The real-valued function whose value is to be either minimized or maximized subject to the constraints defined on the given LPP over the set of feasible solutions. The objective function of a LPP is a linear function of the form z = ax + by.
Answer: The statement implies that the hackers psychologically manipulate the human to access the information they need.
Explanation: The author states that the hacker does not only exploits technology to get system access or to gather information. But there is another pivotal part of hacking. He refers to this part as "social engineering".
Social engineering from information security perspective means manipulate human emotions and convincing them to disclose some confidential information. Hacker often hacks or defrauds after gaining confidence and trust of a person.
Phishing is an example. It is a fraudulent technique for getting some secret information. Phisher sends an email pretending to be from some reputable organization to persuade people to divulge private information like passwords and credit card numbers, ATM card pin etc.
He could use bold or bigger text just a suggestion.
Every application has access to specific opened port. If you only make a exception for the specific application only that application can bypass the firewall.