wget http://mirrors.sohu.com/ubuntu/pool/universe/n/netmask/netmask_2.3.12.tar.gz
tar xf netmask_2.3.12.tar.gz
cd netmask-2.3.12
./configure
make && make install
# netmask -s 192.168.1.1:192.168.1.255 192.168.1.0 1.1.1.0 1.1.1.1 1.1.1.2:1.1.1.3 1.1.1.4:1.1.1.7
1.1.1.0/255.255.255.248
192.168.1.0/255.255.255.0
# netmask -s 192.168.1.1:192.168.1.255
192.168.1.1/255.255.255.255
192.168.1.2/255.255.255.254
192.168.1.4/255.255.255.252
192.168.1.8/255.255.255.248
192.168.1.16/255.255.255.240
192.168.1.32/255.255.255.224
192.168.1.64/255.255.255.192
192.168.1.128/255.255.255.128