June 2013 ~ Techno Critic

Tcp tutorial part 2

TCP Segment format:

The figure below show the TCP segment format. It show the different
field within the TCP header.

bit 0 bit 16 bit 32
------------------------------------------------------------------
Source port (16) Destination port (16)
________________________________________________________________

Sequence number (32)
_________________________________________________________________

Acknowledgement number (32)
_________________________________________________________________

Header Reserved Code Bits Window (16)
Length (6) (6)
(4)
______________________________________________________________

Checksum (16) Urgent (16)
________________________________________________________________

Options (0 or 32 if any)
_________________________________________________________________

Data (varies)

Tcp tutorial part 1

TRANSMISSION CONTROL PROTOCOL (TCP):
TCP takes large blocks of information from an application and
breaks them into segments. It numbers and sequences each
segment so that the destinations TCP protocol can put the
segments back into the order the application intended.
After these segments are sent, TCP (on the transmitting host)
waits for an acknowledgement of the receiving ends TCP virtual
circuit session, retransmitting those that are not acknowledged.

Before a transmitting host starts to send segments down the model,
the senders TCP protocol contacts the destinations TCP protocol
to estasblish a connection. What is created is known as a virtual
circuit. During this initial handshake, the two TCP Layers also
agree on the amount of inforamtion that is going to be sent before
the recipients TCP sends back an acknowledgement. With everything
agreed upon in advance, the path is paved for reliable communication
to take place.

Share an Internet Connection With Multiple Computers

Linux offers the ability to act as both firewall and router for
multiple computers. You can easily set this up using iptables.

Execute the following commands on your Linux box. This example assumes
that eth0 is the network interface connected to the cable or DSL modem.

# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
# modprobe ip_conntrack_ftp
# echo 1 > /proc/sys/net/ipv4/ip_forward
# iptables -P INPUT DROP

Of course, this is greatly simplified; it's just the basics to get you
up and running quickly.

Keep in mind that it doesn't matter what systems you're running on your
network, be it Windows, Macs, or other Linux systems. All you need to
do is tell those clients to use this Linux machine as the gateway.

How to "Delete administrator Password" without any software

Boot up with DOS and delete the sam.exe and sam.log files from Windows\system32\config in your hard drive. Now when you boot up in NT the password on your built-in administrator account which will be blank (i.e No password). This solution works only if your hard drive is FAT kind.

Method 2

Step 1. Put your hard disk of your computer in any other pc .Step 2. Boot that computer and use your hard disk as a secondary hard disk (D'nt boot as primary hard disk ).Step 3. Then open that drive in which the victim’s window(or your window) is installed.Step 4. Go to location windows->system32->configStep 5. And delete SAM.exe and SAM.log
Step 6. Now remove hard disk and put in your computer.
Step 7. And boot your computer :-)

Linux Commands

How to search files for specific terms:

grep -r [search term] .

How to add items such as svn, mvn, java, etc. to your PATH and set environment variables for all users:

Edit the /etc/profile file and then run .[space]/etc/profile with

export PATH=$PATH:/usr/java/jdk1.5.0_07/bin

How to set an environment variable:

export JAVA_HOME=/usr/java/

export ANT_HOME=/usr/ant/

How to find out where and command is installed such as java, ant, mvn:

which java

which ant

which mvn

How to stop a running program:

First determine the pid of the program:

ps -ef | grep [program name]

Then use the pid to kill the program:

kill -9 [pid]

How to search for a file:

find . -name [filename]

How to unmout a drive (Notice the command is umount and NOT UNmount):

umount [mount location]

How to clear the Java Web Start cache:

javaws -uninstall

How to view the Java Web Start Console

javaws -viewer

How to mount a drive:

mount -t [new mount name (this directory must exist)] [mount location]

mount -t /home/user/share /mnt/floppy

Linux Mounted Driver cannot remove directory error message

When running rm -rf [directory name] the following error message occurs:
rm: cannot remove directory '[directory name]': File exists

If this occurs when trying to remove a file from a mounted drive, try unmounting the drive and remounting it.

Windows Vista Connect.dll Error Message

Error message

Component GUID:{7071ECA3-663B-4BC1-A1FA-B97F3B917C55}
Component file: [C:\Windows\system32\connect.dll]
Error: (0x8007277B) .

Additional Info:
Failed to detect Internet connectivity

Description

Received the following error message when trying to connect to the Internet on a Windows Vista computer.

Solutions

TCP/IP stack repair options for use with Windows Vista.

Start, Programs\Accessories and right click on Command Prompt, select "Run as Administrator" to open a command prompt.
Reset WINSOCK entries to installation defaults: netsh winsock reset catalog
Reset IPv4 TCP/IP stack to installation defaults. netsh int ipv4 reset reset.log
Reset IPv6 TCP/IP stack to installation defaults. netsh int ipv6 reset reset.log
Reboot the machine.

Reinstall network/modem Driver

Uninstall the network/modem driver from Device Manager: select the items and hit Delete. Reboot.

Anti Virus and Firewall Software

Installation or Removal of Anti Virus or Firewall product can prevent the network devices from getting an IP.

Windows Update

Windows update has been known to cause this issue. Uninstall the most recent windows updates.

Since its launch, the Surface tablet from Microsoft has reached 400,000 sales, which isn't a bad start for a tablet that is definitely on the pricey side with an $899 price tag. What's even more impressive is that this tablet only launched a month ago. According to IDC Analyst Bob O'Donnell, "That's a respectable number and it leads me to believe that Surface Pro will end up outselling Surface RT."

O'Donnell is, of course, referring to the RT version of the Surface tablet, which is slightly less expensive at $499, though isn't compatible with older Windows software. "It's something that we've predicated all along because of the compatibility that Surface Pro offers," O'Donnell added. Overall, Microsoft has sold nearly 1.5 million Surface devices, including both Pro and RT versions, and was announced only three months ago.

Even though the RT version sold out initially, Microsoft was surprisingly able to keep up with demand quickly. Unfortunately, that hasn't been the case with the Pro. The high-end, 128GB Pro version of Surface has been continuously sold out since it was released on February 9. This model of the Surface tablet has only recently become readily available in the last week or so.

Regardless, the numbers being put up by the Pro are nothing compared to that of Apple's iPad. Apple sold more than 20 million iPads in the quarter ending in December, though Apple has been in this market substantially longer than Microsoft has and has also had time to fine tune its device. However, like Surface RT, the 9.7" Retina iPad starts at $499 while the iPad Mini is even cheaper at $329.

The trick with the Surface is that it puts a conventional, mainstream laptop into a 2 lb, 0.5" thick tablet. The Pro version comes with a 10.6" 1,920 x 1,080 full HD resolution display, Intel Ivy Bridge processor, 4GB of memory and a full-fledged solid-state drive, which is exponentially faster than the flash drives found in Apple and Android tablets.

Nonetheless, the numbers posted by Microsoft are impressive, especially considering the lackluster reviews that Windows 8 has been receiving. Windows 8 is the operating system that the Surface uses, though the OS has clearly been designed for use on touchscreen devices. It will be interesting to see what kind of numbers this tablet will post in the coming months.

Source: CNET - Microsoft Surface Pro sales hit 400K in a hurry

Logitech is a Swiss peripheral device manufacturer that makes PC accessories including keyboards, mice, microphones, game controllers, and webcams. They also produce home and computer speakers, headphones, wireless audio devices, and audio devices for MP3 players and mobile phones. The newest innovation in their computer peripheral department is the Wireless Solar Keyboard K750.

This keyboard brings together all of the latest technology. It features integrated solar panels on the top of the keyboard that collect the power for the K750 so that you can use it without batteries or power cords inside or outside of the office. Logitech has made the incredible claim that when the keyboard is fully charged it can last for up to three months in a pitch black room.

The keyboard has a very sleek design. It is mostly black, except for the slim white frame, and is about one-third of an inch thick. The keys were designed in the chiclet style and have an extremely comfortable feel. The keyboard features an on/off switch that allows you to conserve power when you aren’t utilizing the K750. There also is an indicator light that lets you know when the charge of the keyboard is getting low.

Logitech includes their Unifying Receiver with the Wireless Solar Keyboard K750. It is a thumbnail USB device that gives you the ability to use your keyboard wirelessly. The receiver also features the special ability to sync up to six Logitech peripherals with the one USB device. Another great feature is the solar power app that will allow K750 users to install a lux meter that will measure ambient light levels and the battery life of the keyboard. This app will be available to download on November 15th.

The Wireless Solar Keyboard from Logitech is not shipping yet, but it is available for pre-order. The keyboard will be shipping a little later this month and will cost $79.99. I think that this keyboard is awesome. It’s incredible that when charged the keyboard can last up to three months. Also, wireless really means more convenient to me, which is important. I think that this solar keyboard will definitely be a hit. This is a great keyboard from a great company.

Microsoft's Summer Xbox Deal Is Back!

Microsoft had a nifty back to school special last year that awarded customers a brand new Xbox 360 with the purchase of any new Windows PC. Well, it seems as though the promotion was a success, enough of one at least to make the company want to do it again this year as well. Starting on Sunday, May 20, U.S. students who buy a new Windows 7 PC will also receive a free Xbox 360 as well.

The deal doesn't just apply to U.S. students, however, as Canadian students also qualify for the deal which started on the 18th. In order to be eligible you will have to be a high school or college student with proof of status, like a campus ID or an email address that ends in .edu. If you qualify, you will receive a 4GB Xbox 360 with the purchase of a Windows PC for $699 or more. If you're a Canadian student, you only have to buy a $599 PC.

The Xbox that students will receive is Microsoft's current $199 console, which is the lowest priced model the company offers and the one that doesn't come with a Kinect motion sensor. Best Buy was the only retailer partner that Microsoft paired with for the offer the last time, though the company has greatly increased their partners this time around. In the U.S. Microsoft is partnering with Best Buy and Fry's Electronics while the company will be teaming up with Best Buy, Future Shop, Staples and The Source in Canada. You can also get the deal online through Dell, HP and Newegg in the U.S. and through Dell in Canada.

If you happen to live close to an actual Microsoft store, you can also get the deal there as well. There are 21 Microsoft stores currently open (or expected to open in the summer), all of which are located in the United States. Microsoft's online store will also support the deal. Also new this year is the amount of control Microsoft has left in the hands of the retailers. This means that the deal won't last the same amount of time for every retailer so make sure you check your dates before you go in for the deal.

Source: PC World - Buy a Windows 7 PC, Get an Xbox

Find out what is going on in the Tech Army World.

What are the Top 10 Money Making Missions?
What other companies have joined and what do they do?
How do I join the Tech Army Organization ?

For those of you who don't know, Dropbox is a simple online virtual storage utility that allows you to make your files accessible from almost anywhere. Designed for those who are tired of e-mailing files to themselves and carrying around flash drives, Dropbox looks to revolutionize the way you store and share files.

Here's how it works. After installation and connecting to the server, the Dropbox interface is just like any folder on your computer. You simply drag and drop to move files around and any files or folders that are uploaded to Dropbox will immediately be synchronized within your account. In addition Dropbox also keeps track of every single change made to the contents of your storage and any changes are instantly updated to all computers linked to the account.

What happens if I'm not on any of my computers? Absolutely no need to worry. Just get on the Dropbox web interface and you will be able to access your files from anywhere in the world. The Dropbox web interface also remembers all the changes you make to your files and allows you to restore to any previous versions of the file. You can even un-delete files that you may have accidentally erased.

Where Dropbox really shines is the way it allows you to share whatever you want with other people. Every individual folder can be shared with other people and every member of a shared folder will be able to add, edit, and delete the contents inside but will not be able to access anything outside of that specific folder. This file sharing system is perfect for team projects involving music or video editing, computer and system repairs, or for anything which needs collaboration among its members. There is also a public folder that allows you to share files with non-Dropbox users through the use of a hyperlink.

If you are looking for an easy and reliable way to share files amongst friends, family, and coworkers then take a look at what Dropbox has to offer. Dropbox is free for Windows, Mac, and Linux and you can have share 2 GB of your files for free or upgrade to Dropbox Pro for 50GB of storage.

How much does it cost to run a computer?

Here's something that has always hung around in my mind, but I never got around to looking up the answer. How much will running PCs add to your power bill?

Anandtech posted an article where they calculated the cost of running a PC per hour.

* For a middle of the line system, they figured one year of use is $93.51 for 8 hours a day.
* If you let your PC sit idle 24 hours a day, it will cost you $128.12 a year.
* For a top of the line system that is at full load all day long (like a server) you could spend $440.85.

These prices are calculated at the price of electricity in North Carolina. California PC users will pay almost double.

Well, it's official, you can no longer purchase an upgrade to Windows 8 Pro for the discounted price of $39.99. As of February 1, Microsoft has quintupled the price to $199.99. Just upgrading to the standard Windows 8, which doesn't include corporate features like BitLocker encryption and the ability to remotely connect to a company's network, will cost $119.99, though that edition was never discounted.

Upgrading to Windows 8 from an existing Windows operating system, like XP, Vista or 7, comes with varying degrees of success. It should come as no surprise that upgrading from Windows 7 causes the least amount of hassle with bringing along existing files, settings and applications whereas upgrading from XP is a little more difficult.

In addition to the end of the discount, several other deals also ended, including $69.99 prices for Windows 8 Pro on a DVD and something Microsoft was calling Windows 8 Pro Pack, which upgrades Windows 8 to Windows 8 Pro. The first upgrade will jump to $199.99 with the latter costing $99.99. Windows 8 Media Center pack, which is an add-on that makes it possible to play CDs and DVDs on a Windows PC, now costs $9.99.

Only one time has Microsoft discussed Windows 8 Pro upgrade numbers. This occurred back in October when CEO Steve Ballmer said his company had sold 4 million copies in its first three days. Since then, Microsoft has declined to give any specific sales numbers, even though the firm's CFO recently cited upgrades as one of several reasons why the Windows division's revenue increased 11% in the fourth quarter of 2012.

Purchasers of the Windows 8 upgrade do not have to install it right away. Instead, they can create a bootable flash drive or installation DVD, then set aside the physical media for a later date. The final offer that recently expired was the eight-month deal that offered a $14.99 upgrade for customers who purchased a Windows 7-powered PC between June 2, 2012 and January 31, 2013. Those customers have until February 28 to claim the promotional code for the $14.99 price.

Windows 8 has received quite a bit of flak from users who believe that the heavy focus on touch-screen features do not translate well to desktops and laptops without touchscreens. Having used Windows 8 personally, I can honestly say that the new home screen and layout definitely take some getting used to, especially for long-time Windows users, though some of the features that are available are pretty cool and the operating system itself isn't all that bad (though that was at the time of the $39.99 download). I don't know if the operating system (or any, for that matter) is worth $200.

MANUFACTURER’S DESCRIPTION
$1,199.00

Underneath the sleek exterior, MacBook Air is packed with powerful components that give you smoother graphics, faster storage, and all-around serious performance. Not to mention enough battery life to get you through the day.The result? A computer that's as capable as it is portable.

11-INCH, 256GB FLASH STORAGE

Processor
Processor type	1.3GHz Core i5 dual core
Memory
Memory size	4024.0 MB
Memory speed	1600.0 MHz
Display
Display size	11.6 inches
Display type	Glossy LCD with LED Backlight
Resolution	1366 x 768 pixels
Graphics
Graphics Type	Integrated
Primary Graphics Chipset	Intel HD Graphics 5000
Storage
Drive 1 size	256.0 GB
Drive 1 type	Solid-State Drive
Dimensions
Width	11.5 inches
Depth	7.56 inches
Height	0.68 inches
Weight	2.38 pounds
Storage Media
SD card	SDXC Card
Ports and Connections
Ethernet Type	10/100/1000 Mbps
Available Interfaces	Line Out 1/8 Thunderbolt 2.0 USB 3.0
Wireless connection	802.11a 802.11ac 802.11b 802.11g 802.11n Bluetooth
Warranty
Warranty information	1 Year Limited Warranty

13-INCH, 256GB FLASH STORAGE

Processor
Processor type	1.3GHz Core i5 dual core
Memory
Memory size	4024.0 MB
Memory speed	1600.0 MHz
Display
Display size	13.3 inches
Display type	Glossy LCD with LED Backlight
Resolution	1440 x 900 pixels
Graphics
Graphics Type	Integrated
Primary Graphics Chipset	Intel HD Graphics 5000
Storage
Drive 1 size	256.0 GB
Drive 1 type	Solid-State Drive
Dimensions
Width	12.8 inches
Depth	8.94 inches
Height	0.68 inches
Weight	2.96 pounds
Storage Media
SD card	SDXC Card
Ports and Connections
Ethernet Type	10/100/1000 Mbps
Available Interfaces	Line Out 1/8 Thunderbolt USB 3.0
Wireless connection	802.11a 802.11ac 802.11b 802.11g 802.11n Bluetooth
Warranty
Warranty information	1 Year Limited Warranty

11-INCH, 128GB FLASH STORAGE

Processor
Processor type	1.3GHz Core i5 dual core
Memory
Memory size	4024.0 MB
Memory speed	1600.0 MHz
Display
Display size	11.6 inches
Display type	Glossy LCD with LED Backlight
Resolution	1366 x 768 pixels
Graphics
Graphics Type	Integrated
Primary Graphics Chipset	Intel HD Graphics 5000
Storage
Drive 1 size	128.0 GB
Drive 1 type	Solid-State Drive
Dimensions
Width	11.8 inches
Depth	7.56 inches
Height	0.68 inches
Weight	2.38 pounds
Storage Media
SD card	SDXC Card
Ports and Connections
Ethernet Type	10/100/1000 Mbps
Available Interfaces	Line Out 1/8 Thunderbolt USB 3.0
Wireless connection	802.11a 802.11ac 802.11b 802.11g 802.11n Bluetooth
Warranty
Warranty information	1 Year Limited Warranty

13-INCH, 128GB FLASH STORAGE

Processor
Processor type	1.3GHz Core i5 dual core
Memory
Memory size	4024.0 MB
Memory speed	1600.0 MHz
Display
Display size	13.3 inches
Display type	Glossy LCD with LED Backlight
Resolution	1440 x 900 pixels
Graphics
Graphics Type	Integrated
Primary Graphics Chipset	Intel HD Graphics 5000
Storage
Drive 1 size	128.0 GB
Dimensions
Width	12.8 inches
Depth	8.94 inches
Height	0.68 inches
Weight	2.96 pounds
Storage Media
SD card	SDXC Card
Ports and Connections
Ethernet Type	10/100/1000 Mbps
Available Interfaces	Line Out 1/8 Thunderbolt USB 3.0
Wireless connection	802.11a 802.11ac 802.11b 802.11g 802.11n Bluetooth
Warranty
Warranty information	1 Year Limited Warranty

Top 5 all-in-one PCs

Big-screen all-in-one PCs are increasingly dual-purpose devices: You can use them as computers for playing PC games, using productivity apps, surfing the web and more. But thanks to HDMI inputs, you can also connect a gaming console like an Xbox 360 and play those types of games, or plug in a your cable or satellite TV service provider's set-top box and watch TV! Blu-ray drives were once de rigeur on high-end all-in-ones, but that feature seems to be falling by the wayside as manufacturers assume consumers will watching movies online. Several models boast touch screens to take advantage of Windows 8, but that feature can add considerably to the price tag of units with 27-inch displays.

By Michael Brown

COMPARE

HP Envy 23-d060qd TouchSmart All-in-one

Rated: Jan 5, 2013 12:00 AM

The Envy 23 delivers solid performance and an excellent touchscreen in a sleek, usable package.

4/5

Dell Optiplex 9010 AIO

Rated: Apr 3, 2013 12:00 AM

All-in-ones aren't just for the home. Dell's Optiplex line is designed for business and corporate environments. Its VESA mount gives you the option of using the computer on an articulated arm that will lift it off your desk.

4/5

prices from$1,158.00

Acer 7600U-UR308

Rated: Nov 27, 2012 12:00 AM

The Aspire 7600U is a mesmerizing machine, but its mobile processor delivers less-than-impressive performance.

3.5/5

Samsung Series 7 DP700A3D-A01US All-in-one

Rated: Mar 13, 2013 12:00 AM

Samsung delivers one of the nicer looking all-in-ones on the market with good overall performance, but weak gaming capabilities.

3.5/5

prices from$942.00

Dell XPS One 2710

Rated: Jan 4, 2013 12:00 AM

The XPS One is gorgeous. It has a 27-inch screen boasting resolution of 2560 by 1440 pixels and a Blu-ray drive. Be prepared to pay for all that goodness.

3.5/5

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MANUFACTURER’S DESCRIPTION $1,199.00

11-INCH, 256GB FLASH STORAGE

13-INCH, 256GB FLASH STORAGE

11-INCH, 128GB FLASH STORAGE

13-INCH, 128GB FLASH STORAGE

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MANUFACTURER’S DESCRIPTION
$1,199.00