Category Archives: Linux

How to copy .img files to floppy with DD

If you are into retro computing and need to copy one of the old floppy .img disks to a diskette then it can be done with dd for unix/linux or by using the windows port of dd

My son learning to code Power Basic for DOS and switching floppies 😉

In my case i had 2 computeres with a floppy drive, one was a Windows XP machine and the other was a much older DOS computer without USB or network and i need to test FreeDOS and MS DOS 6.2 but i only had files like disk1.img downloaded from the internet and blank 1.44 floppy disks.

In my first attempt i tried to use a Windows program called winimage but it was not able to run on the old Windows XP, maybe it needed a servicepack or somthing else, so the fastest way was to find a simpler and faster solution and dd came in to my rescue.

here is How to copy a disk.img to floppy with dd

Unix/Linux

dd if=disk1.img of=/dev/fd0

Windows (DOS or CMD Console)

dd if=disk1.img of=\\?\Device\Floppy0

It can be downloaded at http://www.chrysocome.net/download

OR from my server https://www.pvangsgaard.com/download/dd-windows/

How to get an SSL A+ rating with Apache

If you need a high rating with tests like https://www.ssllabs.com then i have an example on a working configuration that will get you the A+ score.

I’m using letsencrypt for my SSL site but you can use any certificate to get the result.

<VirtualHost *:80>
ServerName www.pvangsgaard.com
ServerAlias pvangsgaard.com
Redirect / https://www.pvangsgaard.com/
ErrorLog /var/log/apache2/pvangsgaard.com.error.log
CustomLog /var/log/apache2/pvangsgaard.com.access.log combined
</VirtualHost>
<VirtualHost *:443>
Header always set Strict-Transport-Security "max-age=63072000; includeSubDomains"
ServerName www.pvangsgaard.com
ServerAlias pvangsgaard.com
DocumentRoot /home/pva/public_html/pvangsgaard.com
ErrorLog /var/log/apache2/pvangsgaard.com.error.log
SSLProtocol All -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
SSLEngine on
SSLCipherSuite EECDH+AES:EDH+AES:-SHA1:EECDH+RC4:EDH+RC4:RC4-SHA:EECDH+AES256:EDH+AES256:AES256-SHA:!aNULL:!eNULL:!EXP:!LOW:!MD5
SSLHonorCipherOrder on
SSLCertificateFile    /etc/letsencrypt/live/pvangsgaard.com/cert.pem
SSLCertificateKeyFile /etc/letsencrypt/live/pvangsgaard.com/privkey.pem
SSLCertificateChainFile /etc/letsencrypt/live/pvangsgaard.com/fullchain.pem
</VirtualHost>

Remember to enable headers with:

a2enmod headers
systemctl restart apache

I have also made an example for NGINX at this url https://www.pvangsgaard.com/2018/02/22/how-to-get-an-a-rating-with-100-score-on-the-ssllabs-test-with-nginx/

Linux | How to get Windows 10 License key from BIOS

If you have installed Linux on your laptop but wan’t to have a Windows VM in virtualbox then chances are that you need a serial number for windows 10.

Normally Windows read the embedded key that are hardcodet into the BIOS of the laptop and Windows in a virtual instance will not be able to read other than the vm’s virtual BIOS so you will need to type one in yourself.

With this command you can extract the serial number:

sudo hexdump -s 56 -e '"WIN key: " /29 "%s\n"' /sys/firmware/acpi/tables/MSDM

Exim | How to hide version number

To prevent showing hackers the version number of your Exim SMTP server it can be hidden by setting this SMTP banner.

Search for smtp_banner in /etc/exim.conf and replace it with:

smtp_banner = "${primary_hostname} ESMTP"

In some setups there is no smtp_banner set then just add the line to the config file