Archive for April 26th, 2011

Ubuntu Natty Beta

We’re just a couple of days down the road from the official Ubuntu Natty release. While I haven’t yet tried the beta (I had a really bad experience a few versions back — a lot broke), I’d like to hear thoughts from anyone who has.

Love it? Hate it? Run into an issue? I’d like to hear your thoughts on it. Please share them in the comments below! Thank you!

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Invalid email addresses removed from comment subscriptions

Since I added the feature of subscribing to comments, I’ve noticed a large volume of people subscribing to posts without commenting. Tonight I went through the list and validated email addresses. About 210 email addresses failed validation and were removed. Some mail exchangers refused the connection and those subscriptions were given the benefit-of-the-doubt and left as-is.

I have also switched to a double opt-in method to help prevent subscription spamming. Users will receive a link in their email they will need to click on to confirm the subscription.

I have done this in an effort to prevent subscription abuse.

If you somehow notice that your subscription to an article has been removed, I apologize. Please feel free to sign up again. If you are getting email subscriptions, and are having trouble unsubscribing, please let me know and I’ll take care of it as quickly as I am able.

Questions, comments, and/or feedback is appreciated. Thank you.

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Backing up your server using JungleDisk Server Edition – part 3

This is the third part in a three-part series. Make sure to read part 1 and part 2!

The one bad thing I’ve come to notice about the JungleDisk Server Edition is, over time, it tends to hog a lot of memory, even when it’s not running backups. The author at geektank.net noticed this too, and recommended it may not be a good fit for low-memory VPS configurations.

But if JungleDisk is a good fit for your needs, and the memory usage is the only issue, here’s something to try. It’s either a clever solution or an ugly workaround. Call it what you will.

What we’re going to do is create a cron job that will restart jungledisk when it is done running the backup, which will free up any potentially wasted memory.

So, we’ll start by creating a postbackup.sh script to run after your backup job. For advice on how to create and schedule this script, see my previous article, Backing up your server using JungleDisk Server Edition – part 2.

Create your postbackup.sh file with the following line:

touch /etc/jungledisk/.restartjd

Now, create the following jd-check.sh script and make it executable. It should be setuid root.

#!/bin/bash
if [ -e /etc/jungledisk/.restartjd ]
then
rm /etc/jungledisk/.restartjd && /etc/init.d/junglediskserver restart
fi

That’s about as simple as it gets, right there.

The new script should be run on a cron job that will cause it to run often enough to restart jungledisk after a backup. A suggestion would be to have it run about a half-hour to an hour after your backups are scheduled to start.

There are some security implications to where you store your temp file, what your name it, and what permissions you give it, so use your head. If you carefully read part 2, you can get a good handle on how to be mindful of the security issues.

It’s also possible to simply restart junglediskserver on a cron job, but there’s the potential you could restart it when it’s in the middle of a backup. This would cause the backup to either postpone the backup, or resume immediately, and leave stale memory allocations again, which defeats the point. What I’m aiming for here is to have it restart as quickly as possible once the update completes.

Do you have any thoughts on this approach? Know of a way that might work better? Feel free to share your thoughts in the comments below! Thank you.

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How to securely wipe hard drives

I often times get asked by friends and clients to refer them to a good tool for securely wiping their hard drives. If you’re decommissioning, selling, or returning a drive with sensitive or confidential data on it, you are right to take measures to wipe the drive.

Deleting files from a hard drive doesn’t actually delete them. Instead, it merely “marks” them as deleted, leaving the original data intact until the disk space is reused. It may be that even after that space is reused that partial remnants of the files still remain, and can be easily recovered. TechRepublic wrote up a good article backed by solid research that shows just how many drives contained easily-recoverable data. The results are unnerving, but they don’t have to be.

When wiping drives is a concern, you have two choices — completely wiping a drive that you’re no longer using — that is, if you’re going to part with it; or wiping only the “free space” of your computers hard drive that you’re still using, simply to make sure deleted files are actually gone and unrecoverable.

There are many good, free, easy-to-use utilities that do an excellent job of wiping your drives. Here’s are two that I’m most familiar with and can recommend:

Darik’s Boot and Nuke (DBAN) – (website) (download) – Wipes drives completely

Darik’s Boot and Nuke (“DBAN”) is a self-contained boot disk that securely wipes the hard disks of most computers. DBAN will automatically and completely delete the contents of any hard disk that it can detect, which makes it an appropriate utility for bulk or emergency data destruction.

Eraser – (website) (download) – Can do “free space”-only wiping

Eraser is an advanced security tool for Windows which allows you to completely remove sensitive data from your hard drive by overwriting it several times with carefully selected patterns. Eraser is currently supported under Windows XP (with Service Pack 3), Windows Server 2003 (with Service Pack 2), Windows Vista, Windows Server 2008, Windows 7 and Windows Server 2008 R2.

CCleaner – (website) – Free space and full drive wiping for Windows

Besides being an all-around great cleaner for the registry, CCleaner now includes the ability to wipe both full drives and free space only. A great utility for Windows users.

These are just two programs, and there are many more available.

If you’re a *nix user, Engadget points the way to the shred program. In a nutshell, the following command is what you’re looking for:

shred -vz -n 3 /dev/sda

This will write 3 passes of random data to /dev/sda (make sure that’s the right drive before you start!), followed by a 4th pass of zeros.  It takes some time, so if you don’t mind random (suspiciously random) data on the drive, you can skip the zeroing pass by omitting the z flag.

Do you have a suggestion for a utility that can securely wipe hard drive data? Do you have any questions or feedback on the above? Please voice your thoughts in the comments below! Thank you!

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