Instructions for setting up wireless networks

Wireless network connectivity is gradually becoming a modern, trendy trend in addition to traditional network connections using cables. Reliable quality, stable operation, simple installation procedures, affordable prices are typical factors that demonstrate that wireless connectivity is ready to meet the needs of different information exchange from production. , business to entertainment needs . This article will provide you with the information needed to build a wireless computer network.

Wireless technology standard

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Wireless networking technology is built by IEEE and is officially put into use worldwide by the Wi-Fi Alliance.There are 3 standards: 802.11a standard, maximum transfer rate of 54Mbps;802.11b standard, maximum transmission rate of 11Mbps;802.11g standard, maximum transfer rate of 54Mbps (see also the attached specifications table).General characteristics of each technology are as follows:

The 802.11b standard has the lowest transmission rate (11Mbps) but is commonly used in production, business, and service environments due to low equipment procurement costs, transmission rates that meet the needs exchange information on the internet such as web browsing, e-mail, chat, messaging .

The 802.11g standard has a high transmission rate (54Mpbs), suitable for networks with high data exchange traffic, data circulating in the system are graphics, audio and video files with capacity great. The 802.11g standard radio frequency is the same as 802.11b (2.4GHz), so the 802.11g standard network communicates well with computer networks using 802.11b. However, according to current prices, the cost of equipping an 802.11g wireless connection system is 30% higher than the cost for an 802.11b wireless system.

The 802.11a standard, although having the same transmission rate as 802.11g, but with the highest operating frequency, 5GHz, high bandwidth, can accommodate more information channels than the two standards above. And because of the higher operating frequency of consumer telecommunications devices such as 'mother-to-child' phones, Bluetooth ., the 802.11a wireless network is less affected. due to interference. But this is also the reason why the system uses this standard incompatible with systems that use the other two wireless standards.

How to choose to buy wireless devices

Wireless network devices include 2 types: wireless network card and relay / access point (Access Point - AP). Wireless network cards come in two types: external (USB) and internal (PCI). Choosing which one to buy depends on the hardware configuration (slot, communication port) of the PC. Type to install in communicating with the computer via the PCI slot on the motherboard, so the procedure of installing and installing the software is similar to the one when we install the sound card, the network card, the hard disk controller . Type External mounting connected to the computer via USB port, so disassembly is very convenient, suitable for many different types of computers from desktop to laptop, to avoid electromagnetic interference due to internal devices. computer cause. It should be noted that if the PC uses USB 1.0 port (12Mbps data transfer rate), it is only suitable for 802.11b standard, if used with the other two standards, it will slow down the data transfer rate.

The procedure to build a wireless peer-to-peer network is very simple. Just equip each computer with a wireless network card, adding the device's control software that the computers in the network can exchange data with each other. But if you want to access the existing LAN / WAN system or access the internet, you must equip the Access Point relay device. The main function of this device is to receive and transfer signals between network cards in the coverage area and as an intermediary relay device to help wireless network cards communicate with LAN / WAN systems (sometimes modem) and internet. However, depending on the manufacturer's point of view, usage requirements and convenience for network administrators, some Access Point devices have a few other network functions such as: access gateway (gateway), guide set Road . TGVT A number in April 2003, 5/2003, 8/2003 and 11/2003, there are articles introducing some types of Access Points and features of the device.

Build wireless networks

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Figure 1: Check the broadcast quality of the wireless connection through the utility attached to the device

Setting up a wireless network is not as costly, time-consuming and complex as other traditional network systems, and sometimes not more than an hour of labor is able to form a wireless network.In fact, most of the problems and problems in the wireless network are due to the device control software having errors so it is necessary to prioritize the use of the latest device drivers set by the manufacturer. provided, updated or downloaded from the internet.If the system is running Windows XP, it is also recommended to install the latest Service Pack released by Microsoft.

When installing the equipment, it is recommended to arrange transponders (APs) in high positions, to avoid being obstructed by obstacles as much as possible. Types of construction materials, interior decoration such as metal-covered wallpaper, lighting electrical wiring systems, ornamental plants . can also degrade the signal of AP. Remember to erect straight-angled AP antenna antennas. If you use 802.11b and 802.11g wireless standards, you should be aware of the APs located far away from the electromagnetic transmitting devices that have a frequency range that matches the frequency of the AP ( 2.4Ghz) like microwave oven, phone "baby-holding mother", Bluetooth transceiver . When network construction should move, arrange AP in many different installation locations to find the installation location The device will give the best signal quality.

The distance between the wireless card and AP also greatly affects the transmission speed, the farther away from the AP, the lower the transmission speed. For 802.11b standard wireless networks, for example, the rate decreases gradually, the following level is ½ of the previous level (11Mbps to 5.5Mbps to 2Mbps .). Most utility software comes with a wireless network card and AP has the function of displaying the transmission speed of the network.

If the work space exceeds the available AP coverage, then we must buy an additional amplifier (repeater) to increase the broadcast capacity as well as the coverage area of ​​the AP.

Then proceed to configure software for the network system, namely:

Use a fixed or automatic IP address : If the wireless network under construction has internet access, contact the internet connection provider (ISP) for an IP address and instructions on how to install it. set for wireless network card.

Using DHCP : As with a normal computer network, DHCP should be used so that the system automatically provides an IP address for all network devices participating in the network. Doing so will save a lot of effort for network administrators.

SSID : Similar to the concept of internet domain names, SSID (Service Set Identifier) ​​is a string of characters representing a wireless network system. All network devices (Access Points, wireless network cards, etc.) of a wireless network must be declared with some SSIDs to work together. Often, the network administrator will declare the entire system a network name, but it is this SSID sequence that helps hackers judge the type of network device used in the system to find ways to access it illegally. France.

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Figure 2: Find the network present in the coverage area with Windows XP's Wireless Zero tool

Information channel : The bandwidth of 802.11b and 802.11g standards allows the construction of 14 different channels for information transmission, but now it is common to use one of the numbered channels from 1 to 11, and avoid confusing the Channel 1, 6 and 11 to improve signal quality.

Next, install and configure the wireless network card driver software. There are 2 installation modes: Infrastructure mode if you use an Access Point device, a router, remember to declare SSID and a communication channel; Ad hoc mode is for peer networking mode. After adding the control software, if the computer is running Windows XP, Wireless Zero Configuration (WZC) will be enabled, via this function (the icon is in the tray. system) we will know the list of wireless networks present around the computer (with wireless network card). Double-click on a wireless network in the list to perform the procedure to connect to that network.

As a general rule, the list of wireless networks present around computers will be classified into two categories: Available networks contain a list of all computers that can be connected; Preferred networks is a list of all wireless networks that Windows XP's WZC, ranked from high to low, will automatically perform the network connection procedure. These two lists are in the Properties window of the wireless network configuration utility, the procedure to start this window is as follows: Right-click the icon labeled My Network Places, select the Properties menu and the Wireless Networks menu.

System security: preventing unnecessary curiosity

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Figure 3: Wireless network card configuration window

In order for the system to operate safely and securely in the internal system, you should comply with the following rules:

Use passwords : Do not use the system access password only as a space or automatically created by device software.

No SSID identification number provided : By default, the AP automatically provides the SSID identifier information of the network for all devices within its coverage radius when required. This helps computer users have enough information to participate in the network, but is a disadvantage taken by hackers to illegally penetrate, so for local networks to disable the function. This feature makes the network more secure.

Only allow devices with certain MAC addresses to participate in the system : All networked devices have a unique 12-character string used as an identifier for each device, from a specialty called MAC address (Media Access Control). In order for the system to work more securely, only networked devices that have a certain number of MAC registrations will have access to the system. The MAC address list of wireless network devices used in the network is declared through the Access Point administration software. In Windows XP or 2000, the procedure for determining the MAC address of a network device is as follows: Click Start-> Run, enter the cmd command line and press the OK key. In the DOS window of the cmd utility, enter the command line ipconfig / all (note that between ipconfig and / all there is a space separator), press Enter. After the ':' sign of the Physical Address message line is the MAC address of the network device. With Windows 98 / Me just enter the winipconfig statement into the window of the Run command, the MAC address will be on the message line labeled 'Adapter Address'.

Application of WPA or WEP security standards for the system : WEP (Wireless Encryption Protocol) and WPA (Wi-Fi Protected Access) are wireless network security technologies. However, hackers have now found a way to disable WEP security, so it is important to use WPA standards to secure the system. If your system is currently using WEP standards, contact the manufacturer for instructions on switching to WPA standards.

Turn off Windows file sharing : Start Windows Explorer software.Right-click on each icon representing the drives in your computer and then select the menu labeled Sharing and Security (Windows XP) or Sharing (Windows 9x and NT versions).Uncheck the box labeled 'Sharing this folder on the network'.