#!/usr/local/bin/python

# This uses Googles ipaddr.py from http://code.google.com/p/ipaddr-py/

import ipaddr

def cidr2tcprules(cidr):

    y = ipaddr.IPv4Network(cidr)

    start = str(y.network).split('.')

    end = str(y.broadcast).split('.')

    for i in range(4):
        if start[i] != end[i]:
            break

    if start[i] == '0' and end[i] == '255':
        lastbit = ""
    else:
        lastbit = "%s-%s." % ( start[i], end[i] )

    firstbit = ".".join(start[:i])

    return "%s.%s" % ( firstbit, lastbit )


if __name__ == '__main__':

    print cidr2tcprules('192.168.0.0/17')