Name:

1. What command will clear all firewall rules and allow traffic to your machine?
   

   
   

2. (5 points) Write a script to make iptables rules so that only ports 22, 25, 53, 80 and 443 are open. DO NOT BLOCK the loopback address, and ensure that your system can still access the internet after your script runs. Get Instructor sign-off.
   

   
   

3. (4 points) Set up iptables so that it logs all probes
   

4. What is the difference between the INPUT and OUTPUT chain?
   

   
   

5. What is the difference between the FORWARD and OUTPUT chain?
   

   
   

6. Why might it be a good idea to have multiple NICs in a firewall?
   

   
   

7. What is the difference between using the -I and the -A flags when configuring iptables rules?

   
   

8. What text file lists of the ports on which services typically listen?
9. In which file do iptables log messages get put?
10. (4 points) What would a port scan look like, in terms of the iptables logfile?
    

    
    

11. What command will clear all iptable rules from a chain?
12. What are the 3 default chains used by iptables?
13. When is a chain's policy followed?
    
    
14. What command will set the default policy of the OUTPUT chain to DROP?
15. Why should all traffic on the loopback interface be allowed?