troubleshooting/password_reset - add password reset manual, closes https://github.com/opnsense/docs/issues/413

source/troubleshooting.rst

@@ -71,6 +71,7 @@ be found in the list below.
    :titlesonly:
    :glob:
 
+   troubleshooting/password_reset
    troubleshooting/boot
    troubleshooting/hardening
    troubleshooting/gateways

source/troubleshooting/password_reset.rst

@@ -0,0 +1,71 @@
+====================================
+Password reset
+====================================
+
+Sometimes people lose their passwords, in which case it can be practical to reset the root password
+without performing a reinstall.
+
+This guide describes step by step how to reset the root password.
+
+.. Note::
+
+    You can also use the installer to reset the password,
+    use the :code:`Password Reset - Recover Installation` option in the installer after the keymap selection.
+
+
+-----------------------------
+Step 1 : power
+-----------------------------
+
+Since you need to influence the boot process to reset the password, you should start with powering off the (virtual) device.
+
+-----------------------------
+Step 2 : console
+-----------------------------
+
+Make sure you are able to access the (virtual) console, in case it's a physical machine you might want to connect a
+monitor and keyboard, when it's an appliance with serial access, make sure to connect to the serial/usb port using an application
+like putty.
+
+.. Tip::
+
+    When using devices from the OPNsense shop (https://shop.opnsense.com), usually there's a mini-usb to serial cable included
+    in the box, the :doc:`Serial Console connectivity </hardware/serial_connectivity>` guide will help you with the setup.
+
+-----------------------------
+Step 3 : boot single
+-----------------------------
+
+Swith the power and wait for the OPNsense splash screen to appear, the choose "Boot [S]single User" which should be option 2 in the list.
+(press 2)
+
+-----------------------------
+Step 4: password reset
+-----------------------------
+
+This stage depends on the type of installation, the root filesystem could either be UFS or ZFS, both requiring different commands to
+enable modifications in single user mode.
+
+
+For UFS file systems, execute the following command in the shell to enable disk modifications:
+
+.. code-block:: sh
+
+    /sbin/mount -o rw /
+
+
+When using ZFS, the following commands are required
+
+.. code-block:: sh
+
+    /sbin/mount -u /
+    /sbin/zfs mount -a
+
+Now the disk can be written to, use the following commands to reset the password and reboot the machine:
+
+.. code-block:: sh
+
+    opnsense-shell password
+    reboot
+
+The `opnsense-shell` will ask for a confirmation, respond with `Y`