====== Missing key ======
error message:
<code bash>
  Sub-process /usr/bin/sqv returned an error code (1), error message is: Missing key 827C8569F2518CC677FECA1AED65462EC8D5E4C5, which is needed to verify signature.
</code>
Some genius changed the key...
<code bash>sudo curl -fsSL https://archive.kali.org/archive-key.asc | gpg --dearmor -o /etc/apt/trusted.gpg.d/kali.gpg</code>

====== Fsck at boot ======
Once the node didn't start and was complaining /dev/sda1 had errors.
__**At boot**__:
press "e" to edit Grub's line starting with linux and remove quiet splash to put single fsck.... like:
<code perl>
linux /boot/vmlinuz-<version> root=UUID=<your-uuid> ro single fsck.mode=force fsck.repair=yes

</code>

And voilà !

====== Power Management ethX ======
Ethernet card switches off after a long period of inactivity?
<code bash>ethtool -s <interface_name> wol d</code>
Make it permanent:
<code bash> vi /etc/udev/rules.d/70-disable-ethernet-power-management.rules</code>
<code perl>
ACTION=="add", SUBSYSTEM=="net", KERNEL=="eth*", RUN+="/usr/sbin/ethtool -s %k wol d"
ACTION=="add", SUBSYSTEM=="net", KERNEL=="enp*", RUN+="/usr/sbin/ethtool -s %k wol d"</code>
<code bash>udevadm control --reload-rules</code>