You can prepare a Day 0 configuration file before you launch the ASAv. This file is a text file that contains the ASAv configuration
applied when the ASAv is launched. This initial configuration is placed into a text file named “day0-config” in a working
directory you chose, and is manipulated into a day0.iso file that is mounted and read on first boot. At the minimum, the Day
0 configuration file must contain commands to activate the management interface and set up the SSH server for public key authentication,
but it can also contain a complete ASA configuration.
The day0.iso file (either your custom day0.iso or the default day0.iso) must be available during first boot:
To automatically license the ASAv during initial deployment, place the Smart Licensing Identity (ID) Token that you downloaded
from the Cisco Smart Software Manager in a text file named ‘idtoken’ in the same directory as the Day 0 configuration file.
If you want to access and configure the ASAv from the serial port on the hypervisor instead of the virtual VGA console, you should include the console serial setting in the Day 0 configuration
file to use the serial port on first boot.
If you want to deploy the ASAv in transparent mode, you must use a known running ASA config file in transparent mode as the
Day 0 configuration file. This does not apply to a Day 0 configuration file for a routed firewall.
We are using Linux in this example, but there are similar utilities for Windows.