Multiple choice questions for lab-deter-firewall-instructions.htm

1. Windows XP's firewall by default lets nothing in and everything out. What could best be said about the "optimism" and "pessimism" rating of such a firewall?
 a. the input firewall is optimistic and the output firewall is pessimistic
 b. the input firewall is optimistic and the output firewall is non-existent
 c. the input firewall is pessimistic and the output firewall is pessimistic
 d. the input firewall is pessimistic and the output firewall is non-existent

2. Below is a table of several commonly used port numbers and the services that use them, plus a short iptables firewall script.

Port Service 21 file transfer service 25 mail sending service 22 secure shell service 53 domain name to internet address translation service 80 web service 110 mail receiving service

Firewall script (running these creates a firewall):

1 iptables -F # flush existing rules
2
3 iptables -P INPUT DROP 
4 iptables -P FORWARD DROP 
5 iptables -P OUTPUT DROP 
6 
7 # first service 
8 iptables -A OUTPUT -p udp --dport 53 -d 0.0.0.0/0 -j ACCEPT 
9 iptables -A INPUT -p udp --sport 53 -s 0.0.0.0/0 -j ACCEPT 
10
11 # second service 
12 iptables -A OUTPUT -p tcp --dport 80 -d 0.0.0.0/0 -j ACCEPT
13 iptables -A INPUT -p tcp --sport 80 -s 0.0.0.0/0 -j ACCEPT

The firewall represented will let you succeed to view the UCLA university webpage if you type "www.ucla.edu" in a browser. If lines 8 and 9 were not present that would not be so. The reason for that is:
a. traffic to-and-from the website and your machine would be blocked
b. your machine would not be able to identify a server to translate "www.ucla.edu" into the corresponding IP address 
c. though traffic from the website would not be blocked, blockage to it would prevent your requests from ever reaching it
d. your machine would not be able to reach a server to translate "www.ucla.edu" into the corresponding IP address

3. You have a home LAN containing 2 computers. The first computer is a general purpose PC running Windows XP. The second computer is a typical commersial router, perhaps a Netgear WGR614. The router, in addition to being on the LAN, is on the internet (it has 2 NICs). You want to prevent the XP box from conversing with the internet using certain protocols. To do it, do you need to make the corresponding firewall adjustment(s) on:
a. the router but not XP
b. XP but not the router 
c. both the router and XP
d. either the router or XP, with the other optional should you want double/reinforced protection

4. The Netgear WGR614 you examined is a smart device, not a dumb one. Because it's actually a computer. Though humble in appearance, it contains a CPU, memory, operating system-- the defining essentials. In addition, it has 2 network interfaces. To use this computer as a router for PCs, you need to connect them to it. You could do that just as you connect PCs to each other, by plugging them into a common switch. For marketability the small commercial router makers build a switch into their boxes. You got to have one; they're cheap to build in; the competitors do it. So you can hardly find a home router maker that doesn't build a switch into their router. Suppose you have 4 PCs and plug one into each of router's 4 visible internal/LAN ports (see http://dmorgan.us/cs530l/instructions/lab-deter-firewall-instructions-part3.htm).

Consider the switch built in to the WGR614. Physically, the number of computer connections it provides in the form of RJ-45 connection sockets is 4. Visibly. Electronically, by contrast, how many computer connections does this built-in switch have altogether? That is, if it is an n-port switch (electronically), what is n?
a. 2
b. 4 
c. 5 
d. 6