network security related question

[Rashkae]

Nils Kassube wrote:

> 
> Could it be that you have your router configured in a way that makes 
> your Ubuntu machine the "default server"? Maybe it has a different name 
> in your router software. If you have enabled this option you don't 
> block anything with your NAT setup. Then everything received by the 
> router will be sent to your Ubuntu machine unless you have an extra 
> filter to block specific traffic.
> 
>
This is also called a DMZ host on some routers, and was my first guess
as well.