cidr to ip range

range_of.py

#!/usr/bin/env python
# range_of.py 10.0.0.0/8

import sys

# Get address string and CIDR string from command line
(addrString, cidrString) = sys.argv[1].split('/')

# Split address into octets and turn CIDR into int
addr = addrString.split('.')
cidr = int(cidrString)

# Initialize the netmask and calculate based on CIDR mask
mask = [0, 0, 0, 0]
for i in range(cidr):
    mask[i/8] = mask[i/8] + (1 << (7 - i % 8))

# Initialize net and binary and netmask with addr to get network
net = []
for i in range(4):
    net.append(int(addr[i]) & mask[i])

# Duplicate net into broad array, gather host bits, and generate broadcast
broad = list(net)
brange = 32 - cidr
for i in range(brange):
    broad[3 - i/8] = broad[3 - i/8] + (1 << (i % 8))


net_mask = ".".join(map(str, mask))
from_ip = ".".join(map(str, net))
to_ip = ".".join(map(str, broad))

# Print information, mapping integer lists to strings for easy printing
print "Range:   " , "%s - %s" % (from_ip, to_ip)
print "Netmask: " ,  net_mask