man/orig/pwgen
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PWGEN(1) PWGEN(1)
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[править] NAME
pwgen - generate pronounceable passwords
[править] SYNOPSIS
pwgen [ OPTION ] [ pw_length ] [ num_pw ]
[править] DESCRIPTION
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
passwords.
-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-
mended.
-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 ~/your_favorite.mp3#your@email.com 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
file.
-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 <tytso@alum.mit.edu>. 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
passwd(1)
pwgen version 2.05 January 2006 PWGEN(1)
