Check if user is located at 192.168.*.* in javascript

I need to see if the user is at the office or at home.

[johnhamman]

Hi, I am doing a portal site in which I dispay an Icon based on whether the user is at work or at home. If they are at work the Icon will show and will open an aplication if they are not at work it will just redirect them. Can anyone help me on this.
John

[dingman]

Are you trying to determine whether the person is on the same local network as the server, or trying to determine what IP their machine thinks it has? The first should be done on the server, not in javascript, and the second is pretty much meaningless.

[BjarneDM]

I concur with dingman.

If you want to enable your users to access corporate information *only* from within the lan, then checking of location should only be done on the server iself and never ever at all be done in the clients browser!

If you place your check on the client browser you'll get hacked within 5 seconds or less! It's so simple to do that that it's ridiculous:
1) save the complete page with all files to the HD (Mozilla will do this for you)
2) modify the checking javascript code so that it thinks it's always on the LAN
3) modify clickable links to be absolute links
4) load the page in the brower and you are inside!