Leo's Answers #289 - June 28, 2011 - Confident Computing

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Leo Notenboom

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*** New Articles

What is disk slack space and how do I reduce it?

I've heard quite a bit about disk slack space even though I don't completely understand that. From what I understand, it's the wasted space within the clusters (e.g. if you have a 2 KB file, the rest of the cluster is wasted) and that making smaller clusters (by repartitioning the drive) will make it smaller. What exactly is it, is that a big problem, and what can you do to reduce it in an already-partitioned system?

I wouldn't call it a big problem per se; most folks never notice any issues related to slack space. At worst, it simply means that your hard disk might run out of room a little sooner than it really needs to.

You're right in your analysis of what slack space is within clusters, but partitioning isn't really related and it's certainly not the answer.

I'll review how files are written to disk, what slack space is, and what you can do to minimize it.

If you even care, that is.

But first, we have to define a couple of terms.

Continue reading: What is disk slack space, and how do I reduce it?
http://ask-leo.com/C4857

* * *

How do I delete screen savers from my PC?

How do I delete screensavers from my PC that I'm not interested in?

Depending on the screen saver and where it came from, it's likely to be in one of two places. Regardless of which, screen savers are pretty easy to remove.

I'll show you both places.

Continue reading: How do I delete screen savers from my PC?
http://ask-leo.com/C4856

* * *

How do I figure out what kind of file I have - without the file extension?

I downloaded a few video files without extensions. I tried inserting all of the common extensions, but none of them would play. Is there a way to determine which format the files are in?

When it comes to video files, my gut answer is to say, "I don't know". Video file formats are a complex maze of twisty passages that are all alike.

Perhaps we can get a few clues - not only about your video files, but about other types of files.

Warning: This one gets geeky. Smile

Continue reading: How do I figure out what kind of file I have - without the file extension?
http://ask-leo.com/C4855

* * *

Do I need these Microsoft Visual C++ redistributables?

I have an Acer Aspire One D255 laptop and it runs Windows XP. I'm wondering if I need all of these Microsoft programs on here, like Microsoft Visual C++ 2005 redistributable or Microsoft Visual C++ 2008 redistributable. It's taking up space on my hard drive and I'm wondering if those programs are really necessary. Then, I was also wondering if I need all of these Windows Live programs on here, like Windows Live Essentials or Windows Live Sync.

Time for my most common, and yet most annoying answer....

It depends.

I'll describe what the Visual C++ redistributables are all about and why the safest thing to do is probably to leave them alone. As for Windows Live ... well, that one's up to you.

Continue reading: Do I need these Microsoft Visual C++ redistributables?
http://ask-leo.com/C4854

* * *

How do I send a .exe file if Gmail won't let me?

Can I get Gmail to send executable file attachments; if I can, how do I do so?

Yes. There are actually a variety of ways, so I'll cover a couple of the most common.

The good news is that they tend to work regardless of what email service (Gmail or anything else) that you use.

I'll also explain why Gmail might block this type of attachment and how even the workarounds are fairly secure.

Continue reading: How do I send a .exe file if Gmail won't let me?
http://ask-leo.com/C4853

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*** Last Week's Articles

*** Comments

Why do I have Internet Explorer temporary files if I never use it?

LegendsOfBatman writes:

Thanks for that answer, Leo. I have been wondering that same thing, myself. I do wonder, however, why MS insists that the OS depends on IE, when obviously it does not, because it appears to work in Europe, without IE.

The only thing that has been removed from those versions of Windows is IE's user interface - the "guts" of IE are still there. As I said, they're required by too many other applications.

-Leo

How do I ignore a Windows Update item?

sVen writes:

Not updating Internet Explorer is a bad idea. I don't use IE, but it's core engine is an integral part of Windows. Not updating it can cause security and operational issues in Windows.

There's a subtle difference here. Not taking patches is definitely risky. But skipping an update to a completely new version of the software doesn't carry the same risk until the previous version is no longer supported. MS will be supporting IE8 with security patches for a while.

-Leo

How long should a password be?

Dan Klein writes:

Many websites lock you out after three attempts, so how can a brute force attack work under those conditions?

Most brute force attacks are not against website login pages, but rather are performed offline when a hacker has stolen a list of usernames and encrypted or hashed passwords.

-Leo

How long should a password be?

Glenn P. writes:

For RobertPrice:

Quote: "'Use a different password for each different site login you have. That way a password compromised on one service won't give hackers access to everything else.'

"I think that is completely unreasonable. A different password for "every site"? In my case, that's almost a 100 different passwords. Not very practical."

Dude! That's what programs like Roboform or (my personal favorite) KeePass Password Safe are for! Sheesh!

For Leo:

Twelve is good -- but I understand that 16 should be the minimum, due to rainbow tables.

I'm a little surprised that you didn't mention rainbow tables in your article.

Rainbow tables essentially are databases in which hackers have computed the all hashes for brute-force attacks on all passwords up to a given length in advance. They make the breaking of passwords both much easier, and much faster. The book "Perfect Passwords: Selection, Protection, Authentication" by Mark Burnett ($18.96)" recommends a 16-character minimum length password for this reason, but then, it was written in 2005 -- so I would expect by now that the standard rainbow tables have been rather expanded by now!!! I would very seriously recommend a twenty-character password by now.

Really, folks: There is NO such thing as "a password too long" -- unless it's so long that it's rejected by the system you're feeding it to.

Even using a rainbow table of all possible passwords, once you get beyond 10 or 12 characters, the size of the table becomes pretty impractical. A 12-character password would still need a rainbow table of three sextillion entries to be exhaustive. Most rainbow tables must limit their focus to (extremely large) numbers of common passwords. But 16 -- sure, go for it! As you say, there's no such thing as a password that's too long ... unless the site that you're using it on places some kind of limit on it.

-Leo

*** Leo Recommends

TrueCrypt - Free Open Source Industrial Strength Encryption

TrueCrypt comes up frequently in Ask Leo! answers. Many people are concerned about things like privacy, identity, and data theft, particularly on computers or on portable devices where they might not always have total physical control of the media.

Someone might gain access to sensitive data stored on your computer.

Encrypting your data renders that access useless, even when your computer or your thumbdrive falls into the wrong hands.

And TrueCrypt makes it not only easy, but nearly un-crackable.

Continue reading: TrueCrypt - Free Open Source Industrial Strength Encryption
http://ask-leo.com/C3444

Each week, I recommend a specific product or resource that I've found valuable and that I think you may as well. What does my recommendation mean?

*** Popular Articles

I saw this making the rounds again just the other day. Somewhat silly in my opinion, but people keep looking for conspiracy theories for just about anything that they don't understand, even the most mundane. Hint: There's almost always a rational explanation.

Why can't I create a folder named CON? (And other "Crazy Facts")

A colleague at work got this from the Net. Please check it out and please, please, please try to explain. They're weird. Here it is:

Microsoft's Crazy Facts

MAGIC #1

...several odd behaviours listed...

•

I know I'm straying just slightly off center here dealing with what is essentially just a forwarded urban legend email. But the neat thing about all three of these "magics" is that parts are true, parts are false, and all have completely rational reasons.

Continue reading...
Why can't I create a folder named CON? (And other "Crazy Facts")
http://ask-leo.com/C3433

*** Thoughts and Comments

Webinar

I'm a little behind in getting the last webinar's segments up on the site, but just a reminder that a tentative agenda has been set and registration is open for next month's webinar.

My Excuse

I took most of last week off and attended a meet-up of Corgi owners at a state park out on the Washington coast. (For those that don't know, I'm owned by three Welsh Corgis - two Pembrokes and one Cardigan - with another Cardi on the way).

As we were sitting around the dinner table (the camp fire was off to one side), the discussion turned to ... internet connectivity. Smile

Several folks had already been uploading photos to Facebook and elsewhere; naturally, I had been keeping up with email via my Verizon-connected HTC Incredible set up as a WiFi hotspot. Grayland Beach State Park is on the fringes of most cellular coverage maps and sure enough, the signal was marginal. Fortunately, it was enough to stay connected ... most of the time. Others reported similar experiences both with Verizon and AT&T.

It didn't stop us from sending email from one campsite to the another after we'd retired to our respective tents, trailers, and RVs, though.

I love living in the future. So cool.

'Til next week...

Leo
Leo A. Notenboom
Twitter - Facebook

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