I have been handed the task of creating a function in python (3.1) that will take a CIDR notation and return the list of possible ip addresses. I have looked around python.org and found this: http://docs.python.org/dev/py3k/library/ipaddr.html

but i haven't seen anything that will fill this need... I would be very grateful for any assistance anyone cares to kick my way. thanks in advance. :-)

If you aren't married to using the built-in module, there is a project called netaddr that is the best module I have used for working with IP networks.

Have a look at the IP Tutorial which illustrates how easy it is working with networks and discerning their IPs. Simple example:

>>> from netaddr import IPNetwork
>>> for ip in IPNetwork('192.0.2.0/23'):
...    print '%s' % ip
...
192.0.2.0
192.0.2.1
192.0.2.2
192.0.2.3
...
192.0.3.252
192.0.3.253
192.0.3.254
192.0.3.255

In Python 3 as simple as

>>> import ipaddress
>>> [str(ip) for ip in ipaddress.IPv4Network('192.0.2.0/28')]
['192.0.2.0', '192.0.2.1', '192.0.2.2',
'192.0.2.3', '192.0.2.4', '192.0.2.5',
'192.0.2.6', '192.0.2.7', '192.0.2.8',
'192.0.2.9', '192.0.2.10', '192.0.2.11',
'192.0.2.12', '192.0.2.13', '192.0.2.14',
'192.0.2.15']

I would prefer to do a little math rather than to install an external module, no one has the same taste with me?

#!/usr/bin/env python
# python cidr.py 192.168.1.1/24

import sys, struct, socket

(ip, cidr) = sys.argv[1].split('/')
cidr = int(cidr) 
host_bits = 32 - cidr
i = struct.unpack('>I', socket.inet_aton(ip))[0] # note the endianness
start = (i >> host_bits) << host_bits # clear the host bits
end = start | ((1 << host_bits) - 1)

# excludes the first and last address in the subnet
for i in range(start, end):
    print(socket.inet_ntoa(struct.pack('>I',i)))

Have you checked out iptools? It seems to be a fairly good fit.

It's not in the documentation, but browsing the source suggests that ipaddr implements __iter__ and iterhosts, which is exactly what you want.

Err, nevermind.

It looks like ipaddr.py was added to stdlib in 3.1 beta, but removed by 3.1 rc.
I was looking at the sources from the original ipaddr.py, which seems to have evolved separately from the copy at python.org.

You could just bundle the latter.

Below code will generate range of IPs on providing IP and subnet. Expand the CIDR notation like(255.255.255.0)

from netaddr import *

def getFirstIp(ipAddress,subnet):
  ipBin = IPNetwork(ipAddress).ip.bits().split('.')
  subBin = IPNetwork(subnet).ip.bits().split('.')
  zipped = zip(ipBin,subBin)
  netIdList = []
  for octets in zipped:
    netIdList.append(''.join(str(b) for b in (map((lambda x: int(x[0])*int(x[1])),zip(list(octets[0]),list(octets[1]))))))
  firstIp = ''
  firstIp = '.'.join(str(int(oct,2)) for oct in netIdList)
  return firstIp


def getLastIp(ipAddress,subnet):
  ipBin = IPNetwork(ipAddress).ip.bits().split('.')
  subBin = IPNetwork(subnet).ip.bits().split('.')
  #print ipBin
  #print subBin
  revsubBin = []
  for octets in subBin:
    revB = ''.join('1' if(b == '0') else '0' for b in octets)
    revsubBin.append(revB)
  zipped = zip(ipBin,revsubBin)
  netIdList = []
  for octets in zipped:
    netIdList.append(''.join(str(b) for b in (map((lambda x: 0 if(int(x[0]) == 0 and int(x[1]) == 0) else 1),zip(list(octets[0]),list(octets[1]))))))
  #print netIdList
  lastIp = ''
  lastIp = '.'.join(str(int(oct,2)) for oct in netIdList)
  return lastIp

def getRangeOfIps(firstIp,lastIp):
  start= int(IPAddress(firstIp))
  end = int(IPAddress(lastIp))
  ipList = []
  for ip in range(start,end+1):
    ipList.append(str(IPAddress(ip)))
  return ipList

def manipulateIP():
 firstIp = getFirstIp(ipAddress,subnet)
 lastIp = getLastIp(ipAddress,subnet)
 ipList = getRangeOfIps(firstIp,lastIp)  
 print ipList

Generate all Public IP Addresses given a CIDR

https://github.com/stephenlb/geo-ip will generate a list of Valid IP Public Addresses including Localities.

'1.0.0.0/8' to '191.0.0.0/8' are the valid public IP Address range exclusive of the reserved Private IP Addresses.

IP Generator

Generates a JSON dump of IP Addresses and associated Geo information. Note that the valid public IP Address range is from '1.0.0.0/8' to '191.0.0.0/8' excluding the reserved Private IP Address ranges shown lower down in this readme.

docker build -t geo-ip .
docker run -e IPRANGE='54.0.0.0/30' geo-ip               ## a few IPs
docker run -e IPRANGE='54.0.0.0/26' geo-ip               ## a few more IPs
docker run -e IPRANGE='54.0.0.0/16' geo-ip               ## a lot more IPs
docker run -e IPRANGE='0.0.0.0/0'   geo-ip               ## ALL IPs ( slooooowwwwww )
docker run -e IPRANGE='0.0.0.0/0'   geo-ip > geo-ip.json ## ALL IPs saved to JSON File
docker run geo-ip

A little faster option for scanning all valid public addresses:

for i in $(seq 1 191); do \
    docker run -e IPRANGE="$i.0.0.0/8" geo-ip; \
    sleep 1; \ 
done

This prints less than 4,228,250,625 JSON lines to STDOUT. Here is an example of one of the lines:

{"city": "Palo Alto", "ip": "0.0.0.0", "longitude": -122.1274,
 "continent": "North America", "continent_code": "NA",
 "state": "California", "country": "United States", "latitude": 37.418,
 "iso_code": "US", "state_code": "CA", "aso": "PubNub",
 "asn": "11404", "zip_code": "94107"}

Private and Reserved IP Range

The dockerfile in the repo above will exclude non-usable IP addresses following the guide from the wikipedia article: https://en.wikipedia.org/wiki/Reserved_IP_addresses