A better way would be to share a folder to their Dropbox email account, so you only expose to them what you want.
# link up/down
ip link set dev eth0 up|down
# add a new address
ip addr add dev eth0 172.16.43.124/24
# to clear all IP addresses from eth0
ip addr flush dev eth0
# delete an address
ip addr del dev eth0 172.16.43.124/24
# add default route
ip route add default via 172.16.43.254
Edit: I fail at formatting