Thursday, January 5, 2012

how to extract a rar or zip file on mac os-x

SkyHi @ Thursday, January 05, 2012
Find a file ending in .zip or .rar that you can’t seem to open? If you need to get into and expand RAR files in Mac OS X, check out the free app UnRarX. Not only will UnRarX quickly open and extract .rar files, but it also has the ability to restore corrupted and missing archives using par files.
How to Open .rar Files in Mac OS X
Once you have downloaded UnRarX, opening and expanding rar files is very similar to .zip and .sit archives:
  • Launch UnRarX
  • Drag and drop any rar archives into the open application to unrar them
After UnRarX has been run, it will now be associated with .rar archives on your Mac, allowing you to just double-click on any rar file to extract it in the future. You can also just open the rar file and explore the archive without uncompressing it.
Don’t like UnRarX, well if your picky be sure to check out other decompressing apps available, mind you not all are free.
Other extracting apps for Mac

fixed Header & Footer Layout: A Beginner’s Guide

SkyHi @ Thursday, January 05, 2012

Wi-Fi tech conferences?

SkyHi @ Thursday, January 05, 2012
Even with good enterprise grade Access Points like Cisco Aironet 1200's and with a managed environment (with WDS\WLSE etc infrastructure) you will struggle to sustain >10 active users per AP on 2.4Ghz. If you can use 5Ghz 802.11n\a then you may be able to hit 30 concurrent users and still get acceptable web browsing traffic. To set this sort of thing up properly you would need about 10 AP's with 2.4Ghz kit and you can not do that reliably without using a management system so you can be certain you are getting effective cell coverage and managing interference. Even if you do that the various 2.4Ghz client devices tend to misbehave a lot so if you cannot ensure a uniform set of clients you will struggle to get this to work consistently especially in an environment with a lot of warm wet human bodies moving around.
If you need to support 60 concurrent users in a reasonable space with 5Ghz WiFi standards things are a lot easier - there are (many) more non-overlapping channels available, the RF environment is much cleaner, the Client devices that support 5Ghz are generally much better behaved and you have that basic carrying capacity on each channel that is higher. You might be able to get away with just two but with 3 AP's it should work pretty well for 60 users provided none of them are doing unfriendly things like bit-torrenting or live-video streaming and you have an internet uplink that is fast enough - 100Mbps or so would be ideal.


Five Steps to Creating a Wireless Network

SkyHi @ Thursday, January 05, 2012
Wi-Fi Alliance
Five Steps to Creating a Wireless Network
Can I set up a Wi-Fi network?
Setting up a wireless network is easier than you might think. Whether you are setting up a Wi-Fi network for
you home, or for the office, you don’t have to be a tech guru to handle the job. That is why the Wi-Fi Alliance
has created this easy-to-follow, step-by-step plan to creating your own wireless network. Simply follow the five
steps outlined below and you will be on your way to experiencing the freedom of Wi-Fi.
Five steps to setting up your Wi-Fi network:
ƒ Step 1 — Planning
ƒ Step 2 — Equipment Selection
ƒ Step 3 — Set Up
ƒ Step 4 — Adding Wi-Fi to Desktop Computers
ƒ Step 5 — Security
Step 1—Planning
Setting Up A Wireless Network
Once you've decided to free yourself by "going wireless," you can reap all the benefits of mobile computing —
and it's simple and easy to set up and operate a wireless network. Here's how to plan for, install and operate
your Wi-Fi® network:
What Makes Up a Wireless Network?
Wi-Fi devices "connect" to each other by transmitting and receiving signals on a specific frequency of the
radio band. Your components can connect to each other directly (this is called "peer-to-peer") or through a
gateway or access point. When you create your Wi-Fi network it will consist of two basic components: Wi-Fi
radios and access points or gateways.
Wi-Fi radios are embedded or attached to the desktop computers, laptops and mobile devices in your
network. The access points or gateways act as "base stations" — they send and receive signals from the WiFi radios to connect the various components to each other as well as to the Internet. All computers in your WiFi network can then share resources, exchange files and use a single Internet connection.
Do I Need a Peer-to-Peer Network, Or One with a Base Station (An Access Point or Gateway)?
A peer-to-peer network is composed of several Wi-Fi equipped computers talking to each other without using
a base station (an access point or gateway). All Wi-Fi CERTIFIED™ equipment supports this type of wireless
set-up, which can be useful for transferring data between computers or sharing an Internet connection among
a few computers in a room. A peer-to-peer wireless network can be a good solution if you have three or fewer
computers or if you're on a budget but most users will use an access point to connect Wi-Fi devices since this
will provide for the best user experience and allow for easier Internet sharing.
What Are the Wi-Fi Radio Options for My Laptops, Desktops and PDAs?
Many laptop computers and mobile computing devices come with a Wi-Fi radio built in. They're ready to
operate wirelessly. For most other laptops you will insert a Wi-Fi radio embedded in a simple  PCMCIA
(Personal Computer Memory Card International Association) card — commonly called a PC Card — into the
laptop's expansion slot.
You have several ways to include desktop computers in your network. Since most don't provide slots for PC
Cards, the simplest method is to use a USB (Universal Serial Bus) Wi-Fi radio that plugs into an available
USB port on your desktop computer. Install the software and you're up and running. Wi-Fi Alliance
If you have no available USB port on your system, you need to install a PCI or ISA bus solution. This requires
you to remove your computer casing and open up your computer to find an available PCI or ISA bus slot. The
manufacturer's set-up instructions will show you how to install the device you purchase. (Some Wi-Fi
manufacturers provide one-piece ISA and PCI bus radios. Others provide ISA or PCI bus adapters that
enable you to use the same slide-in Wi-Fi PC Cards that you would use in your laptop.) Apple offers an
embedded Wi-Fi radio, the Apple AirPort Radio, which you can personally install in new Macintosh
Personal Digital Assistants like Palm™, Visor™ and Pocket PC™ have a slot for a Compact Flash format WiFi radio. (Some laptops also have Compact Flash capability.) There are also new small-format Wi-Fi radios
for PDAs and mobile data devices becoming available, offering additional options for wireless connections in
the future.
Planning for Access Points and Gateways
The Wi-Fi access point or gateway functions as the base station for your network. This is the central
connection among all your wireless client devices—laptop computers, PDAs, desktop computers and wireless
peripherals like printers. The base station sends and receives radio signals to and from the Wi-Fi radio in your
laptop or PC, enabling you to share your Internet connection with other users on the network. Access points
and gateways have a wide range of features and performance capabilities, but they all provide this basic
network connection service.
How Many Users Can Use a Single Access Point?
Wi-Fi networks, like wired networks, are a shared medium. An 802.11b Wi-Fi network may provide 11 Mbps
of bandwidth to an individual user. Theoretically, if ten users are simultaneously using the network, each will
have to share and may only get 1 Mbps or so each. However, network sharing is not quite this simple. A lot
depends on the users' behaviors. Someone who is just sending and receiving e-mail just uses the wireless
connection in bursts. They will probably never notice any slow down. On the other hand, a roomful of Wi-Fi
users who are accessing high-resolution multimedia over a single access point may indeed notice a
slowdown. In this instance, they may require additional access points or higher speed access points that use
802.11a or 802.11g that provide 54 Mbps or better of bandwidth.
Note: Depending on how the users connect and what they do once they are on the network, you may need to
use higher speed access points, as well as more of them.
Choosing Components for Your Network
To set up a Wi-Fi network, you need to consider the components, the users and how you will use the network.
The following checklist shows you how to choose components:
First, count your total number of users and computers. Most homes have three computers at most, while a
small business usually has fewer than 15. Each component will need a Wi-Fi radio. If your laptops are not
preconfigured with an embedded Wi-Fi radio, you need a Wi-Fi PC Card radio for each.
How many laptops do you have?
___Need PC Card
___Preconfigured (contain an internal Wi-Fi NIC)
Each of your desktops will need either a Wi-Fi USB adapter (which combines a PC Card radio with a USB
converter circuit) or a Wi-Fi PCI/ISA adapter (which is a radio available with or without a built-in PC Card
How many desktop computers do you have? Wi-Fi Alliance
___PCs with sufficient USB jacks for USB adapter hookup (requires Windows™ 98 or newer)
___PCs that need PCI or ISA adapter
___PCs with existing PC Card slots
Next, your PDAs will also need radio devices. Some can use the same PC Card used in laptops; some use
Compact Flash.
How many PDAs do you have?
___Need PC Card
___Use Compact Flash
___TOTAL Wi-Fi Radio Components Needed
Place a Wi-Fi Radio in Each Computer
After you've determined the number and type of Wi-Fi radios you need, install a radio in each component that
you want to include in your network.
Determine the Number of Base Stations (Access Points or Gateways) You Need
You will also need a Wi-Fi access point or gateway to serve as the central base station for your network. A
typical Wi-Fi access point can support some 15 to 20 users, so most homes and small offices need only a
single access point. However, if you have a very large dwelling (or house) or if your office is spread out, you
may need more. How far will your WLAN go? A basic rule of thumb is 100 to 300 feet indoors and 2000 feet
outdoors. Your range may vary, based on the building or environment you're using it in. For more information,
search Access Point Range Guide.
Of course, the number of access points depends on how the network is used and the total number of users,
as well as how big a space needs to be covered. A single access point can easily handle from 10 to 30 users
who only use the network to send e-mail, cruise the Internet and occasionally save and retrieve large files.
Within a typical office environment, most access points can provide good wireless coverage up to 150 feet or
so. For large facilities with many users, or with users who require a lot of bandwidth, you may need more than
a single access point. Many access points can be connected to each other wirelessly or via Ethernet cables to
create a single large network.
How many users do you have, and is your space unusually large?
___Typical users
(Sending e-mail, surfing the Internet and occasionally saving and retrieving large files). Solution = single
access point
___More demanding users
 (Transferring very large files often, access and use streaming video). Solution = multiple access points
clustered together using different channels
___Large working area
 (In excess of 300 feet as in a warehouse or large open office). Solution = multiple access points spread out
___Estimated Total Wi-Fi Base Stations Needed Wi-Fi Alliance
How Do You Connect Your Wi-Fi Network to the Internet?
You can use a variety of high-speed Internet connections with a Wi-Fi network, including cable modems,
different types of DSL, satellite broadband, ISDN, etc. Your broadband Internet connection will connect to
your gateway or access point, and its Internet connection will be distributed to all the computers on your
network. And don't worry about Wi-Fi slowing down your connection speed: it's at least four times faster than
the fastest of any of these connections. If there's an Ethernet cable attached to your Internet device, you can
connect it to your base station to distribute your Internet connection throughout your home or small office WiFi network.
How Do You Make Printers Work on Your Wi-Fi Network?
If you want to share printers, you can connect them to a computer on the network, you can dedicate a Wi-Fi
equipped computer to act as a printer server or you can connect a Wi-Fi equipped printer or print server to
your network to control your print jobs. (A shared printer connected to a computer must have the computer
turned on to access the printer via the wireless Wi-Fi connection.)
A wireless print server is a small computer and Wi-Fi radio built into a single box; a Wi-Fi equipped printer
connects directly to your Wi-Fi network. A Wi-Fi print server or a Wi-Fi equipped printer can make your printer
accessible to your network.
Many additional Wi-Fi enabled devices will soon be appearing. Each will have its own embedded Wi-Fi radio
to connect directly to your network. That means you won't need to connect your Wi-Fi peripherals to an
always-on computer or a stand-alone Wi-Fi radio adapter. These devices can include scanners, cameras,
telephony devices, video and TV monitors, DVD players, appliance controllers, multimedia players and
Can You Share Devices on Your Network to Save Money?
Yes. If you don't need to have each computer on the network all the time, you can save money by sharing the
PC Cards for your laptops and other mobile computing devices and the USB radio/adapters for your PCs and
laptops. For example, when you're working in the office, your USB radio can be connected to your desktop
computer. When you go on the road with your laptop, the same USB device can connect to your laptop
computer's USB slot to provide mobile connectivity. When you're at home, you can hook the same USB radio
to your desktop computer and use it to access your home Wi-Fi network.
Step 2 — Equipment Selection
Types of Equipment
There are currently two types of Wi-Fi components you'll need to build your home or office network: Wi-Fi
radio (also known as client devices) devices (desktops, laptops, PDAs, etc.), and access points or gateways
that act as base stations. A third type, Wi-Fi equipped peripherals, is emerging and will soon be
commonplace. This group includes printers, scanners, cameras, video monitors, set-top boxes and other
peripheral equipment.
Types of equipment covered in this document:
ƒ PC Card Radio
ƒ Mini-PCI Modules and Embedded Radios
ƒ USB Adapters
ƒ PCI and ISA Bus Adapters
ƒ Compact Flash and Other Small-Client Formats
ƒ Access Points and Gateways
PC Card Radio
Wi-Fi networks use a radio band to "broadcast" data to other Wi-Fi enabled equipment and the most common
client device is the PC Card Wi-Fi radio. There are hundreds of variations, but most look like a standard Type Wi-Fi Alliance
II PC Card that slides into your laptop's PC Card slot. These cards used to be known as PCMCIA (Personal
Computer Memory Card International Association) cards but are now simply called PC Cards.)
The protruding end of most Wi-Fi PC Cards contains a built-in antenna, usually a miniature twin diversity
antenna, which can sometimes spring out to improve coverage. Some of them have a tiny connector on the
end to which you can attach a larger, more powerful antenna to maximize range.
On many laptop computers, the software and drivers for these PC Cards are already built in. If you are using
Windows XP, you may find that when you slide in the card, the drivers and software will load automatically.
The computer will then scan the area to find and log onto the closest Wi-Fi network.
You can also use Wi-Fi PC Card Radios in various cameras, audio systems, PDAs and other mobile
computing devices that have a PC Card slot.
PC Cards
Mini-PCI Modules and Embedded Radios
Your desktop or laptop may be Wi-Fi enabled. If so, it most likely has a Mini-PCI radio installed by the
manufacturer. Many manufacturers now install an embedded Mini-PCI Wi-Fi radio in laptop computers and
other mobile computing devices before they leave the factory. Apple Computers uses a somewhat similar WiFi radio module, the Apple AirPort that can be installed by the factory, the retail outlet or the end user.
If you are using a Windows-based laptop in your network and you can't use a PC Card or other Wi-Fi adapter,
you'll need one with a pre-installed Mini-PCI Wi-Fi radio. You should ask the factory to install one when you
order a new laptop.
Mini-PC Module
USB Adapters
Most desktop computers do not provide PC slots for Wi-Fi PC radios. You can solve this problem by using a
PCI/ISA bus adapter (see below) or a  USB adapter
For most users with desktop computers, the easiest way to add a Wi-Fi radio is to use a USB adapter, a onepiece unit that combines a Wi-Fi radio and a USB converter circuit. Simply plug the USB connector into one of
the USB jacks on your desktop PC. Because their power is delivered through the USB cable, most USB
adapters don't require a separate DC power module. Wi-Fi Alliance
USB Adapters
PCI and ISA Bus Adapters
Many Wi-Fi vendors provide ISA and PCI-compliant radios that fit inside a desktop computer and enable the
computer to work in a Wi-Fi network. (Until recently, most computers internally contained open slots called
ISA and PCI buses, but in most new computers you will find only PCI.) These can be either one-piece ISA or
PCI radios or two-piece units that comprise a PC Card reader or adapter and a separate Wi-Fi PC Card Radio
that slides into the reader.
PCI and ISA Bus Adapters
Compact Flash and Other Small-Client Formats
Designed for smaller PDAs and other mobile computing devices, 802.11b/Wi-Fi radios can be built onto a
Compact Flash format. Much smaller than a typical Type II PC Card, CF (Compact Flash) Wi-Fi cards have
the same range and performance as their larger cousins.
Access Points and Gateways
Even though client device radios can be configured to talk to each other, a Wi-Fi network operates more
effectively when using a central base station to coordinate communications.
There are two types of Wi-Fi wireless base stations: a gateway and an access point. However, the distinctions
between the two are not always clear, in part because the functions they perform can overlap. Even more
confusing, many wired devices and other home Internet appliances also call themselves gateways.
A wireless gateway is targeted toward a totally wireless home or small-office environment; an access point is
targeted toward a more integrated combined Ethernet and wireless environment -- usually larger businesses,
campuses, or corporations. Gateways and access points can also differ regarding their capacity to perform
security functions, provide firewall protection, and manage network traffic and tasks.
Gateways often include NAT (Network Address Translation) routing and DHCP (Dynamic Host Control
Protocol) services. These create and provide the individual IP addresses all the wireless (and wired) clients
need to function in a network and also enable a single Wi-Fi gateway to simultaneously provide Internet
access to numerous users from a single shared Internet connection. Gateways may also include other Wi-Fi Alliance
applications and features such as encryption and security, VPN, firewall, and Voice over Internet Protocol
An access point does not usually furnish NAT routing or DHCP; the wired routers in the system provide those
network functions. Access points work as merely transparent bridges between wired networks and the various
wireless users throughout a facility. Even though access points generally do not provide NAT or DHCP, they
usually enable roaming (the ability to move from one access point to another without losing contact with your
network), higher levels of security, and a high level of network control and management. Some gateways also
provide these services. In fact, by toggling certain functions on and off, many wireless base stations can
operate either as a gateway or as an access point. But a gateway is usually the only wireless base station in a
small office or home, whereas in a large office or campus there might be hundreds or thousands of access
points forming one or multiple overlapping wireless networks.
Access Points and Gateways
Step 3 — Set Up
10 Easy Steps to Setting Up Your Home or Small Office Network
Wi-Fi networks are easy to set up and operate. But if you've never set up a Wi-Fi network, chances are you
may be confused about where to begin. If that’s the case, use this step-by-step guide to help you through the
process of planning and setting up your wireless network.
1. Count Your Computers
2. Pick out the Right Kind of Wi-Fi Radios for Your Computers
3. Decide Between a Wi-Fi Gateway or Access Point
4. Get the Right Wi-Fi Radio and Accessories
5. Read the Installation Instructions
6. Read the Instructions Again
7. Install Your Access Point or Gateway First
8. Install the First Wi-Fi Radio Device
9. Configure the Access Point
10. Connect the Rest of Your Computers and the Printer Wi-Fi Alliance
1. Count Your Computers
How many computers are there in your network? You will need a Wi-Fi radio for every one you want to
connect to the Wi-Fi network.
Your Wi-Fi network can have any of several configurations. You can have just one Wi-Fi equipped computer
talking to your Wi-Fi gateway and the Internet. You can have a Wi-Fi equipped laptop and a Wi-Fi equipped
desktop computer, both talking to each other and to the Internet by connecting through your Wi-Fi gateway.
You can also have a dozen or more Wi-Fi equipped laptops and desktops, all talking to each other and
sharing the same Internet connection through a single Wi-Fi gateway.
2. Pick out the Right Kind of Wi-Fi Radios for Your Computers
If your laptop computers already have a built-in, or embedded, Wi-Fi radio, you're set. If your laptops don't
have embedded Wi-Fi, you will need to get a Wi-Fi radio PC Card for each of them.
If you have desktop computers, you will need to get Wi-Fi radio adapters. You can choose from among
several plug-and-play USB Wi-Fi radio adapters, or you can use USB radios or PC Card radios that go inside
your computer.
USB radio adapters are usually easier to install and can provide better performance, but they do use up one
of your computer's USB connectors and, because of their simple plug-in connection, can easily be
disconnected by anyone. The PCI/ISA adapter radio solution requires some expertise to install and configure
but can be more securely embedded inside your computer.
If you're using an Apple computer, your choice is easy: Add an AirPort radio module. Older Apple laptops can
use PC Card radios.
3. Decide Between a Wi-Fi Gateway or Access Point
A Wi-Fi network operates more effectively when using a central wireless base station to coordinate
communications. There are two types: a gateway and an access point.
Most home and small office networks should use a Wi-Fi gateway.
Depending on how your system is set up now, you may choose an access point rather than a gateway. For
instance, if you have an existing wired network or a combined broadband modem/router, you can use just a
basic access point because the existing wired network router or hub will handle network addressing NAT or
DHCP. If you have a broadband modem with no router connected to a single computer, or if you don't yet
have an existing wired network, then you should get a Wi-Fi gateway that provides NAT (Network Address
Translation) routing and a DHCP (Dynamic Host Control Protocol) server. If your cable modem or DSL
connection is providing NAT or DHCP you can disable NAT and DHCP on your gateway because the network
addressing is already provided by the modem or connection and only one device on a network can provide
these services.
4. Get the Right Wi-Fi Radio and Accessories
Your Wi-Fi components should come with the correct accessories: cables, software, power supplies, AND
mounting hardware. You might also need additional gear like ethernet cables (to connect to your wired
network router) or special antennas to maximize the range of your Wi-Fi network.
5. Read the Installation Instructions Wi-Fi Alliance
Wi-Fi gear is easy to install if you read the instructions. For some Wi-Fi radio devices, it's necessary to install
the software and drivers before you connect the radio. For others, you need to install the device first and then
install the CD-ROM when prompted. For other devices, all the required software and drivers are preloaded
into the computer's operating system and will automatically load. But you won't know unless you read the
directions first.
6. Read the Instructions Again
Really read the instructions. Your Wi-Fi radio device may have different installation instructions for different
versions of Windows.
7. Install Your Access Point or Gateway First
During the installation, make sure you follow the manufacturer's instructions to install an access point- or
gateway-based network, not a peer-to-peer network. For most Wi-Fi systems, you must first plug in and
power up the base station. Then connect the Ethernet cable from your DSL or cable modem to the base
station. If your broadband connection is already connected to your computer, disconnect that cable and attach
it to your base station.
Most cable and DSL modems use Ethernet technology (cable and built in card) to connect to computers or to
networks. However, some versions of DSL or cable modems use a USB cable to connect to computers. Find
out which your system uses because few if any Wi-Fi access points can use USB for their broadband
connection. If your broadband modem connects using a USB cable, you then need to buy the correct RJ-45
Ethernet cable to connect your modem to your Wi-Fi gateway or access point.
8. Install the First Wi-Fi Radio Device
After carefully reviewing instructions, install the Wi-Fi radio device in the first computer. If you're installing
devices in both desktops and laptops, start with the machine with the newest operating system. Follow the
manufacturer's instructions to be sure you're configuring them to work with your base station and not as a
peer-to-peer network. If all your OS's (operating systems) are about the same, begin by installing PC Card
radios in the laptops and then install in the desktops.
If you already have an embedded Wi-Fi radio in your laptop, simply initiate the appropriate program or utility
software to scan and find the new access point. If your desktop has a Windows XP operating system, it
should already contain the software that will automatically scan and find your new Wi-Fi network.
9. Configure the Access Point
Once your Wi-Fi radios are installed, you can configure your gateway or access points. Most gateways and
access points now have web-based set-up that allow you to configure your base station through an easy to
use web based process. It will walk you through the process to ensure your device can talk to your Internet
connection, help configure the connections with the various radios and assist in setting up the appropriate
security levels.
10. Connect the Rest of Your Computers and the Printer
Once you have one Wi-Fi computer talking to the access point or gateway and are connected to the Internet,
repeat the installation process with your other computers. After they are successfully connected to the access
point and to the Internet, you need to use their networking functions to make them talk to each other and
share folders, files and printer connections. This varies from one computer to another and from one operating
system to another so check your networking instructions. Some operating systems have wizards that walk
you through the process; others require a more intensive manual process that involves opening up control
panels and applets. Wi-Fi Alliance
Step 4 — Adding Wi-Fi to Desktop Computers
IMPORTANT: The procedures necessary to complete these steps are often different for each manufacturer.
Whenever you see this image:  , you should look in your specific product manual for the correct procedure
to follow.
 •  USB Radio Installation
 •  PCI Adapter Installation
 •  Is a USB or a PCI Solution Better For You?
You can easily add Wi-Fi® to a laptop computer, but some desktop computers can take a little more effort.
For most laptops, you simply slide in a Type II PC Card Wi-Fi radio, install the software and you're up and
Since very few desktop computers provide PC Card slots, they require a USB [Universal Serial Bus] Wi-Fi
radio adapter or a PCI-based [Peripheral Component Interconnect] Wi-Fi radio adapter to connect to a Wi-Fi
Laptop Computer with PC Card
USB Radio Installation
Installing a USB radio adapter is simple: Plug the radio's USB connector into a spare USB jack on the front or
back of your computer.
Then install the software and configure the radio to talk to your network, and your computer should be ready
to go.
USB Adapter Wi-Fi Alliance
PCI Adapter Installation
Installing a PCI Wi-Fi radio adapter can be a little bit more complicated. There are two types of PCI Wi-Fi
radios: a one-piece PCI Wi-Fi Card Radio, and a two-piece solution that includes a standard Wi-Fi PC Card
Radio and a special PCI PC Card reader or adapter.
The first step is to open up your computer to find a spare PCI slot.
Next, carefully remove the one-piece PC Card or combination PC Card and reader/adapter you've purchased
from its protective wrapper and firmly insert it into an open PCI slot. Make sure you read the instructions that
came with your card--especially the information about properly grounding yourself so that you don't damage
the card because of an accidental spark of static electricity.
Once the card or card reader/adapter is firmly set into the slot, screw it down tight and close up your computer
case. Then, following the manufacturer's instructions, install the software. For two-piece PCI solutions, you
may need to install one set of software for the card reader/adapter and another set for the PC Card Radio
PCI - ISA Adapter
Is a USB or a PCI Solution Better for You?
Most USB and PCI solutions cost about the same. And if they're Wi-Fi CERTIFIED™, you know they have
been rigorously tested by the Wi-Fi Alliance. So which should you choose?
Because a Wi-Fi USB adapter is "plug and play," you don't need to be a technical guru to install and configure
it - it's easy - and most new computers have two or more USB slots. In addition, because it connects via a
cable, the USB solution offers the potential for improved range and performance compared to an embedded
PCI solution. And, you can place the Wi-Fi USB Card Radio adapter anywhere - on top of your desk, on top of
a computer, or on a nearby bookshelf.
If your computer doesn't have an extra USB slot or they're all in use, you can purchase an external USB hub
with additional ports and hook it up to your existing USB jack to add Wi-Fi. But that means more equipment
and more wire management off your computer.
The PCI solution may be best if you need the extra physical security (to safeguard from theft) that is provided
by a Wi-Fi radio adapter firmly embedded inside the computer case. The only downside to locating your Wi-Fi
radio inside the computer chassis is that the surrounding metal can affect both range and performance. Of
course, if your computer doesn't support USB, PCI is your only choice.
Step 5 — Security
Securing your Wi-Fi® Network
Here are a few simple steps you can take to maximize the security of your wireless network and to protect
your data from prying eyes and ears. This section is intended for the home, home office and small office user. Wi-Fi Alliance
IMPORTANT: The procedures necessary to complete these steps are often different for each manufacturer.
Whenever you see this image:  , you should look in the encryption or security section of your specific
product manual for the correct procedure to follow.
 •  Deploy WPA™ (Wi-Fi Protected Access™) or WPA2™
 •  Change Your Default Password
 •  Close Your Network (If Possible)
 •  Change Your Network Name
 •  Move Your Access Point
 •  Use MAC Control Tables
 •  Other Simple Solutions
 •  Use a VPN (Virtual Private Network)
 •  Additional Information
Deploy WPA (Wi-Fi Protected Access) or WPA2
Most importantly, deploy Wi-Fi Protected Access (WPA) or WPA2.  WPA is a standards-based, interoperable
security enhancement that strongly increases the level of data protection and access control for existing and
future wireless LAN systems.
Change Your Default Password
Most wireless networks ship with a default password provided by the manufacturer. Change it as soon as
possible.  Most hackers can easily figure out the default password once they identify the make of your
network access point.
Close Your Network (If Possible)
If possible, block the SSID (Service Set Identifier) from being broadcast.  This has the effect of "closing" your
network. Many Wi-Fi systems enable you to close the network.
All access points ship with a wireless beacon signal so that wireless PCs can more easily find them. In effect,
the signal is shouting, "I'm here! Log on!" By turning the SSID off or by "closing" your network, you make it
much harder for hackers to find you: If they don't know your network exists, there's less chance they will
spend the time to crack your communications. So, if your equipment permits you to close the network, make
sure you do so.
Change Your Network Name
Most access points ship with a default network name. When your network is up and running you should
change the name to something personal, yet hard to guess. In other words, if your last name is Smith, don't
call it the Smith network. Many companies, even large corporations, label their network with their company
name or their address. Don't do it. Be creative. A combination of letters and numbers is recommended, but
don't use your street address!
Move Your Access Point
To increase privacy, place your access point in the middle of the room, away from open windows and doors.
The more metal and wood you put in the way, the less distance your wireless messages can travel. You can
test how much of your signal is escaping from your business or home by taking your Wi-Fi equipped laptop
outside (for a site survey) and checking to see how far you can go and still make a connection. You might be
Use MAC Control Tables
Use MAC (Medium Access Control) tables if your access point supports them.  Like all networking devices, a
Wi-Fi radio, has a unique MAC address coded into its memory. By using the MAC Access Control List (ACL),
you can limit the wireless connection to only those Wi-Fi radios whose MAC addresses are directly enabled in
your access point. It's like call blocking on a telephone, but for a wireless LAN. If a rogue wireless radio with a
MAC address that is not in this table tries to connect to your network, your access point will not let it. Wi-Fi Alliance
Other Simple Solutions
There are various ways to set up your computer's directories and network to protect your stored files and
data. One way is to turn off "Sharing" and use "Passwords" to access directories holding confidential files.
Sharing and Passwords are accessed in Windows by right clicking on the directory and going to the
"Properties" command. Also see Windows Networking Tips and Secrets
Remember that most web sites that handle purchases, credit cards and other financial information usually use
encryption methods such as SSL (secure socket layer) to protect sensitive data. So most financial data
transmitted over the Internet is already encoded from the time it leaves your computer until it reaches the web
Use a VPN (Virtual Private Network)
Many large companies use VPN (Virtual Private Network) technologies for staff that need to remotely access
the company's corporate database. VPN systems also work for Wi-Fi wireless networks.
A VPN creates a virtual tunnel from your computer through the local wireless access point, through the
Internet, and then to your corporate headquarters. Even though it can be complicated and expensive, using
VPN creates an almost impenetrable wall of security for your wireless communications whether you're
working from home, an airport lounge or your company's meeting rooms.


How Many Users Can a Wireless Access Point Handle?

SkyHi @ Thursday, January 05, 2012
How many users can a wireless access point handle? This is a loaded question and not one that many wireless vendors will answer for several reasons.  However, I can give some guidelines and suggestions on what we experience in the field and I can explain some of the differences.

some of the details are there and will help answer many of your questions.
First off this question needs to clarify the type of access point we are talking about. If we are discussing consumer grade wireless routers you will be lucky to get 10 users on one. This is because the chipsets in the wireless routers / access points are designed for homes or SOHO type environments where there aren’t many users or devices accessing wireless. When the thresh hold of what the chipset can handle is exceeded the device will lock up. We installed a wireless network in a school system that had deployed 100+ Linksys wireless access points and had someone who was assigned to go around and reboot access points all day long. The wireless system we installed allowed them to put this person back to doing something much more productive.

If we are discussing enterprise grade access points then there will still be quite some differences in how this question is answered depending on the salesperson you are dealing with.  Enterprise grade access points have more robust chipsets engineered to handle larger client loads as well as being able to offer other services like Intrusion Detection / Prevention and Spectrum Analysis. They are also hopefully built on a software platform, like the products we install, which is designed to appropriately handle traffic loads by load balancing clients across radios and even channels. The software will also manage “air time fairness” so that no one client hogs all the bandwidth.
Here are some of the things we hear clients being told by other vendors:
  • Our access point can handle 100+ clients” – Our response to this is let them show you this works in your environment with your clients running your applications. A controlled demo is easy to create that will achieve this but it is not real world.
  • “Our access point with a dozen radios can handle 100’s of users – you only need to buy one access point for your facility” – Again our response is let them show you this works in the real world using real world tests. One access point for a facility does not work. This whitepaper from Novarum shows a direct correlation between access point density and wireless performance.
The below chart is the guideline I use when designing wireless networks and it has worked well for us. This is especially important to follow now that users are toting around multiple wireless devices with varying transmit and receive sensitivities. Having good access point density will provide optimal wireless client experiences and less aggravation when you have to add on later because someone sold you a bad bill of goods.

How Many Users Can an Access Point Handle?

"The AP has the physical capacity to handle 2048 MAC addresses, but, because the AP is a shared medium and acts as a wireless hub, the performance of each user decreases as the number of users increases on an individual AP. Ideally, not more than 24 clients can associate with the AP because the throughput of the AP is reduced with each client that associates to the AP."


Wednesday, January 4, 2012

Preferred Master Browser

SkyHi @ Wednesday, January 04, 2012
Yes, Domain Controllers should be Master Browsers - setting your domain controllers as "Preferred Master" should fix most of the Master Browser election problem.
One of the common reasons for operating a WINS server is to provide a central reference for NetBIOS names across several subnets. Choosing one primary WINS server and pointing all clients to it lets NetBIOS name resolution work across subnets without requiring the use of Domain Controllers.
But if your system is supposed to rely on domain controllers, loss of replication for site C may explain your symptoms. So start with verifying successful replication.

Setting the IsDomainMaster parameter entry to True or Yes makes that computer a Preferred Master Browser which has priority over other computers in master browser elections. Whenever a preferred master browser starts, it forces a browser election. Any computer running Windows NT Workstation or Windows NT Server can be configured as a preferred master browser. If no other condition prevents it, the preferred master browser will always win the election. Set the parameter in the following registry path:
Key: SYSTEM\CurrentControlSet\Services\Browser\Parameters
Type: REG_SZ
Name: IsDomainMaster
Value: True