I have an external hard drive connected to my airport extreme. I am able to access the drive without any problems. However, I have user accounts set up for my two young children. I want to give access to the shared drive as read only for their accounts. I would like this read only setting to be automatic when these accounts log in.
To get the drive mounted at login, drag the mounted volume to the Login Items in System Preferences → Users & Groups for the user that you want the volume auto mounting.
To set the permissions, Get Info (⌘I) on the drive and set the permissions in the Sharing & Permissions section.