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LOGIN.CONF(5)               BSD File Formats Manual              LOGIN.CONF(5)

NAME
     login.conf -- login class capability database

SYNOPSIS
     /etc/login.conf

DESCRIPTION
     The login.conf file describes the various attributes of login classes.  A
     login class determines what styles of authentication are available as
     well as session resource limits and environment setup.  While designed
     primarily for the login(1) program, it is also used by other programs,
     such as ftpd(8), to determine what means of authentication are available.
     It is also used by programs which need to set up a user environment.

     A special record, ``default'', in /etc/login.conf is used for any user
     without a valid login class in /etc/master.passwd.

     Sites with very large /etc/login.conf files may wish to create a database
     version of the file, /etc/login.conf.db, for improved performance.  Using
     a database version for small files does not result in a performance
     improvement.  To build /etc/login.conf.db from /etc/login.conf the fol-
     lowing command may be used:

           # cap_mkdb /etc/login.conf

     Note that cap_mkdb(1) must be run after each edit of /etc/login.conf to
     keep the database version in sync with the plain file.

CAPABILITIES
     Refer to getcap(3) for a description of the file layout.  All entries in
     the login.conf file are either boolean or use a '=' to separate the capa-
     bility from the value.  The types are described after the capability ta-
     ble.

     Name               Type       Default       Description
     approve            program                  Default program to approve
                                                                login.

     approve-service    program                  Program to approve login for
                                                                service.

     auth               list       passwd        Allowed authentication
                                                                styles.  The
                                                                first value is
                                                                the default
                                                                styles.

     auth-type          list                     Allowed authentication styles
                                                                for the
                                                                authentication
                                                                type type.

     classify           program                  Classify type of login.

     copyright          file                     File containing additional
                                                                copyright
                                                                information.

     coredumpsize       size                     Maximum coredump size limit.

     cputime            time                     CPU usage limit.

     datasize           size                     Maximum data size limit.

     expire-warn        time       2w            If the user's account will
                                                                expire within
                                                                this length of
                                                                time then warn
                                                                the user of
                                                                this.

     filesize           size                     Maximum file size limit.

     hushlogin          bool       false         Same as having a
                                                                $HOME/.hushlogin
                                                                file.  See
                                                                login(1).

     ignorenologin      bool       false         Not affected by nologin
                                                                files.  See
                                                                login(1).

     localcipher        string     blowfish,8    The cipher to use for
                                                                encrypting
                                                                passwords.
                                                                Refer to
                                                                crypt_newhash(3)
                                                                for possible
                                                                values.

     login-backoff      number     3             After login-backoff unsuc-
                                                                cessful login
                                                                attempts dur-
                                                                ing a single
                                                                session,
                                                                login(1) will
                                                                start sleeping
                                                                a bit in
                                                                between
                                                                attempts.

     login-timeout      time       300           Number of seconds before
                                                                login(1) times
                                                                out at the
                                                                password
                                                                prompt.  Note
                                                                that this set-
                                                                ting is only
                                                                valid for the
                                                                default
                                                                record.

     login-tries        number     10            Number of tries a user gets
                                                                to success-
                                                                fully login
                                                                before
                                                                login(1)
                                                                closes the
                                                                connection.

     stacksize          size                     Maximum stack size limit.

     maxproc            number                   Maximum number of processes.

     memorylocked       size                     Maximum locked in core memory
                                                                size limit.

     memoryuse          size                     Maximum in core memoryuse
                                                                size limit.

     minpasswordlen     number     6             The minimum length a local
                                                                password may
                                                                be.  If a neg-
                                                                ative value or
                                                                zero, no
                                                                length
                                                                restrictions
                                                                are enforced.
                                                                Used by the
                                                                passwd(1)
                                                                utility.

     nologin            file                     If the file exists it will be
                                                                displayed and
                                                                the login ses-
                                                                sion will be
                                                                terminated.

     openfiles          number                   Maximum number of open file
                                                                descriptors
                                                                per process.

     password-dead      time       0             Length of time a password may
                                                                be expired but
                                                                not quite dead
                                                                yet.  When set
                                                                (for both the
                                                                client and
                                                                remote server
                                                                machine when
                                                                doing remote
                                                                authentica-
                                                                tion), a user
                                                                is allowed to
                                                                log in just
                                                                one more time
                                                                after their
                                                                password (but
                                                                not account)
                                                                has expired.
                                                                This allows a
                                                                grace period
                                                                for updating
                                                                their pass-
                                                                word.

     password-warn      time       2w            If the user's password will
                                                                expire within
                                                                this length of
                                                                time then warn
                                                                the user of
                                                                this.

     passwordcheck      program                  An external program that
                                                                checks the
                                                                quality of the
                                                                password.  The
                                                                password is
                                                                passed to the
                                                                program on
                                                                stdin.  An
                                                                exit code of 0
                                                                indicates that
                                                                the quality of
                                                                the password
                                                                is sufficient,
                                                                an exit code
                                                                of 1 signals
                                                                that the pass-
                                                                word failed
                                                                the check.

     passwordtime       time                     The lifetime of a password in
                                                                seconds, reset
                                                                every time a
                                                                user changes
                                                                their pass-
                                                                word.  When
                                                                this value is
                                                                exceeded the
                                                                user will no
                                                                longer be able
                                                                to login
                                                                unless the
                                                                password-dead
                                                                option has
                                                                been speci-
                                                                fied.  Used by
                                                                the passwd(1)
                                                                utility.

     passwordtries      number     3             The number of times the
                                                                passwd(1)
                                                                utility
                                                                enforces a
                                                                check on the
                                                                password.  If
                                                                0, the new
                                                                password will
                                                                only be
                                                                accepted if it
                                                                passes the
                                                                password qual-
                                                                ity check.

     path               path       value of _PATH_DEFPATH
                                                                Default search
                                                                path.  See
                                                                /usr/include/paths.h.

     priority           number                   Initial priority (nice)
                                                                level.

     requirehome        bool       false         Require home directory to
                                                                login.

     setenv             envlist                  A list of environment vari-
                                                                ables and
                                                                associated
                                                                values to be
                                                                set for the
                                                                class.

     shell              program                  Session shell to execute
                                                                rather than
                                                                the shell
                                                                specified in
                                                                the password
                                                                file.  The
                                                                SHELL environ-
                                                                ment variable
                                                                will contain
                                                                the shell
                                                                specified in
                                                                the password
                                                                file.

     tc                 string                   Interpolate/expands records
                                                                from corre-
                                                                sponding
                                                                login.conf.
                                                                See getcap(3).

     term               string     su            Default terminal type if not
                                                                able to deter-
                                                                mine from
                                                                other means.

     umask              number     022           Initial umask.  Should always
                                                                have a leading
                                                                0 to ensure
                                                                octal inter-
                                                                pretation.
                                                                See umask(2).

     vmemoryuse         size                     Maximum virtual memoryuse
                                                                size limit.

     welcome            file       /etc/motd     File containing welcome mes-
                                                                sage.

     The resource limit entries (cputime, filesize, datasize, stacksize,
     coredumpsize, memoryuse, memorylocked, maxproc, and openfiles) actually
     specify both the maximum and current limits (see getrlimit(2)).  The cur-
     rent limit is the one normally used, although the user is permitted to
     increase the current limit to the maximum limit.  The maximum and current
     limits may be specified individually by appending a -max or -cur to the
     capability name (e.g., openfiles-max and openfiles-cur).

     OpenBSD will never define capabilities which start with x- or X-, these
     are reserved for external use (unless included through contributed soft-
     ware).

     The argument types are defined as:

     envlist    A comma-separated list of environment variables of the form
                variable=value.  If no value is specified, the '=' is
                optional.  A ~ in the path name is expanded to the user's home
                directory if it is at the end of a string or is followed by a
                slash ('/') or the user's login name.  A $ in the path name is
                expanded to the user's login name.

     file       Path name to a text file.

     list       A comma-separated list of values.

     number     A number.  A leading 0x implies the number is expressed in
                hexadecimal.  A leading 0 implies the number is expressed in
                octal.  Any other number is treated as decimal.

     path       A space-separated list of path names.  Login name and direc-
                tory are substituted as for envlist.  Additionally, a ~ is
                only expanded at the beginning of a path name.

     program    A path name to program.

     size       A number which expresses a size.  By default, the size is
                specified in bytes.  It may have a trailing b, k, m, g or t to
                indicate that the value is in 512-byte blocks, kilobytes,
                megabytes, gigabytes, or terrabytes, respectively.

     time       A time in seconds.  A time may be expressed as a series of
                numbers which are added together.  Each number may have a
                trailing character to represent time units:

                y    Indicates a number of 365 day years.

                w    Indicates a number of 7 day weeks.

                d    Indicates a number of 24 hour days.

                h    Indicates a number of 60 minute hours.

                m    Indicates a number of 60 second minutes.

                s    Indicates a number of seconds.

                For example, to indicate 1 and 1/2 hours, the following string
                could be used: 1h30m.

AUTHENTICATION
     OpenBSD uses BSD Authentication, which is made up of a variety of authen-
     tication styles.  The authentication styles currently provided are:

     activ      Authenticate using an ActivCard token.  See login_activ(8).

     chpass     Change user's password.  See login_chpass(8).

     crypto     Authenticate using a CRYPTOCard token.  See login_crypto(8).

     lchpass    Change user's local password.  See login_lchpass(8).

     passwd     Request a password and check it against the password in the
                master.passwd file.  See login_passwd(8).

     radius     Normally linked to another authentication type, contact the
                radius server to do authentication.  See login_radius(8).

     reject     Request a password and reject any request.  See
                login_reject(8).

     skey       Send a challenge and request a response, checking it with
                S/Key (tm) authentication.  See login_skey(8).

     snk        Authenticate using a SecureNet Key token.  See login_snk(8).

     token      Authenticate using a generic X9.9 token.  See login_token(8).

     yubikey    Authenticate using a Yubico YubiKey token.  See
                login_yubikey(8).

     Local authentication styles may be added by creating a login script for
     the style (see below).  To prevent collisions with future official BSD
     Authentication style names, all local style names should start with a
     dash (-).  Current plans are for all official BSD Authentication style
     names to begin with a lower case alphabetic character.  For example, if
     you have a new style you refer to as slick then you should create an
     authentication script named /usr/libexec/auth/login_-slick using the
     style name -slick.  When logging in via the login(1) program, the syntax
     user:-slick would be used.

     Authentication requires several pieces of information:

     class       The login class being used.

     service     The type of service requesting authentication.  The service
                 type is used to determine what information the authentication
                 program can provide to the user and what information the user
                 can provide to the authentication program.

                 The service type login is appropriate for most situations.
                 Two other service types, challenge and response, are provided
                 for use by programs like ftpd(8) and radiusd.  If no service
                 type is specified, login is used.

     style       The authentication style being used.

     type        The authentication type, used to determine the available
                 authentication styles.

     username    The name of the user to authenticate.  The name may contain
                 an instance.  If the authentication style being used does not
                 support such instances, the request will fail.

     The program requesting authentication must specify a username and an
     authentication style.  (For example, login(1) requests a username from
     the user.  Users may enter usernames of the form ``user:style'' to
     optionally specify the authentication style.)  The requesting program may
     also specify the type of authentication that will be done.  Most programs
     will only have a single type, if any at all, i.e., ftpd(8) will always
     request the ftp type authentication, and su(1) will always request the su
     type authentication.  The login(1) utility is special in that it may
     select an authentication type based on information found in the /etc/ttys
     file for the appropriate tty (see ttys(5)).

     The class to be used is normally determined by the class field in the
     password file (see passwd(5)).

     The class is used to look up a corresponding entry in the login.conf
     file.  If an authentication type is defined and a value for auth-type
     exists in that entry, it will be used as a list of potential authentica-
     tion styles.  If an authentication type is not defined, or auth-type is
     not specified for the class, the value of auth is used as the list of
     available authentication styles.

     If the user did not specify an authentication style the first style in
     the list of available styles is used.  If the user did specify an authen-
     tication style and the style is in the list of available styles it will
     be used, otherwise the request is rejected.

     For any given style, the program /usr/libexec/auth/login_style is used to
     perform the authentication.  The synopsis of this program is:

     /usr/libexec/auth/login_style [-v name=value] [-s service] username class

     The -v option is used to specify arbitrary information to the authentica-
     tion programs.  Any number of -v options may be used.  The login(1) pro-
     gram provides the following through the -v option:

     auth_type       The type of authentication to use.

     fqdn            The hostname provided to login by the -h option.

     hostname        The name login(1) will place in the utmp file for the
                     remote hostname.

     local_addr      The local IP address given to login(1) by the -L option.

     lastchance      Set to ``yes'' when a user's password has expired but the
                     user is being given one last chance to login and update
                     the password.

     login           This is a new login session (as opposed to a simple iden-
                     tity check).

     remote_addr     The remote IP address given to login(1) by the -R option.

     style           The style of authentication used for this user (see
                     approval scripts below).

     The su(1) program provides the following through the -v option:

     wheel           Set to either ``yes'' or ``no'' to indicate if the user
                     is in group wheel when they are trying to become root.
                     Some authentication types require the user to be in group
                     wheel when using the su(1) program to become super user.

     When the authentication program is executed, the environment will only
     contain the values PATH=/bin:/usr/bin and SHELL=/bin/sh.  File descriptor
     3 will be open for reading and writing.  The authentication program
     should write one or more of the following strings to this file descrip-
     tor:

     authorize  The user has been authorized.

     authorize secure
                The user has been authorized and root should be allowed to
                login even if this is not a secure terminal.  This should only
                be sent by authentication styles that are secure over insecure
                lines.

     reject     Authorization is rejected.  This overrides any indication that
                the user was authorized (though one would question the wisdom
                in sending both a reject and an authorize command).

     reject challenge
                Authorization was rejected and a challenge has been made
                available via the value challenge.

     reject silent
                Authorization is rejected, but no error messages should be
                generated.

     remove file
                If the login session fails for any reason, remove file before
                termination.

     setenv name value
                If the login session succeeds, the environment variable name
                should be set to the specified value.

     unsetenv name
                If the login session succeeds, the environment variable name
                should be removed.

     value name value
                Set the internal variable name to the specified value.  The
                value should only contain printable characters.  Several \
                sequences may be used to introduce non printing characters.
                These are:

                \n      A newline.

                \r      A carriage return.

                \t      A tab.

                \xxx    The character represented by the octal value xxx.  The
                        value may be one, two, or three octal digits.

                \c      The string is replaced by the value of c.  This allows
                        quoting an initial space or the \ character itself.

                The following values are currently defined:

                challenge
                        See section on challenges below.

                errormsg
                        If set, the value is the reason authentication failed.
                        The calling program may choose to display this when
                        rejecting the user, but display is not required.

     In order for authentication to be successful, the authentication program
     must exit with a value of 0 as well as provide an authorize or authorize
     root statement on file descriptor 3.

     An authentication program must not assume it will be called as root, nor
     must it assume it will not be called as root.  If it needs special per-
     missions to access files it should be setuid or setgid to the appropriate
     user/group.  See chmod(1).

CHALLENGES
     When an authentication program is called with a service of challenge it
     should do one of three things:

     If this style of authentication supports challenge response it should set
     the internal variable challenge to be the appropriate challenge for the
     user.  This is done by the value command listed above.  The program
     should also issue a reject challenge and then exit with a 0 status.  See
     the section on responses below.

     If this style of authentication does not support challenge response, but
     does support the response service (described below) it should issue
     reject silent and then exit with a 0 status.

     If this style of authentication does not support the response service it
     should simply fail, complaining about an unknown service type.  It should
     exit with a non-zero status.

RESPONSES
     When an authentication program is called with a service of response, and
     this style supports this mode of authentication, it should read two null
     terminated strings from file descriptor 3.  The first string is a chal-
     lenge that was issued to the user (obtained from the challenge service
     above).  The second string is the response the user gave (i.e., the pass-
     word).  If the response is correct for the specified challenge, the
     authentication should be accepted, else it should be rejected.  It is
     possible for the challenge to be an empty string, which implies the call-
     ing program did first obtain a challenge prior to getting a response from
     the user.  Not all authentication styles support empty challenges.

APPROVAL
     An approval program has the synopsis of:

           approve [-v name=value] username class service

     Just as with an authentication program, file descriptor 3 will be open
     for writing when the approval program is executed.  The -v option is the
     same as in the authentication program.  Unlike an authentication program,
     the approval program need not explicitly send an authorize or authorize
     root statement, it only need exit with a value of 0 or non-zero.  An exit
     value of 0 is equivalent to an authorize statement, and non-zero to a
     reject statement.  This allows for simple programs which have no informa-
     tion to provide other than approval or denial.

CLASSIFICATION
     A classify program has the synopsis of:

           classify [-v name=value] [-f] [user]

     See login(1) for a description of the -f, option.  The -v option is the
     same as for the authentication programs.  The user is the username passed
     to login(1) login, if any.

     The typical job of the classify program is to determine what authentica-
     tion type should actually be used, presumably based on the remote IP
     address.  It might also re-specify the hostname to be included in the
     utmp(5) file, reject the login attempt outright, or even print an addi-
     tional login banner (e.g., /etc/issue).

     The classify entry is only valid for the default class as it is used
     prior to knowing who the user is.  The classify script may pass environ-
     ment variables or other commands back to login(1) on file descriptor 3,
     just as an authentication program does.  The two variables AUTH_TYPE and
     REMOTE_NAME are used to specify a new authentication type (the type must
     have the form auth-type) and override the -h option to login, respec-
     tively.

SEE ALSO
     cap_mkdb(1), login(1), authenticate(3), bsd_auth(3), getcap(3),
     login_cap(3), passwd(5), ttys(5), ftpd(8)

BSD                             April 25, 2017                             BSD