Network Computer with Wifi (Wireless Fidelity) / WLAN

Imagine if we were asked to perform computer network design in the office, campus or building a separate room with each other, and each room is already in use with furniture that can not be contested. Of course we will be thinking how to perform the complicated wiring installation in the room. However, it is not too complicated if we do the design using a wireless or WiFi network instead of cable. Certainly the use of Wifi networks contain consequences, including on each client computer must also be installed wifi devices. But all does not matter if it's an option. This paper will discuss the simple design of computer-based wifi network instead of wiring systems.



Wireless devices can work in several modes, among others:

1. AP mode (access point), this mode is often called multipoint. one wireless device can be accessed by many wireless devices.
2 Mode client, a client of the AP mode
3. Bridge mode, used for point to point two wireless devices. Usually used to reach wireless devices attached to long distances. In this mode if the network is very complex will result in an increased traffick broadcast.

On this occasion we will discuss the AP and client mode for the implementation of a computer with a wireless network (WLAN). Scheme are:

<-----> <-------> Internet Router Wireless Access Point Wireless <-------> PC Client With Client

Let us begin to mask the technical steps to setup a Wireless Access Point. In this example use Wireless AP / Client with Senao brand. For other brands pretty much the same process.

1. Prepare equipment including Wireless Radio, make sure all the complete adapter, crossover cable and others.
2. Configuring a PC with an IP address on the 192.168.1.0/24 network, do not use ip 192 .168.0.1 because this ip default Senao.
3.Browse http://192.168.1.1 via web browser, enter the username: admin, password blank.

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Reaping Benefits with Wi-Fi

Wireless Connection is now increasingly be needed. Various devices share of fans scrambling technology without cable connection. The principle is: practical, but still Digdaya.

One wireless technology that is now loved the Wi-Fi (wireless fidelity)-connections that could divide the high-speed Internet access without the mediation of the cable.

This wireless connection has just brought a projector manufacturer InFocus complementary capabilities newest products. With the addition of M1-DA port and M1-D on the projector that can be connected with Wi-Fi adapter called Infocus LiteShow, the projector can be connected with various devices wirelessly.

Deliver presentations from a computer, laptop, PDA, or any other handheld tools that enabled Wi-Fi becomes easier. Users do not have to bother with cable ropes as Wi-Fi coverage radius of 100 meters.

Wi-Fi is a technology that emits a radio signal with an Internet connection up to a certain radius. If this tiny device attached to the modem with a wide banded connections, all computers and devices that have Wi-Fi receiver in the vicinity would be splashed Internet access.

No matter the modem was in the office next door, room door, or the house across the street. Also, no matter whether the owner of the modem that allows its Internet access enjoyed by others without permission. This is a sophisticated method based on the idea of ​​intelligent wild.

Behold: the technology standard 802.11b, aka Wi-Fi using the 2.4 GHz spectrum is capable of transmitting signals as strong as 11 megabits per second (Mbps). Not to mention the presence of two new standards, 802.11a and 802.11g, the more inviting admiration.

802.11a technology, which uses the 5 GHz spectrum, enabling transmission of up to 54 Mbps. While 802.11g, which only uses 2.4 GHz spectrum, capable of transferring data up to two-fold, 22 Mbps.

Therefore, in coffeehouses, restaurants, or airport lounges, you do not have to look for a phone connection just to get Internet access on your laptop.

With this technology, you do not need to be busy heaved a deep cord. Including when to use a projector for presentations, Wi-Fi can be a very kind-hearted gods.

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Several techniques are used on the Wireless Security LAN

Below are some events and activities undertaken to mengamanan wireless networks:
Hiding the SSID
Many administrators hid Services Set Id (SSID) wireless network with the intention
that they only know the SSID can be connected to their network. This is not correct,
because the SSID is not completely masked. At a certain moment or
especially when the client will connect (associate) or when it will decide itself (deauthentication)
of a wireless network, then the client will still send the SSID in plain text
(Although the use of encryption), so if we intend to tap, can be easily
find information. Some tools that can be used to get the ssid
dihidden among others, kismet (kisMAC), ssid_jack (airjack), aircrack,
void11 ​​and much more.
Wireless security with WEP key only
WEP is a security standard & first encryption used on wireless, WEP has
many weaknesses, among others:
● A key problem is weak, the RC4 algorithm used can be solved.
● WEP uses static keys
● Problem initialization vector (IV) WEP
● Problem message integrity Cyclic Redundancy Check (CRC32)
WEP consists of two levels, namely 64 bit key, and 128 bits. Actually, the secret key in the lock
WEP 64 bit only 40 bit, 24bit is an Initialization Vector (IV). Similarly, the key
128-bit WEP 104bit secret key consists of. Seranganserangan
the weaknesses of WEP are:
1. The attack on the weaknesses of the initialization vector (IV), often called the FMS attack. FMS stands for
The third name the inventor of the IV weaknesses Fluhrer, Mantin, and Shamir. This attack
done by collecting a weak sebanyakbanyaknya IV.
The more IV
obtained weak, the sooner discovered the key that is used
(Www.drizzle.com/ ~ aboba/IEEE/rc4_ksaproc.pdf)
2. Obtain a unique IV data obtained through the packet to be processed for the
cracking the WEP key more quickly. This method is called chopping attack, the first time
found by h1kari. This technique only requires a unique IV, thereby reducing
IV needs of the weak in WEP cracking.
3. Both of the above attacks require considerable time and packet, to shorten the time,
hackers usually do traffic injection. Traffic Injection is often done
by collecting the ARP packet and then sends back to the access point. It is
vector resulted in an initial collection easier and faster. Unlike the attack
The first and second, to attack traffic injection, required specification of tools and applications
that start rarely encountered in tokotoko,
ranging from chipsets, firmware version, and versions
drivers, and not infrequently have to do the patching of drivers and applications.
MAC Filtering
Almost every wireless access point or router MAC filtering is facilitated by the security. It is
actually not much help in securing wireless communications, because the MAC address
very easy dispoofing or even altered. Tools ifconfig in OS Linux / Unix or a variety of tools such as
network utility, regedit, SMAC, machange on windows OS easily be used for spoofing
or change the MAC address.
I still often find wifi in the office and even the ISP (which is usually used by
warnetwarnet)
which only use MAC filtering protection. By using the application
wardriving like kismet / aircrack kisMAC or tools, we can obtain the MAC address of each client information
which is connected to an Access Point. After getting this information, we can
connected to the Access point to change the MAC in accordance with this client. In wireless networks,
MAC address duplication does not result in conflict. It only takes a different IP to client
the earlier.
Captive Portals
Captive Portal infrastructure originally designed for the purposes of community that enables all
people can connect (open network). Captive portal is actually a router or gateway machine
which does not protect or allow the traffic to the user registration / authentication.

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Wireless Weaknesses in Physical Layer

Wireless Weaknesses in Physical Layer
WiFi uses radio waves at frequencies that are public property freely used by
all people with certain restrictions restrictions. Every wifi has a certain coverage area depends
power and antenna used. Not easy to narrow down the area to be reached on the wifi.
This causes a variety of activities made possible place among other activities:
- Interception or tapping
It is very easy to do, and already familiar to hackers. Various tools to
easily obtained on the internet. Various cryptographic techniques can be dismantled by tools such tools.
- Injection
At the time of transmission by radio, made possible due to various weaknesses in the injection
wifi workings where there is no validation process who are connected or who
then disconnect.
- Jamming
Jamming is very possible to occur, either intentionally or unintentionally, because of ignorance
wireless users. Setting the frequency channel usage is mandatory in order
jamming can be minimized. Jamming occurs because the frequency used is quite narrow
so that channel reuse difficult in a dense area wireless networks. S
- Locating Mobile Nodes
With a variety of software, each one capable of performing wireless site survey and get
position information of the location of every Wifi and diverse configurations respectively. This can be done
with simple equipment such as PDAs or laptops with the support of GPS as a position marker.
- Access Control
In building a wireless network design needs in order to separate the node or host
trustworthy and untrustworthy hosts. So it requires a good access control
- Hijacking
The attack MITM (Man In The Middle) that can occur due to various weaknesses in wireless
protocol allowing the hijacking or takeover of communication
is going on and doing theft or modification of information.

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Security Wireless LAN (Wifi)

Wifi network has more flaws than with wired networks. Current developments
WiFi technology is very significant in line with the needs of mobile information systems. Many
wireless service providers such as commercial hotspot, ISP, Warnet, kampuskampus
and offices have
started to use wifi on each network, but very little attention
security of data communications on wireless networks. This makes the hacker be interested in
to explore keamampuannya to perform various activities which are usually illegal
using wifi.
In this article will discuss various types of activities and methods that the hacker wireless
or the beginner in doing wardriving. Wardriving is an activity or activities to
get information on a wifi network and gain access to wireless network
them. Generally aim to get an internet connection, but many also do
for maksudmaksud
starting from a certain curiosity, try try, research, practical tasks,
crime and others.
The downside of wireless networks can generally be divided into two types, namely the weakness in
configuration and weakness on the type of encryption used. One example of the causes of weakness
on the current configuration to build a wireless network quite easily. Many
vendors who provide facilities that enable the user or network admin so often
found in wireless that still use the default wireless configuration congenital vendors. The author often
found mounted on the wireless network is still using the default settings the default vendor
such as SSID, IP address, remote management, DHCP enabled, channel frequency, even without encryption
user / password for the wireless administration.
WEP (Wired Equivalent Privacy) is a wireless security standard before, can now be
be easily solved with a variety of tools available free on the internet. WPAPSK
and LEAP
are considered to be a solution to replace WEP, now also has to be solved by the method
offline dictionary attack.

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How it works globally Wifi

How could you, a single computer connected to the other even without cable ...? Is it because they (the computer) has taught mysticism or power in he .. he .. he ..? You certainly have always known with wifi technology that has begun to spread among users of the gadget. Wireless Network is not one branch of mysticism (especially evil, red). Wireless LAN, do not have any relationship with the unseen world, appearance, and the singularity, much less a miracle. Wireless LAN's just a piece of science, the result of creativity, fad, and human curiosity of nature around it. Now we need to know, like what the heck does it work ..? And how to prove the relationship "magic" that can be explained scientifically.
In order for computers or gadgets that are in the area of ​​Wireless Network can be successful in sending and receiving data to and from each other, then there are three components required. Namely:
1. Signal Radio (Radio Signal).
2. Data Format (Data Format).
3. The network structure or the Network (Network Structure).
Each of these three components operate independently. Which means, they should not be independent.
What we mean by stand alone before is the way things work and function. If we want likens a network as a layer cake, then each component was located at different layers. They work and control the different layers.
Radio signals for example, work on the bottom layer is commonly referred to as physical layer, or physical layer. Then Format Data or Data Format controls the multiple layers thereon. Structure and tissue serves as a tool to send and receive radio signals.
You've heard stories about how to work the modem to send and receive data to and from the internet instead? Well, in the world of Wireless LAN, how to work equipment wirelessnya also similar.
We will send data, wireless devices earlier will serve as a device that converts digital data into radio signals. Then when received, the equipment was functioning as a device that converts radio signals into digital data that can be understood and processed by computers.

It's getting clear and satisfied with our explanation about the workings of the Wireless Network in sending and receiving data? Still not satisfied? Well, we try to discuss further. We will ngebahasnya briefly below.
You may still curious and wondering, how the story, koq radio signals that can be converted into digital data, and vice versa. The basic principle used in wireless technology is actually taken from the equation made by James Clerk Maxwell in 1964.
In that equation, with explicit and clear Maxwell successfully demonstrated the fact that, any changes in the magnetic field will create electric fields. And conversely, any changes that occur in electric fields that will menciptaken magnetic fields.
Maxwell further explained ... when an electric current (AC or alternating current) travels through a cable or physical means (conductor) other, then, some parts of energynya be released into free space around it, and then forming a magnetic field or alternating magnetic fields.
Then, the magnetic field created by the energy that escapes it will create an electric field in free space, which then will create a magnetic field again, and again the electric field, magnetic field again, and so on, until the electric current of the original or first stopped (interrupted , red).
Form of energy that is created from these changes, known as electromagnetic radiation (electromagnetic radiation), or we used to know as radio waves. That means, the radio can be defined as the radiation of electromagnetic energy that escapes into the air (free space).
As often you hear that, if the tool was used to produce radio waves called TRANSMITTER. Then the tool used to detect and capture the existing radio air waves, the ordinary is called RECEIVER.
Well, so both devices before (transmitter and receiver) are more focused when you send, create wave patterns, direct, enhance, and capture the radio signals, to and from the air, then dibantulah with other tools, namely ANTENNA.
Thanks to the equations of Maxwell, transmitters, receivers, and antennas, which are then incorporated into all wireless LAN equipment that, then the computer can communicate, send and receive data via radio waves, or commonly referred to as wireless netwok.
But that's a lot of radio stations and frequencynya vary, koq alias collisions can not mingle? Keyboard ngaturnya? In order not to collide with each other, the radio wave is sent into the air that can be arranged frequencynya. That is by way of set or modify an electric current residing on the sender and receiver equipment was (transmitter, receiver).
And the separation distance between the frequency is called SPECTRUM. Then, the smallest part of the spectrum called the BAND. And to measure the amount of repetition from one wave to wave that occurred in a matter of seconds, the unit is used HERTZ (Hz).
Hertz, taken from the name of the person who first attempted to send and pick up radio waves, ie HEINRICH HERTZ. One hertz is calculated as the distance between one wave to the next wave. And radio signals that are usually found on the frequency of thousands, millions, or billions of hertz (KHz, MHz, GHz).
Now, by setting the frequency that the radio signals can not collide. And to the questions whether the equipment could be using that to capture the wireless radio, the answer is not likely to happen. Why?
Why, yes ... that was. Wave signal or a wireless signal that is at a different frequency signals or waves from a radio station that we usually hear. Similarly, at a glance the basic understanding of how wifi works.

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