The system administrator can set the password policy (minimum length, requirement of special characters, password expiry) through the utility included in this configuration program (run as root):
linuxconf
under the menu "user account"-"policies"-"password & account policies". Normal users won't be able to set a password which is too short, is a dictionary word, or does not contain the prescribed number of non-alphanumeric characters (but root can change any password to anything s/he likes, s/he will only be given a warning).
Also make sure that any file that contains any password of yours (e.g., /root/.kde/share/config/kppprc) has proper, secure permissions so that it cannot be read by anybody. For example, most likely you want:
chmod 600 kppprc
If you use an "over the phone" Internet connection for just a couple of hours a week, you may be fine even with a relatively weak password on your system. But please really reconsider your system security if you use a cable modem, or are otherwise connected to the Internet for a significant amount of time.
Most computer semi-literate use amazingly weak passwords. "Around 50 percent of computer users base passwords on the name of a family member, partner or a pet. Thirty percent look to a pop idol or sporting hero," reports CNN (http://www.cnn.com/2002/TECH/ptech/03/13/dangerous.passwords/index.html). Please note the underlined base. Appending a digit to an obvious word hardly makes the password more secure.
4.2.3 I forgot the root password
Even if I never forget any passwords, I would still study this issue in detail because it can give me a hint on how my mother might be reading my ICQ chats history :-)
First method. The easiest way to solve your "forgotten root password" problem is to boot your Linux in the single-user mode, namely at the "lilo"prompt (during bootup) type:
linux single
This will make you "root" without asking for a password. Now, being root, you may change the root password using this command (no knowledge of the old password required):
passwd
If it strikes you as insecure, that's because no computer system is secure if other people have physical access to your hardware. Nevertheless, I did not like the "linux single" hole on my home computer and plugged it by adding the following lines to my /etc/lilo.conf file (at the end of the "image=" section):
password="my_password"
restricted
[This "lilo" password is required when, at the LILO prompt during bootup, somebody enters the word "linux" with any parameter (normal bootup without any parameters will still be possible without a password).] For the changes to /etc/lilo.conf to take effect, I must re-run the command lilo . Since my lilo password is not encrypted, I must make /etc/lilo.conf readable only for root:
chmod 600 /etc/lilo.conf
Second Method. Another way to solve the "lost-root-password" problem is to boot your computer from the Linux boot diskette or the CD. Then find your Linux root partition on the hard drive, mount it, and edit the file /etc/shadow. (I can do it because after booting from the floppy, I become root without being asked for a password.) In the password file, I erase the encrypted password for root (for example, using the pico editor), so it is empty.
Information about a user account is kept in plain-text files: /etc/passwd and /etc/shadow.
The file /etc/passwd contains the "world-readable" information about all accounts on my computer Each line in this file contains information about one account. Each line has 7 colon-delimited fields (this means 8 entries separated by colons): login name, the letter "x", the numerical user ID, the numerical primary group ID for the user, a comment field (for example, the full name of the user), the user's $HOME directory, the name of the shell (meaning the program that is run at login).
The balance of information about accounts on my computer is stored in the file /etc/shadow. This
