Final answer:
The correct log filtering methods are whitelisting, blacklisting, and graylisting. These are key techniques used to control access to systems and are important for maintaining cyber security. They differ in how they manage known and unknown entities.
Step-by-step explanation:
The question asks about methods of log filtering, which is a process used to manage and scrutinize the logs generated by systems to find irregular or suspicious activity. Out of the provided options, the correct methods of log filtering are A. Whitelisting, blacklisting, and graylisting. These techniques help in managing access by categorizing entities like email addresses, IP addresses, or domain names.
Whitelisting is a method where a list of entities that are allowed access is maintained. Anything not on this list is denied by default. Conversely, blacklisting involves creating a list of entities that are denied access, where everything not on the list is permitted by default. Graylisting, particularly used in email filtering, temporarily rejects emails from unknown senders and monitors if the sender attempts to send it again, thereby distinguishing legitimate servers from spam.
These methods are crucial for security and are commonly used in conjunction with other systems like firewalls and intrusion detection systems to protect networks and servers from unauthorized access and potential cyber threats.