Windows XP: Extend evaluation period (Not a permanent solution)

Recently, an old machine running Windows XP SP3 had its hard disk replaced, since then the OS decided that the license was not valid and considered itself to be in a trial/evaluation 30 days period.
Since the activation/validation services of Windows XP got discontinued we could not reactivate the current setup using the internet.
We tried a few times to activate via phone but it failed as well..

Temporary Solution (mitigating the problem)

To give us some time to think about a solution, whenever Windows XP would say that the evaluation period was expired, we would boot into safe mode and then run this command rundll32.exe syssetup,SetupOobeBnk (in cmd.exe or in the Run option that is in the Start menu) that allows you to reset the evaluation period for up to 4 times (and if used properly will give you 150 days in total to find a solution).

Actual Solution

In the end, we used the installation CD to downgrade the installation using the repair option, then we tried the telephone activation again and it worked!
Although Windows XP was not complaining any more, that caused us some problems with the antivirus, as a shared system library (DLL) that was replaced was not compatible with the antivirus.
To resolve this issue, we booted the machine using a GNU/Linux live CD and replaced the library (DLL) from a backup that was in the old disk.

Warning: Downgrading the system using the installation CD most probably re-enabled old exploits and hacks making the system less secure.
Keep this information in mind as you cannot re-apply the updates to the system not even the security updates any more.


ATEN – USB-to-Serial Converter (35cm) UC232A – Windows 10 (64bit) Drivers


Recently we started using the UC232A USB-to-Serial Converter to connect to a board.
The software we used was TeraTerm on a 64bit Windows 10 without installing custom drivers.

Our serial port configuration was the following:

  • Baud rate: 115200
  • Data: 8 bit
  • Parity: none
  • Stop: 1 bit
  • Flow control: none
  • Transmit delay:
    5 msec/char
    5 msec/line

The problem

We noticed that something was wrong with the process as the terminal would not operate consistently.
Some times keystrokes did not appear on screen, in other times results would not appear correctly (they could be truncated or mixed with other data) and in general, the system acted like it was possessed by a ghost.


We played around with the configuration parameters, hoping that it was an issue like having the need to add large transmit delay but it did not change anything, the communication with the board was unstable.
Afterwards, we switched to another cable, of a different company, and everything worked as expected. The data on the screen was consistent and the ghost was banished. The UC232A was brand new so we tested that it works on a GNU/Linux machine, which turned out to be OK. Doing so, these two tests led us to the conclusion that since both the cable operates properly on GNU/Linux and the board operates properly using the other cable, that the issue we had was the automatically installed Windows 10 drivers.


While the cable was unplugged, we installed the official drivers we found here.
To find the drivers on that page, click on Support and Download tab at the bottom and then click on the Software & Drivers panel.
From the new table that will appear, under the category Windows Legacy Software & Driver we used the latest version that was available at the time that this post was written, which was v1.0.082 dated 2016-01-27 ( (6487 downloads) retrieved on the 23rd of November 2016).
After the download was finished, we restarted the machine, plugged in the cable and gave it another go.
The system was working as expected.

Following, you will find the screenshots from the device manager, after we got the cable working right.




Reclaim empty space from VirtualBox VDI disk images by shrinking

Recently, we did some cleanup in certain GNU/Linux virtual machines, where we hoped that VirtualBox would release the disk space that is not used and shrink the size of the VDI files.
Unfortunately, that did not happen even after freeing more than 100GB of space from the guest machine.

We did manage though to reclaim the empty space manually, using the zerofree and VBoxManage utilities.

Following is the guide we followed to do so:

Part 1: Clean-up the guest machine using zerofree

We needed to find the unallocated, blocks with non-zero value content in the ext2, ext3 or ext4 filesystem (e.g. /dev/sda1) and fill them with zeroes.
Since the filesystem has to be unmounted or mounted as read-only for zerofree to work, we decided to use a Live CD to complete this task as it would be the simplest solution to follow.

Step 1: Download SystemRescueCd Live Image

We downloaded the SystemRescueCd Live Image and inserted it to the guest machine as a Live CD.

Step 2: Identify partitions and disks using fdisk -l

We booted the virtual machine from the Live CD, when the terminal appeared, we typed fdisk -l to see all available disks and partitions.

Depending on your configuration you will see the following

If you performed your installation using standard partition

Disk /dev/sda: 200 GiB, 214748364800 bytes, 419430400 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x64af3527

Device     Boot     Start       End   Sectors  Size Id Type
/dev/sda1  *         2048 411043839 411041792  196G 83 Linux
/dev/sda2       411045886 419428351   8382466    4G  5 Extended
/dev/sda5       411045888 419428351   8382464    4G 82 Linux swap / Solaris

or if you performed your installation using LVM

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000523ce

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   419430399   209202176   8e  Linux LVM

Disk /dev/mapper/centos-root: 53.7 GB, 53687091200 bytes, 104857600 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/mapper/centos-swap: 4160 MB, 4160749568 bytes, 8126464 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/mapper/centos-home: 156.3 GB, 156304932864 bytes, 305283072 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

From the above results, we keep the paths to the real partitions and the paths to the LVM partitions, e.g.
/dev/sda1 which is 196GB, /dev/mapper/centos-home and /dev/mapper/centos-root

Step 3: Perform the cleanup

To perform the clean up, execute for each of the above paths the command zerofree, e.g.

zerofree /dev/sda1;
zerofree /dev/mapper/centos-home;
zerofree /dev/mapper/centos-root;

Give it some time to complete the task, the larger the partition, the more the time it will take.

Part 2: Shrink the guest machine disk images using VBoxManage

We used VBoxManage with the parameter --compact, which it is used to compact disk images, i.e. remove blocks that only contains zeroes. It shrinks dynamically allocated images by reducing the physical size of the image without affecting the logical size of the virtual disk. Compaction works both for base images and for diff images created as part of a snapshot. For this operation to be effective, it is required that free space in the guest system first be zeroed out and that is why we had to perform Step 1 using zerofree before.
Please note that compacting is currently only available for VDI images.

To use, just issue the command "C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd --compact <DISK_PATH> pointing to the disk you just cleaned up using zerofree
Please note that the virtual machine should be stopped before starting this operation.

Press the key combination Win + R to pop up the Run prompt.
Type cmd in the input box and hit the Enter key.

"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd --compact "F:\Ubuntu\Ubuntu.vdi"
"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd --compact "C:\Users\bytefreaks\VirtualBox VMs\CentOS\CentOS.vdi"

VirtualBox: Failed to attach the USB device to the virtual machine 25

Recently we were using a Windows 10 64bit machine which had Oracle VirtualBox installed.
At some point all USB devices stopped mounting on the guest systems.
We would get errors similar to the following:

Failed to attach the USB device OnePlus A0001 [0232] to the virtual machine Ubuntu.

USB device 'OnePlus A0001' with UUID {544e5582-9e77-4301-a538-5326cf2250c0} is busy with a previous request. Please try again later.

Result Code: E_INVALIDARG (0x80070057)
Component: HostUSBDeviceWrap
Interface: IHostUSBDevice {c19073dd-cc7b-431b-98b2-951fda8eab89}

Callee: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}

USB device  with UUID  is busy with a previous request. Please try again later.

After a couple of restarts of both the guest and the host machines we realized that this time, a restart was not enough to fix the error.
Right before this error occurred, we had installed Wireshark with USBPcap support.
Apparently this was the root of our problem.


Following are the steps we followed to solve this issue:

Step A: Delete problematic system configuration.

Press the key combination Win + R to pop up the Run prompt.
Type regedit in the input box and hit the Enter key.


On the left side of the new window, navigate to the following location:



In the right part, select the UpperFilters entry, right click it and select Delete.

When a prompt window appear asks you to confirm that you want to delete the value, click Yes.


Step B: Manually re-install VirtualBox USB drivers (Optional)

Just in case there is an issue with the VirtualBox USB drivers, you can re-install them to be sure everything is OK.
To do that, you can either re-install the whole VirtualBox using their installer or manually re-install the driver itself.

To re-install the VirtualBox USB driver manually, using Windows Explore navigate to this folder

C:\Program Files\Oracle\VirtualBox\drivers\USB\filter

Right click the file VBoxUSBMon.inf and select Install.

You will get a confirmation once the installation is complete.
Restart your machine, so that new changes will get applied.
Your USB devices should work as expected.

The disk is offline because it has a signature collision with another disk that is online 1

Recently, we cloned a hard disk using dd.
When we booted into Windows, the new drive was not visible.
After checking with the disk utilities, we got the following informative message:

The disk is offline because it has a signature collision with another disk that is online

To resolve the issue, we used diskpart.
To start diskpart, press the key combination Win + R which will pop up the Run prompt.
Type diskpart in the input box and hit the Enter key.

A new terminal window will appear.
Using that we identified the two disks and changed the label for the second one.

First step:

We issued list disk to get the list of disks.


Microsoft DiskPart version 10.0.14393.0
Copyright (C) 1999-2013 Microsoft Corporation.

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          931 GB      0 B
  Disk 1    Offline         465 GB      0 B

Second step:

We issued select disk 1 so that we could process the disk 1 that was offline and using uniqueid disk we got the signature of the disk.

DISKPART> select disk 1
Disk 1 is now the selected disk.

DISKPART> uniqueid disk
Disk ID: 09FC13CB

Third step:

Set the signature of the disk to a random value other than the one that it already had using the command uniqueid disk ID=FFAABBCCDD


DISKPART> uniqueid disk

The random value must be 8 characters long and each character must be a value between 0-9 or A-F.


Restart the machine to get both disks running.

Activate a wireless hotspot on Windows 10 1


  • You must be an administrator of the machine to complete this guide.
  • You need to have at least two network devices.
  • One of them needs to have access to the internet and the other one needs to be a WiFi adapter which has Hosted Network support.

To check if your wireless adapter supports the functionality for Hosted Network, open a Command Prompt and type NETSH WLAN show drivers.

To open the Command Prompt, press the buttons Windows+R on your keyboard.
A new run command prompt will appear.
Type in the input box cmd and hit the Enter button.

In the new Command Prompt type NETSH WLAN show drivers, the results should be similar to below.

C:\Users\bytefreaks>NETSH WLAN show drivers
Interface name: Wi-Fi
    Driver                    : Realtek RTL8188CU Wireless LAN 802.11n USB 2.0 Network Adapter
    Vendor                    : Realtek Semiconductor Corp.
    Provider                  : Realtek Semiconductor Corp.
    Date                      : 3/4/2016
    Version                   : 1027.4.630.2015
    INF file                  : ????
    Type                      : Native Wi-Fi Driver
    Radio types supported     : 802.11n 802.11b 802.11g
    FIPS 140-2 mode supported : Yes
    802.11w Management Frame Protection supported : Yes
    Hosted network supported  : Yes
    Authentication and cipher supported in infrastructure mode:
                                Open            None
                                WPA2-Personal   CCMP
                                Open            WEP-40bit
                                Open            WEP-104bit
                                Open            WEP
                                WPA-Enterprise  TKIP
                                WPA-Personal    TKIP
                                WPA2-Enterprise TKIP
                                WPA2-Personal   TKIP
                                WPA-Enterprise  CCMP
                                WPA-Personal    CCMP
                                WPA2-Enterprise CCMP
                                Vendor defined  TKIP
                                Vendor defined  CCMP
                                Vendor defined  Vendor defined
                                Vendor defined  Vendor defined
                                WPA2-Enterprise Vendor defined
                                WPA2-Enterprise Vendor defined
                                Vendor defined  Vendor defined
                                Vendor defined  Vendor defined
    Authentication and cipher supported in ad-hoc mode:
                                Open            None
                                Open            WEP-40bit
                                Open            WEP-104bit
                                Open            WEP
                                WPA2-Personal   CCMP
    Wireless Display Supported: Yes (Graphics Driver: Yes, Wi-Fi Driver: Yes)

In the results you need to find the line Hosted network supported and verify that the value is set to Yes, if it is not, then you cannot proceed with this wireless network adapter.

In case you got a permission error on the above command, try to open a new Command Prompt with admin rights.

Press the keys Windows+X, in the pop-up menu select Command Prompt (Admin). If your account has enough access rights, a new run command prompt will appear. In the new Command Prompt (Admin) type NETSH WLAN show drivers, the results should be similar to above.

If this failed as well, you cannot proceed with the current account, you either need to sign in with another account or ask your system administrator to perform this task for you.

How to setup the hotspot

In the Command Prompt enter the following command:

NETSH WLAN set hostednetwork mode=allow ssid=BYTEFREAKS key=0123456789

Update ssid=BYTEFREAKS with the name that you want to give your network. e.g. ssid=MY_NETWORK.

Update key=0123456789 with the password that you want to give your network. e.g. ssid=y0m2ZSQ3ng.

The new network will use WPA/WPA2 PSK security policy so your password needs to be at least 8 characters long.

The results will be similar to the following block.

C:\Users\bytefreaks>NETSH WLAN set hostednetwork mode=allow ssid=HIDDEN007 key=0123456789
The hosted network mode has been set to allow.
The SSID of the hosted network has been successfully changed.
The user key passphrase of the hosted network has been successfully changed.

How to activate the hotspot

Once the Hosted Network is created, enter the following command as is to activate it

NETSH WLAN start hostednetwork

C:\Users\bytefreaks>NETSH WLAN start hostednetwork
The hosted network started.

After this step, your network will be visible to connect to but it will not provide its users with internet access.

Please note that due to the lack of commands in the documentation ( it is not possible to prevent your hotspot from broadcasting its SSID to everyone. In other words, it is not possible to hide your network from other users, so use a strong password!


How to share internet connection with the hotspot

Press on the keyboard Windows+X to open the Power User menu, and select Network Connections.


You will notice that a there is a new device in this list. The name of this device will be something line Local Area Connection* 12. That device is the new virtual device you created in the previous step to create the hotspot.


Right-click the other network adapter, that has an active internet connection and select Properties.


Click on the Sharing tab.


Enable the Allow other network users to connect through this computer's Internet connection option.

From the Home networking connection drop-down menu select the virtual device that we created.

Click OK to close the configuration and apply the changes.

By completing this step, all devices connected to your Hotspot will have access to the internet via the connection of the second network device.

How to restart or shut down Windows through Remote Desktop

Assuming you have the following scenario: you are connected to a remote Windows machine via remote desktop and you need to restart it.
Soon you will realize that there is no restart button on the Start menu to click on….
So.. without that button, how do you restart your machine???

Do not fret as there is a way!

To Restart the remote Windows machine

Press the keys Windows+R on the keyboard together, it will pop-up the run command screen.
In the input line type shutdown /r /t 0 and hit the Enter button to restart the machine immediately.

  • The /r option instructs the machine to reboot
  • The /t 0 option sets the number of seconds to delay before executing the restart to 0 (initiate restart process immediately)

To Shut Down the remote Windows machine

Press the keys Windows+R on the keyboard together, it will pop-up the run command screen.
In the input line type shutdown /s and hit the Enter button to restart the machine immediately.

To Stop a Shut Down or Restart process

To try and stop a shut down process, type shutdown /a and hit enter, it will attempt to abort the shutdown/restart sequence.
Keep in mind though that there still is a high chance for this to fail.

Windows: Kill a service that Windows Task Manager does not stop

In some cases, Windows Task Manager cannot stop a certain service. When the user right clicks on the service and selects the Stop Process option, the status of the service becomes Stopping but never actually stops. This happens when the developer of the service did not handle properly the signal instructing the service to shut down properly.

A way to stop it by force is to use the taskkill command with the help of the task manager. Press at the same time the keyboard keys Ctrl+Shift+Esc this will show the task manager. In the new window, switch to the tab Services. Find the service you want to stop and copy from the column PID the process ID number of the service. In the following example, if we wanted to kill the WinVNC4 service we would copy the number 1828.


Then, press at the same time the keyboard keys Windows+R that will pop up the Run Command screen. In the input line type the following:

taskkill /pid PID

and replace the PID with the PID we copied from the task manager before. In our example the input will become:

taskkill /pid 1828

and then hit the OK button.


Windows: How to start “Remote Desktop Connection” without the icon shortcut

On a Windows machine we were using recently, all shortcuts icons to system applications got corrupt and they were not linking to the applications they were supposed to link to.

We needed to use Microsoft Remote Desktop Connection without the shortcuts icons. To do so we used the shortcut key of the Run Command screen that allows us to start any application that Windows knows where the binary is.

We pressed the keys Windows+R on the keyboard together and that showed the run command screen. In the input line we typed mstsc and hit the Enter button (you can also click on the OK button on the screen).


mstsc is the name that the executable file of Microsoft Remote Desktop Connection application holds in C:\Windows\System32. The easiest way to find the name of a binary is to check the icon shortcut on a machine that it is not corrupted or just search the internet for it.

Using all monitors

If you have multiple monitors that are arranged to form a rectangle, you can instruct mstsc by using the /span parameter to match the Remote Desktop width and height with the local virtual desktop and span across multiple monitors if necessary.

Executing mstsc /span will create a bigger window to the remote machine that will cover all your local monitors. Unfortunately, this window will not operate as if it is composed of multiple monitors. If you set a window to full screen, it will fill ALL local monitors as if they are one.