Context: Today, computer security comprises mainly "preventive" measures, like firewalls or an exit procedure. A firewall can be defined as a way of filtering network data between a host or a network and another network, such as the Internet, and can be implemented as software running on the machine, hooking into the network stack (or, in the case of most UNIX-based operating systems such as Linux, built into the operating system kernel) to provide real time filtering and blocking. Another implementation is a so-called physical firewall which consists of a separate machine filtering network traffic. Firewalls are common amongst machines that are permanently connected to the Internet.

Question: Firewalls and exit procedures are considered what?
Answer: "preventive" measures

Question: What is defined as a way of filtering network data between a host or network and another network?
Answer: A firewall

Question: What does a physical firewall consist of?
Answer: a separate machine filtering network traffic

Question: What type of machines normall have a firewall?
Answer: permanently connected to the Internet

Question: What compromises mainly preventative measures?
Answer: computer security

Question: Computer security is mostly comprised of what?
Answer: Unanswerable

Question: How are firewalls implemented?
Answer: Unanswerable

Question: Which system has a built in firewall?
Answer: Unanswerable

Question: What is another form of having a firewall connected?
Answer: Unanswerable

Question: Which part of a Linux computer is the firewall built into?
Answer: Unanswerable

Question: What types of measures do computer security firms rarely use today?
Answer: Unanswerable

Question: What type of machine rarely uses firewalls?
Answer: Unanswerable

Question: What is an exit procedure?
Answer: Unanswerable

Question: How are exit procedures implemented?
Answer: Unanswerable

Question: What type of OS does not use the operating system kernel?
Answer: Unanswerable