tion files are held.Shell - a program that is executed once the user logs in. In most cases (and in this case too) the shell is a command interpreter(20).In our case, the encrypted password field is empty, which means that the user gets to log in by simply giving a username. This can be changed after we log in by typing passwd to the command interpreter. You will then be asked for a password to be set for your account.Note: on some systems, you have to type passwd your-username instead of simply typing passwd.Note 2: root can do passwd your-username and change your-username's password, no matter who your-username is.Note 3: if you put any characters that are not of the following sets: '. / 0-9 a-z A-Z' (without the quotes) or if you don't put anything in, the account is disabled so that user cannot log in.This is used when you know you might want to enable this account in the future.Cracking the encrypted password*******************************For this you need a password cracker. A password cracker is a program that takes a certain word out of a dictionary file (also referred to as a "wordlist") or a combination of letters, numbers etc' the program makes up systematically ("brute-force cracking"), encrypts it the way Unix encrypts passwords and then compares it to the passwords in a given password file. If the passwords match, it will announce the correct password for that username.34. Thread - right now I'm talking about threads in discussion lists and message boards, not on computer programs. We'll discuss about these in a later time (maybe).A thread is a series of posts which started out from a single one. Let me demonstrate: a person starts a thread by stating a fact or making an opinion. Then, another person comes into the discussion list or into the message board and states his opinion on the subject. Then another person joins in and reply to the replier's opinion. Then another one comes, but chooses to reply to the original mess...
