community.aegirproject.org

Check out the module page: http://drupal.org/project/provisionacl

First, you'll need a running Aegir install (1.0-rc3 or later), see http://community.aegirproject.org/installing. Most (if not all) of these commands will have to be run as root (or using sudo, etc.)

Download and install provision:

drush dl provisionacl

Enable ACLs on your filesystem (using root "/" here):

mount -o remount,acl /

Install ACLs:

apt-get install acl

Create a UNIX group (in this case the group is called "devs"):

groupadd devs

Add one or more UNIX users that you want to give access to that group. For an existing user (socrates32), this would look like:

usermod -a -G devs socrates32

For a new user (ergonlogic), this would look like:

useradd -G devs ergonlogic

Create a client (should be called "devs" for this example) in the frontend at /node/add/client.

Create a site for the client in the frontend at /node/add/site.