Check if two CIDR addresses intersect?

Question

Given two CIDR addresses say 192.168.2.0/14 and 192.168.2.0/32

How do I check if two ip addresses overlap in "python2.6"??

I have gone through netaddr and it allows to check if 192.168.2.0 is in CIDR address 192.168.2.0/14 by

from netaddr import IPNetwork, IPAddress bool = IPAddress("192.168.2.0") in IPNetwork("192.168.2.0/14"): 

But how to check for two CIDR address??

I found a reference :: How can I check if an ip is in a network in python

Answer 1

Using ipaddr:

>>> import ipaddr >>> n1 = ipaddr.IPNetwork('192.168.1.0/24') >>> n2 = ipaddr.IPNetwork('192.168.2.0/24') >>> n3 = ipaddr.IPNetwork('192.168.2.0/25') >>> n1.overlaps(n2) False >>> n1.overlaps(n3) False >>> n2.overlaps(n3) True >>> n2.overlaps(n1) False 

Answer 2

I'll assume you actually want both CIDRs to represent ranges, even though in your example, 192.168.2.0/32 represents only one address. Also note that in 192.168.2.0/14, the .2. is meaningless, because the 14-bit prefix doesn't reach the third octet.

Anyway, there are a several ways to do this. You could notice that for them to overlap, one must always be a subset of the other:

def cidrsOverlap(cidr0, cidr1):     return cidr0 in cidr1 or cidr1 in cidr0 

Or you could notice that for the ranges to overlap, the first range's lowest address must be less than or equal to the second range's highest address, and vice versa. Thus:

def cidrsOverlap(cidr0, cidr1):     return cidr0.first <= cidr1.last and cidr1.first <= cidr0.last  print cidrsOverlap(IPNetwork('192.168.2.0/24'), IPNetwork('192.168.3.0/24')) # prints False  print cidrsOverlap(IPNetwork('192.168.2.0/23'), IPNetwork('192.168.3.0/24')) # prints True