login.defs.5

pwdutils是一套密码管理工具

.\"$Id: login.defs.5,v 1.6 2005/06/03 10:20:10 kukuk Exp $
.\" Copyright 2004 Thorsten Kukuk
.\" Copyright 1991 - 1993, Julianne Frances Haugh and Chip Rosenthal
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.TH LOGIN 5
.SH NAME
/etc/login.defs \- Login configuration
.SH DESCRIPTION
The
.I /etc/login.defs
file defines the site-specific configuration for the shadow login
suite.  This file is required.  Absence of this file will not prevent
system operation, but will probably result in undesirable operation.
.PP
This file is a readable text file, each line of the file describing
one configuration parameter.  The lines consist of a configuration
name and value, seperated by whitespace.  Blank lines and comment
lines are ignored.  Comments are introduced with a `#' pound sign and
the pound sign must be the first non-white character of the line.
.PP
Parameter values may be of four types:  strings, booleans, numbers,
and long numbers.  A string is comprised of any printable characters.
A boolean should be either the value ``yes'' or ``no''.  An undefined
boolean parameter or one with a value other than these will be given
a ``no'' value.  Numbers (both regular and long) may be either decimal
values, octal values (precede the value with ``0'') or hexadecimal
values (precede the value with ``0x'').  The maximum value of the
regular and long numeric parameters is machine-dependant.
.PP
The following configuration items are provided:
.\"
.IP "CHARACTER_CLASS (string)"
User accounts and Group names have to match the regex expression
of this variable.
.\"
.IP "CHFN_AUTH (boolean)"
If
.IR yes ,
the
.B chfn
and
.B chsh
programs will ask for password before making any changes, unless
run by the superuser.
.\"
.IP "CHFN_RESTRICT (string)"
This parameter specifies which values in the
.I gecos
field of the
.I passwd
file may be changed by regular users using the
.B chfn
program.  It can be any combination of letters
.IR f ,
.IR r ,
.IR w ,
.IR h ,
for Full name, Room number, Work phone, and Home phone, respectively.
If not specified, only the superuser can make any changes.
.\"
.IP "DEFAULT_HOME (boolean)"
If the home directory of a user is not reachable, should the
use be allowed to login ?
.\"
.IP "ENV_PATH (string)"
This parameter must be defined as the search path for regular users.
When a login with UID other than zero occurs, the PATH environment
parameter is initialized to this value.
.\"
.IP "ENV_ROOTPATH (string)"
This parameter must be defined as the search path for root.
.\"
.IP "FAIL_DELAY (number)"
Delay time in seconds after each failed login attempt.
.\"
.IP "FTMP_FILE (string)"
If defined and the file exist, login failures will be logged here
in a utmp format.
.BR last ,
when invoked as
.BR lastb ,
will read /var/log/btmp, so you should use this file if any.
.\"
.IP "GID_MAX (number)"
.IP "GID_MIN (number)"
Range of group IDs to choose from for the
.B groupadd
program.
.\"
.IP "HUSHLOGIN_FILE (string)"
This parameter is used to establish ``hushlogin'' conditions.  There
are two possible ways to establish these conditions.  First, if the
value of this parameter is a filename and that file exists in the
user's home directory then ``hushlogin'' conditions will be in effect.
The contents of this file are ignored; its mere presence triggers
``hushlogin'' conditions.  Second, if the value of this parameter is
a full pathname and either the user's login name or the user's shell
is found in this file, then ``hushlogin'' conditions will be in effect.
In this case, the file should be in a format similar to:
.nf
.sp
.ft I
	demo
	/usr/lib/uucp/uucico
	\0\0.
	\0\0.
	\0\0.
.ft R
.sp
.fi
If this parameter is not defined, then ``hushlogin'' conditions will
never occur.  When ``hushlogin'' conditions are established, the
message of the day, last successful and unsuccessful login display,
mail status display, and password aging checks are suppressed.  Note
that allowing hushlogin files in user home directories allows the user
to disable password aging checks.  See MOTD_FILE and
LASTLOG_ENAB for related information. Futures enabled through PAM
modules are not affected by this. pam_mail will show if there is
new mail or not.
.\"
.IP "LASTLOG_ENAB (boolean)"
If
.IR yes ,
and if the
.I /var/log/lastlog
file exists, then a successful user login will be recorded to this
file.  Furthermore, if this option is enabled then the times of the
most recent successful and unsuccessful logins will be displayed to
the user upon login. If ``hushlogin'' conditions are in
effect, then both the successful and unsuccessful login information
will be suppressed.
.\"
.IP "LOG_UNKFAIL_ENAB (boolean)"
If
.I yes
then unknown usernames will be included when a login failure is
recorded.  Note that this is a potential security risk; a common login
failure mode is transposition of the user name and password, thus this
mode will often cause passwords to accumulate in the failure logs.
If this option is disabled then unknown usernames will be suppressed
in login failure messages.
.\"
.IP "LOGIN_RETRIES (number)"
Number of login attempts allowed before the
.B login
program exits.
.\"
.IP "LOGIN_TIMEOUT (number)"
Time in seconds after the
.B login
program exits if the user doesn't type his password.
.\"
.IP "MOTD_FILE (string)"
This parameter specifies a colon-delimited list of pathnames to ``message
of the day'' files.
If a specified file exists, then its contents are displayed to the user
upon login.
If this parameter is not defined or ``hushlogin'' login conditions are
in effect, this information will be suppressed.
.\"
.IP "PASS_MIN_DAYS (number)"
The minimum number of days allowed between password changes.  Any password
changes attempted sooner than this will be rejected.  If not specified, a
zero value will be assumed.
.\"
.IP "PASS_MAX_DAYS (number)"
The maximum number of days a password may be used.  If the password is
older than this, then the account will be locked.  If not specified,
a large value will be assumed.
.\"
.IP "PASS_WARN_AGE (number)"
The number of days warning given before a password expires.  A zero means
warning is given only upon the day of expiration, a negative value means
no warning is given.  If not specified, no warning will be provided.
.\"
.IP "SYSTEM_GID_MAX (number)"
Max group ID value used by automatic gid selection in groupadd for system groups
.IP "SYSTEM_GID_MIN (number)"
Min group ID value used by automatic gid selection in groupadd for system groups
.\"
.IP "SYSTEM_UID_MAX (number)"
Max user ID value used by automatic uid selection in useradd for system accounts
.IP "SYSTEM_UID_MIN (number)"
Min user ID value used by automatic uid selection in useradd for system accounts
.\"
.IP "TTYGROUP (string or number)"
The group ownership of the terminal is initialized to this group
name or number.  One well-known security attack involves forcing terminal
control sequences upon another user's terminal line.  This problem
can be averted by disabling permissions which allow other users to
access the terminal line, but this unfortunately prevents programs
such as
.B write
from operating.  Another solution is to use a version of the
.B write
program which filters out potentially dangerous character sequences,
make this program ``setgid'' to a special group, assign group ownership
of the terminal line to this special group, and assign permissions of
\fI0620\fR to the terminal line.  The TTYGROUP definition has been
provided for just this situation.  If this item is not defined, then
the group ownership of the terminal is initialized to the user's group
number.  See TTYPERMS for related information.
.\"
.IP "TTYPERM (number)"
The login terminal permissions are initialized to this value.  Typical
values will be \fI0622\fR to permit others write access to the line
or \fI0600\fR to secure the line from other users.  If not specified,
the terminal permissions will be initialized to \fI0622\fR.  See
TTYGROUP for related information.
.\"
.IP "TTYTYPE_FILE (string)"
This parameter specifies the full pathname to a file which maps terminal
lines to terminal types.  Each line of the file contains a terminal
type and a terminal line, seperated by whitespace, for example:
.nf
.sp
.ft I
	vt100\0	tty01
	wyse60	tty02
	\0\0.\0\0\0	\0\0.
	\0\0.\0\0\0	\0\0.
	\0\0.\0\0\0	\0\0.
.ft R
.sp
.fi
This information is only used to initialize the TERM environment parameter
when it does not already exist.
A line starting with a ``#'' pound sign will be treated as a comment.
If this paramter is not specified, the file does not exist, or the terminal
line is not found in the file, then the TERM environment parameter will not
be set.
.\"
.IP "UID_MAX (number)"
Max user ID value for automatic uid selection in useradd
.IP "UID_MIN (number)"
Min user ID value for automatic uid selection in useradd
.\"
.IP "UMASK (number)"
The permission mask is initialized to this value. It is used by
useradd and newusers for creating new home directories. If not specified,
the permission mask will be initialized to \fI0077\fR.
.\"
.IP "USERADD_CMD (string)"
If defined, this command is run after adding a user with \fBuseradd\fR.
It can, for example, rebuild the NIS maps in this script.
.\"
.IP "USERDEL_PRECMD (string)"
If defined, this command is run before removing a user with \fBuserdel\fR.
It should remove any at/cron/print jobs etc. owned by the user to be
removed (passed as the first argument).
.\"
.IP "USERDEL_POSTCMD (string)"
If defined, this command is run after removing a user with \fBuserdel\fR.
It can, for example, rebuild any NIS database etc. to remove the account from it.
.\"
.SH CROSS REFERENCE
The following cross reference shows which programs in the shadow login
suite use which parameters.
.na
.IP login 12
DEFAULT_HOME ENV_PATH ENV_ROOTPATH FAIL_DELAY FTMP_FILE
HUSHLOGIN_FILE LASTLOG_ENAB LOG_UNKFAIL_ENAB LOGIN_RETRIES LOGIN_TIMEOUT
MOTD_FILE TTYPERM TTYTYPE_FILE
.IP newusers 12
PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE UMASK
.IP passwd 12
OBSCURE_CHECKS_ENAB PASS_MAX_LEN PASS_MIN_LEN PASS_ALWAYS_WARN
CRACKLIB_DICTPATH PASS_CHANGE_TRIES
.IP pwconv 12
PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
.ad
.SH BUGS
Some of the supported configuration parameters are not documented in this
manual page.
.SH SEE ALSO
.BR login (1),
.BR passwd (5)
.SH AUTHORS
Julianne Frances Haugh ([e-mail])
.br
Thorsten Kukuk ([e-mail])