2015-12-24 21:24:51 -05:00
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.Dd $Mdocdate: October 6 2015 $
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.Dt LOGIN 8
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.Os
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.Sh NAME
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.Nm login
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.Nd authenticate users and run personal session
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.Sh SYNOPSIS
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.Nm login
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.Sh DESCRIPTION
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.Nm login
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interactively authenticates users by asking them to enter their username and
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password. The passwords are checked against the password hashes in
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.Pa /etc/passwd
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as described in
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.Xr passwd 5 .
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.Nm login
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creates a session as the requested user upon successful authentication.
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.Pp
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.Nm login
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has a graphical interface if the display is graphical and uses a textual
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interface otherwise. The textual interface is forced if
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.Pa /etc/login.conf.textual
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exists. The process remains running in the background and takes
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over again when the user session exits.
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.Pp
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Type a special username to perform special options:
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.Pp
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.Bl -tag -width "poweroff" -compact -offset indent
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.It exit
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alias for poweroff
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.It poweroff
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exit asking for powering off the computer
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.It reboot
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exit asking for rebooting the computer
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.El
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.Sh SECURITY
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There is currently no method to confirm the login screen is in fact real other
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than witnessing a pristine boot. Local users can log in and show a counterfeit
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login screen that look and behave like the real
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.Nm login
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program and trick the next user into revealing their password.
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.Sh ENVIRONMENT
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.Nm login
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sets the following environment variables to match the authenticated user:
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.Bl -tag -width "LOGNAME"
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.It Ev HOME
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home directory
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.It Ev LOGNAME
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username
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.It Ev SHELL
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shell
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.It Ev USER
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username
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.El
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.Sh FILES
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.Bl -tag -width "/etc/passwd" -compact
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.It Pa /etc/passwd
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user database (see
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.Xr passwd 5 )
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.It Pa /etc/login.conf.textual
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textual interface is forced if this file exists
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.El
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.Sh EXIT STATUS
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.Nm login
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exits 0 if the computer should power off, exits 1 if the computer should
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reboot, or exits 2 on fatal failure and the boot should halt.
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.Sh SEE ALSO
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2015-11-25 13:18:14 -05:00
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.Xr passwd 1 ,
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2015-12-24 21:24:51 -05:00
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.Xr crypt_checkpass 3 ,
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.Xr passwd 5 ,
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.Xr init 8 ,
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.Xr login 8
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.Sh BUGS
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.Nm login
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only supports a single monitor. The mouse code is less than perfect.
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