How do I determine all of my IP addresses when I have multiple NICs?

You should directly obtain all IP configured IP addresses, e.g. by running ifconfig and parsing its output (it’s also possible to do what ifconfig does directly in Python, see how it is done in C). If you want host names, use gethostbyaddr.

It’s linux only, but there’s a very simple recipe here http://code.activestate.com/recipes/439094/

It probably uses similar code to the netifaces package mentioned in another answer (but current version linked here)

The socket.getaddrinfo() doesn’t actually return the bound ip address for the device. If your hosts file contains a line with “127.0.1.1 yourhost.example.com yourhost”, which is a common configuration, getaddrinfo is only going to return 127.0.1.1.

Here is a routine for finding all IPv4 and IPv6 interfaces. As a previous poster pointed out, socket.gethostbyname_ex() does not work for IPv6, and the Python documentation recommends one use socket.getaddressinfo() instead.

This routine adds the callback IPv4 interface (127.0.0.1), and if there are any IPv6 interfaces then it also adds the callback IPv6 interface (::1). On my machine, socket.getaddrinfo() will give me one or both of these but only if I have no other interfaces available.

For my needs, I wanted to try to open a UDP socket on a specified port on each of my available interfaces, which is why the code has “port” and socket.SOCK_DGRAM in it. It is safe to change those, e.g. if you don’t have a port in mind.

addrinfo_ipv4 = socket.getaddrinfo(hostname,port,socket.AF_INET,socket.SOCK_DGRAM)
addrinfo_ipv6 = []
try:
    addrinfo_ipv6 = socket.getaddrinfo(hostname,port,socket.AF_INET6,socket.SOCK_DGRAM)
except socket.gaierror:
    pass
addrinfo = [(f,t,a) for f,t,p,cn,a in addrinfo_ipv4+addrinfo_ipv6]
addrinfo_local = [(socket.AF_INET,socket.SOCK_DGRAM,('127.0.0.1',port))]
if addrinfo_ipv6: 
    addrinfo_local.append( (socket.AF_INET6,socket.SOCK_DGRAM,('::1',port)) )
[addrinfo.append(ai) for ai in addrinfo_local if ai not in addrinfo]

import socket
[i[4][0] for i in socket.getaddrinfo(socket.gethostname(), None)]

https://docs.python.org/3.4/library/socket.html#socket.if_nameindex

socket.if_nameindex()

Return a list of network interface information (index int, name string) tuples. OSError if the system call fails.

Availability: Unix.

New in version 3.3.

made this code that is runable on Python 3.4, UNIX / Linux

#!/env/python3.4
import socket
import fcntl
import struct

def active_nic_addresses():
    """
    Return a list of IPv4 addresses that are active on the computer.
    """

    addresses = [ip for ip in socket.gethostbyname_ex(socket.gethostname())[2] if not ip.startswith("127.")][:1]

    return addresses

def get_ip_address( NICname ):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    return socket.inet_ntoa(fcntl.ioctl(
        s.fileno(),
        0x8915,  # SIOCGIFADDR
        struct.pack('256s', NICname[:15].encode("UTF-8"))
    )[20:24])


def nic_info():
    """
    Return a list with tuples containing NIC and IPv4
    """
    nic = []

    for ix in socket.if_nameindex():
        name = ix[1]
        ip = get_ip_address( name )

        nic.append( (name, ip) )

    return nic

if __name__ == "__main__":

    print( active_nic_addresses() )
    print( nic_info() )

Will print something like:

['192.168.0.2']
[('lo', '127.0.0.1'), ('enp3s0', '192.168.0.2')]

All addresses in one line with the help of the netifaces module:

[netifaces.ifaddresses(iface)[netifaces.AF_INET][0]['addr'] for iface in netifaces.interfaces() if netifaces.AF_INET in netifaces.ifaddresses(iface)]

You can do it fairly easily like this:

import netifaces

for interface in netifaces.interfaces():
    print netifaces.ifaddresses(interface)

For more information you can look up the netifaces documentation.

This snippet will give a list of all available IPV4 addresses in the system.

import itertools
from netifaces import interfaces, ifaddresses, AF_INET

links = filter(None, (ifaddresses(x).get(AF_INET) for x in interfaces()))
links = itertools.chain(*links)
ip_addresses = [x['addr'] for x in links]

Just for completeness, another option would be to use psutil.

tldr;

import socket
import psutil

def get_ip_addresses(family):
    for interface, snics in psutil.net_if_addrs().items():
        for snic in snics:
            if snic.family == family:
                yield (interface, snic.address)

ipv4s = list(get_ip_addresses(socket.AF_INET))
ipv6s = list(get_ip_addresses(socket.AF_INET6))

Explanation

The function you need is net_if_addrs. I.e.:

import psutil
psutil.net_if_addrs()

Which results in something like this (Python 3):

{'br-ae4880aa80cf': [snic(family=<AddressFamily.AF_INET: 2>, address='172.18.0.1', netmask='255.255.0.0', broadcast='172.18.0.1', ptp=None),
                     snic(family=<AddressFamily.AF_PACKET: 17>, address='02:42:e5:ae:39:94', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)],
 'docker0': [snic(family=<AddressFamily.AF_INET: 2>, address='172.17.0.1', netmask='255.255.0.0', broadcast='172.17.0.1', ptp=None),
             snic(family=<AddressFamily.AF_PACKET: 17>, address='02:42:38:d2:4d:77', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)],
 'eno1': [snic(family=<AddressFamily.AF_PACKET: 17>, address='54:be:f7:0b:cf:a9', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)],
 'lo': [snic(family=<AddressFamily.AF_INET: 2>, address='127.0.0.1', netmask='255.0.0.0', broadcast=None, ptp=None),
        snic(family=<AddressFamily.AF_PACKET: 17>, address='00:00:00:00:00:00', netmask=None, broadcast=None, ptp=None)],
 'wlp2s0': [snic(family=<AddressFamily.AF_INET: 2>, address='192.168.1.4', netmask='255.255.255.0', broadcast='192.168.1.255', ptp=None),
            snic(family=<AddressFamily.AF_PACKET: 17>, address='00:21:27:ee:d6:03', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)]}

(Python 2):

{'br-ae4880aa80cf': [snic(family=2, address='172.18.0.1', netmask='255.255.0.0', broadcast='172.18.0.1', ptp=None),
                     snic(family=17, address='02:42:e5:ae:39:94', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)],
 'docker0': [snic(family=2, address='172.17.0.1', netmask='255.255.0.0', broadcast='172.17.0.1', ptp=None),
             snic(family=17, address='02:42:38:d2:4d:77', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)],
 'eno1': [snic(family=17, address='54:be:f7:0b:cf:a9', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)],
 'lo': [snic(family=2, address='127.0.0.1', netmask='255.0.0.0', broadcast=None, ptp=None),
        snic(family=17, address='00:00:00:00:00:00', netmask=None, broadcast=None, ptp=None)],
 'wlp2s0': [snic(family=2, address='192.168.1.4', netmask='255.255.255.0', broadcast='192.168.1.255', ptp=None),
            snic(family=17, address='00:21:27:ee:d6:03', netmask=None, broadcast='ff:ff:ff:ff:ff:ff', ptp=None)]}

Note: Since you can have more than one address of the same family associated with each interface, the dict values are lists.

Each snic is a namedtuple which includes 5 fields:

• family: the address family, either AF_INET, AF_INET6 or psutil.AF_LINK, which refers to a MAC address.
• address: the primary NIC address (always set).
• netmask: the netmask address (may be None).
• broadcast: the broadcast address (may be None).
• ptp: stands for “point to point”; it’s the destination address on a point to point interface (typically a VPN). broadcast and ptp are mutually exclusive (may be None).

I think @Harley Holcombe’s answer is workable, but if you have some virtual NICs without ip it will error. so this is i modified:

def get_lan_ip():
for interface in interfaces():
    try:
        for link in ifaddresses(interface)[AF_INET]:
            if str(link['addr']).startswith("172."):
                return str(link['addr'])
    except:
        pass

this will only return your lan ipv4

As this thread indicates, there is a lot of ways to acchive the same result, my suggested way is to leverage the build-in family filter in getaddrinfo() and parse the standardised tuple like so:

from socket import getaddrinfo, AF_INET, gethostname

for ip in getaddrinfo(host=gethostname(), port=None, family=AF_INET):   
    print(ip[4][0])

Example output:

192.168.55.1
192.168.170.234

thanks to @The Demz’s answer.
for my config, ubuntu 14.04(kernel 4.0.0), python3.4,
it needs try-catch to skip some nic because it will got
OSError on nic ‘sit0’
here’s the modification:

def nic_info():
    """
    Return a list with tuples containing NIC and IPv4
    """
    nic = []
    for ix in socket.if_nameindex():
        name = ix[1]
        try:
            ip = get_ip_address( name )
            nic.append( (name, ip) )
        except OSError as e:
            pass
        except Exception as e:
            raise e
    return nic

Here is example of get all ipv4 and ipv6 address.

import socket
from socket import AddressFamily


def get_ips():
    ipv4 = list()
    ipv6 = list()
    for item in socket.getaddrinfo(socket.gethostname(), None):
        protocol, *_, (ip, *_) = item
        if protocol == AddressFamily.AF_INET:
            ipv4.append(ip)
        elif protocol == AddressFamily.AF_INET6:
            ipv6.append(ip)

    return ipv4, ipv6


if __name__ == '__main__':
    all_ipv4, all_ipv6 = get_ips()
    print(all_ipv4)
    print(all_ipv6)