Category: sysadmin

System Administration

Online Backup using JungleDisk and Amazon S3

Recently I featured Mozy, a tool for automated online backup on Windows and Mac. I finally got round to using a different solution: JungleDisk, a WebDAV frontend for Amazon Simple Storage Services (S3).

What I really like about the software and the company is that they don’t claim that their data will be safe forever at their location. They confess it is possible for a company to vanish. In order to prevent you from being locked out they have outsourced the storage to Amazon, which provides cheap storage on a “pay what you need” basis.

JungleDisk provides encryption of the documents using AES and only you can decrypt them. To be on the safe side you’ll always be able to retrieve your data, they have released parts of the code covering filename-mangling and encryption under GPL.

JungleDisk is available for Windows, Linux and Mac. As said, they provide a WebDAV frontend so any WebDAV client can interact with it. It also features a local cache to prevent needing to download a file on every access. There is also an automated backup routine.

Costs are reasonably. At the time of writing, JungleDisk costs 20 US-$ once, with promised life-long updates and patches. All you need to pay for is Amazon fees for your usage, which are at 0.15$/GB/month, 0.10$/GB inbound traffic, and 0.18$/GB outbound traffic. You see, you can store lots of data for around 10$ per month.

One big minus-side of this is that Amazon’s data-centers are very slow from Europe, I was able to achieve around 700-800kbit/s (90-100kB/s) from our office connection. On the pro-side, due to the caching and background transfer, you don’t notice that the transfers are so slow, unless you need to download something. As I am using it for automated backup, I hope to never have to download anything.

So if you are searching for an offsite backup solution, you should definitely consider JungleDisk.

Affordable offsite automatic backup for Windows and MacOS

I just discovered Mozy (via TechChrunch), a service for automating the backup process by automatically storing all your data encrypted on their server for backup purposes. It is a Windows software that automates the backup process and provides secure online storage. According to the specification you can either use their encryption key or provide your own public key for the encryption.

Mozy comes in two flavors, a version for home-users which they call MozyHome (4.95$/month for unlimited storage) and a service for businesses, called MozyPro, which bills 3.95$ per computer, but also 0.50$/GB per month. I think the service would definitely be interesting but the storage costs seem to high for me. There is also “MozyHome Free” which provides you with free 2GB of backup storage. Maybe the recent purchase by EMC Corporation will change the pricing list (honestly, I don’t think so…)?

The idea of storing my confident data or even corporate data on remote servers not under my control is a little bit frightening, but in case you are able to believe they have not built a master-key in the software, it might be a nice option for offsite backups which definitely everybody should use. Maybe one should give the “MozyHome Free” a test-drive… Too bad there is no Linux version available.

If I can convince myself to try out the “MozyHome Free” I will write another report here.

Git and Windows Vista

I recently started using Git, the version control system now used for developing the Linux Kernel. While there is no native support for Windows at the moment, you can install it using cygwin. While this works reasonably well in Windows XP, I got into severe troubles when trying the same in Windows Vista.

First, I ran into troubles installing cygwin. I figured out, that it seems to work well if you run both the installer and bash in “Windows XP SP2 compatibility mode”. I needed to adjust the file system permissions of the cygwin folder to give me write permissions, though. (Note: you have to manually install the TK-libs if you want the GUI elements of git to work.)

But Git kept failing with “access denied” messages when trying to commit from command line. The failure message said it was denied access to git-update-index. I soon found out this is due to the “User Account Control” (UAC) default behavior of auto-detecting installers and prompting if you want to execute them with raised privileges. You can see if this is the case by running git-update-index manually from bash; if you get the UAC confirmation dialog you have this problem. It seems the substring “update” triggers this behavior. As the git-update-index is launched by git commit, it won’t display the confirmation dialog of Vista, so the execution will be denied.

There are two possible workarounds:

  • Run bash with administrative privileges (not recommended!)
  • Disable the auto-detection of installers by UAC.

I used the latter way. You can disable the auto-detection by following these instructions. Brief summary:

  • Open the Local Security Policies
  • Disable “User Account Control: Detect application installations and prompt for elevation”
  • Reboot (the security policy will not be updated before!)

It should work now. You can confirm this by running git-update-index manually again. If you do not get the UAC confirmation dialog now, it worked. Try git commit now, and verify it is working. Of course, you will from now on have to right-click and “Run as Administrator” every installer you want to install, as most installers will require administrative privileges.

Update 2007-08-22: Reader EGarcia posted an interesting comment below: using the Microsoft Manifest Tool you can add an according manifest to the git-update-index.exe and git-update-ref.exe

Update 2009-02-12: Reader Kevin Broadey points out the best solution so far: create a seperate .manifest file for the affected files. He has provided an example for git-update.exe.manifest.

Sharing and Synchronizing Data Across Multiple Computers

I have several computers, one at the office (Windows Vista), one at home (Gentoo Linux), and one notebook (Windows XP). On most of them I want to share a common set of files, including letters and other documents, but also Miranda. This time I am going to tell you how I keep my shared data in sync using Unison, PuTTY, and OpenSSH, using a dedicated server as central hub.

(Note: this is a rather advisory level HOWTO, not a step-by-step, command-by-command tutorial. It might give you some ideas nevertheless.)

Continue reading “Sharing and Synchronizing Data Across Multiple Computers”

Ubuntu 7.04 cryptsetup problem

I am using cryptsetup LUKS for storing encrypted office data on my USB memory stick (just in case I lose it). I recently installed Ubuntu 7.04 on one of my machines and wanted to open the encrypted partition using cryptsetup luksOpen, which failed with a rather strange

Unable to make device node for ‘temporary-cryptsetup-32733’

While searching around the net I found a lot of people asking the same question but hardly any answer, until I finally read this article
on the Ubuntu forum.

The solution to the whole problem is rather simple:

sudo mkdir /dev/.static/dev/mapper

With a little bit more verbose error message of cryptsetup I might have figured this out myself…

How to Show Unattached Devices in Windows Device Manager

As I was searching again for this (I once knew it, but I keep forgetting it), I will simply write it down here: if you want to see all the unattached devices in the device manager, you have to set the environment variable devmgr_show_nonpresent_devices to value 1. If you then start the device manager, you have to also check “Show hidden devices“.

This is documented in Microsoft KB315539.

phpMyAdmin with mod_fcgid

I am currently migrating my server configuration away from mod_php towards mod_fcgid (the successor of mod_fastcgi), as this allows me to use different users for executing scripts in different directories. I use this to have every hosted virtual domain using its own system user. This should (in theory) prevent one buggy application to take over all other hosted domains as well.

I though faced one problem: I could not get phpMyAdmin working and this was a requirement of one of my clients. phpMyAdmin kept popping up the authentication dialog over and over again when using HTTP Basic Authentication.

After searching some time, I noticed that, when using PHP in CGI mode, the authentication data is not passed over to the script by default. A FAQ entry of phpMyAdmin brought the solution to this issue: a ReWrite Rule was needed for the directory containing phpMyAdmin:

RewriteEngine On
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]

Suddenly phpMyAdmin worked 😉

Terminal-Server NX 2.0 “Free-Forever” Released

NoMachine has announced the release of version 2.0 of thei terminal-server product NX, codenamed “Free-Forever”.

They have released more of their products under GPL and provide now a restricted version under the codename “NX Desktop Server free-forever”:

NoMachine provides a free-for-download and free-forever NX Desktop Server which allows 2 user sessions providing access to any desktop or any network type.

The 2-user sessions should be quite sufficient for many purposes.

[Source: Golem.de]

WinXP: How to Deactivate the “Windows Genuine Advantage Tool”

To remove Microsoft’s new “Windows Genuine Advantage-Tool”, which in the current version will check the system’s license every day against a Microsoft database, simply remove the registry key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\ CurrentVersion\WinLogon\Notify\WGALogon

Bugzilla: Upgrading MySQL Database from Latin1 to UTF8

IMPORTANT Update 2009-07-09: This information is already several years old! You should not use this information for modern versions of Bugzilla (3.2 and above), which will allow you to convert to UTF-8 using checksetup.pl.

In the present case, we have a Bugzilla database created with a charset of latin1. Unfortunately, now after updating MySQL to 4.1, error occured when trying to assign a new developer to a bug, indicating mismatch of collations (UTF-8 vs. Latin1). This is caused by the fact that there is now latin1-data stored in an UTF-8 table.

The following procedure can be used to upgrade the database to UTF-8, eliminating the problem:

  1. mysqldump -p --default_character-set=latin1 --skip-set-charset bugs > dump.sql
  2. mysql -p --execute="DROP DATABASE bugs; CREATE DATABASE bugs CHARACTER SET utf8 COLLATE utf8_general_ci;"
  3. mysql -p --default-character-set=utf8 bugs < dump.sql
  4. perl -pe 's/latin1_bin/utf8_general_ci/g; s/latin1/utf8/g' dump.sql > dump-utf8.sql
  5. mysql -p --default-character-set=utf8 bugs < dump-utf8.sql

You should of course always check if the Pearl-RegEx only replaced charset declarations and not some matches within the data.

Thanks to TextSnippets for the script.