Sunday, 25 May 2014

Securely wiping a hard disk in Linux

We're getting ready for some changes at home, and I thought I'd go through the old hard disk drives I have laying around. Once I'd managed to get them all together there are a staggering 25 to be wiped :(

Usually I use the excellent Darik's Boot and Nuke (DBAN) which is awesome and very simple to use. In this instance, however, I'm also doing a fairly large data sort, archive etc and I need to have a functional machine to browse the disks prior to their destruction and reissue. Given my well know love for Linux Mint I executed an extensive (20 second) search of Google and came up with the following interesting information:-

ATA, SATA and SSD's now have an internal way of securely wiping themselves! From a command prompt (elevate it to root for ease of use and make a note of your disk drives - if you wipe your system disk or data disk then it's game over! Maybe use a LiveCD?)

Go and check out https://ata.wiki.kernel.org/index.php/ATA_Secure_Erase

The quick version is:

# hdparm -I /dev/sdx (where sdx is your disk) and check that "not frozen" is there. If that's OK proceed:

Set a password on the disk (otherwise the secure wipe won't work):

# hdparm --user-master u --security-set-pass ryv1 /dev/sdx (where ryv1 is the password, and the username is u)

Check it worked:

# hdparm -I /dev/sdx
Security:
       Master password revision code = 65534
               supported
               enabled
       not     locked
       not     frozen
       not     expired: security count
               supported: enhanced erase
       Security level high
       440min for SECURITY ERASE UNIT. 440min for ENHANCED SECURITY ERASE UNIT.


Note the 440min is for a 2TB Western Digital Green drive. 440min is over 6 hours!

Now it's time to unleash the full power of this fully operational command!

# time hdparm --user-master u --security-erase ryv1 /dev/sdg security_password="ryv1"
/dev/sdg:
 Issuing SECURITY_ERASE command, password="ryv1", user=user

It's potentially valuable to note that when I ran the command above on my Linux box I stupidly pressed CTRL-C to copy the above text - which is also the command for cancelling a running program. NOTHING HAPPENED! It's a runaway freight train so be *very* careful to select the right disk or it could be a sad day for you.

The good thing about this command though, the load on your computer is negligible - the disk itself is doing all the work. I can see it's I/O is through the roof, but otherwise normal system actions are not compromised.

The upshot of all of this is as follows - although it's a cool way to do it, I'm going to simply find the data I need off all these disks, then take them and hook them up to another machine with multiple SATA ports and DBAN the lot - much faster in the long run!

Saturday, 24 May 2014

Effects of travel on IT or What the hell do I take when I go overseas?

Recently I was on a trip to Jakarta, for pipe band of all things, however while there I still needed to keep up with my normal information load. My gear load out for work, or for holidays in Australia typically consists of two mobile phones (one work / one private), Google Nexus 7 (WiFi) and my 11" MacBook Air or 15" MacBook Pro. Taking all of this junk to Indonesia was unfeasible - although altogether the weight was under 3KG. I knew I would have my normal number of emails, still want to check my Feedly, Facebook, take photos etc. Keeping everything charged and good to go is a usual challenge, and I imagined it would be worse in Jakarta.

Heading over, I took my HTC One X, Nexus and that was it. It was a gamble because I didn't want to unplug too much, but still needed to have access to a wide variety of data. I wondered at what other people travelling took and it seemed very much that this was fairly typical - tablet + mobile phone. Very few people seemed to have included a laptop of any type. I generally find that typing on a tablet, even one with a bluetooth keyboard, is difficult to do over a long period of time, especially with any degree of accuracy so I thought this was pretty interesting. Also given the data storage limitations of tablets/phones I thought it was interesting given the amount of photos and videos everyone was taking. More than one person remarked to me that they had filled their storage and needed to delete some stuff.

Neither of the devices I took have upgradeable storage, so I had to manage it fairly carefully and took less shots than I might normally have.

Something I found to be very nice was lots and lots of free WiFi everywhere. Hotels, airports, cafes, coffeeshops, etc all had free internet and it was beautiful. As a country lad where we're lucky to get 3G coverage - let alone 4G - it was very exciting. It was nice to see such strong cell coverage everywhere too. I noted that mobile towers were spotted across the landscape. It was even better for me with the photo backups to Dropbox my HTC performs whenever it's on a WiFi connection. This is a cool feature and HTC give you a space upgrade to your Dropbox when you connect. Very nice indeed.

In reflection, I should have taken my MacBook Air at least. There were a number of times I needed to SSH to a server for changes, and using the tablet/phone was awful - slow and cumbersome. Also, I wanted to write up a travel journal, but I found that using the tablet/phone to type was interrupting to my flow - I tend to write, refine and spellcheck as I type, so getting the whole tiny little keyboard, searching for the key etc thing was very hard to get around. Constantly refining my expression was very hard. I asked about and the chaps I travelled with found no difficulty - rarely did they send big messages, and those that did were adept at using tablets to do so. It should be noted they have much smaller hands than I do! USB power adaptors were very useful, although the power in Indonesia can be a bit sketchy at times.

Good luck if you're travelling and be safe.