contains various attributes and capabilities of login classes.
A login class (an optional annotation against each record in the user
account database,
/etc/master.passwd
determines session accounting, resource limits and user environment settings.
It is used by various programs in the system to set up a user's login
environment and to enforce policy, accounting and administrative restrictions.
It also provides the means by which users are able to be
authenticated to the system and the types of authentication available.
Attributes in addition to the ones described here are available with
third-party packages.
A special record "default" in the system user class capability database
/etc/login.conf
is used automatically for any
non-root user without a valid login class in
/etc/master.passwd
A user with a uid of 0 without a valid login class will use the record
"root" if it exists, or "default" if not.
In
Fx ,
users may individually create a file called
.login_conf
in their home directory using the same format, consisting of a single
entry with a record id of "me".
If present, this file is used by
login(1)
to set user-defined environment settings which override those specified
in the system login capabilities database.
Only a subset of login capabilities may be overridden, typically those
which do not involve authentication, resource limits and accounting.
Records in a class capabilities database consist of a number of
colon-separated fields.
The first entry for each record gives one or more names that a record is
to be known by, each separated by a '|' character.
The first name is the most common abbreviation.
The last name given should be a long name that is more descriptive
of the capability entry, and all others are synonyms.
All names but the last should be in lower case and contain no blanks;
the last name may contain upper case characters and blanks for
readability.
Note that since a colon
(`:'
)
is used to separate capability entries, a
`\c'
escape sequence must be used to embed a literal colon in the
value or name of a capability.
The default
/etc/login.conf
shipped with
Fx is an out of the box configuration.
Whenever changes to this, or
the user's
~/.login_conf
file are made, the modifications will not be picked up until
cap_mkdb1
is used to compile the file into a database.
This database file will have a
.db
extension and is accessed through
cgetent(3).
See
getcap(3)
for a more in-depth description of the format of a capability database.
CAPABILITIES
Fields within each record in the database follow the
getcap(3)
conventions for boolean, type string
`='
and type numeric
`#'
,
although type numeric is deprecated in favour of the string format and
either form is accepted for a numeric datum.
Values fall into the following categories:
bool
If the name is present, then the boolean value is true; otherwise, it is
false
file
Path name to a data file
program
Path name to an executable file
list
A list of values (or pairs of values) separated by commas or spaces
path
A space or comma separated list of path names, following the usual csh
conventions (leading tilde with and without username being expanded to
home directories etc.)
number
A numeric value, either decimal (default), hexadecimal (with leading 0x),
or octal (with a leading 0).
With a numeric type, only one numeric value is allowed.
Numeric types may also be specified in string format (i.e., the capability
tag being delimited from the value by '=' instead of '#').
Whichever method is used, then all records in the database must use the
same method to allow values to be correctly overridden in interpolated
records.
size
A number which expresses a size.
The default interpretation of a value is the number of bytes, but a
suffix may specify alternate units:
b
explicitly selects 512-byte blocks
k
selects kilobytes (1024 bytes)
m
specifies a multiplier of 1 megabyte (1048576 bytes),
g
specifies units of gigabytes, and
t
represents terabytes.
A size value is a numeric quantity and case of the suffix is not significant.
Concatenated values are added together.
time
A period of time, by default in seconds.
A prefix may specify a different unit:
y
indicates the number of 365 day years,
w
indicates the number of weeks,
d
the number of days,
h
the number of hours,
m
the number of minutes, and
s
the number of seconds.
Concatenated values are added together.
For example, 2 hours and 40 minutes may be written either as
9600s, 160m or 2h40m.
The usual convention to interpolate capability entries using the special
tc=value
notation may be used.
RESOURCE LIMITS
NameTypeNotesDescription
"coredumpsizesizeMaximum coredump size limit.
"cputimetimeCPU usage limit.
"datasizesizeMaximum data size limit.
"filesizesizeMaximum file size limit.
"maxprocnumberMaximum number of processes.
"memorylockedsizeMaximum locked in core memory size limit.
"memoryusesizeMaximum of core memory use size limit.
"openfilesnumberMaximum number of open files per process.
"sbsizesizeMaximum permitted socketbuffer size.
"vmemoryusesizeMaximum permitted total VM usage per process.
"stacksizesizeMaximum stack size limit.
These resource limit entries actually specify both the maximum
and current limits (see
getrlimit(2)).
The current (soft) limit is the one normally used, although the user is
permitted to increase the current limit to the maximum (hard) limit.
The maximum and current limits may be specified individually by appending a
-max or -cur to the capability name.
ENVIRONMENT
NameTypeNotesDescription
"charsetstringSet $MM_CHARSET environment variable to the specified
value.
"hushloginboolfalseSame as having a ~/.hushlogin file.
"ignorenologinboolfalseLogin not prevented by nologin.
"ftp-chrootboolfalseLimit FTP access with
chroot(2)
to the
HOME
directory of the user.
See
ftpd(8)
for details.
allowed before the backoff delay is inserted after each subsequent
attempt.
The backoff delay is the number of tries above
login-backoff
multiplied by 5 seconds.
"login-retriesnumber10The number of login attempts
allowed before the login fails.
"passwd_formatstringmd5The encryption format that new or
changed passwords will use.
Valid values include "des", "md5" and "blf".
NIS clients using a
non- Fx NIS server should probably use "des".
"passwd_promptstringThe password prompt presented by
"times.allow listList of time periods during which
logins are allowed.
"times.denylistList of time periods during which logins are
disallowed.
"ttys.allowlistList of ttys and ttygroups which users
in the class may use for access.
"ttys.denylistList of ttys and ttygroups which users
in the class may not use for access.
"warnexpiretimeAdvance notice for pending account expiry.
"warnpasswordtimeAdvance notice for pending password expiry.
These fields are intended to be used by passwd(1)
and other programs in the login authentication system.
Capabilities that set environment variables are scanned for both
`~'
and
`$'
characters, which are substituted for a user's home directory and name
respectively.
To pass these characters literally into the environment variable, escape
the character by preceding it with a backslash '\'.
The
host.allow
and
host.deny
entries are comma separated lists used for checking remote access to the system,
and consist of a list of hostnames and/or IP addresses against which remote
network logins are checked.
Items in these lists may contain wildcards in the form used by shell programs
for wildcard matching (See
fnmatch(3)
for details on the implementation).
The check on hosts is made against both the remote system's Internet address
and hostname (if available).
If both lists are empty or not specified, then logins from any remote host
are allowed.
If host.allow contains one or more hosts, then only remote systems matching
any of the items in that list are allowed to log in.
If host.deny contains one or more hosts, then a login from any matching hosts
will be disallowed.
The
times.allow
and
times.deny
entries consist of a comma-separated list of time periods during which the users
in a class are allowed to be logged in.
These are expressed as one or more day codes followed by a start and end times
expressed in 24 hour format, separated by a hyphen or dash.
For example, MoThSa0200-1300 translates to Monday, Thursday and Saturday between
the hours of 2 am and 1 p.m..
If both of these time lists are empty, users in the class are allowed access at
any time.
If
times.allow
is specified, then logins are only allowed during the periods given.
If
times.deny
is specified, then logins are denied during the periods given, regardless of whether
one of the periods specified in
times.allow
applies.
Note that
login(1)
enforces only that the actual login falls within periods allowed by these entries.
Further enforcement over the life of a session requires a separate daemon to
monitor transitions from an allowed period to a non-allowed one.
The
ttys.allow
and
ttys.deny
entries contain a comma-separated list of tty devices (without the /dev/ prefix)
that a user in a class may use to access the system, and/or a list of ttygroups
(See
getttyent(3)
and
ttys(5)
for information on ttygroups).
If neither entry exists, then the choice of login device used by the user is
unrestricted.
If only
ttys.allow
is specified, then the user is restricted only to ttys in the given
group or device list.
If only
ttys.deny
is specified, then the user is prevented from using the specified devices or
devices in the group.
If both lists are given and are non-empty, the user is restricted to those
devices allowed by ttys.allow that are not available by ttys.deny.
The
minpasswordlen
and
minpasswordcase
facilities for enforcing restrictions on password quality, which used
to be supported by
,
have been superseded by the
pam_passwdqc8
PAM module.
RESERVED CAPABILITIES
The following capabilities are reserved for the purposes indicated and
may be supported by third-party software.
They are not implemented in the base system.
NameTypeNotesDescription
"accountedboolfalseEnable session time accounting for all users
in this class.
"authlistpasswdAllowed authentication styles.
The first item is the default style.
"auth-" type Ta listAllowed authentication styles for the
authentication type
"autodeletetimeTime after expiry when account is auto-deleted.
"bootfullboolfalseEnable 'boot only if ttygroup is full' strategy
when terminating sessions.
"daytimetimeMaximum login time per day.
"expireperiodtimeTime for expiry allocation.
"graceexpire timeGrace days for expired account.
"gracetimetimeAdditional grace login time allowed.
"host.accountedlistList of remote host wildcards from which
login sessions will be accounted.
"host.exempt listList of remote host wildcards from which
login session accounting is exempted.
"idletimetimeMaximum idle time before logout.
"minpasswordlennumber6The minimum length a local
password may be.
"mixpasswordcasebooltrueWhether
passwd(1)
will warn the user if an all lower case password is entered.
"refreshtime timeNew time allowed on account refresh.
"refreshperiodstrHow often account time is refreshed.
"sessiontime timeMaximum login time per session.
"sessionlimitnumberMaximum number of concurrent
login sessions on ttys in any group.
"ttys.accountedlistList of ttys and ttygroups for which
login accounting is active.
"ttys.exemptlistList of ttys and ttygroups for which login accounting
is exempt.
"warntimetimeAdvance notice for pending out-of-time.
"weektimetimeMaximum login time per week.
The ttys.accounted
and
ttys.exempt
fields operate in a similar manner to
ttys.allow
and
ttys.deny
as explained
above.
Similarly with the
host.accounted
and
host.exempt
lists.
