Les dejo un listado del equivalente de las mascaras de red a bits, muy util a la hora de manejar firewalls o reglas de iptables en linux.
0.0.0.0 0 bits /0
128.0.0.0 1 bit /1
192.0.0.0 2 bits /2
224.0.0.0 3 bits /3
240.0.0.0 4 bits /4
248.0.0.0 5 bits /5
252.0.0.0 6 bits /6
254.0.0.0 7 bits /7
255.0.0.0 8 bits /8
255.128.0.0 9 bits /9
255.192.0.0 10 bits /10
255.224.0.0 11 bits /11
255.240.0.0 12 bits /12
255.248.0.0 13 bits /13
255.252.0.0 14 bits /14
255.254.0.0 15 bits /15
255.255.0.0 16 bits /16
255.255.128.0 17 bits /17
255.255.192.0 18 bits /18
255.255.224.0 19 bits /19
255.255.240.0 20 bits /20
255.255.248.0 21 bits /21
255.255.252.0 22 bits /22
255.255.254.0 23 bits /23
255.255.255.0 24 bits /24
255.255.255.128 25 bits /25
255.255.255.192 26 bits /26
255.255.255.224 27 bits /27
255.255.255.240 28 bits /28
255.255.255.248 29 bits /29
255.255.255.252 30 bits /30
255.255.255.254 31 bits /31
255.255.255.255 32 bits /32