Can a home user behind a firewall be targetted by a DDoS attack?

Question

I've read about an attack that targets simple home computer users who are playing online poker:

Players A and B join a real money 1 on 1 tournament. You cannot unregister from this tournament and if one player disconnects the other will eventually win. Player A knows player B's IP address. Is there any way that A can deny internet service to B?

Lets assume that they are in different countries and player B is using a clean instalation of Windows 7 and a Security Essentials firewall. Lets also assume that A has no power over B's ISP and etc.

Answer 1

DDOS = Distributed Denial Of Service
It only means you can no longer use/give the desired service.
It doesn't means any computer is "attacked".

For a residential connection, it is really easy: you just have to fill the target's ADSL or fiber link with so much datas that anything legitimate can hardly go thru it. For example you send 100 times more datas than the throughput of the ADSL line. The provider's routers have to randomly discard any data in excess, so only 1% (best case scenario) of the legitimate datas can travel to the target's firewall. The firewall is inside the house, so it can't do anything against the overwhelming amount of datas at the other end of the link.

You don't even have to use a distributed attack. The datas can come for only one computer, because there is no firewall on the right side of the ADSL line. So no IP can be banned.

To really saturate such a link for poker software, you only need 200 to 1000 Mb/s (depending of the throughput of the ADSL or fiber connection). Any cheap dedicated server can do it, but you have to carefully test it before because most of them are under monitoring against this kind of practice. Else you can rent a network of zombi computers. I think this later option is the best: cheap, efficient, and you (probably) can't be discovered. But harder to find when you're novice.

Answer 2

Yes they can - with the proper connection and variety of servers. A firewall can block the IP pf a single computer flooding it with multiple requests, and thereby prevent it from completing the attack. However, with a variety of servers pounding the firewall the connection will eventually lockup and therefore disconnect the user, making the hacker win the game.

Large websites get DDOSed simply due to the large volume of requests from DIFFERENT IPs - it is impossible to block them all, and the site will crash. Ditto for your PC.

As Ramhound said, be smart and don't tell your opponent your IP.