The search for the right dock for Ubuntu on a netbook

The beta version of Ubuntu Lucid Lynx became available last week.  I usually upgrade at least one of my machines to the beta versions, so I went ahead and did so for my netbook. 

The first thing I noticed was that the upgrade removed the Netbook Remix enhancements, and I was looking at a plain vanilla Gnome desktop.  This isn't a terrible problem but it does take up extra space and I started wondering if I could do better.

I remembered hearing about several docks available for Ubuntu and decided to give them a try.  I decided that I really wanted to see the following features:

1. One icon to launch an application or if it were already running, bring the instance of it to the top.  With Gnome, you have your launchers at the top and your running programs at the bottom. So if you want to go to a website, you first have to check the bottom of the screen to see if Firefox is already running (which is especially hard with the new Lucid theme, since the tab for the selected window has white typing on a light-gray backround, which makes it almost impossible to read).  The thing that first made me interested in exploring the possibility of a dock was the idea that when I am ready to browse the web, I have one icon that will launch Firefox if it isn't open already or bring it to the top if it is already open.  
2. The one icon needs to have some visual indicator of whether the application is running.
3. If I am to switch to a dock, it needs to replace all current panels and menus.  That means I want some kind of menu with full access to all of the programs and settings currently in my Applications, Places, and Settings menus.  I also need to be able to control my WiFi, see how much battery is remaining, adjust the volume, and shut down from the dock.
4. It has to be fast and not too flashy.  I've seen some of these docks where the items grow as you hover over them, and I think I would really hate that.  When I am trying to click on an icon I do not want it growing or moving around as my mouse approaches it.  I also want the icons to be in the same position on the screen all the time, which means that I don't want the dock expanding and contracting as I launch applications (I found out later that a few docks supported "panel mode" which fits this requirement nicely).

 The Search

With these criteria in mind, I set off to find the best dock.  I found this blog posting and basically started going down the list.  Docky had a nice-looking panel mode but it wasn't easy enough to use (I couldn't figure out how to add a launcher).  Cairo-dock was nice and I almost stuck with it, but it didn't have the nice panel mode I wanted.  It was only available in the centered, expanding and collapsing mode, and the only theme that provided indication as to whether the application was already running under each launcher also had the icons growing in size when my mouse rolled over it.  So Cairo-dock was close but no cigar.  


I installed WBar but by the time I figured out how to launch it, I was already in the process of installing the dock I stuck with, Avant Window Navigator.


Avant Window Navigator (AWN)

To make a long story short, AWN met all of my specifications to the tee.  It is quite user-friendly and easy to configure, and the repos contain a lot of great plugins (more on that later).  AWN has all of the common options I saw when testing other docks, but also allowed me to configure it just the way I wanted it.  

I used Synaptic Package Manager to install the following packages:

1. avant-window-navigator (with dependancies)
2. awn-applets-c-extras
3. awn-applets-python-extras
4. python-awn-extras

When the setup was complete I ran avant-window-navigator from the command line and my dock popped up at the bottom of the screen.  I set the following settings on the Preferences tab:

1. Size of Icons: 24 pixels
2. Orientation: Bottom
3. Style: None
4. Behavior:  Panel Mode
5. Icon effects:  None
6. Checked the "Expand the Panel" checkbox
7. Slid the "Position on the screen" bar all the way over to the left
8. Checked "Start AWN automatically"

 Then I flipped over to the Applets tab and was blown away by the number of applets!  I found almost everything I could want there, including the battery meter, the volume control, a menu (I recommend the "Yet Another Menu applet" over the "AWN Main Menu" or the "Cairo Main menu"), the date/time, etc.  There were a few things I wasn't looking for but was happy to see:  media player controls (I added the play/pause, previous and next controls to my dock and now can control Rhythmbox with one click), an RSS feed reader, a system monitor, a hardware sensor, a weather indicator, etc.  It's perfect for me today, and has a lot of potential to make my life easier in the future.
It wasn't long before I was totally hooked and ready to abandon the default Gnome panels for good.  I right-clicked and deleted the bottom panel without a problem, but when I went to delete the top panel, I noticed that the Delete option was grayed out.  I guess they do that in order to stop newbies from accidentally deleting the panel, but I had made an informed decision to get rid of it! 

Long story short, here is how to turn off the top panel in ubuntu:  hit Alt+F2 and type "gconf-editor".  That will pop up a window that looks kinda like the Windows Registry Editor.  On the left-hand side, expand Desktop, then Gnome, then highlight Session.  On the right-hand side double-click "reuired_components_list".  That will pop open a new window.  Highlight "panel" and click Remove.  That's it!  Now the next time you log in you won't have any panels.

Here is what I ended up with.  Hope this helps!

Follow-up to "Using passphrase-protected SSH keys in Cron"

So I wrote a while back about automating SSH jobs in Cron when the keys were passphrase-protected.  I was very excited about being able to automate tasks over SSH and I was sure I had it working but a few days later I realized that it wasn't working at all.  It was failing without any error I could see.

I'll spare you the gory details of how many hours I spent and how many things I tried when getting it working.  The bottom line is that this evening I realized that when my Cron job or script ran "ssh-agent -s" another ssh-agent process was being created!  I figured that that command was simply exporting the environment variables necessary for me to use the process created by the Gnome session (you may remember that I have seahorse set to automatically unlock my ssh key when I log in), but instead I was inadvertently creating a new ssh-agent process with no keys in it.  Then when I tried to run Unison, it found the wrong ssh-agent process.

To fix it, I needed to find a way to keep from starting another ssh-agent process, and instead gain access to the one seahorse starts every time I log in.  I made a change to my crontab that would search for the existing ssh-agent process ID and authentication socket and import them into the cron environment.  This is kind of a hack but it actually works (not like last time).  Just add the following to your script before trying to connect to your SSH server (or do what I did and put them right into the cron job, separated by semicolons):

    export SSH_AGENT_PID=`ps -a | grep ssh-agent | grep -o -e [0-9][0-9][0-9][0-9]`
    export SSH_AUTH_SOCK=`find /tmp/ -path '*keyring-*' -name '*ssh*' -print 2>/dev/null`

Playing MIDI files in Ubuntu

Back in the winter of 2005 when I was using Debian (back them Etch was the "testing" version) I spent several frustrated days trying to get Linux to play MIDI files. The best I could come up with was running TiMidiTy from the command line and specifying the "dumb" interface. It was very clumsy because I kept forgetting the command line arguments and would have to look them up whenever I wanted to play a song, and eventually I just decided that playing MIDI files was something that I would have to boot into my Windows partition to be able to do with a reasonable amount of ease.

Fast forward to about half an hour ago. I joined our local Church's choir last fall and wanted to listen to some MIDI files to help me learn my parts. A quick Google search revealed the packages I needed, so I went to the command line and issued the following:

    sudo apt-get install timidity timidity-interfaces-extra freepats

And within a few minutes I was listening to my MIDI files through Totem movie player, with which Ubuntu had automatically associated the MIDI file type. After my last experience I couldn't believe how easy it was!

So I want to send a big shout out to all the devs working on Ubuntu, Gnome, TiMidiTy, PulseAudio, etc. for getting this right. The need for playing MIDI files is definitely something of a niche need, since not too many people listen to them, so it would have been easy to overlook it but instead they did a great job of making it work. This is yet another example of how far Linux has come over the years. The Internet is peppered with stories about how various tasks were recently very difficult to do on Linux and are dead simple now, and I am happy to add mine to the pile. Great work, guys!

XRDP, the best remote access software under Linux

My desktop PC is in my basement office, which is a nice place but somewhat inconvenient.  I really wanted a way to access it remotely from my laptop but had trouble finding a remote-access application that was fast enough.

Both my laptop and desktop are wireless, so there are 2 wireless "hops" between my machines and when logged into my desktop from my laptop each command (i.e. a click or keystroke) has 4 wireless hops to go through before my screen displays the result.  So speed is key. 

Remote access servers that didn't work out

I tried pretty much every remote access server I could find.  I was already familiar with VNC, and that was a perfectly viable option but my desktop has dual monitors, so there was a pretty big difference in screen resolutions and one of VNC's real weaknesses IMHO is that the client is forced to use the screen resolution of the server.  I didn't want to be scrolling around a lot so I axed that idea. 

Next I tried SSH with X forwarding enabled (using the -Y option).  That was nice and simple since all of the software and keys were already in place, but it was too slow, even with the -C option (which enables compression, effectively speeding up the rate of transfer).  FreeNX is a similar solution, and although it was somewhat faster some of the time, it didn't provide a consistently high level of performance so I had to reject both solutions.


Gnome also offers the option of logging into another machine via XDMCP.  When booting my laptop, I would stop at the login screen, hit Options, then "Remote Login via XDMCP".  In addition to stopping me from running any applications or doing anything else on my laptop while logged into my desktop remotely, this proved to be too slow also, so I canned the idea.


I was about to give up when I discovered xrdp.


XRDP

XRDP is a service that I installed on my desktop to enable it to accept RDP connections from my laptop.  Ubuntu already comes with an RDP client, tsclient, installed by default, and I've used Windows XP's Remote Desktop a lot at work so I know how well it works.  XRDP is in the Ubuntu repositories so I installed it on my desktop and now I can log into it from my laptop using the same program I use to log into my computer at work, and the speed more than adequate.  It is really great to be able to program, run virtual machines, and do many other resource-intensive operations from my laptop.

XRDP has a few quirks that I decided I could live with, but it is worth mentioning them here:

1. It depends upon the package "tightvncserver" being installed on the server (the machine you are logging into), although it isn't configured as a dependency in the package (this was the case as of the last time I set up XRDP, which was a while ago so hopefully they have fixed this).  Install tightvncserver before you attempt to install XRDP.
2. You may install the XRDP package and have it work just fine until you reboot the server.  This is because XRDP sometimes has difficulty figuring out whether it is running or not, so when the server is rebooting and it tries to start XRDP, XRDP thinks it is already running even though it isn't and refuses to start.  You can fix that by running this:
        sudo sesman --kill
        sudo xrdp --kill
        sudo rm /var/run/xrdp/xrdp.pid
        sudo sesman
        sudo xrdp
   
3. There is no way to log into the console session.  So if I was working at my desktop and had to get up for something, I can't resume what I was doing on my laptop.  Windows XP provides the "/console" command-line switch which allows you to take over the session that is currently displayed on the machine's screen, but there is no way to do that with XRDP.  There might be a way to do it within Gnome; I'm not sure at the moment.
5. If you do anything in the remote session that makes a sound, the sound will be played on the server's speakers, not your client's speakers.  So the first thing I hear when logging into my desktop is the sound of the Ubuntu login music being played on my desktop speakers, down the stairs and two rooms away.  This is a very minor annoyance to me but it is worth mentioning.

So now I have exactly what I set out to get: an easy-to-use remote access method that is fast and reliable.  It is really great to be able to open tsclient (you will find it on the Internet menu, it is called "Terminal Server Client") and see my desktop.  I highly recommend it!

Using passphrase-protected SSH keys in Cron

Just a few days ago I told you all about the glory that is SSH, and now I want to show you how to automate its use.

I'm sure you noticed while you were setting up your key that it asked you for a passphrase to protect the key.  If you opt not to set a passphrase, it will store your key in plain text, which means that if anyone gets access to your filesystem, they have access to your key.  They can copy it and use it on any computer to log into your server as you, so you are much better off protecting your key with a passphrase.  The key generator will use the passphrase to encrypt your key and give you protection from this threat.

Because the SSH key is encrypted, whenever you want to use it, it will ask you for your passphrase so that it can get access to the key.  This is exactly what you want to keep your key secure, but if you want to automate any of your SSH related tasks in Cron, you will be prompted for the passphrase every time SSH tries to establish a connection with your server.  One quick, easy way out of this situation is to simply keep your SSH key unencrypted and hope that no one who gets near your computer has malicious intentions, but there's a better way: ssh-agent.

Ssh-agent is a process that stores SSH keys in memory.  When you set up your SSH key with a passphrase, you may notice that Gnome gives you the option to "unlock this key automatically when I log in" (Ubuntu offers this option, YMMV); if you select that option, it will use Ssh-agent to store your SSH key in memory.

So at this point you have your SSH key encrypted on disk but unlocked in memory, so you can manually SSH into your server without entering the password for you account on the server or your passphrase for the SSH key, but you want Cron to have the same ability.  At this point, any SSH jobs in Cron will prompt you for your passphrase to unlock the SSH key.  I will show you how to fix that by making your unlocked SSH key (which is stored in memory by ssh-agent) accessible to Cron.

There are 2 steps involved in making your key available to your script running in the Cron environment: Saving the 2 SSH environment variables to disk and reading them into your environment within your Cron job.

Saving the SSH environment variables

Go into your crontab file by entering "crontab -e" at the command line.  Add the following on its own line:

     @reboot ssh-agent -s | grep -v echo > $HOME/.ssh-agent

The @reboot is a special token in cron that will cause the command to be run when you first log in.  The command will cause the SSH_AUTH_SOCK and SSH_AGENT_PID to be written to a file on disk.

Retrieving the SSH environment variables within a Cron job

Basically, in order to make the running instance of ssh-agent available to your cron job, the following line needs to be run:
      
     . ~/.ssh-agent

On my machine, I put it right into crontab just before the job I wanted to run, like this:

     # m h  dom mon dow   command
     30 * * * * . ~/.ssh-agent; unison default -ui text -batch

If you are running a script, you can alternatively put the command at the top of the script.

And that's all there is to it!  You should now be able to run an SSH command using an SSH key that is encrypted on disk but unencrypted in memory within a cron job. 

EDIT:  A few days after posting this, I discovered that it was actually not working for me at all.  The steps I just described probably would have worked just fine if I was trying to start my own ssh-agent process and manually add keys to it using ssh-add, but I was trying to do it using the ssh-agent process and key which seahorse sets up for me when I first log in, and this configuration required a slightly different solution.  See my follow-up post for details.
 

See also:  http://sial.org/howto/openssh/publickey-auth/

SSH, the Secure Shizzle

SSH, the "secure shell" is the ultimate exception to the "security is inversely proportional to convenience" rule.  It is so easy to set up and once you have it running, secure authentication and communication are totally transparent.  It's almost irresponsible not to use it.

In its most basic form, SSH is a secure remote console program, a secure replacement for Telnet, however, it is very flexible and can handle such tasks as secure file copying between machines, proxying, and even tunneling.  Also, it's been around so long that it has become one of the de facto standards for secure authentication and communication on Linux.  Pretty much any network-enabled program worth its salt will feature support for it.

There are many fine tutorials on how to use SSH, my favorite is by the incomparable Chess Griffen on the Linux Reality podcast.  If you aren't already familiar with SSH, stop reading this post and listen to that episode of Linux Reality right away.  I'll wait.

As awesome as it is to be able to type "ssh myserver", enter the password, and start entering commands to be run on your server, there's a better way.  It's called SSH keys, and they will save you the trouble of typing in your password every time you want to connect to the server and they will give your server extra protection from being hacked.  It's easier and more secure, which almost never happens, so you know you have to do it.

Creating an SSH key

Simply hop into the command line and type "ssh-keygen".  It will ask you to give a filename and location for the new keys, and it will ask you to give it a passphrase.  When it is finished, go into your home directory's .ssh folder, and you will see two files: id_rsa and id_rsa.pub.  The id_rsa file is your private key; leave it where it is and don't let anyone have access to it.  Copy the id_rsa.pub file to your server.  On the server, go into your home directory's .ssh folder.  Create a file called authorized_keys if it doesn't already exist and copy the contents of your id_rsa.pub file into it (append the contents if the authorized_keys file already exists).  Now, go back to your client machine and SSH into your server.  It should let you in without asking for a password.

More SSH hardening measures

Let's face it, half the point of SSH is the security.  Setting up keys as I described will protect communications between your computers and ensure that you are actually contacting the server you think you are contacting with almost no effort on your part.  There are a few extra steps that should be taken to gain the highest level of security:

1. Disallow protocol 1: On the server, open /etc/ssh/sshd_config as root.  Find the line that says "Protocol 1,2".  Delete the 1 and the comma, so it only says "Protocol 2".  Don't close sshd_config yet...
2. Also in sshd_config, find the line that says "#PasswordAuthentication yes".  Remove the hash mark from the beginning of the line and change "yes" to "no".  Keep sshd_config open...
3. Find the line that says "Port 22" and change the 22 to another number between 1024 and 65535.  
4. Save that file and restart the ssh daemon (you can usually do this by running "sh /etc/init.d/sshd restart" as root)
5. On your client, open /etc/ssh/ssh_config as root
6. Find the line that says "Port 22" and change it to the same port number you set in step 3 above.
7. Find the line that says "Protocol 1,2" and change it to "Protocol 2", as you did on the server in step 1 above.
8. Find the line that says "Cipher aes128-cbc,3des-cbc,blowfish-cbc...".  Remove the hash mark at the beginning of the line if there is one, then remove all of the ciphers listed except aes256-cbc.  So that line should read, "Cipher aes256-cbc".
9. Save that file
10. Bookmark this blog post, because you will have to repeat steps 5-9 on all of your clients.

This may seem like a lot of work, but please keep in mind that SSH has been around for a very long time and there are a lot of automated ways to attack an SSH server that rely on the default settings, such as support for Protocol 1 and having the SSH daemon listen on port 22.  Changing these defaults takes only a few minutes but makes it exponentially harder for hackers to get in.  These steps are absolutely essential if you are considering exposing your SSH daemon to the public Internet.  

At this point, you are able communicate between machines with more ease and convenience than ever, and those communications are secured by military-grade authentication and encryption.  Security and convenience will never be this close, so take advantage!

Automate gadget-related tasks by setting up a udev rule

If you're reading this post, odds are good that you own a computer.  Since it is specifically this post that you're reading, odds are good that you also have some kind of peripheral, such as a camera, printer, mp3 player, webcam, usb flash drive, usb hard drive, etc, and that there are certain tasks that you need to perform every time you plug it in.

For instance, you may want your computer to automatically import your pictures when you plug in your camera.  You may need to send your printer its firmware (like I do) every time you plug it into your computer.  You may want to back up your phone or send files to your flash drive automatically.  Or perhaps you just want Skype to launch automatically whenever you have your webcam connected.  Whatever your situation, odds are good that there is some way that you can automate tasks and make your life easier by saving time with udev rules.

Udev is the new device manager for the Linux kernel, replacing the older manager, hotplug.  In this post I will show you how to configure a rule so that udev runs a bash script (which I will also show you how to create) whenever you plug in your device.

Creating the udev rule

The nice thing about udev is that you can make rules for individual devices.  This means that you can have a different procedure run when you plug in your external hard drive than the one that runs when you plug in your USB flash drive.  To get started, plug in the device for which you would like the rule created.  Then run lsusb.

You will get a list of 5 or 6 items, and you should see your device listed by manufacturer.  On that same line, just before the manufacturer's name, you should see two 4-digit alphanumeric values seperated by a colon.  The first value is the Vendor ID and the second is the Product ID; you will need both for your udev rule.  As an example, when I created my rule for my mp3 player, this was the output of lsusb:
Bus 001 Device 012: ID 041e:4139 Creative Technology, Ltd Zen Nano Plus
Bus 001 Device 002: ID 0c45:62c0 Microdia Sonix USB 2.0 Camera
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

You can see my mp3 player listed on the first line, and that the Vendor ID is 041e and the Product ID is 4139.  On to the next step.

Go into /etc/udev/rules.d and, as root, create a new file named 85-my_rule.rules (the file must begin with a 2-digit number followed by a hyphen, and it must end with ".rules"; it doesn't really matter what you put in the middle) and open it in your favorite text editor.  Enter the following:

     ACTION=="add", ATTRS{idVendor}=="your-devices-vendor-id", ATTRS{idProduct}=="your-devices-product-id", RUN+="/path/to/your/bash-script"


...so the rule I created for my Zen Nano looked like this:

     ACTION=="add", ATTRS{idVendor}=="041e", ATTRS{idProduct}=="4139", RUN+="/home/jizldrangs/bin/sync-zennano"


This basically tells udev that whenever you plug in a device with the vendor ID and product ID that you specified, it is to execute the bash script that you specified.  With this setup, the options for what you do when the device is plugged in is only limited by what can be scripted in Bash, so you can see how powerful this can be.

If for whatever reason you would like to manually mount or unmount the volume, you can tell udev to place a symlink in the /dev directory by using the SYMLINK keyword.  Just append SYMLINK+="my_symlink_name" to the end of the rule, and after it runs you can find a symlink to the device in /dev which you can use with the mount or umount commands.

When you are finished with that, restart udev:

     sudo service udev restart

Creating the script

The script that is run when the device is connected can do pretty much anything you want.  As long as it can be done from the command line, you can automate it with udev. 

As an example, and as a segue into my discussion on the various pitfalls of udev, here is what I ended up with:

#! /bin/sh

USER=jizldrangs
export HOME=/home/jizldrangs
SHELL=/bin/sh
DISPLAY=:0.0
MAILTO=jizldrangs
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/home/jizldrangs/bin
xhost local:jizldrangs
export DISPLAY=:0.0
LOGFILE="/usr/local/bin/sync-zennano.log"
TIMEFILE="/usr/local/bin/sync-zennano.time"

CURRENTLY=$( date +%s )
if [ -e $TIMEFILE ]; then
  
    echo "sync-zennano.time exists"
    FIRST_RUN_TIME=$( cat $TIMEFILE )
  
    echo $CURRENTLY
    echo $FIRST_RUN_TIME
    NUMOFSECONDS=$(($CURRENTLY - $FIRST_RUN_TIME))
    echo "num of seconds: ${NUMOFSECONDS}"
    if [ $NUMOFSECONDS -gt 60 ]; then
        echo "sync-zennano has not run in over 60 seconds"
        rm -f $TIMEFILE
    fi

fi

if ! [ -e $TIMEFILE ]; then

# Send the following block of commands to the background
{
    sleep 10

    notify-send -u normal -t 2000 -i info "Zen Nano Sync" "Starting synchronization.  Please wait."

    sudo -u jizldrangs unison zennano -auto -batch -terse -ui text

    notify-send -u normal -t 2500 -i info "Zen Nano Sync" "Synchronization of Zen Nano is complete"
} &
    touch $TIMEFILE
    chmod 666 $TIMEFILE
    date +s% > $TIMEFILE

fi

There are several udev "gotchas" that I'm working around here (I only really wanted to run 3 lines, but had to add a bunch of other stuff to get it working right).  It's worth going through each one...

Udev Gotchas

There are a relatively large number of things to watch out for:

1.  For some reason, it is common for udev to run your script many times in quick succession.  Whenever I plug in my mp3 player, udev runs my script at least 10 times.  To get around that, I added a few lines to my script that would write the time to disk the first time it is run, then check for the existence of the file and not run the payload of the script if it had already been run within the last 60 seconds.  It's clunky but it works.
2. Make sure you make the script executable with a "chmod 700 /path/to/script".  
3. Keep in mind that your script will be run as root.  This means:
1. For security reasons, keep it in a folder where it can't be accessed by anyone but root and remove read/write permissions from all other users, including yourself.
2. Any environment variables or elements you may be relying on won't be available.  In my script, I am running a Unison profile located in my home directory, so in order to get it working I had to export the path to my home directory into the HOME variable in the first few lines of the script.  Then when it came time to run Unison, i added "sudo -u jizdrangs" at the beginning of the line, which causes that line to be run as me rather than as root.
4. Udev will wait for your script to finish before mounting the device, so if you are doing any tasks that rely on the device being mounted, send that series of commands to the background by surrounding them with curly braces and adding a space and an ampersand after the close-curly-brace.  This will "detach" the commands, or cause udev to continue its work without waiting for those commands to finish.  Then add a "sleep 10" at the beginning of the commands being sent to the background, so that udev has time to mount the device before the rest of the commands are executed.
5. Because udev runs the script in its own environment, it won't have information on your display.  I like to have notifications pop up, so I added the "export DISPLAY=:0.0" line towards the top.  The notifications I get using notify-send would not work without it.
   

It took me a while to get all this working, but it was worth the knowledge I gained along the way.  Now whenever I plug in my mp3 player, it automatically synchronizes my podcasts, and it displays notifications telling me when it begins the sync process and when it is finished.

See also:
http://reactivated.net/writing_udev_rules.html
http://ubuntuforums.org/archive/index.php/t-502864.html