Networking Inside Out

VNC - Virtual Network Computing Basics

2011-07-24T15:16:00.000+05:30

Virtual Network Computing, or "VNC," is software used to connect remotely to a computer system. This allows a user to see and control one computer from multiple locations. Because this control is transmitted over the Internet, the computer can be viewed from anywhere in the world.

VNC software is fairly uncomplicated and easy to use. Many operating systems, including Microsoft Windows, already include simple VNC programs. These applications allow users to connect remotely and operate another computer loaded with the same software.

VNCs allow computers to become remotely sharable. This means that several different users, each in separate locations, can view a computer desktop at the same time. VNC software makes training, monitoring and troubleshooting easy by making remote access flexible.

Most VNC systems are controlled from a simple graphic user interface. Once the software has been installed on a remote computer, it can be accessed from any location. A server constantly monitors inputs and outputs from one computer, and updates them to the second location.

The interface for most VNCs can operate from any operating system, such as Windows, Macintosh, or Unix. Because information is transmitted over the Internet, the system eliminates many of the traditional cross-platform problems. Just as a website can be viewed on many different operating systems, so can VNC control operate from many different computer types. While "VNC" is a generic term for this type of software, many brands of the software exist, with packages available for all major operating systems.

The connection used to interface data is protected by a password. This prevents unauthorized users from controlling a remote computer. Once the connection is established, information begins to be exchanged. Details on mouse location, keyboard entry, and screen updates are fed over the secure connection, keeping the computers synchronized.

VNC software began as a way to monitor and troubleshoot systems remotely, and this feature remains a common use. Computer technicians can provide tech support using VNC without being physically present. If a user is having a problem installing software, for example, a support professional can connect to her computer, see the problem, and talk the user through the solution.

Use of VNC software has also expanded to other areas. Remote work has become an increasingly popular option. VNC allows workers to access and control software without being in the office. For instance, using VNC, a programmer in India can easily control a desktop computer in California, collaborating with colleagues and working on a project remotely.

Overview

VNC consists of two components. A server, which runs on the computer you want to remotely access, and a viewer, which runs on the computer you are sitting in front of. There are two important features of VNC:

The server and the viewer may be on different machines and on types of computer. The protocol which connects the server and viewer is simple, open, and platform independent.
No state is stored at the viewer. Breaking the viewer's connection to the server and then reconnecting will not result in any loss of data. Because the connection can be remade from somewhere else, you have easy mobility.

So to get started with VNC you need to run a server, and then connect to it with a viewer. First of all, you have to download and install the software on the platforms you want to use. The screenshots on this page refer to VNC Free Edition 4.1, but the general concepts apply to all versions of Free Edition and Enterprise Edition.

Networking

VNC software requires a TCP/IP connection between the server and the viewer. This is the standard networking protocol on LANs, WANs, broadband and dialup ISP. Each computer has a unique IP address and may also have a name in the DNS. You will need to know the IP address or name of the server when you connect a viewer to it.
Sometimes the IP address is fixed, and sometimes it is issued to you dynamically by your ISP. If it is allocated dynamically, you might consider using a third party DNS management service. Try typing "dynamic dns management service" into a google.

Running a Windows server

Installing the Windows server, WinVNC, should create a RealVNC group in your Start... menu. Run the VNC server.

If this is the first time you've used a VNC server on this machine you'll be prompted to set a password, which you'll need when you connect to the machine from a remote location. A small icon will appear in the system tray, and by right-clicking on this you can control most aspects of the server.

The IP address of the computer running the VNC server can be found by hovering over the tray icon in the system tray. Unless this computer has a DNS name, you will need to specify this number to the viewer when you connect.

You can now go to another machine and connect a viewer to the server.

Running a Unix server

To X applications, a VNC server appears just like the standard X display you sit in front of, but without a physical screen attached. The applications don't know this, they just carry on running whether or not a viewer is connected. You can start a new VNC server on a Unix machine by typing:

vncserver

If you haven't run a VNC server before you will be prompted for a password, which you will need to use when connecting to this server. All your servers on the same Unix machine will use the same password, and you can change it at a later date using

vncpasswd

With a normal X system, the main X display of a workstation called ’snoopy’ is usually snoopy:0. You can also run as many VNC servers on a Unix machine as you like, and they will appear as snoopy:1, snoopy:2 etc, as if they were just additional displays. Normally vncserver will choose the first available display number and tell you what it is, but you can specify a display number if you always wish to use the same one:

vncserver :2

You can cause applications to use a VNC server rather than the normal X display them by setting the DISPLAY environment variable to the VNC server you want, or by starting the application with the -display option.

For example:

xterm -display snoopy:2 &

You can kill a Unix VNC server using, for example:

vncserver -kill :2

Full instructions for installing and running VNC server for Unix can be found in the RealVNC Site documentation.
Nothing will appear immediately as a result of starting a Unix VNC server. To see anything you need to connect a viewer to the server, see below.

Running a viewer

You can run the Windows viewer the RealVNC group on the Start... menu.

In this case, you will be prompted for the host name (VNC server name) and display number:

Enter it and click OK, and you will be prompted for your password, after which you should see the remote display. If you are connecting to a Windows or Mac server, the display number will be 0 unless you have explicitly changed it, and can be omitted.

You can run the viewer on Unix and Windows by typing at the command line:

vncviewer snoopy:2

You need to specify the name of the VNC server and the number of the desktop. If, for example, you have started a server as display 2 on a machine called 'snoopy'. Remember that if you are connecting to a Windows or Mac server, the display number will be 0 unless you have explicitly changed it, and can be omitted.

If the machine running the server does not have a DNS entry, you probably won't be able to use the name and will have to replace snoopy with its IP address, for example something that looks like 123.456.78.9.

Using a web browser as a viewer

The VNC servers also contain a small web server. If you connect to this with a web browser, you can download the Java version of the viewer, and use this to view the server. You can then see your desktop from any Java-capable browser, unless you are using a proxy to connect to the web. The server listens for HTTP connections on port 5800+display number. So to view display 2 on machine 'snoopy', you would point your web browser at:

http://snoopy:5802/

The applet will prompt you for your password, and should then display the desktop.

How to Safely Remove Linux OS from Dual boot and restoring your MBR ?

2011-07-24T11:56:00.000+05:30

This tutorial explains how to remove linux operating system safely from your Dual boot systems(i.e. windows and linux both are installed on that computer).

Linux operating systems are pretty good. and because they are free and eaisly available we always want to try a new one. But at the sametime we dont want give up our favorite windows operating systems. so we choose to have a dual boot system where we can switch to any of the OS easily. But when we want to remove Linux OS and return to window we come across a problem that windows cant find MBR (Master Boot Record). To overcome this problem we have to restore MBR. To do this just follow these steps:

First of all you need to know where your Linux OS is installed to,i.e. what drive it is currently living on?
Then next thing is to restore that partition used by Linux to windows. To do this:

1.Click Start > Control Panel > Classic View > Administrative Tools > Computer Management.
2.Click Storage > Disk Management.
3.Select the Linux partition, right click and select Delete volume option to delete linux and grub.
Once you have followed this through, you will now have free space.
Once you have formatted the drive, you need to reformat it to your required file system type. either Fat32 or NTFS.
Now the important part is coming up...!!!

Fixing your Master Boot Record to make Windows Bootable again.

1.Boot up with the Windows CD.
2.Restore your Master Boot Record (MBR) by using the following command:
a.If using a Windows 98 CD, boot into command prompt and enter: fdisk /MBR
b.If using Windows 2000, XP, 2003 CD, enter into “Recovery Console” by pressing “R”, and
enter: fixmbr
c.If using Windows Vista, Server 2008, Windows 7 CD, click on “Repair Computer” link, then click on “Command Prompt”.

Navigate to your CD drive by using cd command and
enter: bootsect /nt60 SYS /mbr
3.Exit from the command prompt and press Enter or restart your computer.

There will be no Grub shown and you will directly boot into Windows. This is how you will return to a normal window operating system from a dual boot system.

Thanks...!!!

Cloud Computing - Overview

2011-07-23T12:11:00.002+05:30

An Overview

Cloud computing is a computing paradigm, where a large pool of systems are connected in private or public networks, to provide dynamically scalable infrastructure for application, data and file storage. With the advent of this technology, the cost of computation, application hosting, content storage and delivery is reduced significantly.

Cloud computing is a practical approach to experience direct cost benefits and it has the potential to transform a data center from a capital-intensive set up to a variable priced environment.

The idea of cloud computing is based on a very fundamental principal of „reusability of IT capabilities'. The difference that cloud computing brings compared to traditional concepts of “grid computing”, “distributed computing”, “utility computing”, or “autonomic computing” is to broaden horizons across

organizational boundaries.

Forrester defines cloud computing as:

“A pool of abstracted, highly scalable, and managed compute infrastructure capable of hosting end-customer applications and billed by consumption.”

Figure 1: Conceptual view of cloud computing

Cloud Computing Models

Cloud Providers offer services that can be grouped into three categories.

1 Software as a Service (SaaS): In this model, a complete application is offered to the customer, as a service on demand. A single instance of the service runs on the cloud & multiple end users are serviced. On the customers‟ side, there is no need for upfront investment in servers or software licenses, while for the provider, the costs are lowered, since only a single application needs to be hosted & maintained. Today SaaS is offered by companies such as Google, Salesforce, Microsoft, Zoho, etc.

2 Platform as a Service (Paas): Here, a layer of software, or development environment is encapsulated & offered as a service, upon which other higher levels of service can be built. The

customer has the freedom to build his own applications, which run on the provider‟s

infrastructure. To meet manageability and scalability requirements of the applications, PaaS providers offer a predefined combination of OS and application servers, such as LAMP platform (Linux, Apache, MySql and PHP), restricted J2EE, Ruby etc. Google‟s App Engine, Force.com, etc are some of the popular PaaS examples.

3. Infrastructure as a Service (Iaas): IaaS provides basic storage and computing capabilities as standardized services over the network. Servers, storage systems, networking equipment, data centre space etc. are pooled and made available to handle workloads. The customer would typically deploy his own software on the infrastructure. Some common examples are Amazon, GoGrid, 3 Tera, etc.

Figure 2: Cloud models

Understanding Public and Private Clouds

Enterprises can choose to deploy applications on Public, Private or Hybrid clouds. Cloud Integrators can play a vital part in determining the right cloud path for each organization.

Public Cloud

Public clouds are owned and operated by third parties; they deliver superior economies of scale to customers, as the infrastructure costs are spread among a mix of users, giving each individual client an attractive low-cost, “Pay-as-you-go” model. All customers share the same infrastructure pool with limited configuration, security protections, and availability variances. These are managed and supported by the cloud provider. One of the advantages of a Public cloud is that they may be larger than an enterprises cloud, thus providing the ability to scale seamlessly, on demand.

Private Cloud

Private clouds are built exclusively for a single enterprise. They aim to address concerns on data security and offer greater control, which is typically lacking in a public cloud. There are two variations to a private cloud:

-On-premise Private Cloud: On-premise private clouds, also known as internal clouds are hosted within one‟s own data center. This model provides a more standardized process and protection, but is limited in aspects of size and scalability. IT departments would also need to incur the capital and operational costs for the physical resources. This is best suited for applications which require complete control and configurability of the infrastructure and security.

-Externally hosted Private Cloud: This type of private cloud is hosted externally with a cloud provider, where the provider facilitates an exclusive cloud environment with full guarantee of privacy. This is best suited for enterprises that don‟t prefer a public cloud due to sharing of physical resources.

Hybrid Cloud

Hybrid Clouds combine both public and private cloud models. With a Hybrid Cloud, service providers can utilize 3rd party Cloud Providers in a full or partial manner thus increasing the flexibility of computing. The Hybrid cloud environment is capable of providing on-demand, externally provisioned scale. The ability to augment a private cloud with the resources of a public cloud can be used to manage any unexpected surges in workload.

Cloud Computing Benefits

Enterprises would need to align their applications, so as to exploit the architecture models that Cloud Computing offers. Some of the typical benefits are listed below:

1. Reduced Cost

There are a number of reasons to attribute Cloud technology with lower costs. The billing model is pay as per usage; the infrastructure is not purchased thus lowering maintenance. Initial expense and recurring expenses are much lower than traditional computing.

2. Increased Storage

With the massive Infrastructure that is offered by Cloud providers today, storage & maintenance of large volumes of data is a reality. Sudden workload spikes are also managed effectively & efficiently, since the cloud can scale dynamically.

3. Flexibility

This is an extremely important characteristic. With enterprises having to adapt, even more rapidly, to changing business conditions, speed to deliver is critical. Cloud computing stresses on getting applications to market very quickly, by using the most appropriate building blocks necessary for deployment.

Cloud Computing Challenges

Despite its growing influence, concerns regarding cloud computing still remain. In our opinion, the benefits outweigh the drawbacks and the model is worth exploring. Some common challenges are:

1. Data Protection

Data Security is a crucial element that warrants scrutiny. Enterprises are reluctant to buy an assurance of business data security from vendors. They fear losing data to competition and the data confidentiality of consumers. In many instances, the actual storage location is not disclosed, adding onto the security concerns of enterprises. In the existing models, firewalls across data centers (owned by enterprises) protect this sensitive information. In the cloud model, Service providers are responsible for maintaining data security and enterprises would have to rely on them.

2. Data Recovery and Availability

All business applications have Service level agreements that are stringently followed. Operational teams play a key role in management of service level agreements and runtime governance of applications. In production environments, operational teams support

· Appropriate clustering and Fail over

· Data Replication

· System monitoring (Transactions monitoring, logs monitoring and others)

· Maintenance (Runtime Governance)

· Disaster recovery

· Capacity and performance management

If, any of the above mentioned services is under-served by a cloud provider, the damage & impact could be severe.

3. Management Capabilities

Despite there being multiple cloud providers, the management of platform and infrastructure is still in its infancy. Features like „Auto-scaling‟ for example, are a crucial requirement for many enterprises. There is huge potential to improve on the scalability and load balancing features provided today.

4. Regulatory and Compliance Restrictions

In some of the European countries, Government regulations do not allow customer's personal information and other sensitive information to be physically located outside the state or country. In order to meet such requirements, cloud providers need to setup a data center or a storage site exclusively within the country to comply with regulations. Having such an infrastructure may not always be feasible and is a big challenge for cloud providers.

With cloud computing, the action moves to the interface — that is, to the interface between service suppliers and multiple groups of service consumers. Cloud services will demand expertise in distributed services, procurement, risk assessment and service negotiation — areas that many enterprises are only modestly equipped to handle.

How to set up your home wireless network

2011-07-23T11:53:00.000+05:30

You can use a wireless network (WLAN) to share Internet access, files, printers, game consoles, and other devices among all the computers in your home. After you’ve completed the initial wireless router setup and added your computers and devices to the network, you can use your home network to surf the web or to play online games—whether you're sitting in your living room or relaxing in your backyard.

It's easier than ever to set up a wireless network, especially now that Internet access and routers (like Linksys wireless routers and D-link wireless routers) have become widely available.

What you’ll need to set up your wireless network

An operating system that supports wireless networking
The Windows 7 operating system fully supports wireless networking. For Windows Vista users, we recommend installing Windows Vista Service Pack 2 before setting up your wireless network. For Windows XP users, we recommend installing Windows XP Service Pack 3. Use Windows Update to check whether you need the service pack and to install it. Click the Start button, click All Programs, click Windows Update, and then click Check for updates. Although the service packs for Windows Vista and Windows XP are not required for wireless networking, they can make things much easier and can help protect you against hackers, worms, and other Internet intruders.
A broadband (DSL or cable) Internet connection
To set up a wireless network, you need a broadband or high-speed Internet connection (not a dial-up connection) provided by an Internet service provider (ISP), usually for a monthly fee. Two common broadband technologies are Digital Subscriber Line (DSL) and cable technology. These require a DSL modem or a cable modem (often provided by your ISP). After you have an ISP and a modem, you're ready to connect to the Internet.

Set up a new connection to the Internet:
- Windows 7 and Windows Vista
- Windows XP
A wireless router, a DSL modem, or a cable modem with built-in wireless networking support
The router converts the signals coming across your Internet connection into a wireless broadcast, sort of like a cordless phone base station. Newer DSL and cable modems come with integrated wireless networking capability and are called modem routers. If the modem router you received or purchased from your ISP already has wireless capability built in, you do not need to purchase a separate wireless router. Just follow the instructions provided by your ISP for activating your wireless connection.

If you do need to purchase a wireless router, be sure that you buy a wireless router and not a wireless access point. The Linksys router is a popular router for wireless networks because it’s simple to set up. There are many routers to choose from, for example:

Linksys wireless D-Link wireless Cisco wireless ASUS wireless routers

While you're looking for a wireless router or other wireless equipment in stores or on the Internet, you might notice that you can choose equipment that supports four different wireless networking technologies: 802.11a, 802.11b, 802.11g, and 802.11n. We recommend 802.11g (Wireless-G) or 802.11n (Wireless-N) because they offer excellent performance and are compatible with almost everything.

NOTE: If you do not want to buy a wireless router or if you want to connect computers or devices temporarily for a specific purpose, like sharing devices or games, you can set up a temporary wireless network without a router. This is called an ad hoc network.

Set up an ad hoc network:
A computer with built-in wireless networking support or a wireless network adapter
If you have a newer computer, you may already have built-in wireless capabilities. If this is the case, you don’t need a wireless network adapter. Here’s how to check whether your computer has wireless support installed:

Windows 7 and Windows Vista
- Click Start, click Control Panel, and then click Network and Internet. If you see any of these words listed, “Wireless,” “WLAN,” “Wi-Fi,” “802.11a,” “802.11b,” “802.11g,” or “802.11n,” your computer has wireless capability installed.
Windows XP
1. Click Start, right-click My Computer, and then click Properties
2. In the System Properties window, click the Hardware tab.
3. Near the top of this window, click the Device Manager button.
4. In the Device Manager window, there is a list of hardware components which are installed on the computer. Press the Plus sign (+) to the left of the icon to open the Network adapters item in the list. The Network adapters section of the window expands to reveal a list of all network adapters installed on the computer.
5. If you see any of these words in the list of installed network adapters, “Wireless,” “WLAN,” “Wi-Fi,” “802.11a,” “802.11b,” “802.11g,” or “802.11n,” your computer has wireless network support installed.
If your desktop or laptop computer does not have built-in wireless support, you need to purchase a network adapter to wirelessly connect your computer to your wireless router. If you need an adapter for a desktop computer, buy a USB wireless network adapter. If you have a laptop, buy a PC card-based network adapter. Make sure that you have one adapter for every computer on your network.

NOTE: To make setup easy, choose a network adapter made by the same vendor that made your wireless router. For example, if you find a good price on a Linksys router, choose a Linksys network adapter to go with it. To make shopping even easier, buy a bundle, such as those available from Linksys, Actiontec, D-Link, Netgear, Microsoft, and Buffalo. If you have a desktop computer, make sure that you have an available USB port where you can plug in the wireless network adapter. If you don't have any open USB ports, buy a USB hub to add additional ports.
A copy of your router setup instructions
Before you begin setting up your wireless network, it’s a good idea to make sure that you have the copy of the setup instructions provided by the router manufacturer or your ISP. If you do not have a copy, visit the manufacturer’s website for get instructions on how to set up your router. All routers vary, and you may need to consult the instructions to set up your wireless network using your specific router.



Linksys wireless	D-Link wireless	Cisco wireless	ASUS wireless routers

1. Connect to the Internet

Make sure that your Internet connection and your DSL or cable modem are working. Your wireless network depends on this connection.

2. Connect your wireless router

These are the steps for connecting a stand-alone wireless router to your DSL modem or cable modem. If you have a modem router, follow your ISP’s instructions for connecting your network.
Since you'll be temporarily disconnected from the Internet, print these instructions before you go any further.
First, locate your cable modem or DSL modem and unplug it to turn it off.
Next, connect your wireless router to your modem. Your modem should stay connected directly to the Internet. Later, after you've hooked everything up, your computer will wirelessly connect to your router, and the router will send communications through your modem to the Internet.
Next, connect your router to your modem:

Note: The instructions below apply to a Linksys wireless router. The ports on your router may be labeled differently, and the images may look different on your router. Check the documentation that came with your equipment for additional assistance. Or do a Bing search on “[your manufacturer/model] wireless router setup” to find images and instructions.

If you currently have your computer connected directly to your modem: Unplug the network cable from the back of your computer, and plug it into the port labeled Internet, WAN, or WLAN on the back of your router.
If you do not currently have a computer connected to the Internet: Plug one end of a network cable (included with your router) into your modem, and plug the other end of the network cable into the Internet, WAN, or WLAN port on your wireless router.
If you currently have your computer connected to a router: Unplug the network cable connected to the Internet, WAN, or WLAN port from your current router, and plug this end of the cable into the Internet, WAN, or WLAN port on your wireless router. Then, unplug any other network cables, and plug them into the available ports on your wireless router. You no longer need your original router, because your new wireless router replaces it.

Next, plug in and turn on your cable or DSL modem. Wait a few minutes to give it time to connect to the Internet, and then plug in and turn on your wireless router. After a minute, the Internet, WAN, or WLAN light on your wireless router should light up, indicating that it has successfully connected to your modem.

3. Configure your wireless router

Using the network cable that came with your wireless router, you should temporarily connect your computer to one of the open network ports on your wireless router (any port that isn't labeled Internet, WAN, or WLAN). If you need to, turn your computer on. It should automatically connect to your router.

Next, open Internet Explorer and type in the URL or address to configure your router.

NOTE: Do this on the computer that you are using to set up your wireless network. The computer automatically links you to the router’s page. If you type the router’s URL on a different computer, typing the address in the navigation bar will not take you to your router’s configuration page.

On the router configuration page, you might be prompted for a password. The address and password you use varies depending on what type of router you have, so refer to the instructions included with your router or on the manufacturer’s website.

For quick reference, this table shows the default addresses, user names, and passwords for some common router manufacturers. If the address is not listed here, you can read the documentation that came with your router or go to the manufacturer's webpage to find it. There may be multiple website addresses you can use.

Router	Address	Username	Password
3Com	http://192.168.1.1	admin	admin
D-Link	http://192.168.0.1	admin	admin
Linksys	http://192.168.1.1	admin	admin
Microsoft Broadband	http://192.168.2.1	admin	admin
Netgear	http://192.168.0.1	admin	password
Actiontec	http://192.168.0.1	username	password

Internet Explorer shows your router's configuration page, along with the modem IP address and other information. Most of the default settings should be fine, but you need to configure three things:

Your wireless network name, known as the SSID. This name identifies your network, and it appears in a list of available wireless networks. You should change the default SSID that your ISP provided and give your network a unique name that none of your neighbors are using. This helps you identify your network, and it can help keep your wireless network secure by preventing it from overlapping with other wireless networks that might be using the default SSID.
Wi-Fi Protected Access (WPA or WPA2), which can help protect your wireless network. It’s important to help secure your wireless network by setting up a network security key, which turns on encryption. With encryption, people can't connect to your network without the security key, and all information sent across your network is encrypted so that only computers with the key to decrypt the information can read it. This can help prevent attempts to access your network and files without your permission. Wi Fi Protected Access (WPA or WPA2) is the recommended wireless network encryption method. Wireless encryption (WEP) is not as secure. Windows 7, Windows Vista Service Pack 2, and Windows XP Service Pack 3 support WPA2.

When you set up most routers (stand-alone routers and modem routers), you are asked to provide a pass phrase that the router uses to generate several keys. Make sure that your pass phrase is unique and long (you don't need to memorize it). Some routers and modem routers now come with a function called Quick Security Setup (or QSS) that automatically issues you a key when you press a button on the router.

Be sure to keep a hard copy and a digital copy of your network security key and pass phrase, in case you lose or misplace them. You can recover a lost network key or reset it on your router, but these are complicated processes that are different for every router and they sometimes entail setting up your network again.
Your administrative password, which controls your wireless network. Just like any other password, it should not be a word that you can find in the dictionary, and it should be a combination of letters, numbers, and symbols. Be sure to save a hard copy and a digital copy of this password, too, because you'll need it if you ever have to change your router's settings.

The exact steps you follow to configure these settings will vary depending on the type of router you have. After each configuration setting, be sure to click Save Settings, Apply, or OK to save your changes.

Now, before connecting your computers and devices to the network, you should disconnect the wireless network cable from your computer.

4. Connect your computers, printers, and other devices to the wireless network

You can connect multiple computers, printers, and many other peripheral devices, such as an Xbox, Xbox 360, TV, cell phone, iTouch, or iPad, to your network. Before you connect them to your network, make sure that the computer or device you want to add has built-in wireless networking or a network adapter. Many newer devices have built-in wireless capability. If the computer or device you want to add does not have built-in wireless network support, plug the network adapter into your USB port and place the antenna on top of your computer (in the case of a desktop computer) or insert the network adapter into an empty PC card slot (in the case of a laptop). Windows automatically detects the new adapter and may prompt you to insert the CD that came with your adapter. The on-screen instructions guide you through the configuration process.
Use the following links to find step-by-step instructions for adding your specific computer or device to your network using your operating system. There are instructions for each operating system, and they show you how to automatically or manually add wired (Ethernet) or wireless computers and how to add computers running Windows 7, Windows Vista, or Windows XP. There are also instructions for adding printers and both wired and wireless devices.

5. Share files, printers, and more

Now that your computers and devices are connected, you can begin sharing files, printers, games, and much more. One of the top reasons for setting up a home network is to share a printer. Another is to share files. The steps for doing this, however, aren’t always obvious, so here are instructions to get you started:

Share a printer

Share files

Types of Wireless Network Security methods

2011-07-23T11:30:00.000+05:30

If you plan to have a wireless network, you should set it up so that only people you choose can access it. Here are a few options for wireless network security.

Wi‑Fi Protected Access (WPA)

WPA encrypts information, and it also checks to make sure that the network security key has not been modified. WPA also authenticates users to help ensure that only authorized people can access the network.

There are two types of WPA authentication: WPA and WPA2. WPA is designed to work with all wireless network adapters, but it might not work with older routers or access points. WPA2 is more secure than WPA, but it will not work with some older network adapters. WPA is designed to be used with an 802.1X authentication server, which distributes different keys to each user. This is referred to as WPA-Enterprise or WPA2-Enterprise. It can also be used in a pre-shared key (PSK) mode, where every user is given the same passphrase. This is referred to as WPA-Personal or WPA2-Personal.

Wired Equivalent Privacy (WEP)

WEP is an older network security method that is still available to support older devices, but it is no longer recommended. When you enable WEP, you set up a network security key. This key encrypts the information that one computer sends to another computer across your network. However, WEP security is relatively easy to crack.

Warning

We don't recommend using WEP. WPA or WPA2 are more secure. If you try WPA or WPA2 and they don't work, we recommend that you upgrade your network adapter to one that works with WPA or WPA2.

802.1X authentication

802.1X authentication can help enhance security for 802.11 wireless networks and wired Ethernet networks. 802.1X uses an authentication server to validate users and provide network access. On wireless networks, 802.1X can work with Wired Equivalent Privacy (WEP) or Wi‑Fi Protected Access (WPA) keys. This type of authentication is typically used when connecting to a workplace network.

Basics of Connecting and Setting Up a Wireless Home Network

2011-07-23T11:26:00.000+05:30

Having Internet access at home is convenient, but wouldn't it feel good to relax on the couch while you check your bank account balance or shop online? At the same time, your daughter could research that book report on her computer while using the same wireless network connection that you're using. When you set up a wireless home network, it's all possible—and it's a lot easier than you might think.

What is a wireless home network?

A home network is simply two or more computers in your home that are connected to each other and can share files, printers, and your Internet connection. In a wireless network, the computers are connected by radio signals instead of wires or cables, which is perfect for mobile PCs: notebooks, Tablet PCs, and ultra-mobile PCs.

A wireless home network

The good news is that having a computer network in your home is no longer as expensive or as hard to set up as it once was. In just an afternoon, you can make viewing your bank account or researching that book report from anywhere in the house a comfortable and convenient reality.

The right equipment

Before you can set up your wireless home network, you need the following things:

Broadband connection and modem
Wireless network adapters and a wireless router

Broadband connection and modem

A broadband connection is a high-speed Internet connection, in contrast to a dial-up connection, which is slower and is not powerful enough for a wireless home network. There are different types of broadband connections. DSL and cable are two of the most common ones. You can get a broadband connection by contacting an Internet service provider (ISP) that offers broadband service. ISPs often provide the broadband modem as well, and may even install it for you.
After you have a broadband connection and modem, you can get the rest of the hardware that you need for your wireless home network.

Wireless network adapters and a wireless router

A network adapter is a hardware device that connects your computer to a network. Most mobile PCs—and many desktop computers—come with a wireless network adapter already installed. You can check each of your computers yourself to see whether they have wireless network adapters. Here's how to determine whether a computer has a wireless network adapter:

Click the Start button , click Control Panel, click System and Maintenance, and then click System.
In the left pane, click Device Manager.
Next to Network adapters, click the plus sign (+).
Look for a network adapter that includes "wireless" in the name.

If one or more of your computers needs a wireless network adapter, you can purchase it from a store that sells computer accessories, and then install it yourself.
If you do need to buy wireless network adapters, it's a good idea to get the same brand as the wireless router that you buy. Hardware from the same manufacturer often works better together than hardware from different manufacturers. For more information, see Wireless networking: frequently asked questions in Windows Help and How-to.

Where to put your wireless router

Follow these tips for placing your wireless router in an area that will give you the strongest signal strength and best connection.

Position your wireless router in a central location. Avoid placing your router next to an outside wall of your home. Most router antennas are omni-directional. This means that the signal radiates from the antenna in all directions equally. Place the router as close to the center of your home as you can to increase the strength of your wireless signal throughout your home.
Move the wireless router off of the floor and away from walls and metal objects, such as metal file cabinets. Putting your router on the floor, or next to walls or metal objects, can diminish the signal strength, because the router's signal is broadcast in the shape of a sphere. The fewer physical obstructions between your computer and the router's signal, the more likely that you'll be using the router's full signal strength. This means a stronger Internet connection from greater distances in your home. For more information, see 10 tips for improving your wireless network.
Reduce wireless interference. Your cordless phone or other wireless electronics are sending signals, too. If they're close together, they may interfere with each other. You can help prevent interference by changing the location of your cordless phone base station, changing the frequency channel on your wireless router, or avoiding wireless electronics that use the 2.4-gigahertz (GHz) frequency. If you have trouble reducing the amount of wireless interference, look for cordless phones and other wireless electronics that use the 5.8-GHz or 900-megahertz frequencies.
Upgrade 802.11b devices to 802.11g. The 802.11g standard is the high-bandwidth successor to 802.11b, and it's nearly five times faster. This increased speed is noticeable if you're sending information from one computer to another on your home network—for example, sending pictures from your mobile PC to your desktop computer—however, it's not as evident when you're simply accessing the Internet. If you're adding a computer to an existing network, you may want to upgrade the other components to 802.11g at the same time.

After you purchase all of the pieces, you have your broadband connection, and you know where you're going to place your wireless router, you're ready to put together your wireless home network. Follow the instructions that came with your router and network adapters, and then activate your router—set the user name, password, and IP address—according to the instructions from your ISP.

Help protect your network

After you set up your home wireless network—but before you connect to the Internet—it's time to help protect it with a few security measures: a network security key, wireless router security, and firewalls.

Network security key

Just as file cabinets have keys and safes have combinations, wireless networks have a network security key, a password that can help protect wireless networks from unauthorized access. Because wireless networks can be seen by outsiders who can pick up the signal, you need to protect your personal information and files.
To establish a network security key, simply run the Set up a wireless router or access point wizard, which makes your network private by issuing a network security key. The wizard also helps you configure a wireless router or access point, set up file and printer sharing, and connect other computers and devices to your network. Here's how to run the Set up a wireless router or access point wizard:

Click the Start button , click Control Panel, click Network and Internet, and then click Network and Sharing Center.
In the left pane, click Set up a connection or network.
In the Choose a connection dialog box, click Set up a wireless router or access point, and then click Next.

Wireless router security

There are two additional methods of securing your wireless network: Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA).
WEP is a basic security measure that comes standard with most routers. It helps to protect your wireless network from unauthorized access by requiring users to enter a network security key before connecting to the network.
WPA is a more robust security measure than WEP because, rather than simply requiring a network security key to access the network, it provides user authentication so that hackers are less likely to gain access to your network. However, WPA doesn't come standard on some routers. For more information about WPA, see your router manufacturer's website.
For more information, see Making your network more secure in Windows Help and How-to.

Firewalls

A firewall is hardware or software that can help protect your computer from hackers or malicious software, which is software designed to deliberately harm your computer (for example, viruses, worms, and Trojan horses). Running a firewall on each computer on your home network can help control the spread of malicious software on your network, as well as help to protect your computers when you're accessing the Internet on public networks, such as your local Internet café. For more information, see Firewall: frequently asked questions in Windows Help and How-to.

A firewall can help protect a computer

For additional protection, some new routers come with a built-in Stateful Packet Inspection (SPI) firewall, which analyzes and filters out malicious data before it can access your network. For more information, see your router manufacturer's website.

Relax, that's all there is to do

Setting up a home network is not difficult, but sometimes the occasional hiccup occurs. If you need help, check the instructions that came with your hardware or search Windows Help and How-to for more information. Set aside enough time so that you don't feel rushed. In just a little while, you and your family will be sharing your Internet connection—and you'll be doing your online shopping from the comfort of your couch or the convenience of your dining room table or patio.

CCNA INTRO: Introduction to Cisco Networking Technologies Study Guide: Exam 640-821

2011-07-16T09:53:00.000+05:30

From bestselling author Todd Lammle comes the most up-to-date book on CCNA exam 640-821, the first exam in Cisco's popular two-exam Cisco Certified Network Associate (CCNA) certification track. Understand networking for the small or home office market, prepare for the exam, and acquire the skills you need with this comprehensive guide.
Inside you'll find:
Complete coverage of all exam objectives in a systematic approach, so you can be confident you're getting the instruction you need Practical hands-on exercises to reinforce critical skills
Real-world scenarios that show you life beyond the classroom and put what you've learned in the context of actual job roles Challenging review questions in each chapter to prepare you for exam day Exam Essentials, a key feature at the end of each chapter that identifies critical areas you must become proficient in before taking exam 640-821 A handy tear card that maps every official exam objective to the corresponding chapter in the book, so you can track your exam prep objective by objective Look inside for complete coverage of all exam objectives.

Download:
Depositfiles
Or
Link_3

IPv6 - Definition

2011-07-13T08:59:00.002+05:30

IPv6 is the next generation protocol for Internet networking. IPv6 expands on the current Internet Protocol standard known as IPv4. Compared to IPv4, IPv6 offers better addressing, security and other features to support large worldwide networks.

In IPv6, IP addresses change from the current 32-bit standard and dotted decimal notation to a new 128-bit address system. IPv6 addresses remain backward compatible with IPv4 addresses. For example, the IPv4 address "192.168.100.32" may appear in IPv6 notation as "0000:0000:0000:0000:0000:0000:C0A8:6420" or "::C0A8:6420".

The most obvious benefit of IPv6 is the exponentially greater number of IP addresses it can support compared to IPv4. Many countries outside the U.S. suffer from a shortage of IP addresses today. Because IPv6 and IPv4 protocols coexist, those locales with an address shortage can easily deploy new IPv6 networks that work with the rest of the Internet. Experts believe it will take many more years before all networks fully change over to IPv6.

Other benefits of IPv6 are less obvious but equally important. The internals of the IPv6 protocol have been designed with scalability and extensibility in mind. This will allow many different kinds of devices besides PCs, like cell phones and home appliances, to more easily join the Internet in future.

IP address - Definition

2011-07-13T08:58:00.000+05:30

An IP address is a logical address for a network adapter. The IP address uniquely identifies computers on a TCP/IP network.

An IP address can be private - for use on a local area network (LAN) - or public - for use on the Internet or other wide area network (WAN). IP addresses can be determined statically (assigned to a computer by a system administrator) or dynamically (assigned by another device on the network on demand).

Two IP addressing standards are in use today. The IPv4 standard is most familar to people and supported everywhere on the Internet, but the newer IPv6 standard is planned to replace it and starting to be deployed.

IPv4 addresses consist of four bytes (32 bits). Each byte of an IP address is known as an octet. Octets can take any value between 0 and 255. Various conventions exist for the numbering and use of IP addresses.

Common IP (IPv4) Addresses -

10.0.0.1
127.0.0.1
192.168.0.1
192.168.1.1
192.168.2.1

FTP - Definition

2011-07-13T08:55:00.000+05:30

FTP allows you to transfer files between two computers on the Internet. FTP is a simple network protocol based on Internet Protocol and also a term used when referring to the process of copying files when using FTP technology.

To transfer files with FTP, you use a program often called the "client." The FTP client program initiates a connection to a remote computer running FTP "server" software. After the connection is established, the client can choose to send and/or receive copies of files, singly or in groups.

To connect to an FTP server, a client requires a username and password as set by the administrator of the server. Many public FTP archives follow a special convention for that accepts a username of "anonymous."

Simple FTP clients are included with most network operating systems, but most of these clients (such as FTP.EXE on Windows) support a relatively unfriendly command-line interface. Many alternative freeware / shareware third-party FTP clients have been developed that support graphic user interfaces (GUIs) and additional convenience features. In any FTP interface, clients identify the FTP server either by its IP address (such as 192.168.0.1) or by its host name.

FTP supports two modes of data transfer: plain text (ASCII), and binary. You set the mode in the FTP client. A common error when using FTP is attempting to transfer a binary file (such as a program or music file) while in text mode, causing the transfered file to be unusable.

Free FTP Server Softwares

2011-07-13T08:53:00.000+05:30

An FTP server is a required software application on networks that wish to support file sharing using the File Transfer Protocol. This page lists the best FTP servers available for the Windows operating system. Evaluation versions of each of these FTP server software products can be downloaded from the vendors' sites.

1. WS_FTP Server

WS_FTP Server is the choice for high-end needs. Though it costs more than competitors' FTP servers, it is extremely robust and full-featured. WS_FTP Server supports 128-bit SSL encryption, nice installation wizards and a full administrative GUI. It also features a built-in log analyzer. WS_FTP Server is designed to run on true Windows servers; it runs on Windows NT, Windows 2000, and Windows XP.

2. War FTP Daemon

War FTP daemon is free FTP software that is also Open Source in current development. It runs on most popular versions of Windows and is designed for a range of needs from basic to advanced. War FTP has been developed over many years and has proven itself as a stable and mature freeware Windows FTP server.

Vendor's Site

3. zFTPServer Suite

Now at version 3.0, zFTPServer Suite is still a free Windows FTP server and has gained a loyal following. It features multi-lingual user interfaces, flexible access control for both accounts and IP addresses, and passive as well as active mode connections. zFTPServer supports all popular Windows operating systems (except Vista) and is designed for ease of use by beginning- and intermediate level users. Some third-party extensions to zFTPServer for advanced, enterprise-level functionality are available at additional cost.

4. FileZilla Server

Another free Windows FTP server download, FileZilla Server is an especially active Open Source community project with both binary and full source code downloads available. FileZilla Server tracks the user ids of all connected sessions and each file transfered.

Vendor's Site

5. Serv-U FTP Server

Serv-U strikes a good balance between cost, features, and stability. Serv-U is one of the most mature Windows FTP servers. Over time, it's user interface has been revamped, SSL support added, and overall robustness improved. Serv-U runs on all popular versions of Windows including Windows 95 and Windows 98 as well as Windows NT and the newer Windows platforms. It is priced affordably.

Vendor's Site

6. Xlight FTP Server

The Xlight personal edition FTP server is free for use by individuals, while standard and professional editions are also available. For businesses, Xlight features Active Directory and LDAP integration support, 128-bit SSL, virtual server support, and a remote administration GUI. It also supports IPv6 networks.

Vendor's Site

7. Golden FTP Server

This FTP server is designed for simplicity and those unfamiliar with FTP or managing servers. The free version supports multiple languages but does not support user accounts, advanced statistics and some other options available in a paid upgrade version.

Server - Definition

2011-07-13T08:50:00.000+05:30

A network server is a computer designed to process requests and deliver data to other (client) computers over a local network or the Internet.
Network servers typically are configured with additional processing, memory and storage capacity to handle the load of servicing clients. Common types of network servers include:

Web servers
Proxy servers
FTP servers
Online game servers

Numerous systems use this client / server networking model including Web sites and email services. An alternative model, peer-to-peer networking enables all computers to act as either a server or client as needed.

Anonymity of a Proxy Server Explained

2011-02-27T19:53:00.001+05:30

How does Proxy Server Works ?

This is the First Question that arises in our mind when we use the Proxy Servers for Surfing the Internet without revealing our Identity to Others. Here all these mindboggling questions are answered with easy to understand examples.

The exchange of information in Internet is made by the “client - server” model. A client sends a request (what files he needs) and a server sends a reply (required files). For close cooperation (full understanding) between a client and a server the client sends additional information about itself: a version and a name of an operating system, configuration of a browser (including its name and version) etc.

This information can be necessary for the server in order to know which web-page should be given (open) to the client. There are different variants of web-pages for different configurations of browsers. However, as long as web-pages do not usually depend on browsers, it makes sense to hide this information from the web-server.

What your browser transmits to a web-server:

name and a version of an operating system
name and a version of a browser
configuration of a browser (display resolution, color depth, java / javascript support, …)
IP-address of a client
Other information

The most important part of such information (and absolutely needless for a web-server) is information about IP-address. Using your IP it is possible to know about you the following:

country where you are from
city
your provider?s name and e-mail
your physical address

Information, transmitted by a client to a server is available (accessible) for a server as environment variables. Every information unit is a value of some variable. If any information unit is not transmitted, then corresponding variable will be empty (its value will be undetermined).

These are some environment variables:

REMOTE_ADDR ? IP address of a client

HTTP_VIA ? if it is not empty, then a proxy is used. Value is an address (or several addresses) of a proxy server, this variable is added by a proxy server itself if you use one.

HTTP_X_FORWARDED_FOR ? if it is not empty, then a proxy is used. Value is a real IP address of a client (your IP), this variable is also added by a proxy server if you use one.

HTTP_ACCEPT_LANGUAGE ? what language is used in browser (what language a page should be displayed in)

HTTP_USER_AGENT ? so called “a user?s agent”. For all browsers this is Mozilla. Furthermore, browser?s name and version (e.g. MSIE 5.5) and an operating system (e.g. Windows 98) is also mentioned here.

HTTP_HOST ? is a web server?s name

This is a small part of environment variables. In fact there are much more of them (DOCUMENT_ROOT, HTTP_ACCEPT_ENCODING, HTTP_CACHE_CONTROL, HTTP_CONNECTION, SERVER_ADDR, SERVER_SOFTWARE, SERVER_PROTOCOL, …). Their quantity can depend on settings of both a server and a client.

[eminimall]

These are examples of variable values:

REMOTE_ADDR = 194.85.1.1
HTTP_ACCEPT_LANGUAGE = ru
HTTP_USER_AGENT = Mozilla/4.0 (compatible; MSIE 5.0; Windows 98)
HTTP_HOST = www.webserver.ru
HTTP_VIA = 194.85.1.1 (Squid/2.4.STABLE7)
HTTP_X_FORWARDED_FOR = 194.115.5.5

Anonymity at work in Internet is determined by what environment variables “hide” from a web-server.

If a proxy server is not used, then environment variables look in the following way:

REMOTE_ADDR = your IP
HTTP_VIA = not determined
HTTP_X_FORWARDED_FOR = not determined

According to how environment variables “hided” by proxy servers, there are several types of proxies

Transparent Proxies

They do not hide information about your IP address:

REMOTE_ADDR = proxy IP
HTTP_VIA = proxy IP
HTTP_X_FORWARDED_FOR = your IP

The function of such proxy servers is not the improvement of your anonymity in Internet. Their purpose is information cashing, organization of joint access to Internet of several computers, etc.

Anonymous Proxies

All proxy servers, that hide a client?s IP address in any way are called anonymous proxies

Simple Anonymous Proxies

These proxy servers do not hide a fact that a proxy is used, however they replace your IP with its own:

REMOTE_ADDR = proxy IP
HTTP_VIA = proxy IP
HTTP_X_FORWARDED_FOR = proxy IP

These proxies are the most widespread among other anonymous proxy servers.

Distorting Proxies

As well as simple anonymous proxy servers these proxies do not hide the fact that a proxy server is used. However a client?s IP address (your IP address) is replaced with another (arbitrary, random) IP:

REMOTE_ADDR = proxy IP
HTTP_VIA = proxy IP
HTTP_X_FORWARDED_FOR = random IP address

High Anonymity Proxies

These proxy servers are also called “high anonymity proxy”. In contrast to other types of anonymity proxy servers they hide a fact of using a proxy:

REMOTE_ADDR = proxy IP
HTTP_VIA = not determined
HTTP_X_FORWARDED_FOR = not determined

That means that values of variables are the same as if proxy is not used, with the exception of one very important thing ? proxy IP is used instead of your IP address.

Summary

Depending on purposes there are transparent and anonymity proxies. However, remember, using proxy servers you hide only your IP from a web-server, but other information (about browser configuration) is accessible!

What Is PPPoE and bridge mode of ADSL Modem

2011-02-27T19:48:00.000+05:30

There are two ways to configure an ADSL modem for broadband connection. One in PPPoE (Point to Point Protocol over Ethernet) and the another is Bridge mode.

1.PPPoE Mode

In this mode the modem works as router and the PPPoE session terminates on WAN port of router. The PPPoE client is in built in the modem and allocated by BRAS server gets assigned to WAN port of modem. The Internal network has to use the private IP and for Internet access NATing happens in modem. In PPPoE mode the modem is configured in such a way that the user id and password are stored inside the Modem. Internet connection will be established as you switch on the Modem.

PPPoE Mode

2.Bridge Mode

In this mode the modem works as transparent Ethernet bridge and therefore you need to run the PPPoE client software ( for login authentication) on your PC/server. WIN XP systems have this feature inbuilt but for other operating systems you need to buy it from market. Some freeware like RASPPPoE, Enternet etc. are also available on the Internet.

bridge mode

Both the modes can be used as per the requirement and application. Here enumerating the main differences

PPPoE mode

1. User id and password stored inside the Modem.

2. Multiple PCs can be connected. For example most of the basic ADSL Modems having at least one ADSL port and one USB port. In PPPoE mode, can connect one PC to Ethernet port and one PC to USB port which enable simultaneous internet usage in both the PCs.

3. PPPoE mode is more secured.

4. For Torrents download, appropriate ports need to be forwarded.

Bridge Mode

1. In bridge mode user id and password to be entered in the dialer of computer.

2. Only single PC can be connected.

3. For torrents download port forwarding is not required.
4. Less secured because all the ports are open need good firewall to avoid virus infection.

Trace Network Information Using Command Prompt

2011-02-10T14:30:00.000+05:30

There are many applications that claim to help network administrators to trace, diagnose and resolve network related issue.

However, I strongly believe that knowing your basics is always the key to success. Therefore, knowledge of performing simple tasks such as checking the latency of your connection and tracing a route is essential for network professionals.

In this article I will tell you how to trace network related information using command prompt commands.

Tracert and netstat are command line names that are enough to scare any user from using the command prompt. Nonetheless, such command are still widely used by network and system administrators to diagnose and resolve some very important network related issue.

Tracert

The path between two computers connected via the internet cannot be defined as a straight line.
It consists of numerous “hops” from one intermediate computer to another.

Tracert or traceroute is a command that shows the time taken for each hop and the IP address for each intermediary computer (as shown below).

An example of a tracert command would be something like: tracert google.com. You can also use the IP address instead of the hostname to use the tracert command. This command is used to see a network packet being sent and received and the amount of hops required for that packet to get to its destination. You can use tracert to determine where a packet stopped on the network. This can allow network professionals to establish if there is a router configuration problem.

Netstat shows the active TCP connections and ports for a computer, Ethernet statistics, the IP routing table, statistics for the IP, ICMP(Internet Control Message Protocol), TCP(Transmission Control Protocol), and UDP(User Datagram Protocol) protocols.

One possible use for Netstat is to determine if a malware may have established connections that you might be unaware of. If you type netstat /? And hit enter in your command prompt, you will be able to see details regarding a list of netstat commands.

For example nestat:
-a displays all connections.
-b displays the executable involved in creating each connection.
-e displays Ethernet statistics.
-f displays the FQDN (Fully Qualified Domain Name) for foreign addresses.
-n displays active TCP connections (addresses and port numbers are expressed numerically).
-p proto shows connections for the protocol specified by Proto.
- r displays the routing table.
-s displays the per protocol statistics.
-t displays the current connection offload state.
interval re-displays selected statistics, pausing interval seconds between each display.

For more information simply use the netstat /? command.

Commands like netstat and tracert are by no means obsolete and will be used for many years to come.

Create A Quick Ad Hoc Wireless Network Connection Between Two Computers In Windows 7/Vista

2011-02-10T10:47:00.001+05:30

Do you want to create a quick network connection between two computers or laptops to share some files?

Or maybe you want to share an internet connection? Windows 7 and Vista have a build-in feature to create a quick ad hoc wireless network connection, this means you can connect directly with another computer or laptop without the need of a router.

To begin, click Start and select Network. Now click on Network And Sharing Center as shown in the screenshot below. If you can’t find Network, then type Network in Start Search and hit Enter.

Now in the left sidebar, click Set Up A Connection Or Network. From the list select Set Up A Wireless Ad Hoc(Computer-To-Computer) Network option and click Next.

Click Next again and it will ask you to type a Network name and select the Security settings as shown in the screenshot below.

Make sure you select a good password, if you don’t know which security type to select, click on Help Me Choose link next to it. After you are done click Next and the Network connection will be ready.
Now in the Network And Sharing Center you can choose what to share as you can see from the screenshot below.

To Share an Internet Connection, click View Status next to the connection that you want to share. Now click on Properties button which you will find under Activity.

Click on the Sharing tab and tick the checkbox where it says Allow Other Network Computers To Connect Through This Computer’s Internet Connection. Under Home Networking Connection select Wireless network Connection and click OK.

Now your connection is ready to to shared. To enable the wireless network connection you just made, go to Start and click Connect To.

You will see your wireless connection listed there. Select your connection and click Connect.

You will see a success message as shown below.

You will see your connection listed under Wireless Network Connection on the other computer. Simply connect from there and you are done sharing the internet connection.

Note: To connect successfully make sure the wireless hardware is enabled on both computers or laptops.

How To Share Internet Connection With Another Computer Using Windows 7/Vista

2011-02-10T09:39:00.000+05:30

Having two computers at your home, you may have only one internet connection which you want to share between two computers.
Now consider there are two computers. Computer A has Windows Vista while computer B has Windows XP. Computer A is connected to internet via cable (so this will be connected through LAN card). Now to connect to Computer B, you will need another LAN card (to connect to more than one computer, you will need a wired hub).

First, Let us connect two computers in LAN

Follow these steps to connect two computers in LAN.

Step 1: In Windows 7/Vista, you should enable Sharing and Discovery before doing that. You can do this by going to Control Panel > Network and Sharing Centre. Under the section Sharing and Discovery, enable Network Discovery, file sharing, public folder sharing and others if you want to. (The screen short below gives you idea). Here first network shows connection to internet and second one the local connection with another computer.

Step 2: If your LAN card that is connecting to another computer is installed, it will be shown at Control Panel > Network Connections.

Step 3: Right click the Local Area Connection and click Properties.

Step 4: Under the tab ‘Networking’, click the properties internet protocol version 4(TCP/IPv4).

Step 5: Click the radio button to ‘use the following IP’ and give an IP address (Forexample: IP address: 192.168.0.1 and Subnet Mask: 255.255.255.0). Do not give any other information, Click OK and close.

Step 6: In Computer B, make sure you enable the LAN card which is used to connect to computer A. Here you need not give any IP information as Computer A will assign an IP address dynamically. If it is not working, make sure there are no IP assigned and change the properties to ‘obtain an IP address automatically’.

Step 7: Test the connection by pinging (You can do this by typing ping 192.168.0.1 or whichever is Computer ‘A’s IP in the command prompt).

Now let us share the internet connection of Computer A with Computer B

Right click the LAN card which is connected to the internet under Control Panel > Network Connections and click the Sharing tab and click both options to connect internet (Remember: Unless there is another enabled LAN setting you will not be able to see the shared tab under properties). Click OK and close. This option is given by Windows known as ICS (Internet Connection Sharing).

That is it, now you can use internet in both computers A and B.

Connect Two Laptops Using WiFi

2011-02-10T09:31:00.000+05:30

This is step by step tutorial on how you can connect two laptops using WiFi (or two desktop computers with WiFi devices). This type of network is known as peer to peer network and is useful for file sharing and using same internet connection on both systems. So as told earlier you should have two laptops with WiFi or desktops with WiFi devices to make this connection.

Connecting Two Computers Using WiFi

Let’s name both laptops as PC1 and PC2. Now we need to set names and workgroups of both computers (Remember both computers will have same workgroups). To set the name and workgroup of both computers right click on My Computer and select Properties.

Click the tab which says Computer Name and change names of computers as you like (Here we will set computer names PC1 and PC2) and also change the Workgroup option as you like (but this Workgroup should be same for both computers).

Now you need to make “Wireless Network Connection” in PC1.
Right click on Wireless Network icon for this and click on option “View Available Wireless Network”.

Now click on option “Change Advance Settings”.

Now a windows “Wireless Internet Connection Properties” will open.

Click on the tab which says “Wireless Network” and then click Add button. Now write a name in Network Name field. You can also set a password here if you like and also remember to check the option “This is computer to computer network”.

Now press OK and “wireless network properties” will be closed.

Now in next step, you need to provide IP for network in “Internet Protocol (TCP/IP)”. For this, right click on “Wireless Internet Connection” and go in Properties and click Internet Protocols and then click Properties.
Here For example.

PC1 = IP Address: 192.168.1.1 Subnet Mask: 255.255.255.0
PC2 = IP Address: 192.168.1.2 Subnet Mask: 255.255.255.0
And Default Gateway as 192.168.1.1 (same as IP address of PC1). Having done this all, you can connect both computers using WiFi.

PC2

File Sharing Between Both Computers

Now for file sharing Enable the Sharing of “Shared Folder” in both computers. So to go in other computer, write IP address of that computer in address bar of first computer and press Enter (in this case write \\192.168.1.1 and press Enter). This will open other computer’s sharing folder where you can share file, delete files or rename them (make sure to allow these actions from other computer).

Wireless Internet Sharing Between Both Computers

It is very easy to do when you have followed above procedure. Right click on “Internet Connections” on one computer (which has internet connection in it) and go in Properties and click on Sharing and check the option which says “Allow other network users to connect through this computer” and select “Wireless Internet Connection” in “Home Network Connection”. If you want you can also check “Establish Dialup Connection” and “Allow Other Network” .

That is it. You have connected both computers using WiFi and now you can share files, play games and chat on this network.

IPv6 Basics III - IPv6 Addressing

2011-02-01T12:29:00.000+05:30

The IPv6 Address Space

The most obvious distinguishing feature of IPv6 is its use of much larger addresses. The size of an address in

IPv6 is 128 bits, which is four times the larger than an IPv4 address. A 32-bit address space allows for 2³² or 4,294,967,296 possible addresses. A 128-bit address space allows for 2¹²⁸ or 340,282,366,920,938,463,463,374,607,431,768,211,456 (or 3.4´10³⁸ or 340 undecillion) possible addresses.

In the late 1970s when the IPv4 address space was designed, it was unimaginable that it could be exhausted.

However, due to changes in technology and an allocation practice that did not anticipate the recent explosion of hosts on the Internet, the IPv4 address space was consumed to the point that by 1992 it was clear a replacement would be necessary.

With IPv6, it is even harder to conceive that the IPv6 address space will be consumed. To help put this number in perspective, a 128-bit address space provides 655,570,793,348,866,943,898,599 (6.5´10²³) addresses for every square meter of the Earth’s surface.

It is important to remember that the decision to make the IPv6 address 128 bits in length was not so that every square meter of the Earth could have 6.5´10²³ addresses. Rather, the relatively large size of the IPv6 address is designed to be subdivided into hierarchical routing domains that reflect the topology of the modern-day Internet. The use of 128 bits allows for multiple levels of hierarchy and flexibility in designing hierarchical addressing and routing that is currently lacking on the IPv4-based Internet.

The IPv6 addressing architecture is described in RFC 4291.

IPv6 Address Syntax

IPv4 addresses are represented in dotted-decimal format. This 32-bit address is divided along 8-bit boundaries. Each set of 8 bits is converted to its decimal equivalent and separated by periods. For IPv6, the 128-bit address is divided along 16-bit boundaries, and each 16-bit block is converted to a 4-digit hexadecimal number and separated by colons. The resulting representation is called colon-hexadecimal.

The following is an IPv6 address in binary form:

0010000000000001000011011011100000000000000000000010111100111011 0000001010101010000000001111111111111110001010001001110001011010

The 128-bit address is divided along 16-bit boundaries:

0010000000000001 0000110110111000 0000000000000000 0010111100111011 0000001010101010 0000000011111111 1111111000101000 1001110001011010

Each 16-bit block is converted to hexadecimal and delimited with colons. The result is:

2001:0DB8:0000:2F3B:02AA:00FF:FE28:9C5A

IPv6 representation can be further simplified by removing the leading zeros within each 16-bit block. However, each block must have at least a single digit. With leading zero suppression, the address representation becomes:

2001:DB8:0:2F3B:2AA:FF:FE28:9C5A

Compressing Zeros

Some types of addresses contain long sequences of zeros. To further simplify the representation of IPv6 addresses, a contiguous sequence of 16-bit blocks set to 0 in the colon hexadecimal format can be compressed to “::”, known as double-colon.

For example, the link-local address of FE80:0:0:0:2AA:FF:FE9A:4CA2 can be compressed to FE80::2AA:FF:FE9A:4CA2. The multicast address FF02:0:0:0:0:0:0:2 can be compressed to FF02::2.

Zero compression can only be used to compress a single contiguous series of 16-bit blocks expressed in colon hexadecimal notation. You cannot use zero compression to include part of a 16-bit block. For example, you cannot express FF02:30:0:0:0:0:0:5 as FF02:3::5. The correct representation is FF02:30::5.

To determine how many 0 bits are represented by the “::”, you can count the number of blocks in the compressed address, subtract this number from 8, and then multiply the result by 16. For example, in the address FF02::2, there are two blocks (the “FF02” block and the “2” block.) The number of bits expressed by the “::” is 96 (96 = (8 – 2)´16).

Zero compression can only be used once in a given address. Otherwise, you could not determine the number of 0 bits represented by each instance of “::”.

IPv6 Prefixes

The prefix is the part of the address that indicates the bits that have fixed values or are the bits of the subnet prefix. Prefixes for IPv6 subnets, routes, and address ranges are expressed in the same way as Classless Inter-Domain Routing (CIDR) notation for IPv4. An IPv6 prefix is written in address/prefix-length notation.

For example, 21DA:D3::/48 and 21DA:D3:0:2F3B::/64 are IPv6 address prefixes.

Note IPv4 implementations commonly use a dotted decimal representation of the network prefix known as the subnet mask. A subnet mask is not used for IPv6. Only the prefix length notation is supported.

Types of IPv6 Addresses

There are three types of IPv6 addresses:

1. Unicast

A unicast address identifies a single interface within the scope of the type of unicast address. With the appropriate unicast routing topology, packets addressed to a unicast address are delivered to a single interface.

2. Multicast

A multicast address identifies multiple interfaces. With the appropriate multicast routing topology, packets addressed to a multicast address are delivered to all interfaces that are identified by the address. A multicast address is used for one-to-many communication, with delivery to multiple interfaces.

3. Anycast

An anycast address identifies multiple interfaces. With the appropriate routing topology, packets addressed to an anycast address are delivered to a single interface, the nearest interface that is identified by the address.

The “nearest” interface is defined as being closest in terms of routing distance. An anycast address is used for one-to-one-of-many communication, with delivery to a single interface.

In all cases, IPv6 addresses identify interfaces, not nodes. A node is identified by any unicast address assigned to one of its interfaces.

Note RFC 4291 does not define a broadcast address. All types of IPv4 broadcast addressing are performed in IPv6 using multicast addresses. For example, the subnet and limited broadcast addresses from IPv4 are replaced with the link-local scope all-nodes multicast address of FF02::1.

Links and Subnets

Similar to IPv4, an IPv6 subnet prefix is assigned to a single link. Multiple subnet prefixes can be assigned to the same link. This technique is called multinetting.

IPv6 Basics II - Differences Between IPv4 and IPv6

2011-02-01T12:16:00.000+05:30

IPv4	IPv6
Source and destination addresses are 32 bits (4 bytes) in length.	Source and destination addresses are 128 bits (16 bytes) in length. For more information, see “IPv6 Addressing.”
IPsec support is optional.	IPsec support is required. For more information, see “IPv6 Header.”
No identification of packet flow for QoS handling by routers is present within the IPv4 header.	Packet flow identification for QoS handling by routers is included in the IPv6 header using the Flow Label field. For more information, see “IPv6 Header.”
Fragmentation is done by both routers and the sending host.	Fragmentation is not done by routers, only by the sending host. For more information, see “IPv6 Header.”
Header includes a checksum.	Header does not include a checksum. For more information, see “IPv6 Header.”
Header includes options.	All optional data is moved to IPv6 extension headers. For more information, see “IPv6 Header.”
Address Resolution Protocol (ARP) uses broadcast ARP Request frames to resolve an IPv4 address to a link layer address.	ARP Request frames are replaced with multicast Neighbor Solicitation messages. For more information, see “Neighbor Discovery.”
Internet Group Management Protocol (IGMP) is used to manage local subnet group membership.	IGMP is replaced with Multicast Listener Discovery (MLD) messages. For more information, see “Multicast Listener Discovery.”
ICMP Router Discovery is used to determine the IPv4 address of the best default gateway and is optional.	ICMP Router Discovery is replaced with ICMPv6 Router Solicitation and Router Advertisement messages and is required. For more information, see “Neighbor Discovery.”
Broadcast addresses are used to send traffic to all nodes on a subnet.	There are no IPv6 broadcast addresses. Instead, a link-local scope all-nodes multicast address is used. For more information, see “Multicast IPv6 Addresses.”
Must be configured either manually or through DHCP.	Does not require manual configuration or DHCP. For more information, see “Address Autoconfiguration.”
Uses host address (A) resource records in the Domain Name System (DNS) to map host names to IPv4 addresses.	Uses host address (AAAA) resource records in the Domain Name System (DNS) to map host names to IPv6 addresses. For more information, see “IPv6 and DNS.”
Uses pointer (PTR) resource records in the IN-ADDR.ARPA DNS domain to map IPv4 addresses to host names.	Uses pointer (PTR) resource records in the IP6.ARPA DNS domain to map IPv6 addresses to host names. For more information, see “IPv6 and DNS.”
Must support a 576-byte packet size (possibly fragmented).	Must support a 1280-byte packet size (without fragmentation). For more information, see “IPv6 MTU.”

IPv6 Basics I - Features of IPv6

2011-02-01T12:14:00.000+05:30

IPv6 Features

The following are the features of the IPv6 protocol:

· New header format

· Large address space

· Efficient and hierarchical addressing and routing infrastructure

· Stateless and stateful address configuration

· Built-in security

· Better support for prioritized delivery

· New protocol for neighboring node interaction

· Extensibility

The following sections discuss each of these new features in detail.

New Header Format

The IPv6 header has a new format that is designed to keep header overhead to a minimum. This is achieved by moving both non-essential fields and optional fields to extension headers that are placed after the IPv6 header. The streamlined IPv6 header is more efficiently processed at intermediate routers.

IPv4 headers and IPv6 headers are not interoperable. IPv6 is not a superset of functionality that is backward compatible with IPv4. A host or router must use an implementation of both IPv4 and IPv6 in order to recognize and process both header formats. The new IPv6 header is only twice as large as the IPv4 header, even though IPv6 addresses are four times as large as IPv4 addresses.

Large Address Space

IPv6 has 128-bit (16-byte) source and destination IP addresses. Although 128 bits can express over 3.4´10³⁸ possible combinations, the large address space of IPv6 has been designed to allow for multiple levels of subnetting and address allocation from the Internet backbone to the individual subnets within an organization.

Even though only a small number of the possible addresses are currently allocated for use by hosts, there are plenty of addresses available for future use. With a much larger number of available addresses, address-conservation techniques, such as the deployment of NATs, are no longer necessary.

Efficient and Hierarchical Addressing and Routing Infrastructure

IPv6 global addresses used on the IPv6 portion of the Internet are designed to create an efficient, hierarchical, and summarizable routing infrastructure that is based on the common occurrence of multiple levels of Internet service providers.

Stateless and Stateful Address Configuration

To simplify host configuration, IPv6 supports both stateful address configuration, such as address configuration in the presence of a DHCP server, and stateless address configuration (address configuration in the absence of a DHCP server). With stateless address configuration, hosts on a link automatically configure themselves with IPv6 addresses for the link (called link-local addresses) and with addresses derived from prefixes advertised by local routers. Even in the absence of a router, hosts on the same link can automatically configure themselves with link-local addresses and communicate without manual configuration.

Built-in Security

Support for IPsec is an IPv6 protocol suite requirement. This requirement provides a standards-based solution for network security needs and promotes interoperability between different IPv6 implementations.

Better Support for Prioritized Delivery

New fields in the IPv6 header define how traffic is handled and identified. Traffic identification using a Flow Label field in the IPv6 header allows routers to identify and provide special handling for packets belonging to a flow, a series of packets between a source and destination. Because the traffic is identified in the IPv6 header, support for prioritized delivery can be achieved even when the packet payload is encrypted with IPsec.

New Protocol for Neighboring Node Interaction

The Neighbor Discovery protocol for IPv6 is a series of Internet Control Message Protocol for IPv6 (ICMPv6) messages that manage the interaction of neighboring nodes (nodes on the same link). Neighbor Discovery replaces the broadcast-based Address Resolution Protocol (ARP), ICMPv4 Router Discovery, and ICMPv4 Redirect messages with efficient multicast and unicast Neighbor Discovery messages.

Extensibility

IPv6 can easily be extended for new features by adding extension headers after the IPv6 header. Unlike options in the IPv4 header, which can only support 40 bytes of options, the size of IPv6 extension headers is only constrained by the size of the IPv6 packet.

The Legal Issues of Cloud Computing

2011-01-03T11:16:00.000+05:30

Cloud Computing can help your business reduce costs as you don’t have to invest in hardware and other physical infrastructure, your data is stored on a secure location and you only pay for what you use – there are no licensing fees associated with cloud computing.

Legal Issues associated with Cloud Computing

That said, there are some important legal issues that must be taken care of before you sign-up with any of the cloud vendors for your business.
These issues, discussed below, are more relevant for business owners who are planning to shift to the cloud and may not really matter if you are a consumer who merely uses the cloud for storing emails or office documents.

1. The Physical Location of your Data

1a. Where is your data stored physically?

Your data could be stored in any country and you may not even know where the data centre is situated. The ‘physical location’ raises the question of legal governance over the data. The customer must be clear so as to the provisions of the prevailing law in that particular nation.

1b. If a dispute arises, what will be the place of jurisdiction?

In case a conflict arises between the cloud vendor and the customer (you), which country’s court system will settle the dispute?
Say you are a business owner in China and your cloud service provider is based in the US. The vendor will definitely prefer settling the case in in an American court but as a customer, do you have the financial means and resources to get the dispute settled in the jurisdiction of another nation?

2. Responsibility of your Data

2a. What if the data centre is hit by a disaster?

It might happen that the vendor’s premises is severely affected due to a disaster. Even the 10-Q filings of Google Inc. with the U.S Securities and Exchange Commission mentions such a risk:

Our systems are vulnerable to damage or interruption from earthquakes, terrorist attacks, floods, fires, power loss, telecommunications failures, computer viruses, computer denial of service attacks, or other attempts to harm our systems.

The question is whether you are indemnified by the insurance company for loss of your business or not?

2b. Is there any liability coverage for breach of privacy?

If a privacy breach occurs due to a fault of cloud vendor, is there any liability coverage policy taken up by the vendor? The scope of breach of privacy has widened considerably over the years in the field of cyber insurance. Some insurance carriers offer coverage even for breach of minor information and the customer is compensated on on behalf of the cloud vendor.

2c. What can be done if the data center gets hacked?

Though all cloud vendors try their best to fend off hackers, no security setting is assumed to be foolproof. If the data center gets hacked, can you move against the vendor for claiming lost profits?

3. Intellectual Property Rights

3a. Is your data protected under intellectual property rights?

If it happens that the data is your own creation (like photographs, literature, etc), then is it protected under the intellectual property rights of that country? What means do you have if they get infringed?

3b. How secure are trade secrets?

Your data stored in the ‘cloud’ may have trade secrets or privileged information which must be protected under attorney-client relationship. How secure will such information be in hands of the cloud vendor?
Or consider a reverse situation. If you leak out a trade secret of another business entity, how far will your cloud storage provider go to protect your data when they have been summoned to the court with all your stored data, access logs, etc.

3c. Third party access?

The vendor may grant some privileged third parties access to your stored data. The identity of such parties, if any, must be disclosed to the customer. Here, the third party could be a legal authority or even an internal employee. The customer should always be informed before the vendor allows third parties to access the stored data.
To protect the interest of your business, it may therefore be extremely essential that your read the terms and conditions meticulously before signing up for a cloud based services.
If the vendor provides a standard form of contract (which is a general practice), then you must be must be fully aware of all the terms and conditions. It will save you from nasty surprises and you will be financially, mentally and legally prepared to save your business from unfavorable consequences of cloud computing.

Whats is NetBIOS?

2011-01-02T17:44:00.000+05:30

NetBIOS (Network Basic Input/Output System) was originally developed by IBM and Sytek as an Application Programming Interface (API) for client software to access LAN resources. Since its creation, NetBIOS has become the basis for many other networking applications. In its strictest sense, NetBIOS is an interface specification for acessing networking services.

NetBIOS, a layer of software developed to link a network operating system with specific hardware, was originally designed as THE network controller for IBM's Network LAN.

NetBIOS has now been extended to allow programs written using the NetBIOS interface to operate on the IBM token ring architecture. NetBIOS has since been adopted as an industry standard and now, it is common to refer to NetBIOS-compatible LANs.

It offers network applications a set of "hooks" to carry out inter-application communication and data transfer. In a basic sense, NetBIOS allows applications to talk to the network. Its intention is to isolate application programs from any type of hardware dependancies. It also spares software developers the task of developing network error recovery and low level message addressing or routing. The use of the NetBIOS interface does alot of this work for them.

NetBIOS standardizes the interface between applications and a LANs operating capabilities. With this, it can be specified to which levels of the OSI model the application can write to, making the application transportable to other networks. In a NetBIOS LAN enviroment, computers are known on the system by a name. Each computer on the network has a permanent name that is programmed in various different ways.

PC's on a NetBIOS LAN communicate either by establishing a session or by using NetBIOS datagram or broadcast methods. Sessions allow for a larger message to be sent and handle error detection and correction. The communication is on a one-to-one basis.

Datagram and broadcast methods allow one computer to communicate with several other computers at the same time, but are limited in message size. There is no error detection or correction using these datagram or broadcast methods. However, datagram communication allows for communication without having to establish a session.

All communication in these enviroments are presented to NetBIOS in a format called Network Control Blocks (NCB). The allocation of these blocks in memory is dependant on the user program. These NCB's are divided into fields, these are reserved for input and output respectively.

NetBIOS is a very common protocol used in todays enviroments. NetBIOS is supported on Ethernet, TokenRing, and IBM PC Networks. In its original induction, it was defined as only an interface between the application and the network adapter. Since then, transport like functions have been added to NetBIOS, making it more functional over time.

In NetBIOS, connection (TCP) oriented and connectionless (UDP) communication are both supported. It supports both broadcasts and multicasting and supports three distinct services: Naming, Session, and Datagram.

VPN Tutorial

2011-01-02T17:02:00.000+05:30

The Virtual Private Network - VPN - has attracted the attention of many organizations looking to both expand their networking capabilities and reduce their costs.
The VPN can be found in workplaces and homes, where they allow employees to safely log into company networks. Telecommuters and those who travel often find a VPN a more convenient way to stay connected to the corporate intranet. No matter your current involvement with VPNs, this is a good technology to know something about. This VPN tutorial involves many interesting aspects of network protocol design, Internet security, network service outsourcing, and technology standards.

What Exactly Is A VPN?

A VPN supplies network connectivity over a possibly long physical distance. In this respect, a VPN is a form of Wide Area Network (WAN). The key feature of a VPN, however, is its ability to use public networks like the Internet rather than rely on private leased lines. VPN technologies implement restricted-access networks that utilize the same cabling and routers as a public network, and they do so without sacrificing features or basic security.
A VPN supports at least three different modes of use:

Remote access client connections
LAN-to-LAN internetworking
Controlled access within an intranet

VPN Pros and Cons

Like many commercialized network technologies, a significant amount of sales and marketing hype surrounds VPN. In reality, VPNs provide just a few specific potential advantages over more traditional forms of wide-area networking. These advantages can be significant, but they do not come for free.

The potential problems with the VPN outnumber the advantages and are generally more difficult to understand. The disadvantages do not necessarily outweigh the advantages, however. From security and performance concerns, to coping with a wide range of sometimes incompatible vendor products, the decision of whether or not to use a VPN cannot be made without significant planning and preparation.

Technology Behind VPNs

Several network protocols have become popular as a result of VPN developments:

PPTP
L2TP
IPsec
SOCKS

These protocols emphasize authentication and encryption in VPNs. Authentication allows VPN clients and servers to correctly establish the identity of people on the network. Encryption allows potentially sensitive data to be hidden from the general public. Many vendors have developed VPN hardware and/or software products. Unfortunately, immature VPN standards mean that some of these products remain incompatible with each other.

A VPN supplies network connectivity over a possibly long physical distance. In this respect, a VPN is a form of Wide Area Network (WAN). VPNs enable file sharing, video conferencing and similar network services. Virtual private networks generally don't provide any new functionality that isn't already offered through alternative mechanisms, but a VPN implements those services more efficiently / cheaply in most cases.

A key feature of a VPN is its ability to work over both private networks as well as public networks like the Internet. Using a method called tunneling, a VPN use the same hardware infrastructure as existing Internet or intranet links. VPN technologies includes various security mechanisms to protect the virtual, private connections.

Specifically, a VPN supports at least three different modes of use:

Internet remote access client connections
LAN-to-LAN internetworking
Controlled access within an intranet

Internet VPNs for Remote Access

In recent years, many organizations have increased the mobility of their workers by allowing more employees to telecommute. Employees also continue to travel and face a growing need to stay connected to their company networks. A VPN can be set up to support remote, protected access to the corporate home offices over the Internet. An Internet VPN solution uses a client/server design works as follows:

1. A remote host (client) wanting to log into the company network first connects to any public Internet Service Provider (ISP).

VPN server

VPN client

3. Once the connection has been established, the remote client can communicate with the internal company systems over the Internet just as if it were a local host. Before VPNs, remote workers accessed company networks over private leased lines or through dialup remote access servers. While VPN clients and servers careful require installation of hardware and software, an Internet VPN is a superior solution in many situations.

VPNs for Internetworking

Besides using virtual private networks for remote access, a VPN can also bridge two networks together. In this mode of operation, an entire remote network (rather than just a single remote client) can join to a different company network to form an extended intranet. This solution uses a VPN server to VPN server connection.

Intranet / Local Network VPNs

Internal networks may also utilize VPN technology to implement controlled access to individual subnets within a private network. In this mode of operation, VPN clients connect to a VPN server that acts as the network gateway. This type of VPN use does not involve an Internet Service Provider (ISP) or public network cabling. However, it allows the security benefits of VPN to be deployed inside an organization. This approach has become especially popular as a way for businesses to protect their WiFi local networks.

VPN Network Scalability

The cost to an organization of building a dedicated private network may be reasonable at first but increases exponentially as the organization grows. A company with two branch offices, for example, can deploy just one dedicated line to connect the two locations, but 4 branch offices require 6 lines to directly connect them to each other, 6 branch offices need 15 lines, and so on. Internet based VPNs avoid this scalability problem by simply tapping into the the public lines and network capability readily available. Particularly for remote and international locations, an Internet VPN offers superior reach and quality of service.

Using a VPN

To use a VPN, each client must possess the appropriate networking software or hardware support on their local network and computers. When set up properly, VPN solutions are easy to use and sometimes can be made to work automatically as part of network sign on. VPN technology also works well with WiFi local area networking. Some organizations use VPNs to secure wireless connections to their local access points when working inside the office. These solutions provide strong protection without affecting performance excessively.

Limitations of a VPN

Despite their popularity, VPNs are not perfect and limitations exist as is true for any technology. Organizations should consider issues like the below when deploying and using virtual private networks in their operations:

1. VPNs require detailed understanding of network security issues and careful installation / configuration to ensure sufficient protection on a public network like the Internet.

2. The reliability and performance of an Internet-based VPN is not under an organization's direct control. Instead, the solution relies on an ISP and their quality of service.

3. Historically, VPN products and solutions from different vendors have not always been compatible due to issues with VPN technology standards. Attempting to mix and match equipment may cause technical problems, and using equipment from one provider may not give as great a cost savings.Virtual private network technology is based on the idea of tunneling. VPN tunneling involves establishing and maintaining a logical network connection (that may contain intermediate hops). On this connection, packets constructed in a specific VPN protocol format are encapsulated within some other base or carrier protocol, then transmitted between VPN client and server, and finally de-encapsulated on the receiving side.

For Internet-based VPNs, packets in one of several VPN protocols are encapsulated within Internet Protocol (IP) packets. VPN protocols also support authentication and encryption to keep the tunnels secure.

Types of VPN Tunneling

VPN supports two types of tunneling - voluntary and compulsory. Both types of tunneling are commonly used.
In voluntary tunneling, the VPN client manages connection setup. The client first makes a connection to the carrier network provider (an ISP in the case of Internet VPNs). Then, the VPN client application creates the tunnel to a VPN server over this live connection.

In compulsory tunneling, the carrier network provider manages VPN connection setup. When the client first makes an ordinary connection to the carrier, the carrier in turn immediately brokers a VPN connection between that client and a VPN server. From the client point of view, VPN connections are set up in just one step compared to the two-step procedure required for voluntary tunnels.

Compulsory VPN tunneling authenticates clients and associates them with specific VPN servers using logic built into the broker device. This network device is sometimes called the VPN Front End Processor (FEP), Network Access Server (NAS) or Point of Presence Server (POS). Compulsory tunneling hides the details of VPN server connectivity from the VPN clients and effectively transfers management control over the tunnels from clients to the ISP. In return, service providers must take on the additional burden of installing and maintaining FEP devices.

VPN Tunneling Protocols

Several computer network protocols have been implemented specifically for use with VPN tunnels. The three most popular VPN tunneling protocols listed below continue to compete with each other for acceptance in the industry. These protocols are generally incompatible with each other.
Point-to-Point Tunneling Protocol (PPTP)
Several corporations worked together to create the PPTP specification. People generally associate PPTP with Microsoft because nearly all flavors of Windows include built-in client support for this protocol. The initial releases of PPTP for Windows by Microsoft contained security features that some experts claimed were too weak for serious use. Microsoft continues to improve its PPTP support, though.
Layer Two Tunneling Protocol (L2TP)
The original competitor to PPTP for VPN tunneling was L2F, a protocol implemented primarily in Cisco products. In an attempt to improve on L2F, the best features of it and PPTP were combined to create a new standard called L2TP. Like PPTP, L2TP exists at the data link layer (Layer Two) in the OSI model -- thus the origin of its name.

Internet Protocol Security (IPsec)
IPsec is actually a collection of multiple related protocols. It can be used as a complete VPN protocol solution or simply as the encryption scheme within L2TP or PPTP. IPsec exists at the network layer (Layer Three) of the OSI model.

PPTP - Point-to-Point Tunneling Protocol - extends the Point to Point Protocol (PPP) standard for traditional dial-up networking. PPTP is best suited for the remote access applications of VPNs, but it also supports LAN internetworking. PPTP operates at Layer 2 of the OSI model.

PTP packages data within PPP packets, then encapsulates the PPP packets within IP packets (datagrams) for transmission through an Internet-based VPN tunnel. PPTP supports data encryption and compression of these packets. PPTP also uses a form of General Routing Encapsulation (GRE) to get data to and from its final destination.

PPTP-based Internet remote access VPNs are by far the most common form of PPTP VPN. In this environment, VPN tunnels are created via the following two-step process:

1. The PPTP client connects to their ISP using PPP dial-up networking (traditional modem or ISDN).

2. Via the broker device (described earlier), PPTP creates a TCP control connection between the VPN client and VPN server to establish a tunnel. PPTP uses TCP port 1723 for these connections.

PPTP also supports VPN connectivity via a LAN. ISP connections are not required in this case, so tunnels can be created directly as in Step 2 above.

Once the VPN tunnel is established, PPTP supports two types of information flow:

control messages for managing and eventually tearing down the VPN connection. Control messages pass directly between VPN client and server.

data packets that pass through the tunnel, to or from the VPN client

PPTP Security

PPTP supports authentication, encryption, and packet filtering. PPTP authentication uses PPP-based protocols like EAP, CHAP, and PAP. PPTP supports packet filtering on VPN servers. Intermediate routers and other firewalls can also be configured to selectively filter PPTP traffic.

PPTP and PPP

In general, PPTP relies on the functionality of PPP for these aspects of virtual private networking.

authenticating users and maintaining the remote dial-up connection

encapsulating and encrypting IP, IPX, or NetBEUI packets

PPTP directly handles maintaining the VPN tunnel and transmitting data through the tunnel. PPTP also supports some additional security features for VPN data beyond what PPP provides.

PPTP Pros and Cons

PPTP remains a popular choice for VPNs thanks to Microsoft. PPTP clients are freely available in all popular versions of Microsoft Windows. Windows servers also can function as PPTP-based VPN servers.

One drawback of PPTP is its failure to choose a single standard for authentication and encryption. Two products that both fully comply with the PPTP specification may be totally incompatible with each other if they encrypt data differently, for example. Concerns also persist over the questionable level of security PPTP provides compared to alternatives.

Source:compnetworking.about.com

Proxy Servers Basics - II (Contd..)

2011-01-02T16:43:00.000+05:30

Proxy Servers and Microsoft Internet Explorer

To take advantage of a proxy server's capabilities, Web browsers like Internet Explorer (IE) must be configured to explicitly use it. In many proxied environments, the client computers do not have direct Internet access, and browsers generally are not configured to use proxies "out of the box." Clients will be unable to access public Web sites in this scenario until proxy settings have been correctly made.

Figure 2: IE5 Tools menu
For example, to configure IE5 to use a proxy server, first click on Tools to access the drop-down menu. Click on the Internet Options... menu item to raise the Internet Options dialog. This dialog is a property sheet featuring multiple tabs.

Clicking on the Connections tab makes available a dialog that includes a button in the bottom-right corner named LAN Settings... . Finally, click this button to raise the Local Area Network (LAN) Settings dialog; here is where proxy information must be entered.

Figure 3: IE5 Internet Options, Connections tab
IE5 supports both manual and automatic configuration options. As shown the Figure, the "Use a proxy server" check box must be checked to enable the manual entering of a proxy.

Either the network host name or the IP address of the proxy server must be typed in the "Address" field. In addition, any internal domains (such as intranet sites) that do not need to go through a proxy can be entered here in order to bypass the server.

Figure 4: IE5 Internet Options, Connections tab
Microsoft provides Knowledge Base article Q135982 to assist in manually configuring proxy servers using other versions of Internet Explorer. Using the Automatically detect settings check box invokes the WPAD mechanism (discussed earlier) to auto-discover the proxy configuration. Finally, using the Use automatic configuration script check box allows clients to specify the URL that points to the JavaScript configuration file.

Proxy Servers and Netscape Navigator

Netscape Navigator (NN) may also be configured manually or automatically to work with a proxy server.

Figure: NN4 Edit menu
For example, to manually configure NN4, first click on Edit to access the drop-down menu. Click on the Preferences... menu item to raise the Netscape Preferences dialog.

This dialog is a property sheet featuring a hierarchical arrangement of buttons in the left channel (as compared to the tabs in IE). Double-clicking on the Advanced item (or single-clicking on the small arrow graphic to the left of this text) displays the Proxies sub-item. Finally, clicking on Proxies displays the proxy server configuration dialog within the window.

Figure 6: NN4 Preferences, Proxies dialog
Within this dialog, use the Direct connection to the Internet option to bypass proxy servers, and use the Automatic proxy configuration option to work with the automation script mechanism discussed earlier. (Navigator does not support WPAD.)

To manually configure the proxy configuration, choose the middle option and click View to raise another dialog where the proxy server's host name or IP address can be entered.

Free Web-Based Anonymous Proxy Servers

The sites listed below support free, Web-based anonymous proxy servers.

An anonymous Web proxy is a type of proxy server that works through a Web form (also often called a CGI proxy). Instead of configuring the address of the server in the browser as is done for HTTP or SOCKS proxies, you simply navigate to the home page of the Web / CGI proxy, where proxy functionality is then enabled for each browsing session. The top free anonymous Web proxy servers are described below.

1. Proxify

Unlike most other anonymous Web proxies, Proxify supports encryption via the SSL and HTTPS network protocols. Proxify also handles the basic functions of an anonymous proxy server well including hiding your IP address and filtering of cookies.

2. Anonymouse

Anonymouse supports Web, email and Usenet (news) proxies and has existed on the Internet for many years now. In addition to the free open access, a low-cost subscription is available for those who want to upgrade to faster proxy servers and additional services. Anonymouse supports both English and German languages.

3. Anonymizer

Anonymizer may the best-known name among the anonymous Web proxy services. While it does offer a free service, most of the Anonymizer site is decided to "up-selling" various related products. WHen using the free proxy, be prepared to see flashing "UPGRADE NOW!" messages in the status bar of your browser.

4. The Cloak

The Cloak is an HTTP/HTTPS free anonymous proxy. A pay service is also available that avoids the bandwidth throttling used in the free version.

Free Proxy Lists (Anonymous and Elite)

Internet proxy servers allow you to (mostly) hide your home IP address and navigate anonymously. However, these free public servers often are taken offline without warning, and some may offer a less reputable service than others. If you are interested in using anonymous proxies, you should maintain a free proxy server list on your home network to ensure at least one is accessible at all times.
Follow these links to obtain free proxy list downloads.

Free Proxy Lists, from Proxy-list.org
Fresh HTTP Proxy Lists, from xroxy.com
Free Anonymous Proxies, from atomintersoft.com

These free proxy lists are updated regularly.

Networking Inside Out

VNC - Virtual Network Computing Basics

VNC Basics

VNC Interface

VNC Uses

Overview

Networking

Running a Windows server

Running a Unix server

Running a viewer

Using a web browser as a viewer

How to Safely Remove Linux OS from Dual boot and restoring your MBR ?

Cloud Computing - Overview

How to set up your home wireless network

What you’ll need to set up your wireless network

Windows 7 and Windows Vista

Windows XP

1. Connect to the Internet

2. Connect your wireless router

3. Configure your wireless router

4. Connect your computers, printers, and other devices to the wireless network

5. Share files, printers, and more

Types of Wireless Network Security methods

Warning

Basics of Connecting and Setting Up a Wireless Home Network

What is a wireless home network?

The right equipment

Broadband connection and modem

Wireless network adapters and a wireless router

Where to put your wireless router

Help protect your network

Network security key

Wireless router security

Firewalls

Relax, that's all there is to do

CCNA INTRO: Introduction to Cisco Networking Technologies Study Guide: Exam 640-821

IPv6 - Definition

IP address - Definition

FTP - Definition

Free FTP Server Softwares

1. WS_FTP Server

2. War FTP Daemon

3. zFTPServer Suite

4. FileZilla Server

5. Serv-U FTP Server

6. Xlight FTP Server

7. Golden FTP Server

Server - Definition

Anonymity of a Proxy Server Explained

What Is PPPoE and bridge mode of ADSL Modem

Trace Network Information Using Command Prompt

Create A Quick Ad Hoc Wireless Network Connection Between Two Computers In Windows 7/Vista

How To Share Internet Connection With Another Computer Using Windows 7/Vista

First, Let us connect two computers in LAN

Now let us share the internet connection of Computer A with Computer B

Connect Two Laptops Using WiFi

Connecting Two Computers Using WiFi

File Sharing Between Both Computers

Wireless Internet Sharing Between Both Computers

IPv6 Basics III - IPv6 Addressing

The IPv6 Address Space

IPv6 Address Syntax

Compressing Zeros

IPv6 Prefixes

Types of IPv6 Addresses

Links and Subnets

IPv6 Basics II - Differences Between IPv4 and IPv6

IPv6 Basics I - Features of IPv6

Better Support for Prioritized Delivery

The Legal Issues of Cloud Computing

Legal Issues associated with Cloud Computing

1. The Physical Location of your Data

2. Responsibility of your Data

3. Intellectual Property Rights

Whats is NetBIOS?

VPN Tutorial

What Exactly Is A VPN?

VPN Pros and Cons

Technology Behind VPNs

Internet VPNs for Remote Access