chpasswd(8)

НАЗВАНИЕ
chpasswd - обновляет пароли в пакетном режиме

СИНТАКСИС

chpasswd [options]

ОПИСАНИЕ

The chpasswd command reads a list of user name and password pairs from standard input and uses this information to update a group of existing users. Each line is of the format:

user_name:password

By default the passwords must be supplied in clear-text, and are encrypted by chpasswd. Also the password age will be updated, if present.

The default encryption algorithm can be defined for the system with the ENCRYPT_METHOD or MD5_CRYPT_ENAB variables of /etc/login.defs, and can be overwritten with the -e, -m, or -c options.

chpasswd first updates all the passwords in memory, and then commits all the changes to disk if no errors occurred for any user.

Данная команда предназначена для работы в крупных системных средах, где за один раз заводится несколько учётных записей.

ПАРАМЕТРЫ

The options which apply to the chpasswd command are:

-c, --crypt-method METHOD
    Использовать указанный метод для шифрования паролей.

    The available methods are DES, MD5, SHA256, SHA512 and NONE if your libc supports these methods.

    By default (if none of the -c, -m, or -e options are specified), the encryption method is defined by the ENCRYPT_METHOD or MD5_CRYPT_ENAB variables of /etc/login.defs.

-e, --encrypted
    Передаваемые пароли заданы в шифрованном виде.

-h, --help
    Показать краткую справку и закончить работу.

-m, --md5
    Использовать алгоритм шифрования MD5 вместо DES, если пароли передаются не шифрованными.

-R, --root CHROOT_DIR
    Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory. Only absolute paths are supported. No SELINUX support.

-P, --prefix PREFIX_DIR
    Apply changes to configuration files under the root filesystem found under the directory PREFIX_DIR. This option does not chroot and is intended for preparing a cross-compilation target. Some limitations: NIS and LDAP users/groups are not verified. PAM authentication is using the host files. No SELINUX support.

-s, --sha-rounds ROUNDS
    Использовать указанное количество раундов шифрования паролей.

    You can only use this option with crypt method: SHA256 SHA512

    By default, the number of rounds for SHA256 or SHA512 is defined by the SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS variables in /etc/login.defs.

    A minimal value of 1000 and a maximal value of 999,999,999 will be enforced for SHA256 and SHA512. The default number of rounds is 5000.

ПРЕДОСТЕРЕЖЕНИЯ

Не забудьте установить права или umask, чтобы не позволить чтение не шифрованных файлов другими пользователями.

НАСТРОЙКА

The following configuration variables in /etc/login.defs change the behavior of this tool:

ENCRYPT_METHOD (string)
    This defines the system default encryption algorithm for encrypting passwords (if no algorithm is specified on the command line).

    It can take one of these values: DES (default), MD5, SHA256, SHA512. MD5 and DES should not be used for new hashes, see crypt(5) for recommendations.

    Note: this parameter overrides the MD5_CRYPT_ENAB variable.

MD5_CRYPT_ENAB (boolean)
    Indicate if passwords must be encrypted using the MD5-based algorithm. If set to yes, new passwords will be encrypted using the MD5-based algorithm compatible with the one used by recent releases of FreeBSD. It supports passwords of unlimited length and longer salt strings. Set to no if you need to copy encrypted passwords to other systems which don't understand the new algorithm. Default is no.

    This variable is superseded by the ENCRYPT_METHOD variable or by any command line option used to configure the encryption algorithm.

    This variable is deprecated. You should use ENCRYPT_METHOD.

SHA_CRYPT_MIN_ROUNDS (number), SHA_CRYPT_MAX_ROUNDS (number)
    When ENCRYPT_METHOD is set to SHA256 or SHA512, this defines the number of SHA rounds used by the encryption algorithm by default (when the number of rounds is not specified on the command line).

    With a lot of rounds, it is more difficult to brute force the password. But note also that more CPU resources will be needed to authenticate users.

    If not specified, the libc will choose the default number of rounds (5000), which is orders of magnitude too low for modern hardware.

    The values must be inside the 1000-999,999,999 range.

    If only one of the SHA_CRYPT_MIN_ROUNDS or SHA_CRYPT_MAX_ROUNDS values is set, then this value will be used.

    If SHA_CRYPT_MIN_ROUNDS > SHA_CRYPT_MAX_ROUNDS, the highest value will be used.

ФАЙЛЫ

/etc/passwd
    содержит информацию о пользователях

/etc/shadow
    содержит защищаемую информацию о пользователях

/etc/login.defs
    содержит конфигурацию подсистемы теневых паролей

СМОТРИТЕ ТАКЖЕ

passwd(1), newusers(8), login.defs(5), useradd(8).