How can I check if an ip is in a network in Python?

Using ipaddress (in the stdlib since 3.3, at PyPi for 2.6/2.7):

>>> import ipaddress>>> ipaddress.ip_address('192.168.0.1') in ipaddress.ip_network('192.168.0.0/24')True

If you want to evaluate a lot of IP addresses this way, you'll probably want to calculate the netmask upfront, like

n = ipaddress.ip_network('192.0.0.0/16')netw = int(n.network_address)mask = int(n.netmask)

Then, for each address, calculate the binary representation with one of

a = int(ipaddress.ip_address('192.0.43.10'))a = struct.unpack('!I', socket.inet_pton(socket.AF_INET, '192.0.43.10'))[0]a = struct.unpack('!I', socket.inet_aton('192.0.43.10'))[0]  # IPv4 only

Finally, you can simply check:

in_network = (a & mask) == netw

I like to use netaddr for that:

from netaddr import CIDR, IPif IP("192.168.0.1") in CIDR("192.168.0.0/24"):    print "Yay!"

As arno_v pointed out in the comments, new version of netaddr does it like this:

from netaddr import IPNetwork, IPAddressif IPAddress("192.168.0.1") in IPNetwork("192.168.0.0/24"):    print "Yay!"

For python3

import ipaddressipaddress.IPv4Address('192.168.1.1') in ipaddress.IPv4Network('192.168.0.0/24')ipaddress.IPv4Address('192.168.1.1') in ipaddress.IPv4Network('192.168.0.0/16')

Output :

FalseTrue