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How To Get The Public Ip Address Of Current Host

08.22.2011
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        In a virtual host, or when your application could run on a multiple type of OS,
it could be difficult to get the IP address corresponding to your default gateway.

Here a solution, which should be 'universal'.

This snippets try to send a datagramme on a distant host (no matter if datagrame
arrive), and retrieve the local IP with the return-value of the connect :

Socket.do_not_reverse_lookup=true

def get_public_ip()
  UDPSocket.open do |s|
    s.connect '208.80.152.2', 1 # wikipedia, connection don't need to be effective
    s.addr.last
  end
end

This option must be positionned :
 Socket.do_not_reverse_lookup=true
If not, your ruby machine will try to find DNS name of wikipedia, which could
take a very long time if host is isolated.