chgpasswd(8)

НАЗВАНИЕ
chgpasswd - обновляет пароли групп в пакетном режиме

СИНТАКСИС

chgpasswd [options]

ОПИСАНИЕ

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

group_name:password

By default the supplied password must be in clear-text, and is encrypted by chgpasswd.

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

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

ПАРАМЕТРЫ

The options which apply to the chgpasswd command are:

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

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

-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.

-s, --sha-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.

Вы должны проверить, что пароль и метод шифрования соответствует политике системных паролей.

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.

MAX_MEMBERS_PER_GROUP (number)
    Maximum members per group entry. When the maximum is reached, a new group entry (line) is started in /etc/group (with the same name, same password, and same GID).

    The default value is 0, meaning that there are no limits in the number of members in a group.

    This feature (split group) permits to limit the length of lines in the group file. This is useful to make sure that lines for NIS groups are not larger than 1024 characters.

    If you need to enforce such limit, you can use 25.

    Note: split groups may not be supported by all tools (even in the Shadow toolsuite). You should not use this variable unless you really need it.

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/group
    содержит информацию о группах

/etc/gshadow
    содержит защищаемую информацию о группах

/etc/login.defs
    содержит конфигурацию подсистемы теневых паролей

СМОТРИТЕ ТАКЖЕ

gpasswd(1), groupadd(8), login.defs(5).