+++ /dev/null
-This is a howto on regaining control of your Linux computer when
-you messed up your normal way to interact with it: keyboard, mouse,
-video or network access.
-
-# You can't interact with your computer anymore
-
-You switched video mode and lost your mouse. Or the screen is suddenly
-blank or freezed. Or you keyboard input echoes garbage. Or if you use
-a server, you can't no more ssh to it.
-
-Your computer is in most likelihood still working ok under the hood,
-and there are quite always better ways to recover than to reboot cold.
-
-## Keyboard input echoes garbage
-
-Most likely culprit is wrong configuration of your tty device. This is
-not critical as you can always switch tty. In general, typing Ctrl-V
-Ctrl-O will restore sane values.
-
-## Mouse invisble or unusable because moving erratically
-
-The mouse invisible can happen inside some sophisticated applications
-(e.g.: some versions of VirtualBox). The best way here is, after
-possibly switching console, to stop the faulty application.
-
-If the mouse seems moving too fast or too slowly, try changing mouse
-parameters with tools like xset, or their highlevel desktop cousins.
-For instance, in Gnome, look for Mouse in the System/Preferences menu.
-
-An erratically moving mouse may indicate, as with keyboard garbage,
-that the mouse device is badly configured; this used to happen in the
-past with serial mice. This can also happen if you use the mouse both
-in X and the console with gpm.
-
-In nothing of the above solves the issue, restarting the X system may
-be needed, see below.
-
-## Screen is freezed or blank
-
-Switch to a console, stop cleanly your graphical applications if
-possible, then restart the X system. If you use gdm, this is how to do
-it on a Debian system:
-
- /usr/sbin/invoke-rc.d gdm stop
- /usr/sbin/invoke-rc.d gdm start
-
-## Nothing solves the issue: trying the network
-
-If nothing of the above works, and you can't even get a text console
-by hitting Shift-Alt-F1, you may connect to your computer through
-telnet, ssh... That is, you have telnetd or sshd running on it. If not
-see below.
-
-## Nothing solves the issue: trying a serial link
-
-The file controlling where to start login processes is /etc/inittab.
-You will have something like that inside:
-
- 1:2345:respawn:/sbin/getty 38400 tty1
- 2:23:respawn:/sbin/getty 38400 tty2
- #T0:23:respawn:/sbin/getty -L ttyS0 9600 vt100
-
-The 2 first lines will give you a login prompt at the screen
-(reachable with Alt-F1 and Alt-F2 in text mode, and with Shift-Alt-F1
-and Shift-Alt-F2 in graphical mode).
-
-The last one (in general commented out with the #), will start getty
-on a serial device. Using a second computer running a tool like
-minicom and linking it using a null modem to the first one, you will
-get a login prompt on that second computer screen to allow
-troubleshoot the first one.
-
-What if the line is commented out, what is a null modem, what to do if
-I have no serial port, and how do I configure minicom? Answers in next
-section.
-
-# Computer control recovery preparation using a serial link
-
-So my advice to maximize your odds to cleanly regain control of your
-computer is to prepare for that case in advance, by allowing a serial
-link login. A serial link login has not the security problem of
-allowing network access.
-
-## No serial port on my computer
-
-Except for servers, the rule now is no serial port. But the rule is
-also to have USB everywhere, and luckily hardware converters
-serial/link exist. Linux has drivers for a lot of these converters,
-and you should have no problem getting one, see for instance:
-[[http://www.gooze.eu/catalog/embedded-components/cables]]
-
-The Linux driver creates a device name like /dev/ttyUSB0 instead of
-/dev/ttyS0.
-
-## Starting a login process on my serial port
-
-You have to edit and uncomment the line in /etc/inittab. Line:
-
- #T0:23:respawn:/sbin/getty -L ttyS0 9600 vt100
-
-becomes in case of a serial/usb converter:
-
- T0:23:respawn:/sbin/getty -L ttyUSB0 9600 vt100
-
-You must force the init process to take into account the modified file
-by issuing command:
-
- telinit q
-
-## The null modem
-
-The link above about serial/usb converters offers also null modems.
-If you don't mind a bit of soldering, it's quite easy to
-[build one yourself](http://www.lammertbies.nl/comm/info/RS-232_null_modem.html).
-
-## Minicom configuration
-
-What is needed at the other end of our serial link is a dumb serial
-terminal. It happens that if you don't have one in your attic, you
-can emulate one with a second computer. Minicom is one of these
-emulators.
-
-At that point, you may also discover that you don't have a serial port
-either on that second computer! Time to go shopping for a second
-serial/usb converter... It's of course possible to have a serial port
-on the blocked computer and none on the terminal emulator.
-
-So when you have all the hardware, you can install and configure
-minicom. Notice that you will have to run minicom as root, or give
-lax permissions to your serial devices. Minicom configuration file
-is called /etc/minicom/minirc.dfl under Debian and should contain:
-
- pu port /dev/ttyS0
- pu baudrate 9600
- pu bits 8
- pu parity N
- pu stopbits 1
- pu minit
- pu mreset
- pu rtscts No
-
-You should only have to change the first line to adapt of your specific serial device name.
-You may have to hit CR to get the login prompt.
-
-## If everything fails
-
-Nothing of the above works? You are in for a reboot, but if the
-keyboard driver is still alive, you can still get a more a less clean
-shutdown using the [SysRq](http://www.linuxhowtos.org/Tips%20and%20Tricks/sysrq.htm).
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