Finding local IP addresses using Python's stdlib

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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?

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不思量自难忘°

2020-11-22 00:24
FYI I can verify that the method:
```
import socket
addr = socket.gethostbyname(socket.gethostname())
```
Works in OS X (10.6,10.5), Windows XP, and on a well administered RHEL department server. It did not work on a very minimal CentOS VM that I just do some kernel hacking on. So for that instance you can just check for a 127.0.0.1 address and in that case do the following:
```
if addr == "127.0.0.1":
     import commands
     output = commands.getoutput("/sbin/ifconfig")
     addr = parseaddress(output)
```
And then parse the ip address from the output. It should be noted that ifconfig is not in a normal user's PATH by default and that is why I give the full path in the command. I hope this helps.
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独厮守ぢ

2020-11-22 00:26

You can use the netifaces module. Just type:

pip install netifaces

in your command shell and it will install itself on default Python installation.

Then you can use it like this:

from netifaces import interfaces, ifaddresses, AF_INET
for ifaceName in interfaces():
    addresses = [i['addr'] for i in ifaddresses(ifaceName).setdefault(AF_INET, [{'addr':'No IP addr'}] )]
    print '%s: %s' % (ifaceName, ', '.join(addresses))

On my computer it printed:

{45639BDC-1050-46E0-9BE9-075C30DE1FBC}: 192.168.0.100
{D43A468B-F3AE-4BF9-9391-4863A4500583}: 10.5.9.207

Author of this module claims it should work on Windows, UNIX and Mac OS X.

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猫巷女王i

2020-11-22 00:27
Socket API method

see https://stackoverflow.com/a/28950776/711085

Downsides:
- Not cross-platform.
- Requires more fallback code, tied to existence of particular addresses on the internet
- This will also not work if you're behind a NAT
- Probably creates a UDP connection, not independent of (usually ISP's) DNS availability (see other answers for ideas like using 8.8.8.8: Google's (coincidentally also DNS) server)
- Make sure you make the destination address UNREACHABLE, like a numeric IP address that is spec-guaranteed to be unused. Do NOT use some domain like fakesubdomain.google.com or somefakewebsite.com; you'll still be spamming that party (now or in the future), and spamming your own network boxes as well in the process.
Reflector method

(Do note that this does not answer the OP's question of the local IP address, e.g. 192.168...; it gives you your public IP address, which might be more desirable depending on use case.)

You can query some site like whatismyip.com (but with an API), such as:
```
from urllib.request import urlopen
import re
def getPublicIp():
    data = str(urlopen('http://checkip.dyndns.com/').read())
    # data = '<html><head><title>Current IP Check</title></head><body>Current IP Address: 65.96.168.198</body></html>\r\n'

    return re.compile(r'Address: (\d+\.\d+\.\d+\.\d+)').search(data).group(1)
```
or if using python2:
```
from urllib import urlopen
import re
def getPublicIp():
    data = str(urlopen('http://checkip.dyndns.com/').read())
    # data = '<html><head><title>Current IP Check</title></head><body>Current IP Address: 65.96.168.198</body></html>\r\n'

    return re.compile(r'Address: (\d+\.\d+\.\d+\.\d+)').search(data).group(1)
```
Advantages:
- One upside of this method is it's cross-platform
- It works from behind ugly NATs (e.g. your home router).
Disadvantages (and workarounds):
- Requires this website to be up, the format to not change (almost certainly won't), and your DNS servers to be working. One can mitigate this issue by also querying other third-party IP address reflectors in case of failure.
- Possible attack vector if you don't query multiple reflectors (to prevent a compromised reflector from telling you that your address is something it's not), or if you don't use HTTPS (to prevent a man-in-the-middle attack pretending to be the server)
edit: Though initially I thought these methods were really bad (unless you use many fallbacks, the code may be irrelevant many years from now), it does pose the question "what is the internet?". A computer may have many interfaces pointing to many different networks. For a more thorough description of the topic, google for gateways and routes. A computer may be able to access an internal network via an internal gateway, or access the world-wide web via a gateway on for example a router (usually the case). The local IP address that the OP asks about is only well-defined with respect to a single link layer, so you have to specify that ("is it the network card, or the ethernet cable, which we're talking about?"). There may be multiple non-unique answers to this question as posed. However the global IP address on the world-wide web is probably well-defined (in the absence of massive network fragmentation): probably the return path via the gateway which can access the TLDs.
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温柔的废话

2020-11-22 00:27

This is a variant of UnkwnTech's answer -- it provides a get_local_addr() function, which returns the primary LAN ip address of the host. I'm posting it because this adds a number of things: ipv6 support, error handling, ignoring localhost/linklocal addrs, and uses a TESTNET addr (rfc5737) to connect to.

# imports
import errno
import socket
import logging

# localhost prefixes
_local_networks = ("127.", "0:0:0:0:0:0:0:1")

# ignore these prefixes -- localhost, unspecified, and link-local
_ignored_networks = _local_networks + ("0.", "0:0:0:0:0:0:0:0", "169.254.", "fe80:")

def detect_family(addr):
    if "." in addr:
        assert ":" not in addr
        return socket.AF_INET
    elif ":" in addr:
        return socket.AF_INET6
    else:
        raise ValueError("invalid ipv4/6 address: %r" % addr)

def expand_addr(addr):
    """convert address into canonical expanded form --
    no leading zeroes in groups, and for ipv6: lowercase hex, no collapsed groups.
    """
    family = detect_family(addr)
    addr = socket.inet_ntop(family, socket.inet_pton(family, addr))
    if "::" in addr:
        count = 8-addr.count(":")
        addr = addr.replace("::", (":0" * count) + ":")
        if addr.startswith(":"):
            addr = "0" + addr
    return addr

def _get_local_addr(family, remote):
    try:
        s = socket.socket(family, socket.SOCK_DGRAM)
        try:
            s.connect((remote, 9))
            return s.getsockname()[0]
        finally:
            s.close()
    except socket.error:
        # log.info("trapped error connecting to %r via %r", remote, family, exc_info=True)
        return None

def get_local_addr(remote=None, ipv6=True):
    """get LAN address of host

    :param remote:
        return  LAN address that host would use to access that specific remote address.
        by default, returns address it would use to access the public internet.

    :param ipv6:
        by default, attempts to find an ipv6 address first.
        if set to False, only checks ipv4.

    :returns:
        primary LAN address for host, or ``None`` if couldn't be determined.
    """
    if remote:
        family = detect_family(remote)
        local = _get_local_addr(family, remote)
        if not local:
            return None
        if family == socket.AF_INET6:
            # expand zero groups so the startswith() test works.
            local = expand_addr(local)
        if local.startswith(_local_networks):
            # border case where remote addr belongs to host
            return local
    else:
        # NOTE: the two addresses used here are TESTNET addresses,
        #       which should never exist in the real world.
        if ipv6:
            local = _get_local_addr(socket.AF_INET6, "2001:db8::1234")
            # expand zero groups so the startswith() test works.
            if local:
                local = expand_addr(local)
        else:
            local = None
        if not local:
            local = _get_local_addr(socket.AF_INET, "192.0.2.123")
            if not local:
                return None
    if local.startswith(_ignored_networks):
        return None
    return local

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醉梦人生

2020-11-22 00:28
I use this on my ubuntu machines:
```
import commands
commands.getoutput("/sbin/ifconfig").split("\n")[1].split()[1][5:]
```
This doesn't work.
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广开言路

2020-11-22 00:29
Well you can use the command "ip route" on GNU/Linux to know your current IP address.

This shows the IP given to the interface by the DHCP server running on the router/modem. Usually "192.168.1.1/24" is the IP for local network where "24" means the range of posible IP addresses given by the DHCP server within the mask range.

Here's an example: Note that PyNotify is just an addition to get my point straight and is not required at all
```
#! /usr/bin/env python

import sys , pynotify

if sys.version_info[1] != 7:
   raise RuntimeError('Python 2.7 And Above Only')       

from subprocess import check_output # Available on Python 2.7+ | N/A 

IP = check_output(['ip', 'route'])
Split_Result = IP.split()

# print Split_Result[2] # Remove "#" to enable

pynotify.init("image")
notify = pynotify.Notification("Ip", "Server Running At:" + Split_Result[2] , "/home/User/wireless.png")    
notify.show()    
```
The advantage of this is that you don't need to specify the network interface. That's pretty useful when running a socket server

You can install PyNotify using easy_install or even Pip:
```
easy_install py-notify
```
or
```
pip install py-notify
```
or within python script/interpreter
```
from pip import main

main(['install', 'py-notify'])
```
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