Category: Foo

Automatic Ubuntu Kernel Clean Up Foo (Update)

Posted on - by peter

Cleaning up old kernel images on a Ubuntu machine is a quite annoying task. If you forget it and you have a separate /boot partition, then you will sooner or later run out of disk space. And then of course all your updates will fail.

Doing the clean up manually is, as mentioned, more than annoying and very tedious. But other smart people have spent some time and created a nice little one-liner that will get rid of old kernel versions. This command line will of course make sure that the currently running kernel is not removed. So it is very important to reboot after a kernel upgrade before you run this script!

And without further ado I present….

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | xargs apt-get -y purge

Update:
Not a big deal but a sudo snuck into the xargs call. It is now removed and shouldn’t cause any trouble anymore.

The Apache “Could not reliably determine the server’s fully qualified domain name, using 127.0.1.1 for ServerName” Foo on Ubuntu

Posted on by peter

If you are using Apache on Ubuntu, then you most likely ran into the annoying warning about determining the fully qualified domain name of your server. Something like this will show up in your logs, on start of the server or on log rotation:

apache2: Could not reliably determine the server's fully qualified domain name, using 10.10.0.40 for ServerName

Luckily there is an easy fix it. All you have to do is adding the ServerName directive to your Apache configuration and specify a good server name. Usually localhost will do fine, unless you are using the machine without virtual hosts, just as a base server.

A quick and dirty way would be adding the following line to /etc/apache2/httpd.conf or to /etc/apache2/apache2.conf and restart your Apache service.

ServerName localhost

And then restart your Apache service with the following command:

/etc/init.d/apache2 restart

Or on newer systems with:

service apache2 restart

Now, if you have a name in /etc/hostname, then you can use that instead. But you have to make sure that the name resolves to something real. If it is not in the DNS, then add it to your /etc/hosts and let it resolve to another loopback address. Here is a sample:

127.0.0.1 localhost
127.0.1.1 myhostname

But as I said, this is quick and dirty and there are much better ways of doing it. So lets take a look at the preferred method. This one differs depending on the Ubuntu version, because the default Apache version changed from 2.2 to 2.4.

Ubuntu 13.04 and older (Apache 2.2)

Apache 2.2 loads additional configuration files from /etc/apache2/conf.d. Just add a file to that directory and add the above mentioned ServerName directive and restart Apache.

Create the file:
vi /etc/apache2/conf.d/servername

Add the directive:
ServerName localhost

Restart Apache:
service apache2 restart
or
/etc/init.d/apache2 restart

Ubuntu 13.10 and newer (Apache 2.4)

Apache 2.4 has the additional configuration organized similar to the modules and sites. All configuration files need to be added to the directory /etc/apache2/conf-available and need to have the extension .conf. Each configuration file can be enabled with a2enconf and disabled with a2disconf.

Create the file:
vi /etc/apache2/conf-available/servername.conf

Add the directive:
ServerName localhost

Activate the configuration:
a2enconf servername

Restart Apache:
service apache2 restart

Windows 7 “The Computer Restarted unexpectedly or encountered an unexpected error” Foo

Posted on by peter

HP’s Windows recovery installation seems to be a little bit broken. Or at least for me it was. While restoring the Windows 7 on an HP Elitebook 8540w I ran into some issues when the drivers installed. The system just stalled and nothing was moving anymore. After a reboot I saw this nice error message:

The Computer Restarted unexpectedly or encountered an unexpected error

Well, not nice at all, but there is a way you can continue from here. Here are the steps:

  1. On that very same screen press SHIFT-F10 and a command prompt should appear.
  2. Enter “regedit” (without the quotes) into the command prompt and press enter.
  3. In the registry editor navigate to HKLM/SYSTEM/SETUP/STATUS/ChildCompletion
  4. Double click on the entry setup.exe and change the value from 1 to 3.
  5. Close the registry editor.
  6. Click OK in the error window, which will restart your machine.

After these steps you should be able to continue with your Windows setup. In my case I had some trouble getting all drivers to work, but that is a different story.

Too Many Open Files Foo With Chrome On Ubuntu 13.10

Posted on by peter

The last Chrome update and one of the last Thunderbird updates caused some strange crashes of either on of them on my Ubuntu 13.10. All is fine, it runs great and all of a sudden *boom*, browser window gone, or email client gone.

Luckily .xsession-errors exists and there I could find some entries like this:

[3827:4038:0518/230904:ERROR:shared_memory_posix.cc(226)] Creating shared memory in /dev/shm/.com.google.Chrome.12UDei failed: Too many open files

Not good. But there is help. For MyEclipse I had the same issue in the past. But it didn’t seem necessary anymore since 13.10. But I also haven’t used it in a while. Anywhoo, here is what has to be done. And before I forget it, all these changes have to be done as root.

First check the setting for file-max with the following command

cat /proc/sys/fs/file-max

In my case this value seems fine, as it is well beyond the 200,000 that they recommend.

peter@majestix:~$ cat /proc/sys/fs/file-max
1627431

If that is below 200,000 you can set by adding the following line to /etc/sysctl.conf

fs.file-max=200000

The next is the ulimit setting for open files. You can check it with the following command

ulimit -n

This one was set to 1024 in my case and that can be a little bit low. At MyEclipse they recommend setting it to 65535 and that’s what I did. Just add the following lines to /etc/security/limits.conf

* hard nofile 65535
* soft nofile 65535

Afterwards restart your machine and all should be fine. If you only have to change the sysctl.conf setting then you can activate that change with the following command

service procps start

PS3 Media Server And Ubuntu Foo… Again

Posted on by peter

It feels like Groundhog Day all over again. After finding a relatively painless way of installing the PS3 Media Server on Ubuntu (PS3 Media Server And Ubuntu Foo), I found an easy way with a PPA (PS3 Media Server made easy) and I thought all will be good when I do the re-install of my server with Saucy. I couldn’t be more wrong. The latest Ubuntu version that is supported by the PPA is Raring and it seems it stopped at version 1.81.0 of the PS3 Media Server. A quick check of the home page and the current version is 1.90.1.

After some thought, I checked my old blog post and the configuration files from the PPA. So, this is a chimera of all these components and most importantly, it works. I can now feed media to my devices that don’t support the Plex Media Server.

So, lets get started. Oh, before I forget it. All these steps need to be done as root!

Dependencies/Repositories

The good thing is, that nowadays most of the media related packages are already part of Ubuntu. So, we can simply pull most dependencies directly from Ubuntu’s repository and don’t have to add tons of PPA’s.

First and foremost you need Java. I prefer for some unrelated reasons to use the Oracle JDK. I know JDK 8 was just released but 7 will do for the moment. And as far as I know PMS (yes, I use the abbreviation again) works fine with the OpenJDK. So this first step is kinda optional.

add-apt-repository ppa:webupd8team/java
apt-get update
apt-get install oracle-java7-installer

And if you want to try OpenJDK, you do the following

apt-get install openjdk-7-jdk

Now we need the media related dependencies. All the encoders, decoders, muxers, etc. Most of it is already in Ubuntu and you might not need all of it (like dcraw). But I think it is better to have it installed and ready use, then be surprised when a feature, you never used before, doesn’t work. So here we go.

apt-get install mplayer mencoder mediainfo ffmpeg imagemagick vlc flac dcraw

tsMuxeR is the only one missing in this list. Luckily Robert Tari created a PPA. Lets just add it:

add-apt-repository ppa:robert-tari/main
apt-get update
apt-get install tsmuxer

Get PS3 Media Server

The project switched from Google Code to SourceForge but has its source code at GitHub. Confused? Well, so am I, but they must have their reasons and I don’t question it. Anywhoo, you can download the latest version (currently 1.90.1) from here:

http://sourceforge.net/projects/ps3mediaserver/

Installation

After downloading you can install PMS into /opt or any other directory you think might be useful (/usr/local, etc.). I personally prefer /opt. Here we go:

tar xzvf pms-1.90.1-generic-linux-unix.tar.gz -C /opt/
ln -s /opt/pms-1.90.1/ /opt/pms

Creating the symlink in the second step makes life easier for later updates. All the configuration and start/stop scripts just look for /opt/pms. Updating should be as easy, as extracting the package into /opt and recreating the symlink.

Start Script

I based my scripts on the scripts from the PPA from Happy-Neko. Currently I did just some path corrections but I am planning on moving more configuration options to the configuration in /etc/default/.

Here are the steps to get the Upstart script, service configuration file and set the legacy link.

wget http://www.rfc3092.net/wp-content/uploads/2014/03/ps3mediaserver.conf_.gz
gunzip ps3mediaserver.conf_.gz
mv ps3mediaserver.conf_ /etc/init

wget http://www.rfc3092.net/wp-content/uploads/2014/03/ps3mediaserver.gz
gunzip ps3mediaserver.gz
mv ps3mediaserver /etc/default

cd /etc/init.d/
ln -s /lib/init/upstart-job ps3mediaserver

initctl reload-configuration

The last two steps set the legacy link, so that you can start the service using the old /etc/init.d mechanism. And the second is to tell Upstart, to scan for new services.

Please check /etc/default/ps3mediaserver, if it fits your needs. For instance, not everybody wants to run PMS as root. So take a minute and clean that up.

Configuration

The configuration for PMS with this setup in the configuration area for the user root.

/root/.config/ps3mediaserver

You can change this in /etc/default/ps3mediaserver. Here is how you get a basic configuration going.

wget http://www.rfc3092.net/wp-content/uploads/2014/03/PMS.conf_.gz
gunzip PMS.conf_.gz
mkdir -p /root/.config/ps3mediaserver
mv PMS.conf_ /root/.config/ps3mediaserver

The configuration file is already updated to reflect the paths for all external tools. It does not contain a UUID for the server, because that is created automatically when you fire up the server for the first time.

You should take a look at the following settings (see also my blog post PS3 Media Server And Ubuntu Foo for tips):

  • folders
  • name
  • network_interface
  • hostname

folders is the only one out of these that you definitely want to set to reflect your setup. The server is running as a service and therefor headless. Just put a comma separated list of directories in there. Something like

folders = /src/videos,/srv/music

name on the other hand is just a cosmetic thing and defines with which name the server shows up on the client.

Yet, the default for network_interfaces can sometimes cause some grieve. You might have to bind the server to a specific interface if some virtual interface seems to be more attractive to PMS.

hostname is similar to network_interfaces. Usually it should not be needed but if you have multiple IP’s on a device you might want to specify which IP it binds itself to.

Service Start

Now that everything is set up you can start the service.

service ps3mediaserver start

The service should fire up without any errors. And if you encounter errors you will find the logs in /var/log/ps3mediaserver/root/.

Happy Streaming!

Final Thoughts

I think it is pretty straight forward to get PMS to work on Ubuntu. If I find some time… did I just write that?! Well, if I find some time, I will create a PPA with the latest version and I will try to keep it up to date.

BIND Journal Foo

Posted on by peter

After doing some updates to my DNS set up I ran some standard checks. And it took me a while to realize that for some reason my zone didn’t load correctly and the secondary server was used.

So I dove into the logs and low and behold I saw this:

zone dusares.com/IN: journal rollforward failed: journal out of sync with zone
zone dusares.com/IN: not loaded due to errors.

And it dawned on me. I am currently implementing my own little dynamic DNS updater and all the updates are stored in a journal. Fine, I can re-run my tests and simply remove that journal (.jnl files. In Debian based distributions they are in /var/lib/bind) before restarting BIND.

That works of course but should not the way how you should handle things. Especially not, if you need the content of the journal. So here is the correct way of doing it:

  1. rndc freeze dusares.com
  2. apply changes to zone file
  3. rndc reload dusares.com
  4. rndc thaw dusares.com

Re-Assign Host Access Permission For User In MySQL Foo

Posted on by peter

Changing the configuration of a VPN can have interesting side effects. In my case I had to open up the host permissions for my MySQL users and databases from a /24 to a /16 network. Should be easy… and it actually is. Here are the SQL commands you have to execute to perform such an update:


update mysql.user set host = '10.42.%' where host = '10.42.42.%;
update mysql.db set host = '10.42.%' where host = '10.42.42.%;
flush privileges;

You can of course go crazy in the where clause and in- or exclude everything you want.

Happy SQL-ing.

Amazon AWS SSL Certificate Import Foo

Posted on by peter

Using Amazon’s Elastic Load Balancer (ELB) with SSL is supposedly an easy thing to set up. And for the most part it is. You can use the command line tools or the web interface and all is good.

But it seems Amazon messed up a little bit the error messaging. When uploading our SSL certificate I got the nice error message Invalid Public Certificate. After double and triple checking the public certificate and not finding anything I asked the beloved oracle called Google.

One of the first things that came up that the intermediate certificate might be in the wrong order, or the root certificate is missing in the chain. Not helping in my case. I had only one certificate in the chain and the root is added automatically according to Amazon’s documentation.

While digging through the AWS documentation I found the little hint, that the private key has to be in RSA format. In other words your file should look like this:

-----BEGIN RSA PRIVATE KEY-----
(tons of text)
-----END RSA PRIVATE KEY-----

and not like this:

-----BEGIN PRIVATE KEY-----
(tons of text)
-----END PRIVATE KEY-----

OpenSSL can do the conversion in one easy step:

openssl rsa -in my_private.key -outform PEM -out my_private.key.pem

After using that version of the private Amazon was accepting the public key as well, despite the error telling me that the public key is invalid. Can now somebody please explain the difference between public and private to Amazon?

Wicd On Ubuntu Fails To Start Foo

Posted on by peter

Running Ubuntu, like most mainstream Linux distribution, means nowadays automatically that your computer gets exposed to the NetworkManager and its sideeffects. Maybe this tool might work for some desktop users, but it definitely never worked for me. It is cumbersome to configure, doesn’t like if an interface is managed manually or you want to change it back to automatic. It has major problems with similar IP ranges for different locations…

Anyways, I digress. I tried a lot of versions of the NetworkManager and it actually got worse and worse. Switching back to manually editing /etc/network/interfaces is not really spouse compatible either. The decision was made, lets install an alternative: wicd.

I think there is enough on the internet on how to transition from NetworkManager to wicd, like this official one here from Ubuntu’s own help pages.

After all is set and done you should have wicd running and you should be able to use the widget of your favorite desktop environment to configure it. But not so in my case. All I saw was that wicd failed to start. And a lot of digging unvealed finally a bug and it is even filed (Launchpad Bug Report).

In short, it is a problem with how the symlinks for resolv.conf are set up. So here is the quick workaround to get wicd to work:


rm /etc/resolv.conf
ln -s /run/resolvconf/resolv.conf
rm /var/lib/wicd/resolv.conf.orig
ln -s /run/resolvconf/resolv.conf /var/lib/wicd/resolv.conf.orig

After that sequence you should be able to start wicd. Happy networking.

Google Chrome With APT On Ubuntu Foo

Posted on - by peter

Installing Google Chrome on a Debian based distribution is actually pretty nice and easy… if you know how.

So lets get started. In the directory /etc/apt/sources.list.d/ create a file called google-chrome.list. Make sure that he extension is .list. The content of the file should be this:

deb http://dl.google.com/linux/chrome/deb/ stable main

After running apt-get update you will see an error message like this (the public key ID might change!):

W: GPG error: http://dl.google.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A040830F7FAC5991

This is just telling you that you have to add Google’s key to your keychain. And here are the commands to do exactly that:

gpg --recv-keys A040830F7FAC5991
gpg --export -a A040830F7FAC5991 | sudo apt-key add -

Here is a sample output of that procedure:

root@majestix:/etc/apt/sources.list.d# gpg --recv-keys A040830F7FAC5991
gpg: requesting key 7FAC5991 from hkp server keys.gnupg.net
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: key 7FAC5991: public key "Google, Inc. Linux Package Signing Key " imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1
root@majestix:/etc/apt/sources.list.d# gpg --export -a A040830F7FAC5991 | sudo apt-key add -
OK
root@majestix:/etc/apt/sources.list.d# apt-get update
...

After that you can look for and install Google Chrome out of the apt repository:

root@majestix:/etc/apt/sources.list.d# apt-cache search google-chrome
google-chrome-beta - The web browser from Google
google-chrome-stable - The web browser from Google
google-chrome-unstable - The web browser from Google