PARAVIRTUALIZATION

 Paravirtualization is an enhancement of virtualization technology in which a guest OS is recompiled prior to installation inside a virtual machine. Paravirtualization allows for an interface to the virtual machine that can differ somewhat from that of the underlying hardware. This capacity minimizes overhead and optimizes system performance by supporting the use of virtual machines that would be underutilized in conventional or full virtualization.
The main limitation of paravirtualization is the fact that the guest OS must be tailored specifically to run on top of the virtual machine monitor (VMM), the host program that allows a single computer to support multiple, identical execution environments. However, paravirtualization eliminates the need for the virtual machine to trap privileged instructions. Trapping, a means of handling unexpected or unallowable conditions, can be time-consuming and can adversely impact performance in systems that employ full virtualization.
Paravirtualization is an expansion of a technology that has existed for years in the IBM OS known as VM. Xen, an open-source software project, incorporates paravirtualization.

host

The term "host" is used in several contexts, in each of which it has a slightly different meaning:
1) In Internet protocol specifications, the term "host" means any computer that has full two-way access to other computers on the Internet. A host has a specific "local or host number" that, together with the network number, forms its unique IP address. If you use Point-to-Point Protocol to get access to your access provider, you have a unique IP address for the duration of any connection you make to the Internet and your computer is a host for that period. In this context, a "host" is a node in a network.
2) For companies or individuals with a Web site, a host is a computer with a Web server that serves the pages for one or more Web sites. A host can also be the company that provides that service, which is known as hosting.
3) In IBM and perhaps other mainframe computer environments, a host is a mainframe computer (which is now usually referred to as a "large server"). In this context, the mainframe has intelligent or "dumb" workstations attached to it that use it as a host provider of services. (This does not mean that the host only has "servers" and the workstations only have "clients." The server/client relationship is a programming model independent of this contextual usage of "host.")
4) In other contexts, the term generally means a device or program that provides services to some smaller or less capable device or program.

A Google dork is an employee who unknowingly exposes sensitive corporate information on the Internet. The word dork is slang for a slow-witted or in-ept person.
Google dorks put corporate information at risk because they unwittingly create back doors that allow an attacker to enter a network without permission and/or gain access to unauthorized information. To locate sensitive information, attackers use advanced search strings called Google dork queries.
Google dork queries are built with the advanced search operators that IT administrators, researchers and other professionals use in their daily work to narrow down search engine results. Commonly used search operators include:

site: restricts query results to a certain site or domain.
filetype: restricts query results to PDF files or other specific file types.
intext: resticts results to those content records that contain specific words or phrases.

Because search operators can be strung together, an attacker can use complex queries to find information that was published on the Internet but was not meant to be found. The use of advanced search operators to find information that is not easily accessed through simple searches is sometimes called Google dorking or Google hacking.

A Google dork is an employee who unknowingly exposes sensitive corporate information on the Internet. The word dork is slang for a slow-witted or in-ept person.
Google dorks put corporate information at risk because they unwittingly create back doors that allow an attacker to enter a network without permission and/or gain access to unauthorized information. To locate sensitive information, attackers use advanced search strings called Google dork queries.
Google dork queries are built with the advanced search operators that IT administrators, researchers and other professionals use in their daily work to narrow down search engine results. Commonly used search operators include:

site: restricts query results to a certain site or domain.
filetype: restricts query results to PDF files or other specific file types.
intext: resticts results to those content records that contain specific words or phrases.

Because search operators can be strung together, an attacker can use complex queries to find information that was published on the Internet but was not meant to be found. The use of advanced search operators to find information that is not easily accessed through simple searches is sometimes called Google dorking or Google hacking.

IP ADDRESS

This definition is based on Internet Protocol Version 4. See Internet Protocol Version 6 (IPv6) for a description of the newer 128-bit IP address. Note that the system of IP address classes described here, while forming the basis for IP address assignment, is generally bypassed today by use of Classless Inter-Domain Routing (CIDR) addressing.
In the most widely installed level of the Internet Protocol (IP) today, an IP address is a 32-bit number that identifies each sender or receiver of information that is sent in packets across the Internet. When you request an HTML page or send e-mail, the Internet Protocol part of TCP/IP includes your IP address in the message (actually, in each of the packets if more than one is required) and sends it to the IP address that is obtained by looking up the domain name in the Uniform Resource Locator you requested or in the e-mail address you're sending a note to. At the other end, the recipient can see the IP address of the Web page requestor or the e-mail sender and can respond by sending another message using the IP address it received.
An IP address has two parts: the identifier of a particular network on the Internet and an identifier of the particular device (which can be a server or a workstation) within that network. On the Internet itself - that is, between the router that move packets from one point to another along the route - only the network part of the address is looked at.

The Network Part of the IP Address

The Internet is really the interconnection of many individual networks (it's sometimes referred to as an internetwork). So the Internet Protocol (IP) is basically the set of rules for one network communicating with any other (or occasionally, for broadcast messages, all other networks). Each network must know its own address on the Internet and that of any other networks with which it communicates. To be part of the Internet, an organization needs an Internet network number, which it can request from the Network Information Center (NIC). This unique network number is included in any packet sent out of the network onto the Internet.

The Local or Host Part of the IP Address

In addition to the network address or number, information is needed about which specific machine or host in a network is sending or receiving a message. So the IP address needs both the unique network number and a host number (which is unique within the network). (The host number is sometimes called a local or machine address.)
Part of the local address can identify a subnetwork or subnet address, which makes it easier for a network that is divided into several physical subnetworks (for examples, several different local area networks or ) to handle many devices.

IP Address Classes and Their Formats

Since networks vary in size, there are four different address formats or classes to consider when applying to NIC for a network number:

• Class A addresses are for large networks with many devices.
• Class B addresses are for medium-sized networks.
• Class C addresses are for small networks (fewer than 256 devices).
• Class D addresses are multicast addresses.

The first few bits of each IP address indicate which of the address class formats it is using. The address structures look like this:
Class A

0

Network (7 bits)

Local address (24 bits)

Class B

10

Network (14 bits)

Local address (16 bits)

Class C

110

Network (21 bits)

Local address (8 bits)

Class D

1110	Multicast address (28 bits)

The IP address is usually expressed as four decimal numbers, each representing eight bits, separated by periods. This is sometimes known as the dot address and, more technically, as dotted quad notation. For Class A IP addresses, the numbers would represent "network.local.local.local"; for a Class C IP address, they would represent "network.network.network.local". The number version of the IP address can (and usually is) represented by a name or series of names called the domain name.
The Internet's explosive growth makes it likely that, without some new architecture, the number of possible network addresses using the scheme above would soon be used up (at least, for Class C network addresses). However, a new IP version, IPv6, expands the size of the IP address to 128 bits, which will accommodate a large growth in the number of network addresses. For hosts still using IPv4, the use of subnets in the host or local part of the IP address will help reduce new applications for network numbers. In addition, most sites on today's mostly IPv4 Internet have gotten around the Class C network address limitation by using the Classless Inter-Domain Routing (CIDR) scheme for address notation.

Relationship of the IP Address to the Physical Address

The machine or physical address used within an organization's local area networks may be different than the Internet's IP address. The most typical example is the 48-bit Ethernet address. TCP/IP includes a facility called the Address Resolution Protocol (ARP) that lets the administrator create a table that maps IP addresses to physical addresses. The table is known as the ARP cache.

Static versus Dynamic IP Addresses

The discussion above assumes that IP addresses are assigned on a static basis. In fact, many IP addresses are assigned dynamically from a pool. Many corporate networks and online services economize on the number of IP addresses they use by sharing a pool of IP addresses among a large number of users. If you're an America Online user, for example, your IP address will vary from one logon session to the next because AOL is assigning it to you from a pool that is much smaller than AOL's base of subscribers.

Top 10 Internet tips and tricks

You don't need the http:// portion of a web page

When entering an Internet address you do not need to type http:// or even www. in the address. For example, if you wanted to visit google.com you could just type .com and press enter. To make things even quicker, if you are visiting a .com address you can type google.com and then press Ctrl + Enter to type out the full http://www.google.com.com address.

Quickly move between the fields of a web page

If you are filling out an online form, e-mail, or other text field you can quickly move between each of the fields by pressing the Tab key or Shift + Tab to move back a field. For example, in the example form below you can click in the "First Name" field type anything and press tab to switch to the next field.

Example Form

First Name:
Last Name:
E-mail:

Tip: This tip also applies to the buttons, if you press tab and the web developer has designed correctly the button should be selected and allows you to press the space bar or enter to push the button.

Tip: With a drop-down box that lists dozens of options you can press the first letter to scroll down to that letter. For example, click the drop down box below and then press "u" to quickly scroll to Utah.

Know your Internet browser shortcuts

There are dozens of different shortcut keys that can be used with Internet browsers. Below are a few of our top suggested Internet browser shortcuts.

• Press Alt + D to move the cursor into the address bar.
• Hold down the Ctrl key and press the + or - to increase and decrease the size of text. Ctrl + 0 will reset the text.
  
• Press the backspace key or press Alt key + left arrow to go back a page.
  
• Press F5 to refresh or reload a web page.
  
• Press F11 to make the Internet browser screen full screen. Press F11 again to return to the normal view.
  
• Press Ctrl + B to open your Internet bookmarks.
  
• Press Ctrl + F to open the find box to search for text within the web page you are reading.

Take advantage of tabbed browsing

Take full advantage of tabbed browsing on all Internet browsers. While reading any web page if you come across a link that interests you open the link in a new tab so it doesn not interrupt your reading. A new tab can be opened by holding down the Ctrl key and clicking the link or if you have a mouse with a wheel press down on the wheel to use it as a middle mouse button to open the link in a new tab.

Use Internet search engines to their full potential

Get the most out of every search result. If you are not finding what you want try surrounding the text in quotes. For example, searching for 'computer help' without quotes returns results with "computer" and "help" anywhere on the page. However, if you search for "computer help" with the quotes it only return pages with "computer" and "help" next to each other.

Tip: In every search box you can press enter instead of using the mouse to click the Search button.

• Top 10 unknown Google tricks

Try alternative browsers

Most computer users use the default browser that comes included with the computer, with Microsoft Windows this is Internet Explorer. There are many great alternative browsers that are all free to download and use and may have features your current browser does not include. Below are a few of our favorites, try one or try them all.

• Google Chrome
• Mozilla Firefox
• Opera

Install plugins and add-ons

All of the above alternative browsers also have a large community of volunteers who develop add-ons and plugins that can be added into the browser. Each of these browsers has hundreds of thousands of these add-ons that can do such things like the current weather in your browser window, changing its color, and adding additional functionality.

• Top 10 Firefox add-ons

Make sure your browser and its plugins are up-to-date

An Internet browser can have many plugins that give it additional functionality. For example, Adobe Flash is a great way to bring movies and other animated content to the Internet. Keeping these plugins up-to-date is vital for your computer stability and also security. Using the below tool you can quickly verify if your plugins are up-to-date and get links to where to download the latest updates.

• Computer Hope system information tool

Use online services

There are hundreds of free online services that can help make using your computer easier, more productive, and more enjoyable. See our top 10 online services for a listing of our favorites.

Basic network troubleshooting

Because of the variety of network configurations, operating systems, setup, etc. not all of the below information may apply to your network or operating system.

Note: We cannot assist you with network problems due to an unknown passwords or unknown ISP settings. Since we have no method of verifying or determining this information.

Adapter resources

Verify that the network adapter is properly installed and detected by the computer with no conflicts. If you're using Microsoft Windows check in Device Manager and verify there are no errors and "Network adapters" is present with each network adapter installed in the computer listed, similar to the example on the right.

• How do I get into Windows Device Manager?
• Identifying problems in Windows Device Manager.

If conflicts exist or the network adapter is being detected as an Other device. The network card has not been properly installed in the computer. Try letting Windows re-detect and install the Network card by removing the network adapter and any other conflict devices from Device Manager and then rebooting the computer. If Windows re-detects the card but does not find the drivers, download the network adapter drivers from the computer manufacturer or the network card manufacturer.

• How do I remove a device in Windows Device Manager?
• Listing of network drivers and network card manufacturers.

Verify connections

Wired Network

If this is a wired network, verify that the network cable is properly connected and make sure the LEDs next to the network jack are properly illuminated. For example, a network card with a solid green LED or light usually indicates that the card is either connected or receiving a signal. If the green light is flashing, this is an indication of data being sent or received. In the picture is an example of LAN port with two LED indicators next to the RJ-45 port. With this port, one LED will light up if connected properly and the other will flash when transmitting data.

If there are no lights or the lights are orange or red the card may be bad, not connected properly, or that the card is not receiving a signal from the network. If you are on a small or local network and have the capability of checking a hub, switch, or router verify that the cables are properly connected and that it has power. If after checking the connections the LED indicators appear bad, the network adapter, port, or cable may be defective.

Wireless Network

If you're using a laptop with a wireless network make sure if the laptop has a Wi-Fi button that it is turned on. Many laptops have a Wi-Fi button that allows the wireless network to be turned on and off. In the picture is an example of a Wi-Fi button that is currently enabled.

If the Wi-Fi button is turned on, make sure you're connecting to the correct Wi-Fi hotspot by right-clicking on the Network icon in the Windows notification area and clicking "Connect to a network". Usually, the network with the strongest connection (the most bars) will be your wireless router.

Finally, when connecting to most wireless networks you need to enter the proper SSID (password) in order to connect to the network. If the incorrect SSID has been entered you cannot access the network.

Adapter functionality

Verify that the network card is capable of pinging itself by using the ping command. Windows users can ping the computer from a Windows command line. Unix and Linux users can ping from the shell.

To ping the card or the localhost, type either

ping 127.0.0.1

or

ping localhost

Doing either of the above commands should get replies from the network card. If you receive an error or if the transmission fails the network card is not physically installed into the computer correctly, has the incorrect drivers, or that the card is bad.

Connect to the router

If all of the above steps have been checked and your network has a router, make sure the computer can connect to the router by performing the below commands.

Determine the routers address

Using the ipconfig command (or ifconfig command for Linux) determine the router's address by looking at the Gateway address. Below are the steps for Microsoft Windows users, Linux users can substitute ipconfig for ifconfig.

1. Open the Windows command line.
2. From the command prompt type ipconfig and press enter. This command should give you an output similar to the example below.

Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : computerhope.com.
IP Address. . . . . . . . . . . . : 192.168.1.103
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1

The Default Gateway is the address of your router. Most home routers have a gateway address that starts with 192.168 like the address shown above. Assuming your gateway address is 192.168.1.1 attempt to ping the router to see if it can send and receive information by running the below command.

ping 192.168.1.1

If you get replies back from the router, the connection between your router and computer are good, and you can skip to the next step.

If you do not receive any replies back from the router either the router is not setup properly or your connection between the router and the computer are not correct. Reset your router to make sure it is not a problem with your router by following the steps below.

1. Turn off the power to the computer and leave it off.
2. Unplug the power to your router and cable modem or DSL modem.
3. Leave the power cables disconnected for 10-15 seconds and then plug in your modem and then your router again.
4. Finally, turn on your computer again and repeat this step to see if you can ping your router.

If you're using a wireless network and have followed all the above steps and still are unable to ping the router try turning off the computer again and connect the computer to the router using a cable instead of trying to connect using wireless. If a wire does also not work connect the manufacturer of the router for additional support or replacement.

Firewall

If your computer network utilizes a firewall, make sure all required ports required are open, especially port 80, which is the HTTP port. If possible, disable the firewall software program or disconnect the computer from the firewall to make sure it is not causing the network problems.

Internet is not working

If you're able to ping the router, but are still unable to connect to the Internet, either your router is improperly configured or the ISP is having issues.

Note: Some ISPs such as Comcast require special software be installed. Make sure any software included with your Modem or other hardware has been installed on at least one computer if you are setting up a new Internet connection.

If your Internet has been working but recently stopped working, give it a few minutes to make sure it is not a temporary outage. If after waiting a few minutes, you still have problems and you have not disconnected the power to your router and modem already follow the steps below.

1. Turn off the power to the computer and leave it off.
2. Unplug the power to your router and cable modem or DSL modem.
3. Leave the power cables disconnected for 10-15 seconds and then plug in your modem and then your router again.
4. Finally, turn on your computer again and repeat this step to see if you can ping your router.

If after following the above steps the Internet is still not working, open the Windows command line and run the below command.

ping google.com

Running the above command should get a reply from Google. If you get a reply, this is an indication that the Internet is working, but you may be encountering a problem with the Internet browser you are using to browse the Internet. Try an alternative browser such as Firefox or Chrome.

If you're getting no reply from Google, your router or modem is not reaching the Internet. If you have a router, make sure your router has DHCP enabled and that the WAN or Gateway address is the proper ISP address.

Finally, after verifying all of the above settings if your Internet is still not working we suggest contacting the ISP to make sure it is not a problem on their end and to assist you further with any special configurations that may not be mentioned in this document.

Additional troubleshooting

Another method of determining network issues is to use the tracert command if you are a Windows user or the traceroute command if you are a Linux or Unix variant user. This command gives you an overview of each of the devices (routers) a packet travels (hops) over a network and can give you an idea of where a problem exists in your network or outside of your network.

To use this command you must be at the command line and type one of the below commands depending on your operating system.

tracert google.com

or

traceroute google.com

If run successfully you should begin to see each hop between the computer and network devices. When the connection fails, determine what device is causing the issue by reviewing the traceroute listing.

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