Answer:
1. Sniffing.
2. Sequence number.
3. Phishing.
4. Null session.
Step-by-step explanation:
1. Sniffing is a situation where someone examines all the network traffic that passes their NIC, whether addressed for them or not.
2. A sequence number is a 32-bit number established by the host that is incremented for each packet sent. It can be used by a computer administrator or network engineer to reorder packets.
3. Phishing is the use of fraudulent e-mails or instant messages that appear to be genuine but are designed to trick users. Informations such as password, credit card details and other personal information can be gotten by an attacker through this process.
4. A null session is a connection to a Windows interprocess communications share (IPC$). A hacker can use a null session to gain unauthorized access to informations such as security settings, registry settings, username (User ID) about an end user.