@Tony_Rider if you have statically assigned IP addresses ( very unlikely if you're using iPads) you can just use this:
session.props.address
If you are on DHCP and the IP address is not guaranteed, you can try to resolve the host name. One way being noted here.
But even once and if you have the host names, you'd still need some physical method to ensure that certain clients were only in the areas you want them in.
Rgds,
Nick