a script to convert a cidr/ip network list to a list of ip addresses

cidr2iplist.py

#!/usr/bin/python3
# writte by David "marvin" Nölte - 2022 
# this script reads a file with a list of ip subnets/cirds and outputs it to a ip list
# input file can be a list of subnets/one per line
# check "./cidr2list.py -h"

import os
import ipaddress
import argparse

def main(i,o):
    # define variables
    iplist = []
    networklist = []

    # read input file and assign to list
    with open(i) as file:
        networklist = [line.rstrip() for line in file]

    print("Found Networks: " + str(len(networklist)))


    # convert every network to ip list and append to iplist
    for net in networklist:
        for ip in ipaddress.IPv4Network(net):
          iplist.append(str(ip))

    print("List contains IP Addresses: " + str(len(iplist)))

    # write list to file, delete is file exists
    if os.path.exists(o):
      os.remove(o)

    textfile = open(o, "w")
    for e in iplist:
        textfile.write(e + "\n")
    textfile.close()

    print("IP List has been written to file: " + o)

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Optional app description')
    parser.add_argument('infile', type=str, help='Input file required')
    parser.add_argument('outfile', type=str, help='Output file required')
    args = parser.parse_args()

    if args.infile and args.outfile:
        main(args.infile, args.outfile)