Hydrian

So on Sunday, I need my laptop for church to stream Zoom. It had been working properly when I shut it down. After connecting all of the A/V I/O, I started it up as my laptop had done before hundreds of times with out issue. This time it hangs at the at the kernel boot screen, just after the GRUB hand-off. Luckily someone else brought up their laptop to do ZOOM A/V. 

So I just spend nearly a day trying to figure out what was wrong with laptop. After stewing over the laptop/GPU may have died, I finally figured it out it was the proprietary Nvidia Linux GPU driver. 

Once I figured out the issue, it took my most of that down time to clean up the mess it had made. Nvidia also changed the API calls to their support libraries so it broke my display manager too!

This is just a quick article I wrote for myself. I keep on forgetting how to make bootable floppy disks in linux.

Get an floppy image from bootdisk.com or some other source

fdformat /dev/fd0

mkfs.vfat /dev/fd0 ## you may need to use the -I option with some USB floppy drives/li>

unzip bootmec.exe ## that makes a file called bootmec.IMA (if you got an image from bootdisk.com)

To import a CSR in to a Windows Certificate Authority Server, you must define a certificate template.  OpenSSL does not do this because this is a Microsoft only concept.  With the use of the 'certreq' command, you can apply a template type during the request import process.  This command should be available on your Microsoft CA server.

INTRODUCTION

Here are a few CLI commands to convert a java key store file to a PKCS12 encoded cert chain and back. This requires the java development kit (Sun/Oracle JDK) 6 or newer.  

INSTRUCTIONS

JKS → P12

$> keytool -importkeystore \ -srckeystore keystore.jks \ -srcstoretype JKS \ -deststoretype PKCS12 \ -destkeystore keystore.p12

P12 → JKS

Here is a POSIX compliant regular expression for testing a host name.  This does not support a fully qualified domain name (FQDN).  This was tested with Linux grep.

'^([[:digit:]a-zA-Z]([-[:digit:]a-zA-Z]{0,61}[[:digit:]a-zA-Z]){0,1})$'

Here is a working example:

I recently was playing with a new 4GB usb stick and I wanted it install a rawdisk VirtualBox VM on it.  This would give a portable VM with decent speed.When I was trying to create the raw disk formated disk with the following command:

#> vboxmanage internalcommands -rawdisk /dev/sdc -filename ~/VirtualBox\ VMs/usbstick.vmdk

I recieved the following error.  I even got this error running as root.  I determined it wasn't a permissons issue.

VBoxManage: error: Cannot open the raw disk '/dev/sdc': VERR_MEDIA_NOT_PRESENT VBoxManage: error: The raw disk vmdk file was not created

After verifying that the device file did truely exist and that the permissions were not an issue.  I did some wondering.  What else would be touching this.  Then I noticed gnome (nautilus) was automounting USB sticks.  I then disabled the usb stick automounting.  This affects all USB mass storage devices.  I did this by opening the gconf-editor program.

#> gconf-editor

I then browsed thought the menu tree to apps -> nautilus -> preferences localtion.  Then in right column I disabled the media_automount and media_automount_open options.  Close gconf-editor.  Unplug and reinsert the usb stick. Now I was able to create the rawdisk without a problem.

#> vboxmanage internalcommands -rawdisk /dev/sdc -filename ~/VirtualBox\ VMs/usbstick.vmdk RAW host disk access VMDK file /home/hydrian/VirtualBox VMs/usbstick.vmdk created successfully.

Most OpenSSL documentation out there only shows you how to create a new key and signs it with in single command.  I wanted to use a self-signed in the interm while waiting for my third-party CA approve my certificate. I already had an existing key.   Here is the command to create a self-signed certificate from an existing RSA key.

This is just a handy command string that is meant for converting images files into base64 for CSS embedding.  

Common command line switches and arguments to disable GPU assisted resources.  

--disable-3d-apis Disables client-visible 3D APIs, in particular WebGL and Pepper 3D. This is controlled by policy and is kept separate from the other enable/disable switches to avoid accidentally regressing the policy support for controlling access to these APIs. 

--disable-accelerated-2d-canvas Disable gpu-accelerated 2d canvas. 

--disable-accelerated-compositing Disables accelerated compositing. 

--disable-accelerated-layers Disables the hardware acceleration of 3D CSS and animation. 

Many times I've had to image/clone partitions of the machines across and SSH connection.  Often there is not sufficient space to compress the whole image and transfer it over to the new machine and the deploy it inside that machine. This is very common with VPS providers.

Instructions

Boot up both machines in single user mode or with a boot CD. I like using rescue CDs/OSs. Make sure all of the source partitions and destination partitions are unmounted or mounted read-only. Also make sure the user you are working with has the permissions to write disk's partition devices.

#> dd if={source partition device}| gzip -1 - | ssh {destination host} 'gunzip - | dd of={target partition device}'

While it isn't required to gzip the data stream, it it highly recommended. If you don't, you'll be wasting lots of time and bandwidth transferring empty space.

Example

0. Show Current MD status

#> cat /proc/mdstat

This command will show you all of the /dev/md devices on your system. Take note that there may be multiple md devices associated with one drive. 

1. Remove Old/Dead Drive

#> mdadm --manage /dev/md0 --fail /dev/sdb1 (Dead Drive)

This remove the old / dead drive from the md0 array. This may have to be run multiple times if you multiple md drives per a single physical drive. 

2. Remove drive. 

If your drive or host controller do not support hot-swapping, shutdown your machine. Remove your bad drive.

If your drive or host controller supports hot-swapping, just remove drive.

3. Insert new drive. 

If your drive or host controller do not support hot-swapping, Insert new/working drive of same size or bigger size. Boot machine. Jump to step 5. 

If your drive or host controller supports hot-swapping, just insert drive.

4. Rescan host adapter.

#> echo ‘- - -’ > /sys/class/scsi_host/host0/scan

Force a SCSI HBA rescan. 

5. Partition New Drive

#> sfdisk -d /dev/sda | sfdisk /dev/sdb

Copy partition format from existing drive and import it to new drive. Warning this only works on msdos table drives. GPT tables do not work. 

6. Add New Drive to MD RAID

#> mdadm --manage /dev/md0 --add /dev/sdb1

Add new drive to existing MD RAID device. 

7. Monitor Rebuild

#> cat /proc/mdstat