Regex: How to match IP address in RFC1918 private IPV4 address ranges (in Python)?

Question

RFC1918 defines private IPv4 addresses as those that fall within any of the following ranges:

10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 -         


        

Answer 1

In Python 3.3+ (you did not specify a version, nor why regular expressions are a requirement, so I’ll put this here for completeness), you can:

import ipaddress

addr_string = # string with your IP address
try:
    addr = ipaddress.IPv4Address(addr_string)
except ValueError:
    raise # not an IP address
if addr.is_private:
    pass # is a private address

See also: ipaddress module documentation