Hello, I have connected my mobile phone to the internet via GPRS. I got the public ip of my phone through 'whatismyip.com' and with this IP I tried to ping it from my laptop which is ofc ourse on the broadband network. The mobile is not 'ping'able. Why?

Mobile data works basically the same way as Native Address Translation (NAT), but the mobile network doesn't use IP internally. Mobile phones don't have an IP address. Mobile phone uses the operator mobile communication network to reach GGSN, which is the gateway to IP networks and Internet in general. The IP address you see is the address of an operator (provider) GGSN. ninje123, currently you can only create mobile originated data connections between an IP server and mobile phone. The MSISDN (or more commonly, phone number) of the SIM card is the identifying number for a mobile phone. our patience is big

so isnt a person connected to the internet(laptop with mobile phone through say bluetooth) visible at all to the outside with his IP? Is there no way to do some ICMP flood on such users??

sorry pal our patience is big

Hey I am not one of those fiddlers! I am genuinely learning to use those flooding tools as part of my training in our company. We do network security for embedded devices. Thats why! If this cant be done at all we dont have to bother about it :) :)