Can I lookup the IP address of a hostname from javascript?

Question

I would like to use javascript to determine the IP address of a host, as seen from the clients computer. Is it possible?

Answer 1

I don't think this is allowed by most browsers for security reasons, in a pure JavaScript context as the question asks.

Answer 2

If the client has Java installed, you could do something like this:

ipAddress = java.net.InetAddress.getLocalHost().getHostAddress();

Other than that, you will probably have to use a server side script.

Alex

Answer 3

There's no notion of hosts or ip-addresses in the javascript standard library. So you'll have to access some external service to look up hostnames for you.

I recommend hosting a cgi-bin which looks up the ip-address of a hostname and access that via javascript.

Answer 4

Doing this would require to break the browser sandbox. Try to let your server do the lookup and request that from the client side via XmlHttp.

Answer 5

Edit: This question gave me an itch, so I put up a JSONP webservice on Google App Engine that returns the clients ip address. Usage:

<script type="application/javascript">
function getip(json){
  alert(json.ip); // alerts the ip address
}
</script>

<script type="application/javascript" src="http://jsonip.appspot.com/?callback=getip"&gt; </script>

Yay, no server proxies needed.

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Pure JS can't. If you have a server script under the same domain that prints it out you could send a XMLHttpRequest to read it.