Simple scraping of page http, problem with http_get()

Hello!
As title I am looking for how to scrape a simple http page.
The problem is that the function http_get($url) give me the following error:

Fatal error: Call to undefined function http_get()

How can I do it?
Thanks

OK seems that the problem is that the web site that I want is forbidden "Destination host forbidden"
The web host that I want is:
$url="www."."geo"."ip"."tool".".com";
:)
is it possible to add it in the whitelist?

Per aggiungerlo alla whitelist devi sbloccare le connesioni server to server a tutti i siti dal pannello di controllo (Risorse -> PHP -> Modifica le impostazioni PHP)

Se è un indirizzo utile "per molti" può essere benissimo messo nella whitelist.

Ciao!