LOGIN.CONF(5)

NAME
login.conf - login class capability database

SYNOPSIS
/etc/login.conf, ~/.login_conf

DESCRIPTION
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.

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 FreeBSD, 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. NOTE: this feature is compile-time disabled by default due to potential security risks.

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.

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 depreciated in favour of the string format and either form is accepted for a numeric datum. Values fall into the following categories:

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 (ie. 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
Name Type Notes Description
cputime time CPU usage limit.
filesize size Maximum file size limit.
datasize size Maximum data size limit.
stacksize size Maximum stack size limit.
coredumpsize size Maximum coredump size limit.
memoryuse size Maximum of core memory use size limit.
memorylocked size Maximum locked in core memory size limit.
maxproc number Maximum number of processes.
openfiles number Maximum number of open files per process.

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
Name Type Notes Description
charset string Set $MM_CHARSET environment variable to the specified
value.
hushlogin bool false Same as having a ~/.hushlogin file.
ignorenologin bool false Login not prevented by nologin.
lang string Set $LANG environment variable to the specified value.
manpath path Default search path for manpages.
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 su 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.

AUTHENTICATION
Name Type Notes Description
minpasswordlen number 6 The minimum length a local password may be.
auth list passwd Allowed authentication styles. The first value is the
default style.
auth-<type> list Allowed authentication styles for the
authentication type 'type'.
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.
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.

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.

ACCOUNTING LIMITS
Name Type Notes Description
accounted bool false Enable session time accounting for all users
in this class.
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.
monthtime time Maximum login time per month.
passwordtime time Time for password expiry.
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.
warnexpire time Advance notice for pending account expiry.
warnpassword time Advance notice for pending password expiry.
warntime time Advance notice for pending out-of-time.
weektime time Maximum login time per week.

These fields are used by the time accounting system, which regulates, controls and records user login access.

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.

SEE ALSO
login(1), getcap(3), getttyent(3), login_cap(3), login_class(3), passwd(5), ttys(5)