1) Password cracking is the process of recovering secret passwords through various techniques like hashing, guessing using dictionaries, using default passwords, brute force, and phishing.
2) Common password cracking techniques include exploiting weak hashing algorithms, guessing using common words and personal details, using default passwords for applications, trying all possible character combinations through brute force, and tricking users into revealing passwords through phishing.
3) IP spoofing involves modifying the source IP address field in the IP packet header to disguise the identity of the sender or impersonate another system and exploit weaknesses in the connection-oriented TCP protocol.