Describe possible occurrences of each of the main types of security threat (threats to processes, threats to communication channels, denial of service) that might occur in the Internet.

What will be an ideal response?

Threats to processes: without authentication of principals and servers, many threats exist. An enemy could access other user’s files or mailboxes, or set up ‘spoof’ servers. E.g. a server could be set up to ‘spoof’ a bank’s service and receive details of user’s financial transactions.
Threats to communication channels: IP spoofing - sending requests to servers with a false source address, man- in-the-middle attacks.

Denial of service: flooding a publicly-available service with irrelevant messages.