Archive for April, 2009

Top 10 Downloads for Ubuntu 9.04

Lifehacker has collected Top 10 Ubuntu Downloads, which they are recommending everyone to try with the new Ubuntu 9.04.

Here is the list:
10. Ubuntu Tweak
9. Screenlets
8. Handbrake
7. Yakuake
6. UNetbootin
5. Songbird
4. Conky
3. VirtualBox
2. DropBox
1. GNOME Do

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  2. Ubuntu Studio
  3. Seamless Windows Applications on Ubuntu Linux Using VirtualBox
  4. Convert from VMWare To VirtualBox
  5. Top 10 Free Windows 7 Applications
  6. Howto use WEP encryption with Ubuntu Linux
  7. Development Release: Ubuntu 8.10 Alpha 4
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  9. Ubuntu Netboot and Netinstall with PXE
  10. Ubuntu Howto: Install Oracle

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Upgrading to Ubuntu 9.04

You can easily upgrade Ubuntu over the network with the following procedure.

1. Start System/Administration/Update Manager

2. Click the Check button to check for new updates.

3. If there are any updates to install, use the Install Updates button to install them, and press Check again after that is complete.

4. A message will appear informing you of the availability of the new release.
5. Click Upgrade and then follow the on-screen instructions.

Related posts:

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  3. Howto: How to Reset the MySQL Root Password
  4. Ubuntu Howto: Install Sun Java
  5. Ubuntu Ubuntu 6.10 (Edgy) – impressive
  6. iTunes on Linux (Ubuntu)
  7. Ubuntu Howto: Install Ruby and Ruby on Rails
  8. Ubuntu Server Edition JeOS
  9. Development Release: Ubuntu 8.10 Alpha 4
  10. Ubuntu Studio

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Migrate existing Ext3 filesystems to Ext4

Any existing Ext3 filesystem can be migrated to Ext4 with an easy procedure which consists in running a couple of commands in read-only mode (described in the next section). This means that you can improve the performance, storage limits and features of your current filesystems without reformatting and/or reinstalling your OS and software environment. If you need the advantages of Ext4 on a production system, you can upgrade the filesystem. The procedure is safe and doesn’t risk your data (obviously, backup of critical data is recommended, even if you aren’t updating your filesystem :) . Ext4 will use the new data structures only on new data, the old structures will remain untouched and it will be possible to read/modify them when needed. This means, that, of course, that once you convert your filesystem to Ext4 you won’t be able to go back to Ext3 again (although there’s a possibility, described in the next section, of mounting a Ext3 filesystem with Ext4 without using the new disk format and you’ll be able to mount it with Ext3 again, but you lose many of the advantages of Ext4).

Migrate a ext3 filesystem to ext4
You need to use the tune2fs and fsck tools in the filesystem, and that filesystem needs to be unmounted. Run:

# tune2fs -O extents,uninit_bg,dir_index /dev/sda1

After running this command you must run fsck. If you don’t do it, Ext4 will NOT be able to mount your filesystem. This fsck run is needed to return the filesystem to a consistent state. It WILL tell you that it finds checksum errors in the group descriptors – it’s expected, and it’s exactly what it needs to be rebuilt to be able to mount it as Ext4, so don’t get surprised by them. Since each time it finds one of those errors it asks you what to do, always say YES. If you don’t want to be asked, add the “-p” parameter to the fsck command, it means “automatic repair”:

# fsck -pDf /dev/sda1

There’s another thing that must be mentioned. All your existing files will continue using the old indirect mapping to map all the blocks of data. The online defrag tool will be able to migrate each one of those files to a extent format (using a ioctl that tells the filesystem to rewrite the file with the extent format; you can use it safely while you’re using the filesystem normally)

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Howto: Convert an OpenSSL key to a public/private OpenSSH key-pair

This howto demonstrates how to convert an OpenSSL key to a public/private OpenSSH key-pair.

The motivation for converting this is simple — dual use. That is to say, any user or application that has been issued a certificate can now use their SSL-based credentials for both SSL- and SSH-based authentication.

Requirements
You’ll need a valid certificate and private key — actually only the key is required. This recipe assumes that your certificate and key will have the names user-crt.pem and user-key.pem, respectively. If your key is encrypted (which it should be), you’ll also need to have it’s passphrase handy.

You’ll need a shell account on a system that supports OpenSSH logins using public/private key authentication.

Solution
The solution is to extract the public key from the private key using ssh-keygen, copy the new key-pair into place, and test them out.

1. Copy the private SSL key to ~/.ssh/id_ssl.
$ cp user-key.pem ~/.ssh/id_ssl
$ chmod 600 ~/.ssh/id_ssl

2. Extract the public SSH key using ssh-keygen.
$ ssh-keygen -y -f ~/.ssh/id_ssl > ~/.ssh/id_ssl.pub
$ chmod 600 ~/.ssh/id_ssl.pub

3. Add the public key to your authorized_keys
$ cat ~/.ssh/id_ssl.pub >> ~/.ssh/authorized_keys

4. Test the new key by attempting to SSH to localhost.
$ ssh -i ~/.ssh/id_ssl localhost

At this point, you’ll need to enter your passphrase (assuming you had one), and if all goes well, you’ll be sitting at a new shell prompt.

5. Remove the test key from your authorized_keys file.

In theory, a single certificate and key issued to an employee would be sufficient to access all participating SSL- and SSH-based resources in a given environment (or perhaps the entire company).

This post is based on an original recipe by Klayton Monroe.

Related posts:

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Microsoft Office Outlook Holidays

One of the more popular features for Outlook’s calendar is the capability to add your country or region’s holidays into your calendar. This way, you’ll never miss the next holiday.

Adding holiday items to your calendar is pretty easy and holiday calendars can be downloaded from the net.

Here I have collected to most used holiday calendars.

How to install the holiday calendars :
* Click the link Download holidays for the selected region or country.
* Select Open
* Chop the box next to the selected region or country
* Select OK

Download holidays for Outlook 2009 – 2012 ( Danish )

American

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Howto: Resize Xen Loop Disk Image

Win4lin, KVM, QEMU, Virtualbox and Xen are all widely used technologies, used in virtual servers. Fairly often a virtual server run from within a loop filesystem and generally start with a fairly small file (1GB is big for a normal file, but not when it is pretending to be an entire filesystem!)

However things often grow over time.

Here is a nice simple procedure for increasing the size of a loop filesystem, if the filesystem is ext2 or ext3 (the procedure should work for ext4 too, but I havn’t tested it yet)

1. Stop the virtual server that is using the loop filesystem
2. Add some extra space to your loop filesystem file
# dd if=/dev/zero bs=1024k count=1024 >> loop_image_file

This adds 1GB to the end of a file called loop_image_file (make sure to use the append output redirector >> not a single >, otherwise you’ll have an empty 1GB file!)

3. Force a check on the resized/increased filesystem
# e2fsck -f loop_image_file

4. Resize the filesystem within the loop filesystem file
# resize2fs loop_image_file

5. Start the virtual server again

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