The Promiscuous mode is a specific receive mode for network-technology devices such as wireless network cards. It is normally used for packet sniffing and bridged network for hardware virtualization. The frames include the MAC (Media Access Control) address of the hardware.

In this mode the device submits all incoming traffic to the network interface and transmits the data for processing to the operating system. Devices that use this mode can be combinations of switches and routers, network tester or even a normal computer with a connection to a network.

For Wireless LANs in promiscuous mode it will only forward the packets of the network (access points) to which the client is currently connected. The Promiscuous Mode is unsuitable to receive packages from a network which you do not own because you need to authenticate yourself with the network.

The opposite of this mode is the non-promiscuous mode. In this mode the unit handles only the packets addressed to it and this happens for example in Ethernet networks, the evaluation of the MAC address plus broadcast packets.

Another method of usage is to detect network connectivity issues. Some programs use this feature to show everything that is transferred by the network and some of them can transfer passwords and data in clear text. So a normal user should stay away of this mode to prevent that someone else could steal this data while the transferring process.

As you can see the Promiscuous Mode should only be used by advanced users to avoid any damage to your system or to open the door for hackers. But when you know what you are doing this mode is quite powerful and you can repair your network without any problem.

Of course not every wireless card drivers support this mode because of it’s not a secure mode. If you need this mode you should watch out for another driver that supports the Promiscuous Mode. You can contact your device’s manufacturer and ask for a new driver.

source: http://ezinearticles.com/?Wireless-Network-Monitor—The-Promiscuous-Mode&id=5160653

Since the inception of wireless networking there have been two types of wireless networks: the infrastructure network, including some local area networks (LANs), and the ad hoc network. Ad hoc is Latin meaning “for this purpose.” Ad hoc networks therefore refer to networks created for a particular purpose. They are often created on-the-fly and for one-time or temporary use. Often, ad hoc networks are comprised of a group of workstations or other wireless devices which communicate directly with each other to exchange information. Think of these connections as spontaneous networks, available to whomever is in a given area.

An ad hoc network is one where there are no access points passing information between participants. Infrastructure networks pass information through a central information hub which can be a hardware device or software on a computer. Office networks, for example, generally use a server to which company workstations connect to receive their information. Ad hoc networks, on the other hand, do not go through a central information hub.

Ad hoc networks are generally closed in that they do not connect to the Internet and are typically created between participants. But, if one of the participants has a connection to a public or private network, this connection can be shared among other members of the ad hoc network. This will allow other users on the spontaneous ad hoc network to connect to the Internet as well.

Ad hoc networks are common for portable video game systems like the Sony PSP or the Nintendo DS because they allow players to link to each other to play video games wirelessly. Some retail stores even create networks within them to allow customers to obtain new game demos via the store’s own ad hoc network.

An ad hoc network can be thought of as a peer-to-peer network for the wireless age. Peer-to-peer or workgroup style networks were used to create a network environment for early Windows computers. This allowed these early computers to connect to each other to exchange information, usually in a smaller office environment without the need for domains and the additional management and overhead that comes with them.

The possibilities with ad hoc networks are quite endless. With connection sharing and other methods to access public or private wired or wireless networks, the reach of an ad hoc network can extend quite far.

source: http://www.wisegeek.com/what-is-an-ad-hoc-network.htm

Home and business networkers looking to buy wireless local area network (WLAN) gear face an array of choices. Many products conform to the 802.11a, 802.11b, 802.11g, or 802.11n wireless standards collectively known as Wi-Fi technologies. Additionally, Bluetooth and various other non Wi-Fi technologies also exist, each also designed for specific networking applications.

This article describes the Wi-Fi and related technologies, comparing and contrasting them to help you make educated network building decisions.
802.11
In 1997, the Institute of Electrical and Electronics Engineers (IEEE) created the first WLAN standard. They called it 802.11 after the name of the group formed to oversee its development. Unfortunately, 802.11 only supported a maximum network bandwidth of 2 Mbps – too slow for most applications. For this reason, ordinary 802.11 wireless products are no longer manufactured.
802.11b
IEEE expanded on the original 802.11 standard in July 1999, creating the 802.11b specification. 802.11b supports bandwidth up to 11 Mbps, comparable to traditional Ethernet.

802.11b uses the same unregulated radio signaling frequency (2.4 GHz) as the original 802.11 standard. Vendors often prefer using these frequencies to lower their production costs. Being unregulated, 802.11b gear can incur interference from microwave ovens, cordless phones, and other appliances using the same 2.4 GHz range. However, by installing 802.11b gear a reasonable distance from other appliances, interference can easily be avoided.

* Pros of 802.11b – lowest cost; signal range is good and not easily obstructed
* Cons of 802.11b – slowest maximum speed; home appliances may interfere on the unregulated frequency band

802.11a
While 802.11b was in development, IEEE created a second extension to the original 802.11 standard called 802.11a. Because 802.11b gained in popularity much faster than did 802.11a, some folks believe that 802.11a was created after 802.11b. In fact, 802.11a was created at the same time. Due to its higher cost, 802.11a is usually found on business networks whereas 802.11b better serves the home market.

802.11a supports bandwidth up to 54 Mbps and signals in a regulated frequency spectrum around 5 GHz. This higher frequency compared to 802.11b shortens the range of 802.11a networks. The higher frequency also means 802.11a signals have more difficulty penetrating walls and other obstructions.

Because 802.11a and 802.11b utilize different frequencies, the two technologies are incompatible with each other. Some vendors offer hybrid 802.11a/b network gear, but these products merely implement the two standards side by side (each connected devices must use one or the other).

* Pros of 802.11a – fast maximum speed; regulated frequencies prevent signal interference from other devices
* Cons of 802.11a – highest cost; shorter range signal that is more easily obstructed

802.11g
In 2002 and 2003, WLAN products supporting a newer standard called 802.11g emerged on the market. 802.11g attempts to combine the best of both 802.11a and 802.11b. 802.11g supports bandwidth up to 54 Mbps, and it uses the 2.4 Ghz frequency for greater range. 802.11g is backwards compatible with 802.11b, meaning that 802.11g access points will work with 802.11b wireless network adapters and vice versa.

* Pros of 802.11g – fast maximum speed; signal range is good and not easily obstructed
* Cons of 802.11g – costs more than 802.11b; appliances may interfere on the unregulated signal frequency

802.11n
The newest IEEE standard in the Wi-Fi category is 802.11n. It was designed to improve on 802.11g in the amount of bandwidth supported by utilizing multiple wireless signals and antennas (called MIMO technology) instead of one.

When this standard is finalized, 802.11n connections should support data rates of over 100 Mbps. 802.11n also offers somewhat better range over earlier Wi-Fi standards due to its increased signal intensity. 802.11n equipment will be backward compatible with 802.11g gear.

* Pros of 802.11n – fastest maximum speed and best signal range; more resistant to signal interference from outside sources
* Cons of 802.11n – standard is not yet finalized; costs more than 802.11g; the use of multiple signals may greatly interfere with nearby 802.11b/g based networks.

What About Bluetooth and the Rest?
Aside from these four general-purpose Wi-Fi standards, several other related wireless network technologies exist.

* Other IEEE 802.11 working group standards like 802.11h and 802.11j are extensions or offshoots of Wi-Fi technology that each serve a very specific purpose.

* Bluetooth is an alternative wireless network technology that followed a different development path than the 802.11 family. Bluetooth supports a very short range (approximately 10 meters) and relatively low bandwidth (1-3 Mbps in practice) designed for low-power network devices like handhelds. The low manufacturing cost of Bluetooth hardware also appeals to industry vendors. You can readily find Bluetooth in the netowrking of PDAs or cell phones with PCs, but it is rarely used for general-purpose WLAN networking due to the range and speed considerations.

* WiMax also was developed separately from Wi-Fi. WiMax is designed for long-range networking (spanning miles or kilometers) as opposed to local area wireless networking.

The following IEEE 802.11 standards exist or are in development to support the creation of technologies for wireless local area networking:

* 802.11a – 54 Mbps standard, 5 GHz signaling (ratified 1999)
* 802.11b – 11 Mbps standard, 2.4 GHz signaling (1999)
* 802.11c – operation of bridge connections (moved to 802.1D)
* 802.11d – worldwide compliance with regulations for use of wireless signal spectrum (2001)
* 802.11e – Quality of Service (QoS) support (not yet ratified)
* 802.11F – Inter-Access Point Protocol recommendation for communication between access points to support roaming clients (2003)
* 802.11g – 54 Mbps standard, 2.4 GHz signaling (2003)
* 802.11h – enhanced version of 802.11a to support European regulatory requirements (2003)
* 802.11i – security improvements for the 802.11 family (2004)
* 802.11j – enhancements to 5 GHz signaling to support Japan regulatory requirements (2004)
* 802.11k – WLAN system management (in progress)
* 802.11l – skipped to avoid confusion with 802.11i
* 802.11m – maintenance of 802.11 family documentation
* 802.11n – 100+ Mbps standard improvements over 802.11g (in progress)
* 802.11o – skipped
* 802.11p – Wireless Access for the Vehicular Environment
* 802.11q – skipped
* 802.11r – fast roaming support via Basic Service Set transitions
* 802.11s – ESS mesh networking for access points
* 802.11T – Wireless Performance Prediction – recommendation for testing standards and metrics
* 802.11u – internetworking with 3G / cellular and other forms of external networks
* 802.11v – wireless network management / device configuration
* 802.11w – Protected Management Frames security enhancement
* 802.11x – skipped (generic name for the 802.11 family)
* 802.11y – Contention Based Protocol for interference avoidance

The Official IEEE 802.11 Working Group Project Timelines page is published by IEEE to indicate the status of each of the networking standards under development.

source: http://compnetworking.about.com/cs/wireless80211/a/aa80211standard.htm

A network router is a small electronic device that allows you build a home network simply. The home router serves as the core or “centerpiece” of the network to which computers, printers and other devices can be connected. Networking with a router helps you to (for example):

* share files between computers
* share an Internet connection between computers
* share a printer
* connect your game console or other home entertainment equipment to the Internet

Routers are not necessarily required to build a network. For example, you can connect two computers directly to each other with just a cable (or without wires in some cases). Home routers offer convenience and easier maintenance as your network grows.

Choosing a Network Router
You can choose from among several different types of home network router products. The two most common types in popular usage are the 802.11b and 802.11g WiFi models. 802.11g is the newer technology, but 802.11b routers often can do the job for an even lower cost.

Installing a Network Router
Network routers receive their power from an ordinary home electrical socket. When powered on, lights (LEDs) signify the unit is operating.

Network routers must be carefully configured when they are first installed. Like computers and other devices on the home network, routers must be set up with IP addresses. Routers also offer optional (but strongly recommended) security features.

Routers contain built-in software to enable setup. You access this software through your Web browser on any computer connected to the router.

Connecting Computers to a Router
The most basic use of a network router involves file sharing (copying files) between multiple computers. You do not technically need a router to set up file sharing (or a home network), but using a router greatly simplifies the task, especially when three or more computers are involved.

Home routers provide connection points (called “ports” or “jacks”) for you to connect computers with Ethernet cables. Plug one end of the cable into the router and the other into the computer’s Ethernet network adapter. Wireless routers alternatively allow computers to connect via WiFi technology, if the computer possesses a WiFi network adapter.

Connecting an Internet Modem to the Router

The ability of a network router to share your Internet connection throughout the residence is a key selling point of these boxes. Internet connection sharing can be set up without a router using alternative methods, but once again, having a router greatly simplifies the task.

To use your router for Internet sharing, connect your Internet modem to the appropropriate router jack designed for this purpose. Many network routers allow broadband modems to be connected with either a USB cable or an Ethernet cable. A few network routers even allow traditional dialup modems to be connected via serial cables to a built-in serial port.
Connecting a Printer to the Router
Sharing one printer between multiple home computers is often desired but surprisingly difficult to achieve. Without a router, people connect their printer to one computer designated as the printer host. This host computer must be specially configured, and it must also be operating whenever anyone needs to use the printer. Moving this responsibility from a host computer to a router makes both network setup and using the printer easier.

Normally you can connect your printer to the router using a USB cable or a USB-to-Ethernet cable. Alternatively, wireless print server hardware also exists. A print server connects to your printer’s USB jack and in turn makes a WiFi connection to a wireless router. A few routers contain built-in print server capabilitity, providing a built-in parallel port for cabling a printer directly.
Connecting Home Entertainment Equipment to the Router
You can connect games consoles such as Xbox, set-top devices like TiVo, and other home entertainment equipment to network routers. Networking home entertaining equipment with a router allows these devices to reach the Internet when you have Internet sharing in place there.

Wireless game adapters (also known as wireless bridges) make WiFi connections and USB-to-Ethernet cables make cabled connections to the router for this type of equipment.
Other Uses of a Network Router
A few other types of devices can be added to a network router for special-purpose applications. Video surveillance cameras, for example, can be connected to a router to allow real-time viewing of video feeds from any computer on the home network (or even remotely over the Internet). VoIP analog terminal adapters (ATAs) will often be connected to routers for enabling Internet VoIP call services.

In WiFi networks, routers can be joined with other devices (called range extenders or signal boosters) that increase the overall reach (range) of the wireless signal. Some people do this to share their home network with a neighbor. Wireless routers can sometimes be connected to each other for a similar purpose, but care must be taken to avoid conflicts or interference between the two devices.

source: http://compnetworking.about.com/od/homenetworking/a/routernetworks.htm

We just purchased a second computer and now we’d like to share the printer and Internet connection between them. How do I set up a simple home network?”

As society and technology change, it’s becoming common for homes to have more than one computer. When an existing computer is a few years old, parents will often take advantage of today’s lower prices, purchase a new computer, and pass the old one down to the kids.

Suddenly, there’s a need for a home network, so all computers in the house can share an files, printers and an Internet connection.

Fortunately, setting up a basic home network is not rocket science. To start, you’ll need a router which becomes the central point of your network. Most office and electronics stores offer home networking kits with a router, ethernet (network) adapters and CAT-5 networking cable.

If your computer was assembled in the past five years, it probably already has an ethernet adapter. Check the back of the system unit for a port that looks like a telephone jack, but slightly bigger.

If you don’t have an ethernet adapter, you can purchase one (about $20) and install it yourself. You can also use a special ethernet adapter that plugs into a USB port, if you can’t stand the thought of opening your system unit to install an ethernet adapter.

Wired or Wireless Networking?

You’ll need to connect each of your computers to the router with a cable, or go wireless. If you want to use wireless connections, you’ll need a wireless router and a wireless adapter for each computer. Most laptops have a wireless adapter built in, most desktop models do not. If you need a wireless adapter, you can purchase one that installs inside the system unit, or get a USB-style adapter.

Having a wireless network eliminates the need to string unsightly cables all around the house, but it can also create a security risk. Wireless networks are often configured by default to allow access to any computer that attempts to connect. So an Evil Hacker driving by with a laptop (or even your neighbor) might be able to tap into your Internet connection or poke around your hard disk.

Fortunately, wireless security encryption is easy to set up. See my article Wireless Security for step-by-step instructions.
Network Configuration

Whether the network signals travel through wires or through the air, network resources must still be shared so that other computers can access them. If you are running Windows XP or MacOS X, all you have to do is connect your computers and high-speed modem to the router, and Internet connection sharing should just work like magic. If not, restart the cable modem, router, and the computers (in that order) and see if that does the trick. If you can’t access the Internet from one or more computers on the network, consult the manual that came with your router.

One nice side benefit of having a router is that they have firewalls built in to the hardware. Firewalls protect you by hiding your computers from network attacks, but still allow you to surf the web and handle email. So after installing a router, you can turn OFF the Windows firewall and any other software-based firewalls you may have running.
Sharing Files and Printers

Sharing files and printers on a Windows network is also pretty painless. To share a printer, go into the Printers section of the Control Panel, right-click the icon for the printer that needs to be shared, and choose Sharing from the resulting menu. By assigning a name to the shared printer, the owner allows other
computers on the network to access the printer by browsing using their Network Neighborhood (or My Network Places) icons. Access can be restricted to only some computers or users through the use of the Security or Permissions options on the Sharing screen.

The same concept applies for shared file and folders on a network. For example, if you want to share a collection of MP3 files on a home network, just browse to the folder using the My Computer icon, right-click the folder name and choose Sharing. After assigning a name to the shared resource and setting Permissions other computers on the network can access that resource via Network Neighborhood or My Network Places.

source: http://askbobrankin.com/home_networking.html