Libuser (5) Linux Manual Page

libuser.conf – configuration for libuser and libuser utilities

File Format

libuser.conf is a text file. Leading and trailing white space on each line is ignored. Lines starting with # are ignored.

The file defines variables grouped into sections. Each section starts with a section header:

[section name]

A single section header can appear more than once in the file.

The lines following a section header define variables from that section:

variable = value

The value can be empty.

A variable can have more than one value, specified by using more than one line defining that variable. All currently defined variables accept only the first value and ignore the others, if any.

`[defaults]`

create_modules

A list of module names to use when creating user or group entries, unless the application specifies a different list. The module names in the list can be separated using space, tab or comma. Default value is files shadow.

crypt_style

The algorithm to use for password encryption when creating new passwords. The current algorithm may be retained when changing a password of an existing user, depending on the application.

Possible values are des, md5, blowfish, sha256 and sha512, all case-insensitive. Unrecognized values are treated as des. Default value is des.

hash_rounds_min, hash_rounds_max

These variables specify an inclusive range of hash rounds used when crypt_style is sha256 or sha512. A number of hash rounds is chosen from this interval randomly. A larger number of rounds makes password checking, and brute-force attempts to guess the password by reversing the hash, more CPU-intensive. The number of rounds is restricted to the interval [1000, 999999999].

If only one of the above variables is specified, the number of rounds used is specified by the other variable. If neither variable is specified, the number of rounds is chosen by libc.

mailspooldir

The directory containing user’s mail spool files. Default value is /var/mail.

moduledir

The directory containing libuser modules. Default value uses the modules installed with libuser, corresponding to the architecture of the libuser library, e.g. /usr/lib/libuser or /usr/lib64/libuser (assuming libuser was configured with –prefix=/usr).

modules

A list of module names to use when not creating user or group entries, unless the application specifies a different list. The module names in the list can be separated using space, tab or comma. Default value is files shadow.

skeleton

The directory containing files to copy to newly created home directories. Default value is /etc/skel.

`[import]`

login_defs

A path to the login.defs file from shadow. If this variable is defined, the variables from the named file are used in place of some libuser variables. Variables explicitly defined in libuser.conf are not affected by contents of login.defs.

The following variables are imported:

Variable	Imported as
ENCRYPT_METHOD
`GID_MIN`	`groupdefaults/LU_GIDNUMBER`
`MAIL_DIR`	`defaults/mailspooldir`
`MD5_CRYPT_ENAB`	`defaults/crypt_style`
`PASS_MAX_DAYS`	`userdefaults/LU_SHADOWMAX`
`PASS_MIN_DAYS`	`userdefaults/LU_SHADOWMIN`
`PASS_WARN_AGE`	`userdefaults/LU_SHADOWWARNING`
`SHA_CRYPT_MIN_ROUNDS`	`defaults/hash_rounds_min`
`SHA_CRYPT_MAX_ROUNDS`	`defaults/hash_rounds_max`
`UID_MIN`	`userdefaults/LU_UIDNUMBER`

The following variables are not imported: CREATE_HOME, GID_MAX, MAIL_FILE, SYSLOG_SG_ENAB, UID_MAX, UMASK, USERDEL_CMD, USERGROUPS_ENAB

default_useradd

A path to the default/useradd file from useradd in shadow. If this variable is defined, the variables from the named file are used in place of some libuser variables. Variables explicitly defined in libuser.conf are not affected by contents of default/useradd.

The following variables are imported:

Variable	Imported as
EXPIRE
`GROUP`	`userdefaults/LU_GIDNUMBER`
`HOME`	`userdefaults/LU_HOMEDIRECTORY`
`INACTIVE`	`userdefaults/LU_SHADOWINACTIVE`
`SHELL`	`userdefaults/LU_LOGINSHELL`
`SKEL`	`defaults/skeleton`

The HOME variable value has /%n appended to it before importing.

`[userdefaults]`

This section defines attribute values of newly created user entities. There is one special variable:

LU_UIDNUMBER: A decimal number, the first allowed UID value for regular users (not system users). Default value is 500.

All other variables have the same names as the attribute names from <libuser/entity.h> and define attribute values. Either the macro name (e.g. LU_GECOS) or the macro content (e.g. pw_gecos) can be used; if both are used, the one appearing later in the configuration file is used.

The % character in the value of the variable introduces an escape sequence: %n is replaced by the user name, %d is replaced by current date in days since the epoch, %u is replaced by the user’s UID. There is no way to escape the % character and avoid this substitution.

After the userdefaults section is processed, modules may define additional attributes or even override the attributes defined in this section.

`[groupdefaults]`

The groupdefaults section is similar to userdefaults. There is one special variable:

LU_GIDNUMBER: A decimal number, the first allowed GID value for regular groups (not system groups). Default value is 500.

The other variables follow the same rules as in the userdefaults section, except that %n and %u are replaced by the group name and group’s GID, respectively.

After the groupdefaults section is processed, modules may define additional attributes or even override the attributes defined in this section.

`[files]`

Configures the files module, which manages /etc/group and /etc/passwd. The configuration variables are probably useful only for libuser development.

directory: The directory containing the group and passwd files. Default value is /etc.
nonroot: Allow module initialization when not invoked as the root user if the value is yes.

`[shadow]`

Configures the files module, which manages /etc/gshadow and /etc/shadow. The configuration variables are probably useful only for libuser development.

directory: The directory containing the gshadow and shadow files. Default value is /etc.
nonroot: Allow module initialization when not invoked as the root user if the value is yes.

`[ldap]`

Configures the ldap module, which manages an user database accessible using LDAP.

userBranch

The LDAP suffix for user entities. Default value is ou=People.

groupBranch

The LDAP suffix for group entities. Default value is ou=Group.

server

A domain name or an URI of the LDAP server. The URI can use the ldap, ldapi or the ldaps protocol. When a simple domain name is used, the connection fails if TLS can not be used; an URI using the ldap protocol allows connection without TLS. TLS is never used with the ldapi protocol. Default value is ldap.

basedn

The base DN of the server. Default value is dc=example,dc=com.

binddn

A DN for binding to the server. If the value is empty or binding using this DN fails, a DN of uid=user,userBranch,basedn is used, where userBranch and basedn are variables from this section and user is the user name of the invoking user, unless overridden by the user variable from this section. Default value is cn=manager,dc=example,dc=com.

user

The SASLv2 identity for authenticating to the LDAP server, also overrides the user name for generating a bind DN. Default value is the name of the invoking user.

password

The password used for a simple bind by default. If not specified, there is no default and the user must supply the password each time.

IT IS STRONGLY RECOMMENDED NOT TO STORE A PASSWORD IN THE SYSTEM-WIDE /etc/libuser.conf FILE. The configuration file is world-readable by default, and setuid programs that prompt for a server name could be used to send the password to an attacker-controlled server.

authuser

The SASLv2 authorization user, if non-empty. Default value is empty.

bindtype

The list of bind types to use, separated by commas. Allowed bind types are simple, sasl, and sasl/mechanism, where mechanism is a SASL mechanism. The bind types (but not necessarily mechanism) are case-insensitive. If more than one bind type is specified, their relative order is ignored. Default value is simple,sasl.

`[sasl]`

Configures the sasl module, which manages a SASLv2 user database.

appname: Name of the SASLv2 application. Default value is empty.
domain: Domain used by libuser for the SASLv2 authentication object. Default value is empty.

Bugs

Invalid lines in the configuration file (or the imported shadow configuration files) are silently ignored.

Files

/etc/libuser.conf: The default location of the configuration file. Can be overridden by the LIBUSER_CONF environment variable, except in set-uid or set-gid programs.

libuser (5) Linux Manual Page