In my last blog I covered a dubious report that suggested the only way to prevent secondhand purchasers from recovering deleted data from hard disks was to physically smash them to pieces. That of course is bunkum. So what are the open source alternatives?

The simplest whole-disk solution is DBAN -- Darik's Boot and Nuke -- "a self-contained boot disk that securely wipes the hard disks of most computers." Download and run it from CD, DVD, floppy disk or USB stick and DBAN will nuke the contents of any hard disk it can detect.

DBAN is partially funded by GEEP International who claim to be "the most efficient, and the most environmentally conscientious consumer electronics recycling company in North America." There's even an enterprise version called EBAN -- Enterprise Boot an Nuke -- that comes with technical training, certification and support.


Linux Level Tools

shred is a simple command-line tool that comes ready installed on most distributions. It overwrites the specified file(s) with random junk -- 25 times by default. It does however come with a couple of caveats. (The man shred command will give you the full details.) Essentially it assumes that the file system overwrites data in place. That's the usual way of doing things, but Linux has a wide variety of possible file systems and they don't all work the same way! But shred works just fine with the default ext3 file system used on most distributions.

Here's how to use it:

shred secrets.txt

Will shred the contents of secrets.txt but it leaves the file in place! While this is a good way of checking what shred does, you probably really want to ...

shred -u secrets.txt

... remove the file after you've shredded it. For extra security you can ...

shred -u -n 100 secrets.txt

... tell it to overwrite the file 100 times instead of the default 25, and even ...

shred -u -n 100 -z secrets.txt

... overwrite the file with zeros on its last pass. This disguises the fact that there was ever any file there at all!

Linux also has a suite of more sophisticated tools, but I'll look at those next time.


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Posted by Geoff Palmer at 8:38 AM | Permalink | Comments (4)

The BBC are reporting that British consumer magazine Which? Computing recommends taking a hammer to your old hard disk drive to prevent secondhand purchasers recovering data from it. They purchased eight computers on e-Bay and reportedly recovered 22,000 "deleted" files.

But is a hammer really necessary?

There's a popular misconception that Delete actually deletes files. It doesn't. It simply removes them from the disk's index. (Ever wondered why it's just as quick to delete a 2GB file as it is a 2-byte one...?) The same applies to the Format command. It doesn't delete files either, it simply prepares the disk drive for new data by completely wiping the index. Recovering "deleted" and "formatted" files is just a matter of using the right software to rebuild the index. 

Instead of a hammer, I suggest you use a good file shredder instead. These overwrite the target file(s) with garbage -- again and again and again.

While it's theoretically possible to recover at least some overwritten data, it's highly unlikely that the person picking up your old drive will have access to a scanning transmission electron microscope and the other bits and pieces necessary!

There are plenty of file shredders around. Even a free one for Windows users. Leave the hammer in the toolshed and shred instead!

Posted by Geoff Palmer at 7:13 PM | Permalink | Comments (3)

Bootchart is a clever little tool that runs in the background as Linux boots. It collects details of all processes started along with disk usage and CPU statistics, and saves them to a log file. But that's not all. It then runs a small Java application that turns the log file into a highly readable performance chart ...



Click for the full chart!

Based on the results, you can then look at optimising the boot process.

Installation
Bootchart comes ready-packaged for most of the major distributions or you'll find it available for download here. (Ubuntu users simply need to type sudo apt-get install bootchart in a console window.)

After installation, reboot the system and check out the charts in the /var/log/bootchart folder. Each time you boot a new chart is created, tagged with the date and a separate boot number so you can follow the effectiveness of your optimisations.

Optimisation Ideas
This is a b-i-g subject. Here's a few links to get you started ...

• Improving Boot Time on a General Linux Distribution
• Boot Linux faster
• Making An Operating System Faster
• Ubuntu Wiki: Faster Boot Process

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Posted by Geoff Palmer at 11:21 PM | Permalink | Comments (0)

Rumours have been circulating since mid-December that Microsoft plan to layoff 10-17% of its 91,000-strong global workforce next week. The date of January 15th has been cited as it falls neatly between the launch of the public beta of Windows 7 and the company's next quarterly earnings call.

There are lots of "no comments" at the moment, but the axe is expected to fall hardest on the Entertainment & Devices and the Online Business divisions along with MSN and the European, Middle Eastern and African sales groups. No rumours about local jobs -- yet.


Things are tough for the old monopolist. After all, they did pay a whopping 0.038% tax in 2007. According to Irish public service broadcaster RTE;

Accounts for Microsoft Ireland Research, an Irish subsidiary of the global software giant, show that the company paid just €460,000 in tax, on profits of more than €1.2 billion last year, by using provisions in Irish tax law to take its corporation tax bill down from €158m. Much of Microsoft's international profits are channelled through Ireland, but because the main company for Microsoft's activities has unlimited liability, it does not have to file detailed accounts.

To put that in perspective, imagine earning $100,000 and giving the IRD $38.


On Christmas day Micrsoft received a US patent for pay-as-you-go computing. The idea is that you buy a cheap PC and only pay for software you use, each time you use it -- a bit like the way you pay for electricity or the phone.

While it might appeal to some, it strikes me as a foot in the door for an unprecedented level of user surveillance. Not only will Microsoft know what you're doing, when and for how long, but they'll have a name, address and credit card number to go with it. Imagine the possibilites of tying that sort of data to search engines or advertising agency browser spies.

It also begs a lot of questions. What if your machine gets hijacked and Outlook fires off a million spam messages at a cent a pop? Ooops. That'll be $10,000 please.

According to one source, internet browsing will cost US$0.80 per hour. But surely that's what Microsoft will pay users for putting up with Internet Explorer...

Still, there is an alternative. It's called free-as-you-go. All the software you could ever want, for nothing. It's known as Linux!

Posted by Geoff Palmer at 10:07 PM | Permalink | Comments (2)