check-password.4th
—
FreeBSD password-checking boot module
The file that goes by the name of
check-password.4th
is a set of commands designed to
do one or more of the following:
o Prevent booting without
password
o Prevent modification of boot
options without password
o Provide a password to mount geli(8)
encrypted root disk(s)
The commands of check-password.4th
by
themselves are not enough for most uses. Please refer to the examples below
for the most common situations, and to
loader(8)
for additional commands.
Before using any of the commands provided in
check-password.4th
, it must be included through the
command:
include
check-password.4th
This line is present in /boot/loader.4th
file, so it is not needed (and should not be re-issued) in a normal
setup.
The commands provided by it are:
check-password
- Multi-purpose function that can protect the interactive boot menu, prevent
boot without password, or prompt for geli(8) passphrase (depending on
loader.conf(5)
settings).
First checks bootlock_password and
if-set, the user cannot continue until the correct password is
entered.
Next, checks geom_eli_passphrase_prompt
and if set to YES
(case-insensitive) prompts the
user to enter their GELI password for later mounting of the root
device(s) during boot.
Last, checks password and if-set, tries
to autoboot
and only prompts for password on
failure or user-interrupt. See
loader.conf(5)
for additional information.
The environment variables that effect its behavior are:
- bootlock_password
- Sets the bootlock password (up to 255 characters long) that is required by
check-password
to be entered before the system is
allowed to boot.
- geom_eli_passphrase_prompt
- Selects whether loader(8) will prompt for GELI credentials, handing-off to
the kernel for later mounting of
geli(8)
encrypted root device(s).
- password
- Sets the password (up to 255 characters long) that is required by
check-password
before the user is allowed to visit
the boot menu.
- /boot/loader
- The
loader(8).
- /boot/check-password.4th
check-password.4th
itself.
- /boot/loader.rc
- loader(8)
bootstrapping script.
Standard i386 /boot/loader.rc:
include /boot/loader.4th
check-password
Set a password in
loader.conf(5)
to prevent modification of boot options:
Set a password in
loader.conf(5)
to prevent booting without password:
Add the following to
loader.conf(5)
to generate a prompt at boot to collect GELI credentials for mounting
geli(8)
encrypted root device(s):
geom_eli_passphrase_prompt="YES"
The check-password.4th
set of commands
first appeared in FreeBSD 9.0.
The check-password.4th
set of commands was
written by Devin Teske
⟨dteske@FreeBSD.org⟩.