Finding local IP addresses using Python's stdl

Question

How can I find local IP addresses (i.e. 192.168.x.x or 10.0.x.x) in Python platform independently and using only the standard library?

Answer 1

im using following module:

#!/usr/bin/python
# module for getting the lan ip address of the computer

import os
import socket

if os.name != "nt":
    import fcntl
    import struct
    def get_interface_ip(ifname):
        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        return socket.inet_ntoa(fcntl.ioctl(
                s.fileno(),
                0x8915,  # SIOCGIFADDR
                struct.pack('256s', bytes(ifname[:15], 'utf-8'))
                # Python 2.7: remove the second argument for the bytes call
            )[20:24])

def get_lan_ip():
    ip = socket.gethostbyname(socket.gethostname())
    if ip.startswith("127.") and os.name != "nt":
        interfaces = ["eth0","eth1","eth2","wlan0","wlan1","wifi0","ath0","ath1","ppp0"]
        for ifname in interfaces:
            try:
                ip = get_interface_ip(ifname)
                break;
            except IOError:
                pass
    return ip

Tested with windows and linux (and doesnt require additional modules for those) intended for use on systems which are in a single IPv4 based LAN.

The fixed list of interface names does not work for recent linux versions, which have adopted the systemd v197 change regarding predictable interface names as pointed out by Alexander. In such cases, you need to manually replace the list with the interface names on your system, or use another solution like netifaces.

Answer 2

A slight refinement of the commands version that uses the IP command, and returns IPv4 and IPv6 addresses:

import commands,re,socket

#A generator that returns stripped lines of output from "ip address show"
iplines=(line.strip() for line in commands.getoutput("ip address show").split('\n'))

#Turn that into a list of IPv4 and IPv6 address/mask strings
addresses1=reduce(lambda a,v:a+v,(re.findall(r"inet ([\d.]+/\d+)",line)+re.findall(r"inet6 ([\:\da-f]+/\d+)",line) for line in iplines))
#addresses1 now looks like ['127.0.0.1/8', '::1/128', '10.160.114.60/23', 'fe80::1031:3fff:fe00:6dce/64']

#Get a list of IPv4 addresses as (IPstring,subnetsize) tuples
ipv4s=[(ip,int(subnet)) for ip,subnet in (addr.split('/') for addr in addresses1 if '.' in addr)]
#ipv4s now looks like [('127.0.0.1', 8), ('10.160.114.60', 23)]

#Get IPv6 addresses
ipv6s=[(ip,int(subnet)) for ip,subnet in (addr.split('/') for addr in addresses1 if ':' in addr)]

Answer 3

On Debian (tested) and I suspect most Linux's..

import commands

RetMyIP = commands.getoutput("hostname -I")

On MS Windows (tested)

import socket

socket.gethostbyname(socket.gethostname())

Answer 4

This answer is my personal attempt to solve the problem of getting the LAN IP, since socket.gethostbyname(socket.gethostname()) also returned 127.0.0.1. This method does not require Internet just a LAN connection. Code is for Python 3.x but could easily be converted for 2.x. Using UDP Broadcast:

import select
import socket
import threading
from queue import Queue, Empty

def get_local_ip():
        def udp_listening_server():
            s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
            s.bind(('<broadcast>', 8888))
            s.setblocking(0)
            while True:
                result = select.select([s],[],[])
                msg, address = result[0][0].recvfrom(1024)
                msg = str(msg, 'UTF-8')
                if msg == 'What is my LAN IP address?':
                    break
            queue.put(address)

        queue = Queue()
        thread = threading.Thread(target=udp_listening_server)
        thread.queue = queue
        thread.start()
        s2 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        s2.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
        waiting = True
        while waiting:
            s2.sendto(bytes('What is my LAN IP address?', 'UTF-8'), ('<broadcast>', 8888))
            try:
                address = queue.get(False)
            except Empty:
                pass
            else:
                waiting = False
        return address[0]

if __name__ == '__main__':
    print(get_local_ip())

Answer 5

netifaces is available via pip and easy_install. (I know, it's not in base, but it could be worth the install.)

netifaces does have some oddities across platforms:

• The localhost/loop-back interface may not always be included (Cygwin).
• Addresses are listed per-protocol (e.g., IPv4, IPv6) and protocols are listed per-interface. On some systems (Linux) each protocol-interface pair has its own associated interface (using the interface_name:n notation) while on other systems (Windows) a single interface will have a list of addresses for each protocol. In both cases there is a protocol list, but it may contain only a single element.

Here's some netifaces code to play with:

import netifaces

PROTO = netifaces.AF_INET   # We want only IPv4, for now at least

# Get list of network interfaces
# Note: Can't filter for 'lo' here because Windows lacks it.
ifaces = netifaces.interfaces()

# Get all addresses (of all kinds) for each interface
if_addrs = [netifaces.ifaddresses(iface) for iface in ifaces]

# Filter for the desired address type
if_inet_addrs = [addr[PROTO] for addr in if_addrs if PROTO in addr]

iface_addrs = [s['addr'] for a in if_inet_addrs for s in a if 'addr' in s]
# Can filter for '127.0.0.1' here.

The above code doesn't map an address back to its interface name (useful for generating ebtables/iptables rules on the fly). So here's a version that keeps the above information with the interface name in a tuple:

import netifaces

PROTO = netifaces.AF_INET   # We want only IPv4, for now at least

# Get list of network interfaces
ifaces = netifaces.interfaces()

# Get addresses for each interface
if_addrs = [(netifaces.ifaddresses(iface), iface) for iface in ifaces]

# Filter for only IPv4 addresses
if_inet_addrs = [(tup[0][PROTO], tup[1]) for tup in if_addrs if PROTO in tup[0]]

iface_addrs = [(s['addr'], tup[1]) for tup in if_inet_addrs for s in tup[0] if 'addr' in s]

And, no, I'm not in love with list comprehensions. It's just the way my brain works these days.

The following snippet will print it all out:

from __future__ import print_function  # For 2.x folks
from pprint import pprint as pp

print('\nifaces = ', end='')
pp(ifaces)

print('\nif_addrs = ', end='')
pp(if_addrs)

print('\nif_inet_addrs = ', end='')
pp(if_inet_addrs)

print('\niface_addrs = ', end='')
pp(iface_addrs)

Enjoy!

Answer 6

import socket
socket.gethostbyname(socket.gethostname())

This won't work always (returns 127.0.0.1 on machines having the hostname in /etc/hosts as 127.0.0.1), a paliative would be what gimel shows, use socket.getfqdn() instead. Of course your machine needs a resolvable hostname.