Category Archives: Windows

SSH keys and Windows – easy way

How many times I’ve helped customers and friends on this? I’ve lost the count.

So, I thought to write a little article to help whoever will face the same in the future. This might clean up a bit my karma too heheh 😀

Jokes apart, at work we mostly likely get a Windows laptop and you might need to work on remote Linux servers. And yes, you also might have Putty pre installed or shining on your desktop. And it’s perfectly fine, until you realise that the remote server is accessible ONLY using SSH keys. And here is when the fun starts.

Sounds familiar?

You can configure that with Putty, but generating the keys, setting up the application etc could be messy.

Since Windows 10 (latest versions), Microsoft added WSL, which is basically a minimal Linux virtual machine running on your Windows pc/laptop. This means that you can SUPER EASILY create ssh keys, use them and remove all the potential issues that you can face while configuring Putty.

So, ready to do it?

You can follow the official documentation here: https://learn.microsoft.com/en-us/windows/wsl/install

In short:

  1. Open CMD as Administrator
  2. run wsl --install

Yes, that easy!

The process will require you to reboot the Windows machine – mostly likely – but after that, you’ll have a proper Linux shell available.

At that point, you can use ssh-keygen command to generate your keys.

You will be able to see the content of the public key simply using cat command:

cat .ssh/id_rsa.pub

And yes, you will use the output of that command to configure your cloud provider or your remote server to accept ssh connections using the key.

Quick note: if you want to connect from your shining brand new WSL shell to your remote server, you need to be sure that the content of .ssh/id_rsa.pub is stored in .ssh/authorized_keys under the user’s home, on the remote server.

For example, to connect to myserver.example.com (public IP 213.045.046.32), as root, you need to:

  1. create the ssh key on the local WSL user account
  2. have the content of .ssh/id_rsa.pub appended/added into /root/.ssh/authorized_keys
  3. from WSL shell run ssh myserver.example.com -l root or ssh 213.045.046.32 -l root

And yes, super easy, isn’t it? 🙂

Enjoy! 😉

Ping on WSL

Do we really need to be root to simply to a ping from your WSL on Windows?
Apparently yes.
You have probably faced the following error:

ping: socktype: SOCK_RAW
ping: socket: Operation not permitted
ping: => missing cap_net_raw+p capability or setuid?

Wanna fix it?

sudo setcap cap_net_raw+ep /bin/ping

Run this command once, and the command ping will be “usable” again 😉

Happy ping’ing! 😉

Mount Windows Network drives in WSL

In Windows WSL, you can access the local disk navigating the path /mnt/c/ for the C: drive, for example.

Sometimes, network drives mounted on boot aren’t automatically mounted within your WSL Linux shell. You can do it manually using the following commands:

# For a drive already mapped in Windows (e.g. Z: drive)
$ sudo mkdir /mnt/z
$ sudo mount -t drvfs Z: /mnt/z

# For a network drive accessible via \\myserver\dir1 in Explorer
$ sudo mkdir /mnt/dir1
$ sudo mount -t drvfs '\\myserver\dir1' /mnt/dir1

Windows 10 – VMWare Disk cleanup and shrink

Simple batch script to run as Administrator in order to cleanup the disk, defrag and shrink.

Please note that the shrink works only if the VMWare tools are installed on the guest VM.

@ECHO OFF
REM Make sure to run the script as Administrator
whoami /groups | find "S-1-16-12288" > nul

if %errorlevel% == 0 (
 echo Welcome, Admin
) else (
 echo You must run this script as Administrator. Aborting...
 goto EOF
)

REM Enable components to cleanup
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Active Setup Temp Folders" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\BranchCache" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Downloaded Program Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\GameNewsFiles" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\GameStatisticsFiles" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\GameUpdateFiles" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Internet Cache Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Memory Dump Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Offline Pages Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Old ChkDsk Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Previous Installations" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Recycle Bin" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Service Pack Cleanup" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Setup Log Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\System error memory dump files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\System error minidump files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Temporary Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Temporary Setup Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Temporary Sync Files" /V StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Thumbnail Cache" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Update Cleanup" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Upgrade Discarded Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\User file versions" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Windows Defender" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Windows Error Reporting Archive Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Windows Error Reporting Queue Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Windows Error Reporting System Archive Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Windows Error Reporting System Queue Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Windows ESD installation files" /v StateFlags0100 /d 2 /t REG_DWORD /f
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Windows Upgrade Log Files" /v StateFlags0100 /d 2 /t REG_DWORD /f
 
REM Run cleanup
IF EXIST %SystemRoot%\SYSTEM32\cleanmgr.exe START /WAIT cleanmgr /sagerun:100

echo *** DEFRAGGING DRIVES ***
echo DEFRAG C:
defrag c: -f

if not exist "C:\Program Files\VMware\VMware Tools" goto NOVMWARE
echo.
echo *** SHRINKING DRIVES ***
cd "C:\Program Files\VMware\VMware Tools\"
VMwareToolboxCmd.exe disk shrink c:\

if not exist D: goto NODDRIVESHRINK
VMwareToolboxCmd.exe disk shrink D:\
:NODDRIVESHRINK
:NOVMWARE


echo *** SHUTTING DOWN ***
shutdown -s -t 30

:EOF
echo Terminating script
pause

Save this content in a .bat file and… enjoy it!

Manage PDF files

Merge multiple files into single PDF

I’m sure that we all had the need to send a single PDF file, maybe a signed contract. Yes, those 20 or more pages that you need to return, probably with just two of them filled up and signed.

Some PDF give you the ability to digitally sign them. But in my experience, most of them aren’t so modern.

So, what do I do?

I print ONLY the pages that I need to sign, scan them and here I am, with the need to “rebuild” the PDF, replacing the pages signed.

Example.
You have the file contract.pdf, with 20 pages and you need to sign page 10 and page 20.
The scan has a different resolution (or, even worse, it’s a different format, like jpg).

Here the command to make the magic happen:

convert contract.pdf[0-8] mypage10.jpg contract.pdf[10-18] mypage20.jpg -resize 1240x1753 -extent 1240x1753 -gravity center -units PixelsPerInch -density 150x150 contract_signed.pdf

The bit before -resize is pretty self explanatory. The bit after is a way to have the size of all pages fitting an A4 format, with a good printable resolution.

Of course, to make this happen, you need Linux (or WSL on Windows 10) and imagemagick installed.

Another way is using ghostscript.

A simple Ghostscript command to merge two PDFs in a single file is shown below:

gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=combine.pdf -dBATCH 1.pdf 2.pdf

What about a quick onliner to reduce and convert to grayscale your pdf?

ghostscript -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -sProcessColorModel=DeviceGray -sColorConversionStrategy=Gray -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

PDF size reduce

Sometimes instead, you need to reduce the size of an existing PDF. Here a handy oneliner, using ghostscript:

ghostscript -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

Other options for PDFSETTINGS:

  • /screen selects low-resolution output similar to the Acrobat Distiller “Screen Optimized” setting.
  • /ebook selects medium-resolution output similar to the Acrobat Distiller “eBook” setting.
  • /printer selects output similar to the Acrobat Distiller “Print Optimized” setting.
  • /prepress selects output similar to Acrobat Distiller “Prepress Optimized” setting.
  • /default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.

Happy PDF’ing 🙂

Sources:
https://stackoverflow.com/questions/23214617/imagemagick-convert-image-to-pdf-with-a4-page-size-and-image-fit-to-page
https://www.shellhacks.com/merge-pdf-files-linux-command-line/
https://gist.github.com/firstdoit/6390547

Migrate Linux Subsystem from one PC to another

Are you enjoying your favorite Linux distro running within the Windows 10 Linux Subsystem?

Have you configured all nicely?

What happened if you get a new pc and you’d like to migrate your VM across?

This is what happened to me. And looking around, I found this post that gave me this kinda-dirty way, but did work!

After that, I decided to review the steps, and I’ve added these directories in the exclude’s list, to make clearer the process of export/import:

/dev
/proc
/sys
/run
/tmp
/media
/mnt
/var/cache
/var/run

Of course, if you have important data in these folders and you want to move across too, just update the one-liner below accordingly. 😉

On your OLD PC

  • Open your Linux VM
  • Get inside your Downloads directory (replace <user> with your username):

    cd /mnt/c/Users/<user>/Downloads
  • Make sure to be root (sudo su -)
  • Run:

    tar -cvpzf backup.tar.gz --exclude=/backup.tar.gz --exclude=/dev --exclude=/proc --exclude=/sys --exclude=/run --exclude=/tmp --exclude=/media --exclude=/mnt --exclude=/var/cache --exclude=/var/run --one-file-system /

    NOTE: you could achieve the same using the option --exclude-from=file.txt, and having the list of exclusions in this file. I used a one-liner as it’s quicker to copy and paste.
  • Once done, close your Linux VM
  • Verify that you have a new file called backup.tar.bz in Downloads

On your NEW PC

  • Install from Microsoft Store the same Linux VM (or reinstall in the same way you have done originally on your old pc)
  • Copy across your backup.tar.bz within your new Downloads folder
  • Open the VM that you’ve just installed (minimal setup – this will be completely overwritten, so don’t be bothered too much)
  • Once you’re inside and your backup.tar.bz is in Download, run the following (replace <user> with your username):

    sudo tar -xpzf /mnt/c/Users/<user>/Downloads/backup.tar.gz -C / --numeric-owner
  • Ignore the errors
  • Close and re-open the VM: DONE! 🙂

Happy migration! 😉