Question of the Week

Increase your Ping-Fu!

October 15, 2012 by kronos. 4 comments

User George Duckett came across a weird thing while performing a simple ping:

He performed a simple ping request but missed a ‘dot’.  I assume he meant to ping 192.168.0.72 but instead ended up typing 192.168.072.  What’s really amazing though (as pictured below) was that it worked!!! but not to 192.168.0.72 it sent the ping request to 192.168.0.58 :

enter image description here

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Is your browser telling on you?

October 1, 2012 by kronos. 5 comments

Browsing on the web may seem harmless to most, but we SuperUsers are typically a secretive bunch.  We’ don’t like data being shared about us unless we tell them to.

So when user Pickledegg asked about how much info can websites can get, it became a pretty popular question.

I am trying to determine if the information shown on the website www.whatsmyip.org is the absolute maximum amount of information that a webserver can obtain from a web visitor. Does anyone know of any other sites that will be able to get more information from the user passively like this? I’m not talking about port-sniffing or any kind of interaction from the user, just the info that a server can get from a ‘dumb’ visit.

So what’s the verdict?

Here’s what we found.  From What’s my IP they can determine the following (I removed un-important info, if I missed something feel free to comment):

  • External IP
  • Homename
  • Proxy
  • Internal (LAN) IP
  • Operating System and version
  • Screen Resolution
  • Cookies Enabled
  • Browser Plugins
  • Location (kinda sorta)
  • And a WHOIS Lookup

Basically is looked like this (I put green checkmarks across things that were correct):

 

But there’s more!  A browser can also give away your installed fonts! GASP.  Wait… what?  Why is that important?

User Informaficker had this to say:

Installed fonts are probably the most identifying piece of information as soon as you start adding one or two. Just because of the amount of fonts out there, it is unlikely to have the same set of fonts on two different computers. (As long as they are used by different persons)

This means that if you have any custom installed fonts on your computer, you have a greater likelihood to have a different “Font Identity” than others since there are lots of fonts out there.

How do I stop this monstrosity?

First DON’T LET IT!!!

Browsers are typically good at telling you what’s going on.  I suggest that you NEVER select Always run on this site (or other browser equivalents), and only allow trusted websites to run Java or Flash.  Disabling Java or Flash is another option, however with a majority of websites using either Java or Flash this can be difficult and annoying.

However, the browser can still access your External IP address.  A way around that is to use a Virtual Private Network (VPN).  I tested this out and it worked, including getting the wrong internal IP, since it picked up the VPN’s Internal IP and not my actual home networks IP.

Overall, it goes without saying to just be careful when ever your browsing the interwebs.

Super User Review of Hyper-V for Windows 8

September 17, 2012 by kronos. 10 comments

This weeks question of the week come from these two questions:

One of them asked by Graham Clark, and the other is a self post by myself.  This prompted me to do a more formal review of Microsoft’s Hyper-V for Windows 8.

What is Hyper-V for Windows 8?

Hyper-V for Windows 8 is really called Client Hyper-V.  It’s similar in many aspects to the Microsoft Server’s Hyper-V (2008 and the upcoming 2012).  What’s different about Client Hyper-V is that it was customized to fit the portable environments, such as laptops, that developer’s find themselves in.  What does Hyper-V do?

In brief, Hyper-V lets you run more than one 32-bit or 64-bit x86 operating system at the same time on the same computer. Instead of working directly with the computer’s hardware, the operating systems run inside of a virtual machine (VM).

(source)

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Question of the Week #42: 42 Questions of Awesomeness!

September 10, 2012 by kronos. 0 comments

The number 42 is amazing, and so to honor Douglas Adams answer to live, the universe and everything, I have collected 42 amazing questions/answers that we haven’t featured yet.  These aren’t in any particular order, as they are all interesting or awesome in some way or another.

1 Storing hard drive near electric wireEver wonder if your hard drive could be ruined while being near electical lines well here’s the tl;dr answer:

In short, don’t worry about it, unless you’re working with some kind of industrial equipment with VERY high currents on that cable (the amount of interference emitted from a power cable is proportional to the current on it). Household currents are unlikely to be a problem.

2 What are PATH and other environment variables, and how can I set or use them? – Environment variable can be a powerful tool to use.  The answer is a great guide on the how’s what’s and why’s of environment variables within Windows.

3 Why do disks fragment? – With the advent of SSD’s and their completive prices there may come a day when fragmentation will become a thing of the past, but for now it’s something we need to deal with.  The answers still provide insight to the woe’s of the the past when it comes to disk drive fragmentations.

4 How does a CPU ‘know’ what commands and instructions actually mean? – There’s a lot of “magic” that goes on behind the scenes as you operate your computer.  All of this magic eventually ends up being assembly level instructions which in turn…  well that’s the question, and the answers are pretty good at explaining the basics.

5 What makes a laptop overheat? – Laptops are notorious for overheating, and this question/answer duo helps to try to explain what it is.

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The Super User’s Windows 8 Guide

August 27, 2012 by kronos. 1 comments

Windows 8 is out for MSDN account holders (including students with MSDN-AA access)!  And it’s set to release on October 26th.  With that there are bound to be tons of questions in regards to Windows 8.   This post is meant to be a collection awesome questions/answers found on Super User that are tagged Windows 8.  This is what we’ve got so far:

General Understanding/Installation

The New Modern Apps

As time goes on, and more questions/answers come along, we’ll update this help all you Super Users out there with the new Windows 8.

A Super User’s Guide to Memory (QotW #40)

August 14, 2012 by kronos. 1 comments

Memory.  Every Super User knows that they need it, and if you’re like me, you can never get enough.  I know I somehow find ways to use up all 16 Gb of my memory on my desktop.  In fact, back in Nov 2010 Tom’s Hardware suggested that the minimum system RAM should be around 8Gb!

But what’s really frustrating is buying memory.  There are so many factors to consider that it can get overwhelming.  This is the same issue that Super User nathpilland had:

What am I looking for in RAM?

This is the one area of computer building that still has me in the dark, and I think a lot of people are with me… There are many different types of RAM, with each company having high and low end sticks. What is the difference between the high and low end? Also, what do the numbers in the latency mean? What is the speed rating (I know 1600 MHz is about normal) and how much is too much? What’s the difference between dual channel and single channel? Can you overclock/overvolt? Is there even a point to do so if this was possible? As you can see, I’m thoroughly confused here. I tried doing some research, but I can’t find this information anywhere on the internet. I’m not actually buying RAM, I’m just trying to get a better picture as to how all this works so I can be more educated on the hardware in computers.

So here we go.  This blog post is a stab at defining the basics you need to know about RAM.

A quick look over at NewEgg there were a few major categories that advertising threw at me:

  • Type (DDR, DDR2, DDR3)
  • Speed (typically in terms of 1066, 1333, 1600, etc)
  • Timings
  • CAS Latency

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Question of the Week: What are cookies and why am I being asked about them?

August 6, 2012 by kronos. 4 comments

A lot of people have heard about Internet “cookies” and often they have a bad connotation  to them, but to web developers they are very useful.  So what exactly are they?  The official Wikipedia definition states:

A cookie, also known as an HTTP cookie, web cookie, or browser cookie, is usually a small piece of data sent from a website and stored in a user’s web browser while a user is browsing a website. When the user browses the same website in the future, the data stored in the cookie can be retrieved by the website to notify the website of the user’s previous activity.  Cookies were designed to be a reliable mechanism for websites to remember the state of the website or activity the user had taken in the past. This can include clicking particular buttons, logging in, or a record of which pages were visited by the user even months or years ago.

This basically means that websites will save small pieces of data on your machine in plain text.  These have a wide range of uses, but here are some common examples that I can think of:

  1. Netflix: Isn’t is awesome how it remember where you last left off?  This is done through cookies
  2. Amazon (and other shopping sites): They remember what was in your basket last time you visited.
  3. Stack Exchange: Remembers you, so you don’t have to log in every time.  (Actually this is a WAY more complicated process detailed here, but you get the picture)

Question of the Week: How can computers calculate exponential math without overflow errors?

July 30, 2012 by kronos. 5 comments

This weeks question of the week comes from Kit-Ho who poses:

Studying some RSA encrypt/decrypt methods, I found this article: An Example of the RSA Algorithm It requires this to decrpyt this message enter image description here The total result of enter image description here is so big, for a 64-bit/32-bit machine, I don’t believe it can hold such a big value in one register. How does the computer do it without an overflow?

 

For those of you that may not know what this “Overflow” that Kit mentioned, he’s talking about a term Stack Overflow.   Here’s the official “Wiki” definition:

 

In software, a stack overflow occurs when too much memory is used on the call stack. The call stack contains a limited amount of memory, often determined at the start of the program. The size of the call stack depends on many factors, including the programming language, machine architecture, multi-threading, and amount of available memory. When a program attempts to use more space than is available on the call stack (that is, when it attempts to access memory beyond the call stack’s bounds, which is essentially a buffer overflow), the stack is said to overflow, typically resulting in a program crash.  This class of software bug is usually caused by one of two types of programming errors.    

 

As pointed out by Dennis (thanks!) I completely got this wrong.  Stack overflow isn’t the issue, but rather integer overflow:

In computer programming, an integer overflow occurs when an arithmetic operation attempts to create a numeric value that is too large to be represented within the available storage space. For instance, adding 1 to the largest value that can be represented constitutes an integer overflow. The most common result in these cases is for the least significant representable bits of the result to be stored (the result is said to wrap). On some processors like GPUs and DSPs, the resultsaturates; that is, once the maximum value is reached, attempts to make it larger simply return the maximum result.  

For example, a mechanical odometer, has a rollover (or reset) after a certain amount of miles:

This is the same as computer integer overflow, where the size of the numbers needed are greater than the object type can hold.  Kit-Ho’s example RSA link exceedes the C#’s max value of 18,446,744,073,709,551,615 of the long type.

Dietrich Epp came up with a great answer as to how computers can calculate these large numerical calculations:

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How to check if you’ve been infected by DNS Changer virus.

July 23, 2012 by kronos. 5 comments

Kira asked an interesting question:

How to know if your computer is hit by a dnschanger virus?

In case you didn’t hear, back in November, the FBI took down the company “Rove Digital” which was actually a set of cyber criminals, that created and distributed a DNS changing malware.  Here’s a little more detail straight from the FBI:

Criminals have learned that if they can control a user’s DNS servers, they can control what sites the user connects to on the Internet. By controlling DNS, a criminal can get an unsuspecting user to connect to a fraudulent website or to interfere with that user’s online web browsing. One way criminals do this is by infecting computers with a class of malicious software (malware) called DNSChanger. In this scenario, the criminal uses the malware to change the user’s DNS server settings to replace the ISP’s good DNS servers with bad DNS servers operated by the criminal.

HackToHell also gave a great explanation of what a DNS Changer virus does:

DNS (Domain Name System) is an Internet service that converts user-friendly domain names into the numerical Internet protocol (IP) addresses that computers use to talk to each other. For example, google.com is actually an IP address (173.194.38.164). DNS makes it easier for us to remember the site names. DNS servers convert the domain names into IP addresses. Now the malware, changes the domain naming servers in your computer and uses a different malicious DNS server. This malicious DNS server, swaps IP’s and takes the user to a fake site. enter image description here

Unfortuantely his answer to checking if your computer is infected, is now obsolete.  So here’s and alternative:

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Are all Windows Updates really necessary?

October 31, 2011 by nhinkle. 2 comments

We return with a new Question of the Week, this time addressing Windows Updates. Lital maatuk asks,

Which of the Windows updates are really necessary?

I downloaded a lot of Windows updates in the automatic mode. Are they all necessary? Can I remove some of them? How do I know which ones are necessary?

Jens Erat, one of our newest users, gave a very detailed and well thought-out answer about the different types of Windows updates and their relative importance.

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