To know Allocation of Total Lan ips AngryIpScanner is the best tool
apt-get install gdebi
wget http://github.com/angryziber/ipscan/releases/download/3.3.3/ipscan_3.3.3_amd64.deb
gdebi ipscan_3.3.3_amd64.deb
you can open with GUI and with terminal after Installtion
In Terminal Enter below command
ipscan
OR
you can try with below process
sudo add-apt-repository ppa:upubuntu-com/network
sudo apt-get update
sudo apt-get install ipscan
ipscan$ sudo apt-get remove ipscan