login.conf



LOGIN.CONF(5)                 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
     following 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
     capability from the value.  The types are described after the capability
     table.

     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
                                                 unsuccessful login attempts
                                                 during 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 setting is only valid
                                                 for the default record.

     login-tries        number     10            Number of tries a user gets
                                                 to successfully 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
                                                 negative 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
                                                 session 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
                                                 authentication), 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 password.

     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 password failed the
                                                 check.

     passwordtime       time                     The lifetime of a password in
                                                 seconds, reset every time a
                                                 user changes their password.
                                                 When this value is exceeded
                                                 the user will no longer be
                                                 able to login unless the
                                                 password-dead option has been
                                                 specified.  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 quality 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
                                                 variables 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 environment
                                                 variable will contain the
                                                 shell specified in the
                                                 password file.

     tc                 string                   Interpolate/expands records
                                                 from corresponding
                                                 login.conf.  See getcap(3).

     term               string     su            Default terminal type if not
                                                 able to determine from other
                                                 means.

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

     vmemoryuse         size                     Maximum virtual memoryuse
                                                 size limit.

     welcome            file       /etc/motd     File containing welcome
                                                 message.

     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
     current 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
     software).

     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
                directory 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 terabytes, 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
     authentication 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(8).  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
     authentication 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
     authentication 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
     authentication programs.  Any number of -v options may be used.  The
     login(1) program 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
                     identity 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
     descriptor:

     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
     permissions 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
     challenge that was issued to the user (obtained from the challenge
     service above).  The second string is the response the user gave (i.e.,
     the password).  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
     calling 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
     information 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
     authentication 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
     additional 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
     environment 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, respectively.


SEE ALSO

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

OpenBSD 5.9                     October 1, 2015                    OpenBSD 5.9

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