First of all, check the requirements for Barracuda on the project page. You need a freshly installed server that matches one of the distributions listed (all of them are Debian or Ubuntu).

Open the terminal of the server (ssh to it if it's remote), (you might need to switch to root) and grab the script (open the Readme to make sure the link is correct):

wget -q -U iCab http://files.aegir.cc/versions/BARRACUDA.sh.txt

Then edit the IP of the server and hostname in the script (using vi or nano). You can use 127.0.0.1 or 127.0.11 for localhost. Check /etc/hosts for the hostname and corresponding IP. If you don't have public DNS setup, add the aegir frontend as a host.:

_MY_OWNIP="127.0.1.1"
_MY_HOSTN="yourhostname"
_MY_FRONT="aegir.yourhostname"

You can also change

_MY_EMAIL="youremailhere"

Try running the script now.

bash BARRACUDA.sh.txt

If you run into the "invalid DNS setup" error, you can try disabling the DNS check in the script. Note that after you run Barracuda installer for the first time, it creates a configuration file and will use the values from this files for the installation. So if you need to modify them, you can either delete this file and modify Barracuda script or edit the config file directly:

nano /root/.barracuda.cnf

Search (Ctrl+W in nano) for _DNS_SETUP_TEST and set it to NO:

_DNS_SETUP_TEST=NO

You might also need to disable _SMT_RELAY_TEST in the same manner if you're installing Barracuda on the local server.

Run the script again and wait for all the components to be installed. You'll get prompted about the MySQL passwords and optional components. Once you're done, you'll get the link to your Aegir frontend. Check the previous screencasts on how to use Aegir.

Optionally, you can try installing Octopus to create instances of Aegir on the same server with prebuilt platforms based on popular Drupal distributions.