How can I convert a ipv4 subnet mask to cidr notation using netaddr
library?
Example: 255.255.255.0 to /24
Using netaddr
:
>>> from netaddr import IPAddress
>>> IPAddress('255.255.255.0').netmask_bits()
24
Using ipaddress
from stdlib:
>>> from ipaddress import IPv4Network
>>> IPv4Network('0.0.0.0/255.255.255.0').prefixlen
24
You can also do it without using any libraries: just count 1-bits in the binary representation of the netmask:
>>> netmask = '255.255.255.0'
>>> sum(bin(int(x)).count('1') for x in netmask.split('.'))
24