get the IP address of a host

Lee Harr lee at
Wed Jan 5 17:41:15 EST 2005

On 2005-01-05, none <""> wrote:
> I want to determine the outside (non local, a.k.a. 127.0.0.x) ip 
> addresses of my host. It seems that the socket module provides me with 
> some nifty tools for that but I cannot get it to work correctly it seems.
> Can someone enlightened show a light on this:
> import socket
> def getipaddr(hostname='default'):
>      """Given a hostname, perform a standard (forward) lookup and return
>      a list of IP addresses for that host."""
>      if hostname == 'default':
>          hostname = socket.gethostname()
>      ips = socket.gethostbyname_ex(hostname)[2]
>      return [i for i in ips if i.split('.')[0] != '127'][0]
> It does not seem to work on all hosts. Sometimes socket.gethostbyname_ex 
> only retrieves the 127.0.0.x ip adresses of the local loopback. Does 
> someone has a more robust solution?
> Targetted OS'es are Windows AND linux/unix.

I found that the socket solutions only work if your
DNS entries are correct ... which in my case was not
true. So I came up with this:

import commands

ifconfig = '/sbin/ifconfig'
# name of ethernet interface
iface = 'eth0'
# text just before inet address in ifconfig output
telltale = 'inet addr:'

def my_addr():
    cmd = '%s %s' % (ifconfig, iface)
    output = commands.getoutput(cmd)

    inet = output.find(telltale)
    if inet >= 0:
        start = inet + len(telltale)
        end = output.find(' ', start)
        addr = output[start:end]
        addr = ''

    return addr

Basically, it scrapes the output from ifconfig for the
actual address assigned to the interface. Works perfectly
on FreeBSD and Linux (given the correct configuration).

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