How Bluetooth Works

Bluetooth devices will normally operate at 2.4 GHZ in the license free, globally available ISM radio band. The advantage to this band includes worldwide availability and compatibility. A disadvantage to this however, is that the devices must share this band with other RF emitters. This includes automobile security systems, other wireless devices, and other noise sources, such as microwaves.

To overcome this challenge, Bluetooth employs a fast frequency hopping scheme and therefore uses shorter packets than other standards within the ISM band. This scheme helps to make Bluetooth communication more robust and more secure.

Frequency hopping

Frequency hopping is basically jumping from frequency to frequency within the ISM radio band. After a bluetooth device sends or receives a packet, it and the device (or devices) it's communicating with hop to another frequency before the next packet is sent. This scheme offers three advantages:

1. Allows Bluetooth devices to use the entirety of the available ISM band, while never transmitting from a fixed frequency for more than a short period of time. This helps insure that Bluetooth conforms to the ISM restrictions on the transmission quantity per frequency.

2. Ensures that any interference won't last long. Any packet that doesn't arrive safely to its destination can be resent to the next frequency.

3. Provides a base level of security as it's very hard for an eavesdropping device to predict which frequency the Bluetooth devices will use next.

The connected devices however, must agree upon the frequency they will use next. The specification in Bluetooth ensures this in two ways. First, it defines a master and slave type relationship between bluetooth devices. Next, it specifies an algorithm that uses device specific information when calculating the frequency hop sequences.

A Bluetooth device that operates in master mode can communicate with up to seven devices that are set in slave mode. To each of the slaves, the master Bluetooth device will send its own unique address and the value of its own internal clock. The information sent is then used to calculate the frequency hop sequences.

Because the master device and each of the slave devices use the same algorithm with the same initial input, the connected devices will always arrive together at the next frequency that they have agreed upon.

As a replacement for cable technology, it's no wonder that Bluetooth devices are usually battery powered, such as wireless mice and battery powered cell phones. To conserve the power, most devices operate in low power. This helps to give Bluetooth devices a range of around 5 - 10 meters.

This range is far enough for wireless communication but close enough to avoid drawing too much power from the power source of the device.

What Is An Intranet? Definition and Uses...

An intranet is basically a private web based network. It uses all of the technology of the internet but is safe and protected behind a firewall that keeps unauthorized personnel out. Companies have been using them for years as a method of streamlining their internal communications.
Because a web browser can run on any type of computer, the need to maintain multiple paper copies of documents that are constantly changing can be eliminated. Documents like training manuals, internal phone books, procedure manuals, benefits information, employee handbooks, requisition forms, etc. can be maintained as electronic documents and updated at almost no cost. The savings in paper and other material costs can be significant, but the most powerful aspect of an intranet is its ability to display information in the same format to every computer being used. That allows all of the different software and databases a company uses to be available to all employees without any special equipment or software being installed on their systems.

This universal availability of information is sparking an era of collaboration unlike anything ever seen before. The departmental barriers that exist in many companies are slowing breaking down because now colleagues can share information readily using the company intranet.

Options for implementing an intranet

There are a variety of options for setting up an intranet. They include building your own intranet technology, purchasing and installing third-party software, or purchasing access through an extranet ASP. Here is a quick summary of the advantages and disadvantages of each approach:

1. Building it yourselfAdvantages:

Complete control of user interface design; ability to customize level of functionality; integration into internal systems, and direct access to user activity.
Disadvantages: High up-front development cost; requires staff expertise in the development of extranets, commitment of internal staff for 6 months to a year for planning, execution, review and implementation; and an ongoing commitment of internal staff for internal and client support, hosting, maintenance and upgrades.

2. Purchasing/installing third-party softwareAdvantages:

Proven track-record of packaged solution; ability to choose functions and tocustomize user interface, more rapid implementation compared to building it yourself.
Disadvantages: High up-front purchase cost; commitment of internal staff for customization and implementation; on-going commitment of internal staff for internal and client support, hosting, maintenance and upgrades; and extensive internal and client training

3. Using a Service Provider (ASP)Advantages:

Proven track-record of the application; low cost of entry and predictable cost over time; virtually immediate implementation; no commitment of internal staff for internal support, hosting, or maintenance; and upgrades at no cost by extranet experts, and savings on internal server use.
Disadvantages: Less freedom in user interface design, and fixed functionality.

In the final analysis…The approach you choose depends on how you work, the technical and financial resources at your disposal, and how rapidly you need to move forward.

Surfing the Web Anonymously

Whenever you surf the web it is possible to find out information about you even when you do not want to publicize who you are. This is a fact, even if your computer contains no virus or malware software. The information that can be tracked easily include IP address, country, computer system being using, browser, browser history, and other related information. It gets even worse. People can get your computer's name and even find out your name. Also, cookies can track your habits as you move from one computer to another.

How do people get this basic information about you?

When you visit one website to another web site, information about you can be recovered. Basically, information is intercepted and used by others to follow your Internet activities.

How do you stop this from happening?

First of all, it is possible to surf the web anonymously and thereby stop leaving a trail for others to find. Note that this is not fool-proof, but it makes it much harder for people to know who you are. There are some sophisticated products called anonymous proxy servers that help in protecting you. These anonymous proxy servers replace user’s Internet address for its own. This has the effect of hiding your IP address and making it much harder for people to track you.


How do I get an anonymous proxy server?

There are many vendors who sell anonymous proxy servers. There are also free proxy servers available to you. Two such products are ShadowSurf and Guardster. They provide various services for anonymous and secure access to the web, some are paid and some are free as well. They provide anonymous surfing at their site for free. Go to it and you will find a box to enter a URL that you want no one to track. There are many others, but here are two that are frequently used.

Another wonderful product, given the recent news about the Google search engine filtering its findings for the Chinese government, is Anonymizer. This company pressed that it is developing a new anti-censorship solution that will enable Chinese citizens to safely access the entire Internet filter-free

Does an anonymous proxy server make you 100% safe?

No. Still, you are much better off if you use such technology.

What other things should I be concerned about when trying to keep my private information private?

Three other items come to mind when trying to keep your information private. First, you can use an encrypted connection to hide your surfing. Secondly, delete cookies after each session. Third, you can configure your browser to remove JavaScript, Java, and active content. This actually leads to limitations, so you need to think about the cost/benefit of this course of action.