Decompose a range of IP addresses

[ikaro]

Hi,

I got a file with a load of ip ranges ( 123.123.123.13-145.155.155.155)

Now i want to decompose/convert that file with the huge list into a new file, where the addresses are in network/host format.

example:
file1: 199.232.0.0-199.232.255.255

new file: 199.232.0.0/16

off course, some solution must be able to read "file1" and convert all the ipranges into the new format and create file2.

ive been looking everywhere and couldnt find any tool do make this



Thanks.

[petrjanda]

Hmm, the number behind the slash is not a host portition of an IP address, it's the number of bits borrowed (i think? my memory is not good lately). What exactly do you mean by network/host format?

[rewt]

The number indicates where the network identifying part of the IP address stops and the host identifying part begins which is what he means. It's just a shorthand form of the netmask indicating how many 1's are in it in the binary form which I think is what you mean by bits borrowed?

As to a program to do this... no idea, sorry

[petrjanda]

The number indicates where the network identifying part of the IP address stops and the host identifying part begins which is what he means. It's just a shorthand form of the netmask indicating how many 1's are in it in the binary form which I think is what you mean by bits borrowed?

As to a program to do this... no idea, sorry

sounds like it.
For example, i have /18, therefore its a class B network with 2 bits borrowed from the host portition? right? Therefore the subnet mask would be 255.255.192.0?

[ecatmur]

Looks like a job for python - although you could cheat and do it in sed.
How regular are the address ranges? Could you post a few lines of the file?

[DaveArb]

where the addresses are in network/host format.

Those are more commonly called CIDR addresses or ranges, that might help you in finding resources.

Sendmail comes with a user-contributed PERL program called `cidrexpand` that takes CIDR addresses and expands them to Sendmail access-acceptable entries. That program might help you with a headstart in writing one, if you do PERL.

From experience, the real PITA is if the input IP ranges are not normalized, ie. if they don't map one for one into a single CIDR.

Dave

[ikaro]

Looks like a job for python - although you could cheat and do it in sed.
How regular are the address ranges? Could you post a few lines of the file?

sure

Code: Select all

199.232.0.0-199.232.255.255
194.76.38.0-194.76.39.255
195.37.190.41-195.37.190.41
80.146.186.80-80.146.186.87
195.243.81.0-195.243.81.7
217.19.187.0-217.19.187.15
217.19.187.64-217.19.187.95
217.19.187.96-217.19.187.103
81.209.246.15-81.209.246.15
62.67.62.15-62.67.62.15
193.7.0.0-193.7.127.255
62.154.151.32-62.154.151.47
212.185.124.72-212.185.124.79
62.156.153.103-62.156.153.104
62.134.136.10-62.134.136.10
62.154.204.168-62.154.204.175
195.145.34.96-195.145.34.111
212.111.240.0-212.111.240.127
...

[ecatmur]

OK, this is possibly the most obvious solution:

Code: Select all

#!/usr/bin/python
import sys

def log2(x, n=0):
	if x==0: return n
	return log2(x>>1, n+1)

def range_to_cidr(range):
	try:
		lower, upper = map(lambda x: x.split('.'), range.split('-'))
		bits = 32 - sum(map(lambda l, u: log2(int(l)^int(u)), lower, upper))
		return "%s/%d" % (".".join(lower), bits)
	except ValueError, TypeError:
		return ""

print "\n".join([range_to_cidr(x.split()[0]) for x in sys.stdin.readlines()])

[ecatmur]

Another, more functional solution, showing off some advanced python features:

Code: Select all

#!/usr/bin/python
from sys import stdin
from math import frexp
from operator import xor, getitem
from string import split

def compose(*funs):
	if len(funs)==0: return lambda x: x
	elif len(funs)==1: return funs[0]
	else: return lambda *args: funs[0](compose(*funs[1:])(*args))
partial  = lambda fun, *l_args: lambda *r_args: fun(*(l_args+r_args))
rpartial = lambda fun, *r_args: lambda *l_args: fun(*(l_args+r_args))

log2 = compose(rpartial(getitem, 1), frexp)
ip4_to_quad = compose(partial(map, int), rpartial(split, '.'))

def range_to_cidr(lower_ip, upper_ip):
	try:
		lower, upper = map(ip4_to_quad, (lower_ip, upper_ip))
		bits = 32 - sum(map(compose(log2, xor), lower, upper))
		return "%s/%d" % (lower_ip, bits)
	except ValueError, TypeError:
		return ""

def range_list_to_cidr_list(list):
	for range in list:
		yield range_to_cidr(*range.split()[0].split('-'))

for x in range_list_to_cidr_list(stdin.readlines()):
	print x

[ikaro]

erm .. I appreciate the effort, but how does it works ?
im trying to run ./file.py file-with-the-ranges and nothing happens ....

[ecatmur]

It operates on stdin, so run it with:
cat file-with-the-ranges | ./file.py

[ikaro]

HI.

I think its almost there, but not quite.

for example 194.76.38.0-194.76.39.255 is 194.76.38.0/23
but your script says 194.76.38.0/9

Thanks until now

[ecatmur]

Oh yeah, I forgot to subtract from 32. It's fixed now above.

[ikaro]

Thank you _very much_
I hope it was good to solve this problem.

[ecatmur]

It was actually, I got to learn some new Python features that are on the way soon.
Try and read the first program, see if you can work out how it works. Python tends to be very easy to read.