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Python: check whether a network interface is up

In Python, is there a way to detect whether a given network interface is up?
In my script, the user specifies a network interface, but I would like to make sure that the interface is up and has been assigned an IP address, before doing anything else.
I'm on Linux and I am root.

The interface can be configured with an IP address and not be up so the accepted answer is wrong. You actually need to check /sys/class/net/<interface>/flags. If the content is in the variable flags, flags & 0x1 is whether the interface is up or not.
Depending on the application, the /sys/class/net/<interface>/operstate might be what you really want, but technically the interface could be up and the operstate down, e.g. when no cable is connected.
All of this is Linux-specific of course.

As suggested by #Gabriel Samfira, I used netifaces. The following function returns True when an IP address is associated to a given interface.
def is_interface_up(interface):
addr = netifaces.ifaddresses(interface)
return netifaces.AF_INET in addr
The documentation is here

Answer using psutil:
import psutil
import socket
def check_interface(interface):
interface_addrs = psutil.net_if_addrs().get(interface) or []
return socket.AF_INET in [snicaddr.family for snicaddr in interface_addrs]

With pyroute2.IPRoute:
from pyroute2 import IPRoute
ip = IPRoute()
state = ip.get_links(ip.link_lookup(ifname='em1'))[0].get_attr('IFLA_OPERSTATE')
ip.close()
With pyroute2.IPDB:
from pyroute2 import IPDB
ip = IPDB()
state = ip.interfaces.em1.operstate
ip.release()

You can see the content of the file in /sys/class/net/<interface>/operstate. If the content is not down then the interface is up.

If the question is about checking if the cable is conencted (FreeBSD);
[status for status in run.cmd(' /usr/local/bin/sudo ifconfig %s ' % interface).split("\t") if status.strip().startswith("status")][0].strip().endswith("active")
For this, no api support so far :( ...

Python Sockets: Enabling Promiscuous Mode in Linux

We know that Python Allows enabling promiscuous mode under Windows through
s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)
However, The RCVALL_* and SIO_* is only available in windows.
Using C socket api, in Linux, one can use :
ethreq.ifr_flags |= IFF_PROMISC;
ioctl(sock, SIOCSIFFLAGS, &ethreq);
or through,
setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, PACKET_MR_PROMISC)
Is there any option in python socket API that allows us to set promiscuous mode in Linux?

Use an AF_NETLINK socket to issue a request to turn on IFF_PROMISC. Python can construct AF_NETLINK sockets on Linux:
>>> from socket import AF_NETLINK, SOCK_DGRAM, socket
>>> s = socket(AF_NETLINK, SOCK_DGRAM)
>>>
See the example at the end of the netlink(7) manual page for an example of how to issue a netlink request. You can use ctypes (or even struct) to construct the serialized nlmsghdr message to send over the netlink socket. You may also need it to call sendmsg and recvmsg, since Python still doesn't expose these APIs. Alternatively, there are some third-party modules available which expose these two APIs.
Alternatively, you can go the old school route of using ioctl, which sadly turns out to be rather simpler.
First define the ifreq structure using ctypes:
import ctypes
class ifreq(ctypes.Structure):
_fields_ = [("ifr_ifrn", ctypes.c_char * 16),
("ifr_flags", ctypes.c_short)]
Then make a socket to use with the ioctl call:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
Then copy a couple constant values out of /usr/include since they're not exposed by Python:
IFF_PROMISC = 0x100
SIOCGIFFLAGS = 0x8913
SIOCSIFFLAGS = 0x8914
Create an instance of the ifreq struct and populate it to have the desired effect:
ifr = ifreq()
ifr.ifr_ifrn = "eth4"
Populate the ifr_flags field with an ioctl call so that you don't clobber whatever flags are already set on the interface:
import fcntl
fcntl.ioctl(s.fileno(), SIOCGIFFLAGS, ifr) # G for Get
Add the promiscuous flag:
ifr.ifr_flags |= IFF_PROMISC
And set the flags on the interface:
fcntl.ioctl(s.fileno(), SIOCSIFFLAGS, ifr) # S for Set
To remove the flag, mask it off and set again:
ifr.ifr_flags &= ~IFF_PROMISC
fcntl.ioctl(s.fileno(), SIOCSIFFLAGS, ifr)

There is another way I thought of. Maybe not as elegant but seems to work fine.
In linux (with root permissions), one can use :
# ifconfig eth0 promisc
# ifconfig eth0 -promisc
To enable/ disable promisc mode on your interface (eth0 in this case).
So, in python (with root permissions) one could use :
import os
ret = os.system("ifconfig eth0 promisc")
if ret == 0:
<Do something>
Comments are welcome on this way of doing it.

How to get Network Interface Card names in Python?

Is there anyway to get the names of the NIC cards in the machine etc. eth0, lo? If so how do you do it?
I have researched but so far I have only found code to get IP addresses and MAC addresses only such as
import socket
socket.gethostbyname(socket.gethostname())
Advice on the code would really be appreciated.

A great Python library I have used to do this is psutil. It can be used on Linux, Windows, and OSX among other platforms and is supported from Python 2.6 to 3.6.
Psutil provides the net_if_addrs() function which returns a dictionary where keys are the NIC names and value is a list of named tuples for each address assigned to the NIC which include the address family, NIC address, netmask, broadcast address, and destination address.
A simple example using net_if_addrs() which will print a Python list of the NIC names:
import psutil
addrs = psutil.net_if_addrs()
print(addrs.keys())

On Linux, you can just list the links in /sys/class/net/ by
os.listdir('/sys/class/net/')
Not sure if this works on all distributions.

Since this answer pops up in Google when I search for this information, I thought I should add my technique for getting the available interfaces (as well as IP addresses). The very nice module netifaces takes care of that, in a portable manner.

socket module in Python >= 3.3:
import socket
# Return a list of network interface information
socket.if_nameindex()
https://docs.python.org/3/library/socket.html#socket.if_nameindex

I don't think there's anything in the standard library to query these names.
If I needed these names on a Linux system I would parse the output of ifconfig or the contents of /proc/net/dev. Look at this blog entry for a similar problem.

Using python's ctypes you can make a call to the C library function getifaddrs:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from ctypes import *
class Sockaddr(Structure):
_fields_ = [('sa_family', c_ushort), ('sa_data', c_char * 14)]
class Ifa_Ifu(Union):
_fields_ = [('ifu_broadaddr', POINTER(Sockaddr)),
('ifu_dstaddr', POINTER(Sockaddr))]
class Ifaddrs(Structure):
pass
Ifaddrs._fields_ = [('ifa_next', POINTER(Ifaddrs)), ('ifa_name', c_char_p),
('ifa_flags', c_uint), ('ifa_addr', POINTER(Sockaddr)),
('ifa_netmask', POINTER(Sockaddr)), ('ifa_ifu', Ifa_Ifu),
('ifa_data', c_void_p)]
def get_interfaces():
libc = CDLL('libc.so.6')
libc.getifaddrs.restype = c_int
ifaddr_p = pointer(Ifaddrs())
ret = libc.getifaddrs(pointer((ifaddr_p)))
interfaces = set()
head = ifaddr_p
while ifaddr_p:
interfaces.add(ifaddr_p.contents.ifa_name)
ifaddr_p = ifaddr_p.contents.ifa_next
libc.freeifaddrs(head)
return interfaces
if __name__ == "__main__":
print(get_interfaces())
Do note though this method is not portable.

To add to what #Kristian Evensen's mentions, here is what I used for a problem i was having.
If you are looking to just get a list of the interfaces, use:
interface_list = netifaces.interfaces()
If you are wanting a specific interface, but don't know what the number at the end is (ie: eth0), use:
interface_list = netifaces.interfaces()
interface = filter(lambda x: 'eth' in x,interface_list)

Like David Breuer say, you can just list the directory "/ sys / class / net" on Linux. (It works on Fedora at least). If you need detailled information about some interface you can navigate on the intefaces's directories for more.
def getAllInterfaces():
return os.listdir('/sys/class/net/')

There is a python package get-nic which gives NIC status, up\down, ip addr, mac addr etc
pip install get-nic
from get_nic import getnic
getnic.interfaces()
Output: ["eth0", "wlo1"]
interfaces = getnic.interfaces()
getnic.ipaddr(interfaces)
Output:
{'lo': {'state': 'UNKNOWN', 'inet4': '127.0.0.1/8', 'inet6': '::1/128'}, 'enp3s0': {'state': 'DOWN', 'HWaddr': 'a4:5d:36:c2:34:3e'}, 'wlo1': {'state': 'UP', 'HWaddr': '48:d2:24:7f:63:10', 'inet4': '10.16.1.34/24', 'inet6': 'fe80::ab4a:95f7:26bd:82dd/64'}}
Refer GitHub page for more information: https://github.com/tech-novic/get-nic-details

figuring out how to get all of the public ips of a machine

I am running my code on multiple VPSes (with more than one IP, which are set up as aliases to the network interfaces) and I am trying to figure out a way such that my code acquires the IP addresses from the network interfaces on the fly and bind to it. Any ideas on how to do it in python without adding a 3rd party library ?
Edit I know about socket.gethostbyaddr(socket.gethostname()) and about the 3rd party package netifaces, but I am looking for something more elegant from the standard library ... and parsing the output of the ifconfig command is not something elegant :)

The IP addresses are assigned to your VPSes, no possibility to change them on the fly.
You have to open a SSH tunnel to or install a proxy on your VPSes.
I think a SSH tunnel would be the best way how to do it, and then use it as SOCKS5 proxy from Python.

This is how to get all IP addresses of the server the script is running on:
(this is as much elegant as possible and it only needs the standard library)
import socket
import fcntl
import struct
import array
def all_interfaces():
max_possible = 128 # arbitrary. raise if needed.
bytes = max_possible * 32
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
names = array.array('B', '\0' * bytes)
outbytes = struct.unpack('iL', fcntl.ioctl(
s.fileno(),
0x8912, # SIOCGIFCONF
struct.pack('iL', bytes, names.buffer_info()[0])
))[0]
namestr = names.tostring()
return [namestr[i:i+32].split('\0', 1)[0] for i in range(0, outbytes, 32)]

Getting MAC Address

I need a cross platform method of determining the MAC address of a computer at run time. For windows the 'wmi' module can be used and the only method under Linux I could find was to run ifconfig and run a regex across its output. I don't like using a package that only works on one OS, and parsing the output of another program doesn't seem very elegant not to mention error prone.
Does anyone know a cross platform method (windows and linux) method to get the MAC address? If not, does anyone know any more elegant methods then those I listed above?

Python 2.5 includes an uuid implementation which (in at least one version) needs the mac address. You can import the mac finding function into your own code easily:
from uuid import getnode as get_mac
mac = get_mac()
The return value is the mac address as 48 bit integer.

The pure python solution for this problem under Linux to get the MAC for a specific local interface, originally posted as a comment by vishnubob and improved by on Ben Mackey in this activestate recipe
#!/usr/bin/python
import fcntl, socket, struct
def getHwAddr(ifname):
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
info = fcntl.ioctl(s.fileno(), 0x8927, struct.pack('256s', ifname[:15]))
return ':'.join(['%02x' % ord(char) for char in info[18:24]])
print getHwAddr('eth0')
This is the Python 3 compatible code:
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import fcntl
import socket
import struct
def getHwAddr(ifname):
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
info = fcntl.ioctl(s.fileno(), 0x8927, struct.pack('256s', bytes(ifname, 'utf-8')[:15]))
return ':'.join('%02x' % b for b in info[18:24])
def main():
print(getHwAddr('enp0s8'))
if __name__ == "__main__":
main()

netifaces is a good module to use for getting the mac address (and other addresses). It's crossplatform and makes a bit more sense than using socket or uuid.
import netifaces
netifaces.interfaces()
# ['lo', 'eth0', 'tun2']
netifaces.ifaddresses('eth0')[netifaces.AF_LINK]
# [{'addr': '08:00:27:50:f2:51', 'broadcast': 'ff:ff:ff:ff:ff:ff'}]
pypi location
Good Intro to netifaces

Sometimes we have more than one net interface.
A simple method to find out the mac address of a specific interface, is:
def getmac(interface):
try:
mac = open('/sys/class/net/'+interface+'/address').readline()
except:
mac = "00:00:00:00:00:00"
return mac[0:17]
to call the method is simple
myMAC = getmac("wlan0")

One other thing that you should note is that uuid.getnode() can fake the MAC addr by returning a random 48-bit number which may not be what you are expecting. Also, there's no explicit indication that the MAC address has been faked, but you could detect it by calling getnode() twice and seeing if the result varies. If the same value is returned by both calls, you have the MAC address, otherwise you are getting a faked address.
>>> print uuid.getnode.__doc__
Get the hardware address as a 48-bit positive integer.
The first time this runs, it may launch a separate program, which could
be quite slow. If all attempts to obtain the hardware address fail, we
choose a random 48-bit number with its eighth bit set to 1 as recommended
in RFC 4122.

Using my answer from here: https://stackoverflow.com/a/18031868/2362361
It would be important to know to which iface you want the MAC for since many can exist (bluetooth, several nics, etc.).
This does the job when you know the IP of the iface you need the MAC for, using netifaces (available in PyPI):
import netifaces as nif
def mac_for_ip(ip):
'Returns a list of MACs for interfaces that have given IP, returns None if not found'
for i in nif.interfaces():
addrs = nif.ifaddresses(i)
try:
if_mac = addrs[nif.AF_LINK][0]['addr']
if_ip = addrs[nif.AF_INET][0]['addr']
except IndexError, KeyError: #ignore ifaces that dont have MAC or IP
if_mac = if_ip = None
if if_ip == ip:
return if_mac
return None
Testing:
>>> mac_for_ip('169.254.90.191')
'2c:41:38:0a:94:8b'

You can do this with psutil which is cross-platform:
import psutil
nics = psutil.net_if_addrs()
print [j.address for j in nics[i] for i in nics if i!="lo" and j.family==17]

The cross-platform getmac package will work for this, if you don't mind taking on a dependency. It works with Python 2.7+ and 3.4+. It will try many different methods until either getting a address or returning None.
from getmac import get_mac_address
eth_mac = get_mac_address(interface="eth0")
win_mac = get_mac_address(interface="Ethernet 3")
ip_mac = get_mac_address(ip="192.168.0.1")
ip6_mac = get_mac_address(ip6="::1")
host_mac = get_mac_address(hostname="localhost")
updated_mac = get_mac_address(ip="10.0.0.1", network_request=True)
Disclaimer: I am the author of the package.
Update (Jan 14 2019): the package now only supports Python 2.7+ and 3.4+. You can still use an older version of the package if you need to work with an older Python (2.5, 2.6, 3.2, 3.3).

Note that you can build your own cross-platform library in python using conditional imports. e.g.
import platform
if platform.system() == 'Linux':
import LinuxMac
mac_address = LinuxMac.get_mac_address()
elif platform.system() == 'Windows':
# etc
This will allow you to use os.system calls or platform-specific libraries.

To get the eth0 interface MAC address,
import psutil
nics = psutil.net_if_addrs()['eth0']
for interface in nics:
if interface.family == 17:
print(interface.address)

nice actually return a dictionary within the dictionary it returns a list and within the list, it returns a staple. but nics['Ethernet'][0].address iteration solve the problem.
import psutil
nics = psutil.net_if_addrs()
mac_address = nics['Ethernet'][0].address
print(mac_address)

This cross-platform code does not 100% work on Windows. This works on Windows:
import psutil
print([(k, addr.address) for k, v in psutil.net_if_addrs().items() for addr in v if addr.family == -1])
Example:
[
('Local Area Connection', '01-23-45-67-89-0A'),
('Wireless Network Connection', '23-45-67-89-0A-BC'),
('Bluetooth Network Connection', '45-67-89-0A-BC-DE'),
('isatap.{01ABCDEF-0123-4567-890A-0123456789AB}', '00-00-00-00-00-00-00-01')
]

I dont know of a unified way, but heres something that you might find useful:
http://www.codeguru.com/Cpp/I-N/network/networkinformation/article.php/c5451
What I would do in this case would be to wrap these up into a function, and based on the OS it would run the proper command, parse as required and return only the MAC address formatted as you want. Its ofcourse all the same, except that you only have to do it once, and it looks cleaner from the main code.

Alternatively,
import uuid
mac_id=(':'.join(['{:02x}'.format((uuid.getnode() >> ele) & 0xff)

For Linux let me introduce a shell script that will show the mac address and allows to change it (MAC sniffing).
ifconfig eth0 | grep HWaddr |cut -dH -f2|cut -d\ -f2
00:26:6c:df:c3:95
Cut arguements may dffer (I am not an expert) try:
ifconfig etho | grep HWaddr
eth0 Link encap:Ethernet HWaddr 00:26:6c:df:c3:95
To change MAC we may do:
ifconfig eth0 down
ifconfig eth0 hw ether 00:80:48:BA:d1:30
ifconfig eth0 up
will change mac address to 00:80:48:BA:d1:30 (temporarily, will restore to actual one upon reboot).

For Linux you can retrieve the MAC address using a SIOCGIFHWADDR ioctl.
struct ifreq ifr;
uint8_t macaddr[6];
if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0)
return -1;
strcpy(ifr.ifr_name, "eth0");
if (ioctl(s, SIOCGIFHWADDR, (void *)&ifr) == 0) {
if (ifr.ifr_hwaddr.sa_family == ARPHRD_ETHER) {
memcpy(macaddr, ifr.ifr_hwaddr.sa_data, 6);
return 0;
... etc ...
You've tagged the question "python". I don't know of an existing Python module to get this information. You could use ctypes to call the ioctl directly.