15 August 2011

generate passwords with pwgen

Install pwgen in ubuntu 11.04 with:
sudo apt-get install pwgen
excerpt from man pwgen - generate pronounceable passwords
pwgen [ OPTION ] [ pw_length ] [ num_pw ]

The pwgen program generates passwords which are designed to be easily memorized by humans, while being as secure as possible. Human-memorable passwords are never going to be as secure as completely completely random passwords.

The pwgen program is designed to be used both interactively, and in shell scripts.

Used interactively, pwgen will display a screenful of passwords, allowing the user to pick a single password, and then quickly erase the screen. This prevents someone from being able to "shoulder surf" the user's chosen password.

When standard output (stdout) is not a tty, pwgen will only generate one password, as this tends to be much more convenient for shell scripts, and in order to be compatible with previous versions of this program.


-0, --no-numerals Don't include numbers in the generated passwords.
-A, --no-capitalize Don't bother to include any capital letters in the generated passwords.
-B, --ambiguous Don't use characters that could be confused by the user when printed, such as 'l' and '1', or '0' or 'O'. This reduces the number of possible passwords significantly, and as such reduces the quality of the passwords. It may be useful for users who have bad vision, but in general use of this option is not recommended.
-c, --capitalize Include at least one capital letter in the password. This is the default if the standard output is a tty device.
-N, --num-passwords=num Generate num passwords. This defaults to a screenful if passwords are printed by columns, and one password.
-n, --numerals Include at least one number in the password. This is the default if the standard output is a tty device.
-s, --secure Generate completely random, hard-to-memorize passwords. These should only be used for machine passwords, since otherwise it's almost guaranteed that users will simply write the password on a piece of paper taped to the monitor...
-v, --no-vowels Generate random passwords that do not contain vowels or numbers that might be mistaken for vowels. It provides less secure passwords to allow system administrators to not have to worry with random passwords accidentally contain offensive substrings.
-y, --symbols Include at least one special character in the password.

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