Dumb question

I'm probably just avoiding using my own brain here but could someone please help with a simple question. I have installed a web server on my laptop (using WampServer), so I can test a mysql/php driven package I'm working on. Most of the time the machine is connected to the internet through a NAT router with firewall. Sometimes I connect wirelessly through my mobile. How can I make sure that no one can access the server from the internet?

Just make sure you haven't forwarded port 80 (http) or 443 (https) inbound on your router to your laptop.

Thanks. And when I'm connected wirelessly with no router?

You'll have to rely on WEP/WPA encryption in that case to prevent eavesdropping or connection to your wireless router.

The quickest way is just to block the incoming connections via the software firewall on your laptop. I'd also configure Apache and MySQL to only bind on the loopback:

http://httpd.apache.org/docs/2.0/bind.html
http://dev.mysql.com/doc/refman/5.1/en/server-option...

I think others missed what you meant, which seems to be the laptop hosting server is using the mobile for its internet connection...

The firewall you are running locallly on your laptop ( you will of course already have one running, mad not to) will protect your server from being found. So if no software firewall get one, the one with XP should be enough if you have it turned on and don't add an expection for the webserver

Thanks everyone for your help