www.chengfu.net http://www.chengfu.net Coding for fun Sun, 17 Feb 2008 12:54:52 +0000 http://wordpress.org/?v=2.2 en This is an XML content feed. It is intended to be viewed in a newsreader or syndicated to another site, subject to copyright and fair use. Freudian typo http://feedproxy.google.com/~r/chengfunet/~3/ApBQLnE-N-Y/ http://www.chengfu.net/2008/02/freudian-typo/#comments Sun, 17 Feb 2008 12:54:50 +0000 chengfu http://www.chengfu.net/2008/02/freudian-typo/ You know you have done too much blogging and not enough programming when this happens: undefined method `from_blog` for Magick::Image:Class Social bookmark this: You know you have done too much blogging and not enough programming when this happens:

undefined method `from_blog` for Magick::Image:Class

]]> http://www.chengfu.net/2008/02/freudian-typo/feed/ http://www.chengfu.net/2008/02/freudian-typo/ Hot or not for websites http://feedproxy.google.com/~r/chengfunet/~3/iQ0C_Y5MZXE/ http://www.chengfu.net/2008/01/hot-or-not-for-websites/#comments Wed, 30 Jan 2008 11:58:15 +0000 chengfu http://www.chengfu.net/2008/01/hot-or-not-for-websites/ A hot-or-not voting for websites - great idea: webhotornot.com Social bookmark this: A hot-or-not voting for websites - great idea: webhotornot.com

]]> http://www.chengfu.net/2008/01/hot-or-not-for-websites/feed/ http://www.chengfu.net/2008/01/hot-or-not-for-websites/ SQL Injection Examples http://feedproxy.google.com/~r/chengfunet/~3/BLYzgAGzb_o/ http://www.chengfu.net/2008/01/sql-injection-examples/#comments Sat, 26 Jan 2008 09:18:08 +0000 chengfu http://www.chengfu.net/2008/01/sql-injection-examples/ SQL injections are something you have to worry about with every web application you build. As I am right now building a now website (going to be my first Ruby on Rails project) this article on unixwiz came up at just the right time: SQL Injection Attacks by Example Social bookmark this: SQL injections are something you have to worry about with every web application you build. As I am right now building a now website (going to be my first Ruby on Rails project) this article on unixwiz came up at just the right time: SQL Injection Attacks by Example

]]> http://www.chengfu.net/2008/01/sql-injection-examples/feed/ http://www.chengfu.net/2008/01/sql-injection-examples/ Prebuilt guest images for xen http://feedproxy.google.com/~r/chengfunet/~3/crynu4wVzvM/ http://www.chengfu.net/2008/01/prebuilt-guest-images-for-xen/#comments Fri, 25 Jan 2008 12:18:27 +0000 chengfu http://www.chengfu.net/2008/01/prebuilt-guest-images-for-xen/ Every now and then I need to set up a new xen machine that should not be based on an existing one. Until now I have not found out how to install from an iso or similar and thus downloading an image and dd’ing it to an empty lvm partition is the easiest way. A good [...] Every now and then I need to set up a new xen machine that should not be based on an existing one. Until now I have not found out how to install from an iso or similar and thus downloading an image and dd’ing it to an empty lvm partition is the easiest way.
A good start is jailtime.org which has a prebuilt guest dom for some big distros. Anybody know of more sites for downloading images?

]]> http://www.chengfu.net/2008/01/prebuilt-guest-images-for-xen/feed/ http://www.chengfu.net/2008/01/prebuilt-guest-images-for-xen/ Ubuntu not booting anymore: initramfs - failed to set xfermode http://feedproxy.google.com/~r/chengfunet/~3/XgFmQ2Tp0vA/ http://www.chengfu.net/2008/01/ubuntu-not-booting-anymore-initramfs-failed-to-set-xfermode/#comments Fri, 25 Jan 2008 07:44:57 +0000 chengfu http://www.chengfu.net/2008/01/ubuntu-not-booting-anymore-initramfs-failed-to-set-xfermode/ The 2.6.22-14-generic kernel on ubuntu seems to have a problem with sata controllers used by Dell. I first experienced this problem when setting up a new kubuntu machine yesterday and today it also showed up on my ubuntu system. Both machines are Dell Vostro 200 (having the same name but for some reasons only dell [...] The 2.6.22-14-generic kernel on ubuntu seems to have a problem with sata controllers used by Dell. I first experienced this problem when setting up a new kubuntu machine yesterday and today it also showed up on my ubuntu system. Both machines are Dell Vostro 200 (having the same name but for some reasons only dell understands with different cpus).
The boot process takes a real long time and then stops with a busybox prompt and a line

(initramfs)

A short while later message likes the following start to pop up:

[ 60.101981] ata2.01: failed to set xfermode (err_mask=0×4)
[ 95.974137] ata2.01: failed to set xfermode (err_mask=0×4)
[ 131.706301] ata2.01: failed to set xfermode (err_mask=0×4)
[ 136.705051] ata2.00: failed to set xfermode (err_mask=0×40)

At least for this machines the solution was adding the “irqpoll” parameter to the kernel. For a quick start this can be done by pressing ESC on the grub prompt, then pressing “e”, selecting the line beginning with “kernel”, pressing “e” again and adding “irqpoll” to the end of the line. After this press enter and then “b” to boot the kernel.
To make the change permanent the /boot/grub/menu.lst has to be edited. Open it in your favorite editor using sudo (e.g. “sudo vim /boot/grub/menu.lst”) and change the following line

# defoptions=quiet splash

by adding “irqpoll”

# defoptions=quiet splash irqpoll

and then running “sudo update-grub”.

]]> http://www.chengfu.net/2008/01/ubuntu-not-booting-anymore-initramfs-failed-to-set-xfermode/feed/ http://www.chengfu.net/2008/01/ubuntu-not-booting-anymore-initramfs-failed-to-set-xfermode/ There is no 2.0 bubble http://feedproxy.google.com/~r/chengfunet/~3/ShIuJPFPvf0/ http://www.chengfu.net/2008/01/there-is-no-20-bubble/#comments Wed, 09 Jan 2008 15:47:10 +0000 chengfu http://www.chengfu.net/2008/01/there-is-no-20-bubble/   Link to Youtube Social bookmark this:  
Link to Youtube

]]> http://www.chengfu.net/2008/01/there-is-no-20-bubble/feed/ http://www.chengfu.net/2008/01/there-is-no-20-bubble/ Tunnelling munin with ssh http://feedproxy.google.com/~r/chengfunet/~3/XW57fJCwc-E/ http://www.chengfu.net/2007/11/tunnelling-munin-with-ssh/#comments Thu, 08 Nov 2007 20:49:18 +0000 chengfu http://www.chengfu.net/2007/11/tunnelling-munin-with-ssh/ Munin has been monitoring all my servers for some time now but I have always used the unencrypted connection because there is not much secret data transfered anyway and the built-in ssl connection did not work right away. Now I found a small guide to building an ssh-tunnel for munin. The solution is obvious, why didn’t [...] Munin has been monitoring all my servers for some time now but I have always used the unencrypted connection because there is not much secret data transfered anyway and the built-in ssl connection did not work right away.
Now I found a small guide to building an ssh-tunnel for munin. The solution is obvious, why didn’t I do that? Anyway, need to do some changes to my munin setup during the next days.

]]> http://www.chengfu.net/2007/11/tunnelling-munin-with-ssh/feed/ http://www.chengfu.net/2007/11/tunnelling-munin-with-ssh/ Skype for Linux finally gets Video! http://feedproxy.google.com/~r/chengfunet/~3/GKmDL9qz1hQ/ http://www.chengfu.net/2007/11/skype-for-linux-finally-gets-video/#comments Wed, 07 Nov 2007 22:05:01 +0000 chengfu http://www.chengfu.net/2007/11/skype-for-linux-finally-gets-video/ At last Skype has got Video support on Linux. Today the Skype Linux team announced a new beta with video support. I have installed it on my new Ubuntu machine and it worked right out of the box. Unfortunately my screen captures did not contain the video image so I cannot provide an image here. Anyway, [...] At last Skype has got Video support on Linux. Today the Skype Linux team announced a new beta with video support. I have installed it on my new Ubuntu machine and it worked right out of the box. Unfortunately my screen captures did not contain the video image so I cannot provide an image here.

Anyway, great feature - thanks to skype!

]]> http://www.chengfu.net/2007/11/skype-for-linux-finally-gets-video/feed/ http://www.chengfu.net/2007/11/skype-for-linux-finally-gets-video/ No loopback device in OpenVZ/Virtuozzo servers http://feedproxy.google.com/~r/chengfunet/~3/nEqktgm77a8/ http://www.chengfu.net/2007/11/no-loopback-device-in-openvzvirtuozzo-servers/#comments Sun, 04 Nov 2007 14:17:43 +0000 chengfu http://www.chengfu.net/2007/11/no-loopback-device-in-openvzvirtuozzo-servers/ Last week I tried to use two virtual servers (based on Virtuozzo) to learn something about DRBD. As DRBD syncs a block debice I wanted to set up a loopback device and sync that across both servers. Unfortunately all my tries to get the loopback device to work resulted in an error “no permission to look [...] Last week I tried to use two virtual servers (based on Virtuozzo) to learn something about DRBD. As DRBD syncs a block debice I wanted to set up a loopback device and sync that across both servers.
Unfortunately all my tries to get the loopback device to work resulted in an error “no permission to look at /dev/loop#”.
Today I found the solution in the OpenVZ forum: there is no support for loopback devices in machines running on OpenVZ/Virtuozzo.

]]> http://www.chengfu.net/2007/11/no-loopback-device-in-openvzvirtuozzo-servers/feed/ http://www.chengfu.net/2007/11/no-loopback-device-in-openvzvirtuozzo-servers/ Secure backup with Amazon S3 http://feedproxy.google.com/~r/chengfunet/~3/rsEhf43NUT0/ http://www.chengfu.net/2007/11/secure-backup-with-amazon-s3/#comments Sun, 04 Nov 2007 13:32:04 +0000 chengfu http://www.chengfu.net/2007/11/secure-backup-with-amazon-s3/ For a real long time I have been looking for a good backup solution for my notebook. A long time I had been using boxbackup to backup up to a fileserver at my employer. While being the sysadmins makes this a possible solution I didn’t like the idea of backing up all my personal data [...] For a real long time I have been looking for a good backup solution for my notebook. A long time I had been using boxbackup to backup up to a fileserver at my employer. While being the sysadmins makes this a possible solution I didn’t like the idea of backing up all my personal data to a disk in the company.
Another solution was using reoback and a wireless harddisk at home - but this suffered from the vfat filesystem on the disk and bad throughput on wifi.

Some weeks ago I stumbled over remote storage systems and especially Amazons S3 (Simple Storage Service). Amazon is offering expandable diskspace on its cluster systems with a pay-per-use pricing. What does that mean? There are now setup and no monthly fees, you really only pay for what you use. All stored files are calculated on a gigabyte/month price and this is really broken down to a daily calculation. So if you store 1 gigabyte for only 3 days, they charge you only for 0.1 gigabytes-months. Added to this are fees for requests (directory listings, storing and retrieving files) and data transfer.
The problem with S3 is that it works as a webservice and so there is no straight-forward way to put files there.

The solution for me is called Jungledisk: Jungledisk offers a webdav access to data stored in amazon S3 and thus makes it accessible with standard system tools. Thanks to gnome-vfs (and I understand KDE has a similar systems) virtually every software can access the data. Added to this is the ability to schedule automatic backups with include/exclude lists and bandwidth limits.
What is missing? Right: Amazon is a big company but that does not force me to trust them when storing all my data. Jungledisk solves this by encrypting all data on the client system before uploading it to Amazon. That way neither Jungledisk (as a company) nor Amazon can open any of the files.

Setting up Jungledisk is easy. All you need to do is download the package, extract it to a folder of your choice and run “junglediskmonitor”. The software can be used free for a test phase of 30 days. I tried it for a day and then chose to buy it: The price tag ist 20$ for lifetime upgrades and of course you need to pay the monthly usage fees to amazon s3. So far I am paying between four and five dollars a month for the backup and have saved all my personal data to an encrypted external storage. When my notebook drive failed last week Jungledisk already saved a lot more than it has cost me so far.

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