WiFi - All about

access point WiFi
access point WiFi

WiFi : Vocabulary

- Wireless : in English means "wireless".

- WLAN : as Wireless LAN : wireless LAN.
- WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
: the name WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
(contraction of Wireless Fidelity) initially corresponds to the name given to the certification issued by the WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
Alliance 2, formerly WECA (Wireless Ethernet Compatibility Alliance), the body responsible for maintaining interoperability between devices meeting the 802.11 standard. By abuse of language (and for marketing reasons) the name of the standard is now confused with the name of the certification. Thus a WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
network is actually a network that meets the 802.11 standard.
- Hot Spot : public area covered by a wireless network.
- WA : as Wireless Adapter. That is : wireless network interface.
- AP : Access Point access point in "infrastructure" mode.
- BSS : Basic Service Set set of basic services. Set consisting of an access point and the stations connected to it. Also called "Cell".
- BSSID : identifier of a BSS. Absolutely fundamental, this is actually the MAC address of the access point.
- ESS : in an "infrastructure" type network, it will often be that a single AP is not enough to provide the desired coverage. In this case, it will be necessary to add other access points, taking care that they can work in good understanding. If we succeed, we will then have created an ESS : Extended Service Set, which is ultimately only a homogeneous set of BSS. This set, by extension, can relate to a single access point.
- ESSID : identifier of the ESS. This is a name that the administrator will give to the access point(s) that make up theESS. In the particular case where theESS consists of a single BSS, we can also talk about SSID.
- DS : Distribution System : distribution system that is there to connect several APs to each other so that they can constitute an ESS.
- IBSS : Independent BSS same as a BSS, but without AP. That is, it is a set of stations connected in ad-hoc mode. An IBSS must have a unique SSID.
- WEP Wired Equivalent Privacy : network encryption system (at the link level, i.e. at level 2) whose ambitious goal is to make a wireless network as secure as a wired network. Seen from the user side, WEP comes down to an encryption key that will have to be shared between the partners of the same ESS.
- WPA : WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
Protected Access, as WEP did not really convince everyone, the WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
Alliance decided to standardize a new security system.

Authentication

Absent from the WEP, authentication makes its appearance in WPA. The Protocol provides for two modes of authentication :
a company - that means to install a central server (of type Radius for example) to identify any person wishing to connect a mode and personal.
WPA leverages the 802.1 x family and Protocol EAP (Extensible Authentification Protocol)extension of the Protocol 9PPP(Point to Point Protocol), that can support many mechanisms of authentication such as token cards, one-time passwords and public key authentication using smart cards.
- MIMO : Multiple-Input Multiple-Outputstill called multipath. It is a very complex technology, using multiple antennas to broadcast radio waves.
Practically, the goal is to improve performance by correcting as much as possible interference problems. The announced result is a minimization of the shadow points and an increase in the scope. Exists for 802 .11b and 802.11 g and should be standardized in 802.11n.
network scheme WiFi
network scheme WiFi

The wired network

We have a wired Ethernet, we use of course TCP/IPthe network uses the IP 172.16.0.0/16 range.
A gateway to the Internet
Internet box
ADSL is a technology developed to be able to pass computer data through telephone lines. The high frequency bands of ADSL are those not used by the telephone (300 - 3400 Hz), multiplexing and modulation techniques are implemented.
However, using the high frequencies of the telephone line implies the use of a filter on both sides of the line so that there is no disturbance. The streams are asymmetric, which means that
is present (Linux machine with) IPtables), there is a server on this network DHCP allows to automatically configure hosts on the network. This works perfectly, and now we want to expand this network with a WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
access so that mobile stations can simply access this network.
So let's add an AP (Access Point) which will be the DWL-2100AP Terminal.

It is a \simple\ access point, in the sense where there is modem or router built into the casing.
It is typically designed to be connected to an existing wired network
The back side shows the extreme simplicity of this type of equipment. From left to right :
- the antenna,
- the power plug,
- the button reset,
- the RJ45
RJ45
RJ45 - Registered Jack - is the wired standard that allows the network connection for example to the Internet via a box. This type of cable has 8 pins of electrical connections.
This cable is also called ETHERNET cable its connector is called 8P8C connector (8 positions and 8 electrical contacts). This connector is physically compatible with the RJ11 connector if an adapter is used. On RJ45 computer cabling in 10/10
network jack.

Almost just plug in to make it work. Almost, because, as we shall see, this has a default IP address AP equal to 192.168.0.50.
It's good, but it won't with the addressing plan that we have in the example. Here, simply plug is only the first step, but for now, the Terminal remains unusable.
username and password travels in clear
username and password travels in clear

password WiFi

The Terminal is provided with a utility that should be able to solve this problem :
Once the IP address problem is solved, we can dispense with this utility, the point access shipping a mini web server that allows you to configure.
Any station connected to the network will have access to this web server.
There is still a required identification. By default, the user is called admin and the password is empty.
The first thing to do is to change this :

If your hardware allows, use a name to administrator that out a little of the ordinary and above all, a password that is solid and even, why not a user name not trivial.
AP Manager uses the tftp protocol there is no username and password circulates there also in the clear.

The third solution, it would be telnet, but then again, the login information go clear.
Local network, it is already not terrible on the safe side. On a corporate network, it's tricky.
On the customer side there are used different wireless cards :

- a D-Link DWL-G650 802.11g (PCMCIA)the only of the four to support the WPA system
- a D-Link DWL-650 802.11bthe only we can do work properly under Linux with the drivers Hostap
- a BeWAN PCMCIA 802.11b
- a Marvell 802.11g integrated to the motherboard Asus P5GD2
accessible IP address for administration
accessible IP address for administration

Simple config

We assume that our access point is properly configured local network, with an available IP address for administration side.
Simply configure the Terminal to access point, to assign an SSID, possibly a channel. If we have a DHCP server on the local network, it won't be necessary to set up one that is present on the Terminal. Otherwise, it will be easier for clients to use the DHCP server on the Terminal, then configure.

You take a cell phone equipped with WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
, do a search for available Wi - Fi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
networks :
Normally, it is within reach of your terminal, to easily find and tell you the SSID of the network :

It remains to connect :

Anyone can do that. Think a WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
network there going where he wants.
Here is a small graphical utility, Linux, which does the same thing :

Kismet
Airodump

Anyone within reach of your base station, can connect to your WiFi
WiFi
In the family of networks 'Wireless', are those which are built according to the 802.11 standards family networks WiFi. The most common fields of application are : - in the personal environment, the deployment of a small network, mainly intended to share an internet connection broadband.
- in-house, to allow easy connection of mobile workstations (laptop) to the network or a part of the network of the company. -
network and can for example :

- consume your bandwidth
- integrate into the local network and take advantage of shared resources.
- take possession of machines for all sorts of things that can be used, then, from the Internet
Internet box
ADSL is a technology developed to be able to pass computer data through telephone lines. The high frequency bands of ADSL are those not used by the telephone (300 - 3400 Hz), multiplexing and modulation techniques are implemented.
However, using the high frequencies of the telephone line implies the use of a filter on both sides of the line so that there is no disturbance. The streams are asymmetric, which means that
.
- use the Internet
Internet box
ADSL is a technology developed to be able to pass computer data through telephone lines. The high frequency bands of ADSL are those not used by the telephone (300 - 3400 Hz), multiplexing and modulation techniques are implemented.
However, using the high frequencies of the telephone line implies the use of a filter on both sides of the line so that there is no disturbance. The streams are asymmetric, which means that
to engage in all kinds of reprehensible activities.

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