After you clone a virtual machine, it will still contain some garbage from the previous installation that we want to clean up.
To do so, I usually run the following commands. These are not only debian-specific, although some modifications might be necessary for other distributions.
These are created to uiniquely associate device names, by serial number or so, and are responsible for things like your first vm network card being named eth1 etc. So, just remove them:
Usually, only the history for root will be “dirty” (although you can avoid writing it in the template by setting HISTFILE= in the terminal you use for administration tasks).
To clean up the bash history for all the users in the system, you can use this:
cat /etc/passwd | cut -d: -f6 | sed 's@$@/.bash_history@' | xargs -d '\n' rm -fv
To rebuild the SSH keys of this machine, in order to avoid having the same key used amongst many machines:
rm -fv /etc/ssh/ssh_host_* dpkg-reconfigure openssh-server