So, you have a Linux system and want to show its hawtness to random stranges, but without having them mess with the system permanently? And use that account for those airport checks automatically? Well, it’s easy.

  1. Disable remote login for the guest account: 
    echo DenyUsers guest >> /etc/ssh/sshd_config
service sshd condrestart
  2. Create the guest account: 
    adduser guest
  3. Make the guest account home directory a filesystem in RAM: 
    echo "guest /home/guest tmpfs size=20%,
  mode=0700,uid=$(id -u guest),gid=$(id -g guest) 0 0" >> /etc/fstab
  4. And finally configure the system to automatically login as guest: 
    echo '
[daemon]
TimedLoginEnable=true
TimedLogin=guest
TimedLoginDelay=15
' >> /etc/gdm/custom.conf

That’s it. On your next reboot, and if you do nothing, you’ll be logged in as guest. If you don’t like that the terminal for the guest user doesn’t include a pretty prompt, you may change the fstab entry, mounting the tmpfs somewhere else, like /home/.guest, and then have a funionfs mount for ~ with /etc/skel on top.

On boot, just make sure to cancel the automatic login, if you want to log in as another user.