Gestion des utilisateurs et des groupes locaux

Changer le groupe d’un utilisateur usermod -g jedi dark_vador
Bloquer un utilisateur: usermod -L dark_vador
Débloquer un utilisateur usermod -U dark_vador
Définir une date d’expiration usermod -e 2020-05-29 dark_vador
Définir un nouveau mot de passe (non chiffré à la saisie) usermod -p test_password dark_vador
Changer l'id de l’utilisateur usermod -u 1234 dark_vador

Politique de gestion de mot de passe
#

Il est possible de définir la politique de gestion de mot de passe

Par commandes:

chage [-d lastday] [-m mindays] [-M maxdays] [-w warndays] [-I inactivedays] [-E expiredate] user

Par édition de fichier de configuration:

/etc/login.def

Les valeurs PASS* permettent de définir la politique à établir la longueur, la durée de validité d’un mot de passe et la méthode de cryptage du mot de passe.

# Please note that the parameters in this configuration file control the
# behavior of the tools from the shadow-utils component. None of these
# tools uses the PAM mechanism, and the utilities that use PAM (such as the
# passwd command) should therefore be configured elsewhere. Refer to
# /etc/pam.d/system-auth for more information.
#

# *REQUIRED*
#   Directory where mailboxes reside, _or_ name of file, relative to the
#   home directory.  If you _do_ define both, MAIL_DIR takes precedence.
#   QMAIL_DIR is for Qmail
#
#QMAIL_DIR	Maildir
MAIL_DIR	/var/spool/mail
#MAIL_FILE	.mail

# Password aging controls:
#
#	PASS_MAX_DAYS	Maximum number of days a password may be used.
#	PASS_MIN_DAYS	Minimum number of days allowed between password changes.
#	PASS_MIN_LEN	Minimum acceptable password length.
#	PASS_WARN_AGE	Number of days warning given before a password expires.
#
PASS_MAX_DAYS	99999
PASS_MIN_DAYS	0
PASS_MIN_LEN	5
PASS_WARN_AGE	7

#
# Min/max values for automatic uid selection in useradd
#
UID_MIN                  1000
UID_MAX                 60000
# System accounts
SYS_UID_MIN               201
SYS_UID_MAX               999

#
# Min/max values for automatic gid selection in groupadd
#
GID_MIN                  1000
GID_MAX                 60000
# System accounts
SYS_GID_MIN               201
SYS_GID_MAX               999

#
# If defined, this command is run when removing a user.
# It should remove any at/cron/print jobs etc. owned by
# the user to be removed (passed as the first argument).
#
#USERDEL_CMD	/usr/sbin/userdel_local

#
# If useradd should create home directories for users by default
# On RH systems, we do. This option is overridden with the -m flag on
# useradd command line.
#
CREATE_HOME	yes

# The permission mask is initialized to this value. If not specified, 
# the permission mask will be initialized to 022.
UMASK           077

# This enables userdel to remove user groups if no members exist.
#
USERGROUPS_ENAB yes

# Use SHA512 to encrypt password.
ENCRYPT_METHOD SHA512
The following is a partial list of /etc/login.defs directives:

Changement d’utilisateur
#

Commande: su - username

Elevation de privilège
#

Commandes:

sudo command
visudo - Editeur de texte du fichier /etc/sudoers avec vérification de conformité à l’enregistrement.

Fichier:

/etc/sudoers

#Allow member of group admin to execute any command
%admin ALL=(ALL)   ALL

#Allow member of group sudo to execute any command
%sudo ALL=(ALL:ALL)  ALL
root ALL=(ALL:ALL) ALL

Parcourront la règle en détail: