Thursday, 7 February 2008

Finding a User Mac Address (Javascript)

Unless a user is on an internal network, there is no way server-side (I know of) to retrieve the mac address of a user accessing a web page, simply because it isn't sent in the http headers for a request. Any attempt to analyze the underlying network communications server side is pointless as it will just return the MAC address for the last routing machine. However, it is possible to retrieve the mac address of the user simply using client-side Javascript in IE.

Once you've accessed the WMI and got the MAC address you can even send the value server-side if necessary.

Implications: You are connecting to the WMI (Windows Management Instrumentation) for the local machine and therefore you may have a problem if your IE security settings are restrictive. Also, this won't work in non-IE browsers; only works for Windows operating systems. Not all that restrictive then?! ;)

Troubleshooting: If you get an 'automation server can't create object' error when running the script it is probably for one of the reasons below.

  • You need to enable 'Initialize and script ActiveX controls not marked as safe' on the security tab -> custom level options in IE
  • WMI isn't installed correctly
  • WMI isn't installed
  • Some other permission issue. Are you an administrator? If on Windows 2000 server, have you installed sp4?

P.S. Another plausible option is to use an ActiveX control in connecting to WMI.


Anonymous said...


The code works fine when i use it in localhost and only works for IE.

Can you let me know how this can be achieved in the Firefox?

Anonymous said...