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[править] NAME

      pwgen - generate pronounceable passwords

[править] SYNOPSIS

      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. In particular, passwords generated by pwgen without the -s option should not be used in places where the password could be attacked via an off-line brute-force attack. On the other hand, completely randomly generated passwords have a tendency to be written down, and are subject to being compromised in that fashion.

The pwgen program is designed to be used both interactively, and in shell scripts. Hence, its default behavior differs depending on whether the standard output is a tty device or a pipe to another program. 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.

In addition, for backwards compatibility reasons, when stdout is not a tty and secure password generation mode has not been requested, pwgen will generate less secure passwords, as if the -0A options had been passed to it on the command line. This can be overriden using the -nc options. In the future, the behavior when stdout is a tty may change, so shell scripts using pwgen should explicitly specify the -nc or -0A options. The latter is not recommended for security reasons, since such passwords are far too easy to guess.

[править] OPTIONS

      -0, --no-numerals
             Don't include numbers in the generated passwords.
      -1     Print the generated passwords one per line.
      -A, --no-capitalize
             Don't bother to include any capital  letters  in  the  generated
      -a, --alt-phonics
             This  option doesn't do anything special; it is present only for
             backwards compatibility.
      -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 recom-
      -c, --capitalize
             Include  at  least  one capital letter in the password.  This is
             the default if the standard output is a tty device.
      -C     Print the generated passwords in columns.  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 pass-
             words 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.
      -H, --sha1=/path/to/file[#seed]
             Will  use the sha1's hash of given file and the optional seed to
             create password. It will allow you to compute the same  password
             later, if you remember the file, seed, and pwgen's options used.
             ie: pwgen -H ~/ gives a list  of
             possibles  passwords for your pop3 account, and you can ask this
             list again and again.
             WARNING: The passwords generated using this option are not  very
             random.   If you use this option, make sure the attacker can not
             obtain a copy of the file.  Also, note that the name of the file
             may  be  easily available from the ~/.history or ~/.bash_history
      -h, --help
             Print a help message.
      -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.

[править] AUTHOR

This version of pwgen was written by Theodore Ts'o <>. It is modelled after a program originally written by Brandon S. Allbery, and then later extensively modified by Olaf Titz, Jim Lynch, and others. It was rewritten from scratch by Theodore Ts'o because the original program was somewhat of a hack, and thus hard to maintain, and because the licensing status of the program was unclear.

[править] SEE ALSO


pwgen version 2.05 January 2006 PWGEN(1)

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