Python function to determine if a string is like an IPv4 address. Its lame but works; to be improved at a later date.

is_ipv4.py

def is_ipv4(ip):
	match = re.match("^(\d{0,3})\.(\d{0,3})\.(\d{0,3})\.(\d{0,3})$", ip)
	if not match:
		return False
	quad = []
	for number in match.groups():
		quad.append(int(number))
	if quad[0] < 1:
		return False
	for number in quad:
		if number > 255 or number < 0:
			return False
	return True

Hagen - https://pypi.python.org/pypi/netaddr. There are a couple more useful similar libs but this is the one I've used.

bad = "hagen"
good = "10.0.0.1"
netaddr.ip.IPAddress(bad)
Traceback (most recent call last):
File "", line 1, in
File "/Library/Python/2.7/site-packages/netaddr-0.7.10-py2.7.egg/netaddr/ip/init.py", line 315, in init
'address from %r' % addr)
AddrFormatError: failed to detect a valid IP address from 'hagen'
netaddr.ip.IPAddress(good)
IPAddress('10.0.0.1')

Note that this will throw an exception if you pass a string such as '192.168..' because the regex allows 0-3 but the 0-255 test doesn't take into account empty quads. Simple workaround is to just change the regex to {1,3}.

Also note that this returns true for zero-padded octets such as 192.168.01.1, which may not be what you expect. You could insert something crude such as:

if len(number) > 1 and number[0] == '0':
return False

...in the first for loop.

Hi Ben,
this is my version of the function: https://gist.github.com/Pr1meSuspec7/d6154c4f9b01d2ea80cd5fd51ddfb8eb
I hope it can help you

Bye