--- /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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