many people, nevertheless, claimed that the birth of the
Internet, since 1969, started the open source movement, while others do
not distinguish between open source and free software movements.

The Free Software Foundation (FSF), started in 1985, intended the word
\'free\' to mean \"free as in free speech\" and not \"free as in free
beer.\" Since a great deal of free software already was (and still is)
free of charge, such free software became associated with zero cost,
which seemed anti-commercial.

The Open Source Initiative (OSI) was formed in February 1998 by Eric S.
Raymond and Bruce Perens. With at least 20 years of evidence from case
histories of closed development versus open development already provided
by the Internet, the OSI presented the \'open source\' case to
commercial businesses, like Netscape. OSI hoped that the usage of the
label \"open source,\" a term suggested by Peterson of the Foresight
Institute at the strategy session, would eliminate ambiguity,
particularly for individuals who perceive \"free software\" as
anti-commercial. They sought to bring a higher profile to the practical
benefits of freely available source code, and they wanted to bring major
software businesses and other high-tech industries into open source.
Perens attempted to register \"open source\" as a service mark for OSI,
but that attempt was impractical by trademark standards. Meanwhile,
Raymond encouraged Netscape to adopt the \"open source\" label. Netscape
released its Navigator source code as open source, with favorable
results.

Critics have said that the term \"open source\" fosters an ambiguity of
a different kind such that it confuses the mere availability of the
source with the freedom to use, modify, and redistribute it. Developers
have used the term Free/Open-Source Software (FOSS), or
Free/Libre/Open-Source Software (FLOSS), consequently, to describe
open-source software that is freely available and free of charge.

## Open source model

![](media/image18.jpeg){width="1.875in" height="2.8958333333333335in"}

In his 1997 essay The Cathedral and the Bazaar \[RAY2000\], Eric Raymond
suggests a model for developing OSS known as the Bazaar model. Raymond
likens the development of software by traditional methodologies to
building a cathedral, \"*fully crafted by individual wizards or small
bands of mages working in splendid isolation*\" \[RAY2000\]. He suggests
that all software should be developed using the bazaar style, which he
described as \"*a great babbling bazaar of differing agendas and
approaches*.\"

In the Cathedral, model development takes place in a centralized way.
Roles are clearly defined. Roles include people dedicated to designing
(the architects), people responsible for managing the project, and
people responsible for implementation. Traditional software engineering
follows the Cathedral model. F.P. Brooks in his book *The Mythical
Man-Month* advocates this sort of model. He goes further to say that in
order to preserve the architectural integrity of a system, the system
design should be done by as few architects as possible.

The Bazaar model, however, is different. In the Bazaar model, roles are
not clearly defined. Gregorio Robles suggests that software developed
using the Bazaar model should exhibit the following patterns:

-   *Users should be treated as co-developers.* The users are treated
    like co-developers and so they should have access to the source code
    of the software. Furthermore users are encouraged to submit
    additions to the software, code fixes for the software, bug reports,
    documentation etc. Having more co-developers increases the rate at
    which the software evolves. Linus' law states that, \"Given enough
    eyeballs all bugs are shallow.\" This means that if many users view
    the source code they will eventually find all bugs and suggest how
    to fix them. Note that some users have advanced programming skills,
    and furthermore, each user\'s machine provides an additional testing
    environment. This new testing environment offers that ability to
    find and fix a new bug.

-   *Early Releases.* The first version of the software should be
    released as early as possible so as to increase one\'s chances of
    finding co-developers early.

-   *Frequent Integration.* New code should be integrated as often as
    possible so as to avoid the overhead of fixing a large number of
    bugs at the end of the project life cycle. Some Open Source projects
    have nightly builds where integration is done automatically on a
    daily basis.

-   *Several Versions.* There should be at least two versions of the
    software. There should be a buggier version with more features and a
    more stable version with fewer bugs. The buggy version (also called
    the development version) is for users who want the immediate use of
    the latest features, and are willing to accept the risk of using
    code that is not yet thoroughly tested. The users can then act as
    co-developers, reporting bugs and providing bug fixes. The stable
    version offers the users fewer bugs and fewer features.

-   *High Modularization.* The general structure of the software should
    be modular allowing for parallel development.

-   *Dynamic decision making structure.* There is a need for a decision
    making structure, whether formal or informal, that makes strategic
    decisions depending on changing user requirements and other factors.

![](media/image19.png){width="6.0in" height="3.9972222222222222in"}

Most well-known OSS products follow the Bazaar model as suggested by
Eric Raymond. These include projects such as Linux, Netscape, Apache,
the GNU Compiler Collection, and Perl to mention a few. SourceForge,
which maintains that it is the largest repository of Open Source code
and applications available on the Internet, had 102,818 Open Source
projects as of writing. These projects are all undertaken based on the
Bazaar model.

## Open-source license

Open-source licenses define the privileges and restrictions a licensor
must follow in order to use, modify or redistribute the open source
software. Open source software includes software with source code in the
public domain and software distributed under an open-source license.

Examples of open source licenses include Apache License, BSD license,
GNU General Public License, GNU Lesser General Public License, MIT
License and Mozilla Public License.

## Open source movement

![](media/image20.wmf){width="4.28125in"
height="3.0104166666666665in"}The open source movement is a large
movement of computer scientists, programmers, and other computer users
that advocates unrestricted access to the source code of software. It
grew out of licenses such as BSD, the ubiquitous access to Unix source
code at universities. The line between the open source movement and the
free software movement is somewhat blurry. Both are founded in the
hacker culture. Mostly, the Free software movement is based upon
political and philosophical ideals, while open source proponents tend to
focus on more pragmatic arguments. Openness is a term that has evolved
now to refer to projects that are open to anyone and everyone to
contribute to, before and/or after the actual programming. Both groups
assert that this more open style of licensing allows for a superior
software development process (when compared to closed source), and
therefore that pursuing it is in line with rational self-interest. Free
software advocates argue that \"freedom\" is a paramount merit that one
should prefer even in any cases where proprietary software has some
superior technical features.

Proponents of the open source development methodology claim that it is
superior in a number of ways to the closed source method. Some, notably
Eric S. Raymond, go so far as to suggest that the open source
methodology is able to produce higher quality software than any other
methodology or technique. Raymond has written a series of works
exploring this theme, including The Cathedral and the Bazaar and
Homesteading the Noosphere.

Open source advocates point out that as of the early 2000s, at least 90
percent of computer programmers are employed not to produce software for
direct sale, but rather to design and customize software for other
purposes, such as in-house applications. According to advocates, this
statistic implies that the value of software lies primarily in its
usefulness to the developer or developing organization, rather than in
its potential sale value \-- consequently, there is usually no
compelling economic reason to keep source code secret from competitors.
Open-source advocates further argue that corporations frequently
over-protect software in ways actually damaging to their own interests,
for reasons ranging from mere institutional habit through reflexive
territoriality to a rational but incorrect evaluation of the tradeoffs
between collecting secrecy rent and the quality and market payoff of
openness.

Open source is a term that is applied to the entire concept that the
creation and organization of knowledge is best created through open and
cooperative efforts---this movement, variously called \"open content\"
or \"free culture,\" has been expressly endorsed by advocates of OSS,
including Linus Torvalds who said \"The future is \'open source
everything.\'\"

## Open source vs. closed source

The *open source vs. closed source* (alternatively called proprietary
development) debate is sometimes heated.

Making money through traditional methods, such as sale of the use of
individual copies and patent royalty payment, is more difficult and
sometimes impractical with open-source software. Some closed-source
advocates see open source software as damaging to the market of
commercial software. This complaint is countered by a large number of
alternative funding streams such as:

-   giving the software for free and instead charge for installation and
    support (used by many Linux distributions)

-   make the software available as open-source so that people will be
    more likely to purchase a related product or service you do sell
    (e.g. Openoffice.org vs StarOffice)

-   cost avoidance / cost sharing: many developers need a product, so it
    makes sense to share development costs (this is the genesis of the X
    Window System and the Apache web server)

Studies about security in open-source software versus closed-source
software show that closed-source software have fewer advisories but
open-source software usually has less time between flaw discovery and a
patch or fix. Advocates of closed source argue that since no one is
responsible for open-source software, there is no way to know whether it
has been fixed. Open-source advocates argue that since the source code
of closed-source software is not available, there is no way to know what
security vulnerabilities or bugs may exist.

## Open source vs. free software

The definition of open source software was written to be almost
identical to the free software definition. There are very few cases of
software that is free software but is not open source software, and vice
versa.

The difference in the terms is where they place the emphasis. Free
software is defined in terms of giving the user freedom. This reflects
the goal of the free software movement. Open source highlights that the
source code is viewable to all and proponents of the term usually
emphasize the quality of the software and how this is caused by the
development models which are possible and popular among free
software/open source software projects.

## Participants in OSS development projects

Participants in OSS development projects fall broadly into two
categories. There are the Core and the Peripheral.

The Core or Inner Circle are developers who modify codes that constitute
the project.

The Peripheral are usually made up of users who use the software. They
report bugs, and suggest fixes.

The participants may then be further divided into the following.

1.  Project leaders who have the overall responsibility (Core). Most of
    them might have been involved in coding the first release of the
    software. They control the overall direction of individual projects.

2.  Volunteer developers (Core / Periphery) who do actual coding for the
    project. These include:

    -   Senior members with broader overall authority

    -   Peripheral developers producing and submitting code fixes

    -   Occasional contributors

    -   Maintainers who maintain different aspects of the project

3.  Everyday users who perform testing, identify bugs, deliver bug
    reports, etc. (Periphery)

4.  Posters (Periphery) who participate frequently in newsgroups and
    discussions, but do not do any coding.

## Influence on other fields

The open source movement has been the inspiration for increased
transparency and liberty in other fields. For example the release of
biotechnology research by CAMBIA, and the encyclopedia named Wikipedia.
The open-source concept has also been applied to media other than
computer programs, e.g., by Creative Commons. It also constitutes an
example of user innovation (see for example the book Democratizing
Innovation).

Open Cola is another idea inspired by the open source movement. Soft
drink giants like Coke and Pepsi hold their formulas closely guarded
secrets. Now volunteers have posted the recipe for a similar soda drink
on the internet. The taste is said to be comparable to that of the
standard beverages.

## Advocates

Leading open source advocates include Brian Behlendorf, Tim O\'Reilly,
Eric Raymond, Linus Torvalds, Mitch Kapor and Paul Vixie. Others that
advocate open source software, but do so under its original name \"free
software\" include Alan Cox, Jimbo Wales, and Eben Moglen. Bruce Perens
is a prominent figure that uses both terms.

Richard Stallman, the founder of the free software movement in 1983,
does not want his name associated with the term *open source* due to its
philosophical rejection that computer users deserve freedom.

Leading open source critics include Bill Gates.

## Prominent projects and organizations

-   Apache Software Foundation, Debian, Eclipse Foundation, FreeBSD,
    GNU, JBoss, Linux, Mozilla Foundation, NetBSD, ObjectWeb, OpenBSD,
    OpenOffice.org, Open Source Development Labs, Open Source
    Initiative, Python, SourceForge, Chandler (PIM)

> I Know What You Took Last Night:
>
> radio frequency identifiers (RFID)

![](media/image21.png){width="4.986805555555556in"
height="3.821527777777778in"}

+---------------------+------------------------------------------------+
| ![](media/image22.  | Signs of the Apocalypse                        |
| png){width="1.85in" |                                                |
| height="1.3875in"}  | RFID                                           |
+---------------------+------------------------------------------------+

**R**adio **F**requency **ID**entification (**RFID**) is an automatic
identification method, relying on storing and remotely retrieving data
using devices called RFID tags or transponders. An RFID tag is a small
object that can be attached to or incorporated into a product, animal,
or person. RFID tags contain antennas to enable them to receive and
respond to radio-frequency queries from an RFID transceiver. Passive
tags require no internal power source, whereas active tags require a
power source.

## History of RFID tags

It has been suggested that the first *known* device was an espionage
tool invented by Léon Theremin for the Russian Government in 1945. This
is not quite the case: Theremin\'s device was a passive covert listening
device, not an identification tag. The technology used in RFID has been
around since the early 1920\'s according to one source (although the
same source states that RFID *systems* have been around just since the
late 1960s).

A similar technology, the IFF transponder, was invented by the British
in 1939, and was routinely used by the allies in World War II to
identify airplanes as friend or foe.

Another early work exploring RFID is the landmark 1948 paper by Harry
Stockman, entitled \"Communication by Means of Reflected Power\"
(Proceedings of the IRE, pp1196-1204, October 1948). Stockman predicted
that \"\...considerable research and development work has to be done
before the remaining basic problems in reflected-power communication are
solved, and before the field of useful applications is explored.\" It
required thirty years of advances in many different fields before RFID
became a reality.

## Types of RFID tags

RFID tags can be either *active* or *passive*.

Passive RFID tags have no internal power supply. The minute electrical
current induced in the antenna by the incoming radio frequency signal
provides just enough power for the tag to transmit a response. Due to
limited power and cost, the response of a passive RFID tag is brief ---
typically just an ID number (GUID). Lack of an onboard power supply
means that the device can be quite small: commercially available
products exist that can be embedded under the skin. As of 2005, the
smallest such devices commercially available measured 0.4 mm × 0.4 mm,
which is thinner than a sheet of paper; such devices are practically
invisible. Passive tags have practical read distances ranging from about
10 mm up to about 6 metres.

![](media/image23.jpeg){width="2.3333333333333335in"
height="1.4895833333333333in"}Active RFID tags, on the other hand, have
an internal power source, and may have longer range and larger memories
than passive tags, as well as the ability to store additional
information sent by the transceiver. At present, the smallest active
tags are about the size of a coin. Many active tags have practical
ranges of tens of metres, and a battery life of up to 10 years.

Because passive tags are cheaper to manufacture and have no battery, the
majority of RFID tags in existence are of the passive variety. As of
2004, these tags cost from US\$0.40 at high volumes. Universal RFID
tagging of individual products will become commercially viable at very
large volumes of 10 billion units per year, driving production cost to
less than US\$0.05 according to one manufacturer. Current demand for
RFID integrated circuit chips is not close to supporting that price.
Analysts from independent research companies Gartner and Forrester
Research agree that a price less than \$0.10 (production volume of one
billion units) is achievable in 6--8 years, thus limiting near-term
prospects for widespread adoption of passive RFID. Other analysts
believe such prices are achievable within 10-15 years.

While the cost advantages of passive tags over active tags are
significant, other factors including accuracy, performance in certain
environments such as around water or metal, and reliability make the use
of active tags very common today.

There are four different kinds of tags commonly in use. They are
categorized by their radio frequency: low frequency tags (125 or 134.2
kHz), high frequency tags (13.56 MHz), UHF tags (868 to 956 MHz), and
microwave tags (2.45 GHz). UHF tags cannot be used globally as there
aren\'t any global regulations for their usage.

There are some transponder devices and contactless chip cards which
deliver a similar function.

## The RFID system

An RFID system may consist of several components: tags, tag readers,
edge servers, middleware, and application software.

The purpose of an RFID system is to enable data to be transmitted by a
mobile device, called a tag, which is read by an RFID reader and
processed according to the needs of a particular application. The data
transmitted by the tag may provide identification or location
information, or specifics about the product tagged, such as price,
color, date of purchase, etc. The use of RFID in tracking and access
applications first appeared during the 1980s. RFID quickly gained
attention because of its ability to track moving objects. As the
technology is refined, more pervasive and possibly invasive uses for
RFID tags are in the works.

![](media/image24.jpeg){width="2.6041666666666665in"
height="1.7291666666666667in"}In a typical RFID system, individual
objects are equipped with a small, inexpensive tag. The tag contains a
transponder with a digital memory chip that is given a unique electronic
product code. The interrogator, an antenna packaged with a transceiver
and decoder, emits a signal activating the RFID tag so it can read and
write data to it. When an RFID tag passes through the electromagnetic
zone, it detects the reader\'s activation signal. The reader decodes the
data encoded in the tag\'s integrated circuit (silicon chip) and the
data is passed to the host computer for processing.

Take the example of books in a library. Security gates can detect
whether or not a book has been properly checked out of the library. When
users return items, the security bit is re-set and the item record in
the Integrated library system is automatically updated. In some RFID
solutions a return receipt can be generated. At this point, materials
can be roughly sorted into bins by the return equipment. Inventory wands
provide a finer detail of sorting. This tool can be used to put books
into shelf-ready order.

## Current usage

-   Talking Prescriptions - 13.56 MHz tags are being placed on
    prescriptions for Visually Impaired Veterans. The Department of
    Veterans Affairs Outpatient pharmacies are now supplying the tags
    with label information stored inside that can be read by a battery
    powered, talking prescription reader. This reader speaks information
    such as: Drug Name; Instruction; Warnings; etc.

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-   Low-frequency RFID tags are commonly used for animal identification.
    Pets can be implanted with small chips so that they may be returned
    to their owners if lost. Beer kegs are also tracked with LF RFID.
    Two RFID frequencies are used in the United States: 125 kHz (the
    original standard) and 134.2 kHz (the international standard).

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-   High-frequency RFID tags are used in library book or bookstore
    tracking, pallet tracking, building access control, airline baggage
    tracking, and apparel item tracking. High-frequency tags are widely
    used in identification badges, replacing earlier magnetic stripe
    cards. These badges need only be held within a certain distance of
    the reader to authenticate the holder. The American Express Blue
    credit card now includes a high-frequency RFID tag, a feature
    American Express calls ExpressPay.

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-   UHF RFID tags are commonly used commercially in pallet and container
    tracking, and truck and trailer tracking in shipping yards.

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-   Microwave RFID tags are used in long range access control for
    vehicles.

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-   RFID tags are used for electronic toll collection at toll booths
    with California\'s FasTrak, Illinois\' I-Pass, the expanding eastern
    state\'s E-ZPass system, The \"Cross-Israel Highway\" (Highway 6),
    Philippines South Luzon Expressway E-Pass and Central Highway
    (Autopista Central) in Chile. The tags are read remotely as vehicles
    pass through the booths, and tag information is used to debit the
    toll from a prepaid account. The system helps to speed traffic
    through toll plazas.

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-   Sensors such as seismic sensors may be read using RFID transceivers,
    greatly simplifying remote data collection.

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-   Precise and milimeter accurate location sensing of RFID is possible
    by adding a low cost photosensor.

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-   In January 2003, Michelin began testing RFID transponders embedded
    into tires. After a testing period that is expected to last 18
    months, the manufacturer will offer RFID enabled tires to car
    makers. Their primary purpose is tire-tracking in compliance with
    the United States Transportation, Recall, Enhancement,
    Accountability and Documentation Act (TREAD Act).

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-   Some smart cards embedded with RFID chips are used as electronic
    cash, e.g. Octopus Card in Hong Kong and the Netherlands and United
    Kingdom (In the form of the London Underground Oyster Card) to pay
    fares in mass transit systems and/or retails.

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-   Starting with the 2004 model year, a *Smart Key* option is available
    to the Toyota Prius and some Lexus models. The key fob uses an
    active RFID circuit which allow the car to acknowledge the key\'s
    presence within 3 feet of the sensor. The driver can open the doors
    and start the car while the key remains in a purse or pocket.

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-   In August 2004, the Ohio Department of Rehabilitation and Correction
    (ODRH) approved a \$415,000 contract to evaluate the personnel
    tracking technology of Alanco Technologies. Inmates will wear
    wristwatch-sized transmitters that can detect if prisoners have been
    trying to remove them and send an alert to prison computers. This
    project is not the first such rollout of tracking chips in US
    prisons. Facilities in Michigan, California and Illinois already
    employ the technology.

## RFID mandates

Wal-Mart and the United States Department of Defense have published
requirements that their vendors place RFID tags on all shipments to
improve supply chain management. Due to the size of these two
organizations, their RFID mandates impact thousands of companies
worldwide. The deadlines have been extended several times because many
vendors face significant difficulties implementing RFID systems. In
practice, the successful read rates currently run only 80%, due to radio
wave attenuation caused by the products and packaging. In time it is
expected that even small companies will be able to place RFID tags on
their outbound shipments.

Since January, 2005, Wal-Mart has required its top 100 suppliers to
apply RFID labels to all shipments. To meet this requirement, vendors
use RFID printer/encoders to label cases and pallets that require EPC
tags for Wal-Mart. These smart labels are produced by embedding RFID
inlays inside the label material, and then printing bar code and other
visible information on the surface of the label.

### Human implants

Implantable RFID chips designed for animal tagging are now being used in
humans as well. An early experiment with RFID implants was conducted by
British professor of cybernetics Kevin Warwick, who implanted a chip in
his arm in 1998. Applied Digital Solutions proposes their chip\'s
\"unique under-the-skin format\" as a solution to identity fraud, secure
building access, computer access, storage of medical records,
anti-kidnapping initiatives and a variety of law-enforcement
applications. Combined with sensors to monitor body functions, the
Digital Angel device could provide monitoring for patients. The Baja
Beach Club in Barcelona, Spain uses an implantable Verichip to identify
their VIP customers, who in turn use it to pay for drinks. The Mexico
City police department has implanted approximately 170 of their police
officers with the Verichip, to allow access to police databases and
possibly track them in case of kidnapping.

Amal Graafstra, a Washington state native and business owner, had a RFID
chip implanted in his left hand in early 2005. The chip was 12 mm long
by 2 mm in diameter and has a basic read range of two inches (50 mm).
The implant procedure was conducted by a cosmetic surgeon, although the
name of the doctor was not released. When asked what he planned to do
with the implant Graafstra responded:

*Because I\'m writing my own software and soldering up my own stuff,
pretty much anything I want. Well, more accurately, anything I have the
time and inspiration to do. Ultimately though, I think true keyless
access will require an implantable chip with a very strong encryption
system; right now I'm only looking at this type of thing in a personal
context.*\
---*One Small Step For Hand*---The Present Tense

## Potential uses

RFID tags are often envisioned as a replacement for UPC or EAN barcodes,
having a number of important advantages over the older barcode
technology. They may not ever completely replace barcodes, due in part
to their relatively higher cost. For some lower cost items the ability
of each tag to be unique may be considered to be overkill, though it
would have some benefits such as the facilitation of taking inventory.

It must also be recognised that the storage of data associated with
tracking goods down to item level will run into many terabytes. It is
much more likely that goods will be tracked at pallet level using RFID
tags, and at item level with product unique rather than item unique
barcodes.

RFID codes are long enough that every RFID tag may have a unique code,
while current UPC codes are limited to a single code for all instances
of a particular product. The uniqueness of RFID tags means that a
product may be individually tracked as it moves from location to
location, finally ending up in the consumer\'s hands. This may help
companies to combat theft and other forms of product loss. It has also
been proposed to use RFID for point of sale store checkout to replace
the cashier with an automatic system which needs no barcode scanning.
However this is not likely to be possible without a significant
reduction in the cost of current tags. There is some research taking
place into ink that can be used as an RFID tag, which would
significantly reduce costs. However, this is some years from reaching
fruition.

### Gen 2

An organization called EPCglobal is working on an international standard
for the use of RFID and the Electronic Product Code (EPC) in the
identification of any item in the supply chain for companies in any
industry, anywhere in the world. The organization\'s board of governors
includes representatives from EAN International, Uniform Code Council,
The Gillette Company, Procter & Gamble, Wal-Mart, Hewlett-Packard,
Johnson & Johnson, Checkpoint Systems and Auto-ID Labs. Some RFID
systems use alternative standards based on the ISO-classification
18000-6.

The EPCglobal gen 2 standard was approved in December 2004, and is
likely to form the backbone of RFID tag standards moving forward. This
was approved after a contention from Intermec that the standard may
infringe a number of their RFID related patents. It was decided that the
standard itself did not infringe their patents, but it may be necessary
to pay royalties to Intermec if the tag were to be read in a particular
manner. EPC Gen2 is short for EPCglobal UHF Generation 2.

### Patient identification

In July 2004, the Food and Drug Administration issued a ruling that
essentially begins a final review process that will determine whether
hospitals can use RFID systems to identify patients and/or permit
relevant hospital staff to access medical records. The use of RFID to
prevent mixups between sperm and ova in IVF clinics is also being
considered.

Also, the FDA recently approved the country\'s first RFID chips that can
be implanted in humans. The 134.2 kHz RFID chips, from VeriChip Corp., a
subsidiary of Applied Digital Solutions Inc., can incorporate personal
medical information and could save lives and limit injuries from errors
in medical treatments, according to the company. The FDA approval was
disclosed during a conference call with investors.

Some in-home uses, such as allowing a refrigerator to track the
expiration dates of the food it contains, have also been proposed, but
few have moved beyond the prototype stage.

### Traffic and positioning

Another proposed application is the use of RFID for intelligent traffic
signs called *Road Beacon System* or RBS. It is based in the use of RFID
transponders buried under the pavement that are read by an onboard unit
(OBU) in the vehicle which filters the different traffic signs and
translates them into voice messages or gives a virtual projection using
a HUD (Heads-Up Display). Its main advantage compared with
satellite-based systems is that road beacons do not need digital mapping
associated with them, as long as they provide traffic sign symbol and
actual position information by themselves. RFID road beacons are also
useful for complementing satellite positioning systems in places like
tunnels or indoors.

## Security

A primary security concern surrounding RFID technology is the illicit
tracking of RFID tags. Both personal location privacy and
corporate/military security may be violated if tags may be read
arbitrarily. This is of particularly concern in the context of ongoing
efforts to embed electronic product code (EPC) RFID tags in consumer
products.

Duplication, or cloning of RFID tags is another security concern.
Because many RFID tags can be scanned at a distance and without the tag
holder\'s knowledge, they may be vulnerable to unauthorized duplication.
This is of particular concern when RFID tags are embedded into proximity
cards which are used to access buildings. It is also a problem when RFID
is used for payment systems, as in the case of contactless credit cards,
the ExxonMobil Speedpass, and in RFID enhanced casino chips. Speedpass
in particular used a tag manufactured by Texas Instruments that
incorporated a weak, proprietary encryption scheme. In 2005, researchers
from RSA Labs and Johns Hopkins University reverse engineered the
algorithm and were able to clone Speedpass tags \[11\].

One major challenge in securing RFID tags is a shortage of computational
resources within the tag. Standard cryptographic techniques require more
resources than are available in most low cost RFID devices. Many
security measures have been proposed for RFID in the academic
literature. Several low strength cryptographic solutions have been
proposed, including hash locks, backward channel XORing, third party
privacy agents, and LPN authentication. RSA Security has patented a
prototype device that locally jams RFID signals by interrupting a
standard collision avoidance protocol, allowing the user to prevent
identification if desired. Various policy measures have also been
proposed, such as marking RFID tagged objects with an industry standard
label.

## Controversy

> *How would you like it if, for instance, one day you realized your
> underwear was reporting on your whereabouts?*
>
> --- California State Senator Debra Bowen, at a 2003 hearing

The use of RFID technology has engendered considerable controversy and
even product boycotts. The four main privacy concerns regarding RFID
are:

-   The purchaser of an item will not necessarily be aware of the
    presence of the tag or be able to remove it;

-   The tag can be read at a distance without the knowledge of the
    individual;

-   If a tagged item is paid for by credit card or in conjunction with
    use of a loyalty card, then it would be possible to tie the unique
    ID of that item to the identity of the purchaser; and

-   The EPCglobal system of tags create, or are proposed to create,
    globally unique serial numbers for all products, even though this
    creates privacy problems and is completely unnecessary for most
    applications.

Most concerns revolve around the fact that RFID tags affixed to products
remain functional even after the products have been purchased and taken
home, and thus can be used for surveillance and other nefarious purposes
unrelated to their supply chain inventory functions. Although RFID tags
are only officially intended for short-distance use, they can be
interrogated from greater distances by anyone with a high-gain antenna,
potentially allowing the contents of a house to be scanned at a
distance. Even short range scanning is a concern if all the items
detected are logged in a database every time a person passes a reader,
or if it is done for nefarious reasons (e.g., a mugger using a hand-held
scanner to obtain an instant assessment of the wealth of potential
victims). With permanent RFID serial numbers, an item leaks unexpected
information about a person even after disposal; for example, items that
are resold or given away can enable mapping of a person\'s social
network.

Another privacy issue is due to RFID\'s support for a singulation
(anti-collision) protocol. This is the means by which a reader
enumerates all the tags responding to it without them mutually
interfering. The structure of the most common version of this protocol
is such that all but the last bit of each tag\'s serial number can be
deduced by passively eavesdropping on just the *reader\'s* part of the
protocol. Because of this, whenever RFID tags are near to readers, the
distance at which a tag\'s signal can be eavesdropped is irrelevant;
what counts is the distance at which the much more powerful reader can
be received. Just how far this can be depends on the type of the reader,
but in the extreme case some readers have a maximum power output (4 W)
that could be received from tens of kilometres away.

The potential for privacy violations with RFID was demonstrated by its
use in a pilot program by the Gillette Company, which conducted a
\"smart shelf\" test at a Tesco in Cambridge. They automatically
photographed shoppers taking RFID-tagged safety razors off the shelf, to
see if the technology could be used to deter shoplifting.

In another study, uncovered by the Chicago Sun-Times, shelves in a
Wal-Mart in Broken Arrow, Oklahoma, were equipped with readers to track
the Max Factor Lipfinity lipstick containers stacked on them. Webcam
images of the shelves were viewed 750 miles (1200 km) away by Procter &
Gamble researchers in Cincinnati, Ohio, who could tell when lipsticks
were removed from the shelves and observe the shoppers in action.

In January 2004 a group of privacy advocates was invited to METRO Future
Store in Germany, where an RFID pilot project was implemented. It was
uncovered by accident that METRO \"Payback\" customer loyalty cards
contained RFID tags with customer IDs, a fact that was disclosed neither
to customers receiving the cards, nor to this group of privacy
advocates. This happened despite assurances by METRO that no customer
identification data was tracked and all RFID usage was clearly
disclosed.

The controversy was furthered by the accidental exposure of a proposed
Auto-ID consortium public relations campaign that was designed to
\"neutralize opposition\" and get consumers to \"resign themselves to
the inevitability of it\" while merely pretending to address their
concerns.

The standard proposed by EPCglobal includes privacy related guidelines
for the use of RFID-based EPC. These guidelines include the requirement
to give consumers clear notice of the presence of EPC and to inform them
of the choice that they have to discard, disable or remove EPC tags.
These guidelines are non-binding, and only partly comply with the joint
statement of 46 multinational consumer rights and privacy groups.

In 2004, Lukas Grunwald released a computer program *RFDump* which with
suitable hardware allows reading and reprogramming the metadata
contained in an RFID tag, although not the unchangeable serial number
built into each tag. He said consumers could use this program to protect
themselves, although it would also have significant malicious uses.

### Passports

A number of countries have proposed to implant RFID devices in new
passports, to facilitate efficient machine reading of biometric data.
Security expert Bruce Schneier said of these proposals: \"It\'s a clear
threat to both privacy and personal safety. Quite simply, it\'s a bad
idea.\" The RFID-enabled passport uniquely identifies its holder, and in
the proposal currently under consideration, will also include a variety
of other personal information. This could greatly simplify some of the
abuses of RFID technology, and expand them to include abuses based on
machine reading of data such as a person\'s nationality. For example, a
mugger operating near an airport could target victims who have arrived
from wealthy countries, or a terrorist could design a bomb which
functioned when approached by persons from a particular country.

The US State Department initially rejected these concerns on the grounds
that they believed the chips could only be read from a distance of 10 cm
(4 in), but in the face of 2,400 critical comments from security
professionals, and a clear demonstration that special equipment can read
the test passports from 30 feet (10 m) away, as of May 2005 the proposal
is being reviewed.

The Pakistan Passport Authority has started issuing passports with RFID
tags.

### Driver\'s licenses

The US state of Virginia has considered putting RFID tags into driver\'s
licenses in order to make lookups faster for police officers and other
government officials. The Virginia General Assembly also hopes that by
including the tags, false identity documents would become much harder to
obtain. The proposal was first introduced in the \"Driver\'s License
Modernization Act\" of 2002, which was not enacted, but as of 2004 the
concept was still under consideration.

The idea was prompted by the fact that several of the September 11
hijackers held fraudulent Virginia driver\'s licenses. However the
American Civil Liberties Union has noted that in addition to being a
risk to privacy and liberty, the RFID proposal would not have hindered
the hijackers, since the false documents they carried were valid,
officially issued documents obtained with other false identification.
The weakness in the system is not failure to validate documents in the
field, but failure to verify identity before issuing them.

Under the proposal, no information would be stored on the tag other than
a number corresponding to the holder\'s information in a database, only
accessible by authorized personnel. Also, to deter identity thieves one
would simply need to wrap one\'s drivers\' license in aluminium foil.

### The mark of the beast?

There has been discussion within part of the Christian community that
RFID tagging could represent the mark of the beast mentioned
specifically in the Book of Revelation (see Revelation 13:16). This
subject is studied by those Christians interested in the fields of
eschatology (last things) and dispensationalism. Previously, other forms
of identification such as credit cards and UPC codes had been suggested
as candidates for the mark.

Adapted from http://en.wikipedia.org/wiki/RFID\"