Quick and dirty solution to translate IPv4 and IPv6 CIDR blocks into a list of IPs for further digestion.

cidr-to-ip.py

#!/usr/bin/env python3
# Translates IPv4/6 CIDR blocks into a list of IPs and writes
# them into a text file. Requires netaddr (pip install netaddr).

import netaddr

ip_list = netaddr.IPNetwork('192.168.1.0/21')

with open('ips-from-cidr.txt', 'w') as f:
    for ip in ip_list:
        f.write(str(ip) + '\n')
        #print(str(ip)) # additionally print to stdout if you like
    f.close()
    print('\nGenerated "{0:s}" with {1:d} IPs.\n'.format((f.name),
        len(ip_list)))