The defaults for setting up VM's as if they were private machines used by customers of a cloud, everything isolated. This describes how to set up VM's that are more like having several desktops on a local network. They are secure, but they can also work together behind a firewall.
The VM host server can be libvirt, VMWare, etc. This could be a Jenkins (formerly Hudson) slave for builds, or just a desktop for running Ubuntu. I don't set up anything for lots of users, like LDAP or NIS. For less than 5 users, doing this with passwd files works. This works in an environment of Fedora, CentOS, Ubuntu of several versions.
adduser --uid=27 --gid=27 --home=/ --no-create-home --disabled-password --disabled-login sudo
# Doesn't quite work :(
# Uncomment to allow users in group sudo to not need password
# %sudo ALL=NOPASSWD: ALL
# Move to end of file
# Add user who need sudo to the sudo group.
The host is running a private and public Jenkins with shared workspace partitions.