Retrieving network mask in Python

Question

How would one go about retrieving a network device\'s netmask (In Linux preferably, but if it\'s cross-platform then cool)? I know how in C on Linux but I can\'t find a way

Answer 1

Did you look here?

http://docs.python.org/library/fcntl.html

This works for me in python 2.5.2 on Linux. Was finishing it when Ben got ahead, but still here it goes (sad to waste the effort :-) ):

vinko@parrot:~$ more get_netmask.py
# get_netmask.py by Vinko Vrsalovic 2009
# Inspired by http://code.activestate.com/recipes/439093/
# and http://code.activestate.com/recipes/439094/
# Code: 0x891b SIOCGIFNETMASK

import socket
import fcntl
import struct
import sys

def get_netmask(ifname):
        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        return socket.inet_ntoa(fcntl.ioctl(s.fileno(), 0x891b, struct.pack('256
s',ifname))[20:24])

if len(sys.argv) == 2:
        print get_netmask(sys.argv[1])
vinko@parrot:~$ python get_netmask.py lo
255.0.0.0
vinko@parrot:~$ python get_netmask.py eth0
255.255.255.0

Answer 2

In Windows this piece of code may be useful:

import os
import sys
import _winreg


def main():
    adapter_list_key = _winreg.OpenKey(_winreg.HKEY_LOCAL_MACHINE,
        r'SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkCards')

    adapter_count = _winreg.QueryInfoKey(adapter_list_key)[0]

    for i in xrange(adapter_count):
        sub_key_name = _winreg.EnumKey(adapter_list_key, i)
        adapter_key = _winreg.OpenKey(adapter_list_key, sub_key_name)
        (adapter_service_name, _) = _winreg.QueryValueEx(adapter_key, "ServiceName")
        (description, _) = _winreg.QueryValueEx(adapter_key, "Description")

        adapter_registry_path = os.path.join(r'SYSTEM\ControlSet001\Services',
            adapter_service_name, "Parameters", "Tcpip")
        adapter_service_key = _winreg.OpenKey(_winreg.HKEY_LOCAL_MACHINE,
            adapter_registry_path)
        (subnet_mask, _) = _winreg.QueryValueEx(adapter_service_key, "SubnetMask")
        (ip_address, _) = _winreg.QueryValueEx(adapter_service_key, "IpAddress")

        sys.stdout.write("Name: %s\n" % adapter_service_name)
        sys.stdout.write("Description: %s\n" % description)
        sys.stdout.write("SubnetMask: %s\n" % subnet_mask)
        sys.stdout.write("IpAdress: %s\n" % ip_address)


if __name__ == "__main__":
    main()

Get network adapters list from HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkCards registry key and than extract more info about each adapter from HKLM\SYSTEM\ControlSet001\Services\{adapter_guid}\Parameters\Tcpip key.

I test it on Windows XP with 2 virtual adapters, it works fine. Should work in 2000, 2003, and Vista too.

Answer 3

The netifaces module deserves a mention here. Straight from the docs:

>>> netifaces.interfaces()
['lo0', 'gif0', 'stf0', 'en0', 'en1', 'fw0']

>>> addrs = netifaces.ifaddresses('en0')
>>> addrs[netifaces.AF_INET]
[{'broadcast': '10.15.255.255', 'netmask': '255.240.0.0', 'addr': '10.0.1.4'}, {'broadcast': '192.168.0.255', 'addr': '192.168.0.47'}]

Works on Windows, Linux, OS X, and probably other UNIXes.

Answer 4

This works for me in Python 2.2 on Linux:

iface = "eth0"
socket.inet_ntoa(fcntl.ioctl(socket.socket(socket.AF_INET, socket.SOCK_DGRAM), 35099, struct.pack('256s', iface))[20:24])

Answer 5

I had the idea to rely on subprocess to use a simple ifconfig (Linux) or ipconfig (windows) request to retrieve the info (if the ip is known). Comments welcome :

WINDOWS

ip = '192.168.1.10' #Example
proc = subprocess.Popen('ipconfig',stdout=subprocess.PIPE)
while True:
    line = proc.stdout.readline()
    if ip.encode() in line:
        break
mask = proc.stdout.readline().rstrip().split(b':')[-1].replace(b' ',b'').decode()

UNIX-Like

ip = '192.168.1.10' #Example
proc = subprocess.Popen('ifconfig',stdout=subprocess.PIPE)
while True:
    line = proc.stdout.readline()
    if ip.encode() in line:
        break
mask = line.rstrip().split(b':')[-1].replace(b' ',b'').decode()

IP is retrieved using a socket connection to the web and using getsockname()[0]

Answer 6

You can use this library: http://github.com/rlisagor/pynetlinux. Note: I'm the author of the library.