1) Computer security involves network security, host security, physical security, and encryption techniques like hashing and public/private key encryption.
2) Passwords should be complex, containing a mix of characters, and different for each account. Strong passwords are at least 16 characters.
3) Hackers can be categorized by their motives - white hats help security, black hats harm systems, and grey hats can be either. Black hats are also called crackers.
36. Normally white hats tend to help others (free or for a fee) and make the world a better place. Black hats tend to make the world much worse for their own benefits only.
37. Both use the same knowledge, have the same skills.
82. Active connection: Port 20, normal 3 way connection RELATED to the previous connection, initiated by client
83. Passive connection: 3 way connection RELATED to the control connection, initiated by the server from a random port on the server to a random port at the client
84.
85.
86.
87. iptables -A INPUT -p tcp --sport 1024: --dport 1024: -m state --state RELATED,ESTABLISHED -j ACCEPT