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@nboubakr
Created December 20, 2012 11:23
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A simple python script converts a Classless Inter-Domain Routing (CIDR)-formatted IP address into an IP range and netmask.
#!/usr/bin/env python
# python subnet.py 200.100.33.65/26
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))
# Print information, mapping integer lists to strings for easy printing
print "Address: " , addrString
print "Netmask: " , ".".join(map(str, mask))
print "Network: " , ".".join(map(str, net))
print "Broadcast: " , ".".join(map(str, broad))
@nitishprajapati5
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(addrString,cidrString) = sys.argv[1].split('/')
IndexError: list index out of range

@DevBaka
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DevBaka commented Jun 17, 2019

Thanks for that, it have rescue much time for me! :)
But i use Python3 and no Python2 atm, because i have some little errors.
I have just only addet a / to the calculations and addet the new () syntax for the prints.
old:
mask[i/8] = mask[i/8] + (1 << (7 - i % 8))
print "Address: " , addrString
new:
mask[i//8] = mask[i//8] + (1 << (7 - i % 8))
print("Address: " , addrString)

For Python3 users:
`
import sys

(addrString, cidrString) = sys.argv[1].split('/')

addr = addrString.split('.')
cidr = int(cidrString)

mask = [0, 0, 0, 0]
for i in range(cidr):
mask[i//8] = mask[i//8] + (1 << (7 - i % 8))

net = []
for i in range(4):
net.append(int(addr[i]) & mask[i])

broad = list(net)
brange = 32 - cidr
for i in range(brange):
broad[3 - i//8] = broad[3 - i//8] + (1 << (i % 8))

print("Address: " , addrString)
print("Netmask: " , ".".join(map(str, mask)))
print("Network: " , ".".join(map(str, net)))
print("Broadcast: " , ".".join(map(str, broad)))`

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