John has a proxy server on his network which caches and filters web access. He shuts down all unnecessary ports and services. Additionally, he has installed a firewall (Cisco PIX) that will not allow users to connect to any outbound ports. Jack, a network user has successfully connected to a remote server on port 80 using netcat. He could in turn drop a shell from the remote machine. Assuming an attacker wants to penetrate John's network, which of the following options is he likely to choose?

The following is part of a log file taken from the machine on the network with the IP address of 192.168.1.106:
Time:Mar 13 17:30:15 Port:20 Source:192.168.1.103 Destination:192.168.1.106 Protocol:TCP
Time:Mar 13 17:30:17 Port:21 Source:192.168.1.103 Destination:192.168.1.106 Protocol:TCP
Time:Mar 13 17:30:19 Port:22 Source:192.168.1.103 Destination:192.168.1.106 Protocol:TCP
Time:Mar 13 17:30:21 Port:23 Source:192.168.1.103 Destination:192.168.1.106 Protocol:TCP
Time:Mar 13 17:30:22 Port:25 Source:192.168.1.103 Destination:192.168.1.106 Protocol:TCP
Time:Mar 13 17:30:23 Port:80 Source:192.168.1.103 Destination:192.168.1.106 Protocol:TCP
Time:Mar 13 17:30:30 Port:443 Source:192.168.1.103 Destination:192.168.1.106 Protocol:TCP
What type of activity has been logged?

Which of the following are valid types of rootkits? (Choose three.)

Which of the following is a preventive control?

Rebecca has noted multiple entries in her logs about users attempting to connect on ports that are either not opened or ports that are not for public usage. How can she restrict this type of abuse by limiting access to only specific IP addresses that are trusted by using one of the built-in Linux Operating System tools?