Python, How to get all external ip addresses with multiple NICs

Question

What is the most efficient way to get all of the external ip address of a machine with multiple nics, using python? I understand that an external server is neeeded (I have one available) but am un able to find a way to find a good way to specify the nic to use for the connection (So I can use a for loop to iterate through the various nics). Any advice about the best way to go about this?

Deberadeberry

Why would you need to specify the NIC to use? If you open a connection to another machine your OS will automagically use the correct interface. If not, you have to fix your machine setup, not your program. – Hyland

If a machine had multiple external ip address (though various nics) The OS would always use the same nic, resulting in the same ip. I'm looking to find all external ips, the only way I could think of would be to specify the nic. If there is a better way, please do tell. – Deberadeberry

On example of this could be in a hosting environment with many nics, each corresponding to a different virtual server. – Deberadeberry

Answer 1

You should use netifaces. It is designed to be cross-platform on Mac OS X, Linux, and Windows.

>>> import netifaces as ni
>>> ni.interfaces()
['lo', 'eth0', 'eth1', 'vboxnet0', 'dummy1']
>>> ni.ifaddresses('eth0')
{17: [{'broadcast': 'ff:ff:ff:ff:ff:ff', 'addr': '00:02:55:7b:b2:f6'}], 2: [{'broadcast': '24.19.161.7', 'netmask': '255.255.255.248', 'addr': '24.19.161.6'}], 10: [{'netmask': 'ffff:ffff:ffff:ffff::', 'addr': 'fe80::202:55ff:fe7b:b2f6%eth0'}]}
>>> 
>>> ni.ifaddresses.__doc__
'Obtain information about the specified network interface.\n\nReturns a dict whose keys are equal to the address family constants,\ne.g. netifaces.AF_INET, and whose values are a list of addresses in\nthat family that are attached to the network interface.'
>>> # for the IPv4 address of eth0
>>> ni.ifaddresses('eth0')[2][0]['addr']
'24.19.161.6'

The numbers used to index protocols are from /usr/include/linux/socket.h (in Linux)...

#define AF_INET         2       /* Internet IP Protocol         */
#define AF_INET6        10      /* IP version 6                 */
#define AF_PACKET       17      /* Packet family                */

Harrar

Wow Perfect! Thank you. I now can also see additional ways to rewrite my code to utilize this! Thank you! – Deberadeberry

ni.ifaddresses('eth0')[2][0]['addr'] this line will give you your local IP address, not external IP address if you are behind a router/NAT. – Kirsti

Answer 2

For the general case, there is no solution. Consider the case where the local machine is behind a machine with two IP addresses doing NAT. You can change your local interface to anything you like, but it's unlikely that you'll convince the NAT machine to make a different routing decision on its outgoing connections.

Millner

Answer 3

Required: WMI / PyWin32 (https://sourceforge.net/projects/pywin32/)

Use the following snippet to get the IP of the network card(s) on Windows.

import wmi
c = wmi.WMI()

for interface in c.Win32_NetworkAdapterConfiguration(IPEnabled=1):
    print("Description: " + interface.Description)
    print("IP: " + str(interface.IPAddress[0]))
    print("MAC: " + str(interface.IPAddress[1]))

For more information on what parameters you can provide Win32_NetworkAdapterConfiguration with visit: https://msdn.microsoft.com/en-us/library/aa394217(v=vs.85).aspx

Maud

Answer 4

Get address of all NICs without any external package

import socket
print socket.gethostbyname_ex(socket.gethostname())[2]

Defiance

This solution as well, will not give an EXTERNAL IP. Look at Jean-Paul Calderone's answer. – Kirsti

Answer 5

Use the subprocess module to connect to your usual systems tools like ifconfig or netstat:

>>> import subprocess
>>> print subprocess.check_output(['ifconfig'])

Painful

But ifconfig on displays the local ip address, correct? Not sure about netstat, but I think it's the same issue. :( – Deberadeberry

@Raymond Hettinger, FYI, Linux has deprecated ifconfig in favor of ip link show / ip addr show (10 years ago!)... sadly, most distros still leave ifconfig there for fear of breaking old scripts – Harrar

@MikePennington Since ip never made it to the Mac OS, I tend to forget it's there :-) – Painful