Create Wildcard Mask

wildcard.py

# Simple function to create a wildcard mask from a subnet mask 

def wildcard_mask(netmask): 
    # Ensure netmask provided is a basic string (ie not an IPv4Address)
    netmask = str(netmask)
    # Break into a list of octets as integers 
    netmask_list = map(int, netmask.split("."))
    # Use XOR to "invert" each octect
    wildcard_list = [ 255^octet for octet in netmask_list ]
    # Join wildcard octets into a single wildcard mask string 
    wildcard_mask = ".".join(map(str,wildcard_list))
    return wildcard_mask

# Alternative using IPv4Address math (thanks to simingy) 
def wildcard_mask2(netmask): 
    host_mask = ipaddress.IPv4Address("255.255.255.255")
    my_subnet = ipaddress.IPv4Address(netmask)

    wildcard_mask = host_mask - int(my_subnet)
    return wildcard_mask
    
# Sample usage 
wildcard_mask("255.255.255.0")
wildcard_mask("255.255.255.248")

import ipaddress 
mynetwork = ipaddress.ip_network("192.168.23.0/27")
wildcard_mask(mynetwork.netmask) 


# And continuing to make it even easier... @plajjan mentioned this gem 
wildcard_mask = ipaddress.ip_network("10.1.0.0/22").hostmask