CONTENTS

Firewalls: Attacking the Server Without a Firewall

1.  Attack the Server Without a Firewall. 

1.  Open 6 terminals on the client and resize them within one window so that you can see all the terminals.

2.  In five terminals, type the following command:



3.  Check to see if any of the ping packets were got through the firewall.  In the 6th terminal, open an FTP connection to the server using the following command and log-in information. 

$ ftp 192.168.24.100
Username : firewall
Password : goodguy

4. After you have logged-in to the FTP server, use command as follow to retrieve a file.  

ftp> binary
ftp> get firewall.doc

5. Record the total time of the transmission.  Repeat this process three times.

Repetition Time (sec.)
1 __________________
2 __________________
3 __________________

AVERAGE TIME : __________________________ FILE SIZE : __________________ Bytes

6. Using the following command to quit the FTP connection.

ftp> bye

7. Use Ctrl-C to quit the PING process in the other five terminals.

2.  Attack the Server With a Firewall.

1.  Configure the console computer. 

a.   Log-in or continue the session

b.  Type in the following configuration settings:

> add filter ether1.in
> set filter ether1.in 1 permit tcp 192.168.23.0/24
> set ether1 ifilter ether1.in
> save filter

To show the rules, which were entered to the firewall use Command > show filter ether1.in

2. Configuring the client computer

a.   Follow the previous steps to attack the server with a firewall that you used to Attack the Server Without a Firewall. 

b.  Record the total time of the transmission.  Repeat this process three times.

Repeat this process three times.

Repetition Time (sec.)
1 __________________
2 __________________
3 __________________

AVERAGE TIME : __________________________

3. Questions. 

1.  Explain the attack and discuss the results when compared with those of the section above, Attack the Server Without a Firewall.

2.  What is the message returned by the PING command and why was this the message returned?  You answer should be based on the configuration above.

3.  Assume that there are two subnets, i.e., 192.168.22.0 and 192.168.23.0. Is it possible for a subnet 192.168.22.0 to ftp this server? Why?

4. An Alternative Rule Set. 

1. At the console computer, type in the commands as follows:

> delete filter ether1.in
> add filter ether1.in
> set filter ether1.in 1 deny icmp
> set filter ether1.in 2 permit tcp
> set ether1 ifilter ether1.in
> save filter

2. Repeat the steps found in  Attack the Server Without a Firewall section. 

3. Record the total time of the transmission.  Repeat this process three times.

Repeat this process three times.

Repetition Time (sec.)
1 __________________
2 __________________
3 __________________

AVERAGE TIME : __________________________

5. Questions.

1.  Do you see any different in the results between this step and the previous step in  the section Attack the Server With a Firewall? Why?

2.  Assume that there are two subnets, i.e., 192.168.22.0 and 192.168.23.0. Is it possible for a subnet 192.168.22.0 to ftp to this server? Why?