Raul is worried that his network might be attacked through modified ICMP messages. What can he do to prevent this?
A.
Disable anonymous logins
B.
Filter ICMP packets at the firewall
C.
Configure the firewall to block zone transfers
D.
Scan ICMP messages for viruses at the firewall
Explanation:
The thing to do is to prevent the ICMP packets from passing the firewall. No one really needs to have users from outside the network from being able to ping their machines. In addition, ICMP is used for traceroute will allow someone to map out the network, so why even open the network to that type of exposure.
Incorrect Answers:
A: The login process, whether anonymous or not, does not use ICMP messages, so this will not have an effect.
C: ICMP messages are not used in zone transfers, so this will have no effect.
D: A ICMP message can be dangerous just based on the size of the message. Using a message too large can overflow buffers. It could be spoofed and you can’t check that. An ICMP message would not be used to pass a virus in its payload, so scanning will have no effect.