get the IP address of a host

[Jp Calderone]

On Thu, 06 Jan 2005 14:35:16 +0100, J Berends <j.p.t.j.berends@[n0sp4m].nl> wrote:
>
>  From several approached I came up with the following code:
> 
> 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]
>      ips = [i for i in ips if i.split('.')[0] != '127']
>      if len(ips) != 0:
>          # check if we have succes in determining outside IP
>          ip = ips[0]
>      elif len(ips) == 0 and hostname == socket.gethostname():
>          # when we want to determine local IP and did not have succes
>          # with gethostbyname_ex then we would like to connect to say... 
> 
>          # google.com and determine the local ip address bound to the
>          # local socket.
>          try:
>              s = socket.socket()
>              s.connect(('google.com', 80))
>              print ('___ connecting to internet to determine local ip')
>              ip = s.getsockname()[0]

    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.connect(('1.2.3.4', 56))
    ip = s.getsockname()[0]


>              del s
>          except:
>              print ('*** cannot connect to internet in order to \
>                     determine outside IP address')
>              raise Exception
>      if len(ip) != 0:
>          return ip
>      else:
>          print ('*** unable to determine outside IP address')
>          raise Exception
> 
> It returns the IP address with which it connects to the world (not lo), 
> might be a pvt LAN address or an internet routed IP. Depend on where the 
> host is.
> 
> I hate the google trick actually, so any suggestions to something better 
> is always welcome.

  Jp