1. Find out whether there all the tables mentioned in the lecture are available in your system. What predefined chains do they contain? What are their default targets? 2. Set up the firewall so that it drops all packets coming from the computer of your selected neighbour while all others are able to access network services of your computer with no restrictions. 3. How would you drop all packets coming to TCP port 23 (telnet)? 4. How will you deny access from all computers in the range 10.0.0.1 - 10.0.0.15? How will you deny your computer to send packets to those machines? What would change if you wanted to block only a range of TCP ports (e.g. 20 - 25) instead of all packets? 5. How would you block all attempts to establish a new TCP connecction? And how about "connections" using UDP? 6. Achieve that all attempts to establish a new connection will be refused with a Port unreachable message.