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Man Pages

Manual Reference Pages  -  LOGIN.CONF (5)


login.conf - login class capability database


Resource Limits
Reserved Capabilities
See Also


/etc/login.conf, ~/.login_conf


login.conf 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.

.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_mkdb(1) 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.


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
  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.


Name   Type    Notes   Description
coredumpsize  size            Maximum coredump size limit.
cputime       time            CPU usage limit.
datasize      size            Maximum data size limit.
filesize      size            Maximum file size limit.
maxproc       number          Maximum number of processes.
memorylocked  size            Maximum locked in core memory size limit.
memoryuse     size            Maximum of core memory use size limit.
openfiles     number          Maximum number of open files per process.
sbsize        size            Maximum permitted socketbuffer size.
vmemoryuse    size            Maximum permitted total VM usage per process.
stacksize     size            Maximum stack size limit.
pseudoterminals       number          Maximum number of pseudo-terminals.
swapuse       size            Maximum swap space 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.


Name   Type    Notes   Description
charset       string          Set $MM_CHARSET environment variable to the specified
cpumask        string          List of cpus to bind the user to. The syntax is the same as for the -l argument of cpuset(1) or the word default’. If set to default’ no action is taken.
hushlogin      bool    false   Same as having a ~/.hushlogin file.
ignorenologin bool    false   Login not prevented by nologin.
ftp-chroot    bool    false   Limit FTP access with
  chroot(2) to the HOME directory of the user. See ftpd(8) for details.
label  string          Default MAC policy; see maclabel(7).
lang   string          Set $LANG environment variable to the specified value.
manpath       path            Default search path for manpages.
nocheckmail   bool    false   Display mail status at login.
nologin       file            If the file exists it will be displayed and
  the login session will be terminated.
path   path    /bin /usr/bin   Default search path.
priority      number          Initial priority (nice) level.
requirehome   bool    false   Require a valid home directory to login.
setenv        list            A comma-separated list of environment variables and
  values to which they are to be set.
shell  prog            Session shell to execute rather than the shell specified in the passwd file. The SHELL environment variable will contain the shell specified in the password file.
term   string          Default terminal type if not able to determine from other means.
timezone       string          Default value of $TZ environment variable.
umask number  022     Initial umask. Should always have a leading 0 to
  ensure octal interpretation.
welcome        file    /etc/motd       File containing welcome message.


Name   Type    Notes   Description
copyright     file            File containing additional copyright information
host.allow    list            List of remote host wildcards from which users in
  the class may access.
host.deny      list            List of remote host wildcards from which users in the class may not access.
login_prompt   string          The login prompt given by login(1)
login-backoff  number  3       The number of login attempts 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-retries  number  10      The number of login attempts allowed before the login fails.
passwd_format  string  sha512  The encryption format that new or changed passwords will use. Valid values include "des", "md5", "blf", "sha256" and "sha512"; see crypt(3) for details. NIS clients using a non- Fx NIS server should probably use "des".
passwd_prompt  string          The password prompt presented by login(1)
times.allow    list            List of time periods during which logins are allowed.
times.deny     list            List of time periods during which logins are disallowed.
ttys.allow     list            List of ttys and ttygroups which users in the class may use for access.
ttys.deny      list            List of ttys and ttygroups which users in the class may not use for access.
warnexpire     time            Advance notice for pending account expiry.
warnpassword  time            Advance 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 ’#146;.

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 login.conf, have been superseded by the pam_passwdqc(8) PAM module.


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.
Name   Type    Notes   Description
accounted     bool    false   Enable session time accounting for all users
  in this class.
auth   list    passwd  Allowed authentication styles. The first item is the default style.
auth- type      list          Allowed authentication styles for the authentication type.
autodelete     time            Time after expiry when account is auto-deleted.
bootfull      bool    false   Enable ’boot only if ttygroup is full’ strategy
  when terminating sessions.
daytime        time            Maximum login time per day.
expireperiod  time            Time for expiry allocation.
graceexpire   time            Grace days for expired account.
gracetime     time            Additional grace login time allowed.
host.accounted        list            List of remote host wildcards from which
  login sessions will be accounted.
host.exempt    list            List of remote host wildcards from which login session accounting is exempted.
idletime       time            Maximum idle time before logout.
minpasswordlen        number  6       The minimum length a local
  password may be.
mixpasswordcase        bool    true    Whether passwd(1) will warn the user if an all lower case password is entered.
monthtime      time            Maximum login time per month.
passwordtime  time            Used by
  passwd(1) to set next password expiry date.
refreshtime    time            New time allowed on account refresh.
refreshperiod str             How often account time is refreshed.
sessiontime   time            Maximum login time per session.
sessionlimit  number          Maximum number of concurrent
  login sessions on ttys in any group.
ttys.accounted list            List of ttys and ttygroups for which login accounting is active.
ttys.exempt    list            List of ttys and ttygroups for which login accounting is exempt.
warntime       time            Advance notice for pending out-of-time.
weektime      time            Maximum 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.


cap_mkdb(1), login(1), chroot(2), getcap(3), getttyent(3), login_cap(3), login_class(3), pam(3), passwd(5), ttys(5), ftpd(8), pam_passwdqc(8)
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