Linux


Encrypting and forwarding local email to an external email address

Last week I set out to find a reliable and permanent solution to my problems with unread system mail and undelivered cron error messages, and I can now see that sending, delivering, and receiving email is far more complicated than I had thought. I have had to learn more about SMTP, SSL/TLS, and email delivery than I ever wanted to know, and I still only know the bare basics.

When I started I had two requirements:

  1. All local email sent to the root user (and preferably everyone else) must be forwarded to an external SMTP server and email account
  2. All email that leave my network must be encrypted

After experimenting with number of different applications (GNU Anubis, Nullmailer, ESMTP, MSMTP, etc) I finally found something that worked; Postfix with GPG-Mailgate. If all you need is the ability to send email to an external account then there are other applications you could use instead (I had some success with MSMTP and Nullmailer). The advantage of using Postfix is its flexibility and maturity. All other applications I tried had some small thing they could not do reliably or would fail in some edge cases, such as only forwarding some of the emails sent to root, but not quite all of them.

This guide will show each step needed to set this up, and a few mistakes to look out for. The first part will cover Postfix and how to configure it to forward all emails sent to a local user to an external email account. The second part will show how to set up GPG-Mailgate so that all emails that are sent to certain accounts are encrypted with GPG before they leave the server. If all you need is mail forwarding then you can stop after the first part, and if you already have Postfix configured you can jump straight to the second part.

A few assumptions will be made in this guide.

  1. You are using the root account. If you are not then you will have to prepend ‘sudo’ to some commands.
  2. You are using Debian. Everything should still work if you are using a different Linux distribution, but you may have to make some minor changes.
Names and servers

I will be using the following user names, email accounts, and servers in this guide.

User names

root : The local root user

gpgmap : The user account used for GPG-Mailgate

Email accounts

[email protected] : The fully qualified email address of the root user

[email protected] : An external email account that we want to send email through

[email protected] : An external email account that we want to forward all local emails to

Domains

yourdomain.com : Your local domain

emailprovider.com : The domain of your email provider

anotherdomain.com : The domain of the email provider for the account you want to forward all local email to

Servers

smtp.emailprovider.com : The SMTP server of your email provider

server.yourdomain.com : The computer you want to forward local emails from

Part 1 – Forwarding local email to an external SMTP server

The first step is to install and configure Postfix to forward all emails sent to the root user (or any user you want) to an external SMTP server and email account. This is not difficult, but it does require a few steps.

First, if you do not already have Postfix install it and some dependencies.

apt-get install postfix libsasl2-modules

Fill in any domain names the installer asks for and choose the “satellite” option.

If you are not already using Postfix then you are probably running Sendmail. Before starting Postfix you will have to turn it off. To avoid future error messages and warnings I also recommend you completely uninstall it.

service sendmail stop

apt-get remove sendmail-base sendmail-cf sendmail-doc

Next, start postfix.

service postfix start

Make sure that it started correctly.

service postfix status

Next comes the hard part (not really); configuring Postfix. The exact details depends on your email provider. Everything I describe here will be completely compatible with Gmail.

Most of the settings you need should have been configured for you by the installer.

Open ‘/etc/postfix/main.cf’ and make sure that the relay host is set to your email provider’s SMTP server.

relayhost = smtp.emailprovider.com:587

And add these lines:

smtp_use_tls=yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

Next, create a password file ‘/etc/postfix/sasl_passwd’ and add the following to it:

smtp.emailprovider.com:587 [email protected]:yourpassword

The SMTP hostname and port must match relayhost in the main.cf file.

Update Postfix’s password database and settings.

postmap /etc/postfix/sasl_passwd
service postfix reload

Everything you need to send emails through Postfix using your email provider’s SMTP server should now be in place. Before proceeding you should test that it is working.

echo "Testing Postfix email delivery" | mail -s "Test email" [email protected]

If the email doesn’t arrive check in ‘/var/log/sysIog’ for errors and make sure that you can successfully send emails using the same settings from an email client (such as Thunderbird).

Now that that is working we only need to tell Postfix to forward all emails sent to the root user to an external email account. Open ‘/etc/aliases’ and add the following line:

root: [email protected]

If you want to forward emails for other users than root you simply add them to the list as well. When you are done run:

newaliases

That’s it. If everything is configured properly all emails sent to the root user will now be forwarded to [email protected]

echo "Testing Postfix forwarding" | mail -s "Test email" root

If that was all you needed then you can stop here, but you are now sending unencrypted emails through the internet containing potentially sensitive information. If you think that sounds dangerous then continue to the second part were we will set up some automated GPG encryption.

A warning about restrictive SMTP servers and the From header

It is possible that these settings won’t work with your particular email provider. I’m using a Gmail account to forward email. It isn’t my primary email provider, but there are practical reasons for using it in this case. Unlike some other email providers Gmail does not care about what you specify in the ‘From’ header. It will overwrite whatever is in it with the Gmail user you used. This simplifies things greatly when forwarding local emails since you would otherwise have to change the contents of the header before sending it out. Postfix has the ability to replace addresses in outbound email (just google smtp_generic_maps or sender_canonical_maps and you should find instructions for how to configure Postfix), however, depending on how an application fills out the headers in emails they send out this may not work reliably in all situations. I tried to set this up with a more restrictive Zoho.com email account, but I could not get it to forward cron error messages.

If you need this for your email provider, and if you manage to set it up successfully, please leave a comment explaining how you did it. For everyone else; just use a Gmail account. It’s easier.

Part 2 – Encrypting outgoing email with GPG

It is possible that some of the applications sending email to your local accounts might send data that you don’t want any stranger on the internet to see. In my paranoid mind that just isn’t acceptable, and so we will be adding a layer of encryption to Postfix using GPG-Mailgate. GPG-Mailgate is a content filter script for Postfix that will encrypt a received email if there is a public GPG key available for its recipient, and if the email is not already encrypted. It is relatively easy to install and configure, but be warned that if you do not configure it correctly it will probably fail silently and send out empty emails.

First, either download the source code from Github or clone it.

git clone https://github.com/ajgon/gpg-mailgate.git

Next, manually put everything where it needs to be. Replace python2.6 with your python version.

cd gpg-mailgate
cp gpg-mailgate.py /usr/local/bin/gpg-mailgate.py
cp -r GnuPG /usr/lib/python2.6/

Make sure that all permissions are correct.

chown root:root /usr/local/bin/gpg-mailgate.py
chmod 755 /usr/local/bin/gpg-mailgate.py
chown -R root:root /usr/lib/python2.6/GnuPG
chmod 755 /usr/lib/python2.6/GnuPG
chmod 644 /usr/lib/python2.6/GnuPG/__init__.py

Create a user to run the GPG-Mailgate script as and import the public key you want to encrypt forwarded email with.

useradd -s /bin/false -d /var/gpg -M gpgmap
mkdir -p /var/gpg/.gnupg
chown -R gpgmap:gpgmap /var/gpg/.gnupg
chmod 700 /var/gpg/.gnupg
sudo -u gpgmap /usr/bin/gpg --import yourpublic.key

yourpublic.key is the public part of your GPG key pair. If you don’t have one already then your will need to create one. How to do that is beyond the scope of this guide, but it isn’t difficult.

Check that everything worked and that the key is in place.

sudo -u gpgmap /usr/bin/gpg --list-keys  --keyid-format long

This should give you something like this.

/var/gpg/.gnupg/pubring.gpg
 ---------------------------
pub 4096R/0123456789ABCDEF 2014-09-17
uid                        Your Name <[email protected]>
sub 4096R/FEDCBA9876543210 2014-09-17

Save whatever you have instead of ‘0123456789ABCDEF’. This is the identifier of your public key and you will need it later.

Add the following to the end of ‘/etc/postfix/master.cf’:

#GPG-Mailgate
gpg-mailgate unix - n n - - pipe
flags= user=gpgmap argv=/usr/local/bin/gpg-mailgate.py ${recipient}

127.0.0.1:10028 inet n - n - 10 smtpd
  -o content_filter=
  -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks
  -o smtpd_helo_restrictions=
  -o smtpd_client_restrictions=
  -o smtpd_sender_restrictions=
  -o smtpd_recipient_restrictions=permit_mynetworks,reject
  -o mynetworks=127.0.0.0/8
  -o smtpd_authorized_xforward_hosts=127.0.0.0/8

Make certain that the user name and script location matches what you used above.

Add the following to ‘/etc/postfix/main.cf’:

content_filter = gpg-mailgate

And reload Postfix’s settings.

service postfix reload

Create a configuration file for GPG-Mailgate at ‘/etc/gpg-mailgate.conf’ and add the following to it:

[default]
# whether gpg-mailgate should add a header after it has processed an email
# this may be useful for debugging purposes
add_header = yes

# whether we should only sign emails if they are explicitly defined in
# the key mappings below ([keymap] section)
# this means gpg-mailgate won't automatically detect PGP recipients
keymap_only = yes

[gpg]
# the directory where gpg-mailgate public keys are stored
# (see INSTALL for details)
keyhome = /var/gpg/.gnupg

[logging]
# For logging to syslog. 'file = syslog', otherwise use path to the file.
file = syslog
verbose = no

[relay]
# the relay settings to use for Postfix
# gpg-mailgate will submit email to this relay after it is done processing
# unless you alter the default Postfix configuration, you won't have to modify this
host = 127.0.0.1
port = 10028

[keymap]
# You can find these by running the following command:
# gpg --list-keys --keyid-format long [email protected]
# Which will return output similar to:
# pub 1024D/AAAAAAAAAAAAAAAA 2007-10-22
# uid Joe User <[email protected]>
# sub 2048g/BBBBBBBBBBBBBBBB 2007-10-22
# You want the AAAAAAAAAAAAAAAA not BBBBBBBBBBBBBBBB.
#[email protected] = <gpg key id>
[email protected] = 0123456789ABCDEF
[email protected] = 0123456789ABCDEF

Replace the addresses and keys on the last two lines with the email address you want to forward emails to and the identifier of the public key you imported earlier.

The final line is a bit of a hack. GPG-Mailgate uses the ‘To’ header to find the GPG key to use when encrypting email. If it can’t find a matching entry in the configuration file it will not encrypt it. This creates a minor complication since Postfix doesn’t rewrite the ‘To’ header when forwarding local email. Any email sent to the root user will therefore have a ‘To’ address of ‘[email protected]’; which GPG-Mailgate won’t recognise. To fix this we add the local email address to the configuration file as well.

This should be all. Now test that everything is working.

echo "Testing GPG encryption" | mail -s "Test GPG" [email protected]
echo "Testing GPG encryption to root user" | mail -s "Test GPG root" root

These commands should both send an encrypted email to [email protected] If it doesn’t work check ‘/var/log/syslog’ for errors.

If GPG-Mailgate did not encrypt your emails then it is likely that it did not find a matching public key. Make sure that the keys and addresses in ‘/etc/gpg-mailgate.conf’ are correct.

If you get empty messages then it is likely that GPG returned an error to GPG-Mailgate. This will cause GPG-Mailgate to fail silently. Make sure that the gpgmap user has the permissions needed to use the GPG keys in ‘/var/gpg/.gnupg’ and that gpgmap is used by Postfix when running GPG-Mailgate.

If you get an error about a missing GnuPG module then you either set the wrong permissions for the GnuPG folder and its contents, or you placed it in the wrong python folder.

If everything is working than this should be it.

  • You can now send email through an external SMTP server from the command line
  • All emails sent to the root user are forwarded to an external email address
  • All emails sent to [email protected] are automatically encrypted before they leave the server

How to use the serial interface to communicate with an FRDM-KL25Z in Linux

This short guide will show how to communicate with the FRDM-KL25Z using the Serial and USBSerial classes from the mbed library in Linux.

Serial and USBSerial are two different methods for creating serial connections using mbed. USBSerial creates an emulated serial port over a normal USB port while Serial uses the built in serial port (if there is one). In the case of the FRDM-KL25Z  this can be done through the virtual serial port provided by OpenSDA.

This small example will create two serial connections; one using the serial port built into OpenSDA, and one over the normal USB port. It will pass everything given to either interface on to the other interface.

#include <mbed.h>
#include <USBSerial.h>

Serial debug(USBTX, USBRX);
USBSerial usb;

int main()
{
  while(1) {
    if(usb.readable()) {
      debug.putc(usb.getc());
    }
    if(debug.readable()) {
      usb.putc(debug.getc());
    }
  }
}

Compile the code and load it onto your FRDM-KL25Z, then  connect it to your computer using both USB ports and run the following command.

ls -l /dev/ttyACM*

Your output should look something like this.

crw-rw---- 1 root dialout 166, 0 Aug 19 13:56 /dev/ttyACM0
crw-rw---- 1 root dialout 166, 1 Aug 19 14:19 /dev/ttyACM1

Each of these device files are connected to one of the serial interfaces on the FRDM-KL25Z. To use them you will first have to add your user to the dialout group.

sudo usermod -a -G dialout USERNAME

You can use any terminal emulator of your choice to connect to these serial ports. I will be using minicom for this example.

Open two terminals. On the first run:

minicom -b 9600 -D /dev/ttyACM0

And in the second:

minicom -b 9600 -D /dev/ttyACM1

‘-b 9600’ sets the baud rate. The default value used by mbed is 9600.

If everything is working correctly whatever you write in one terminal should now appear on the other, and vice versa. If it doesn’t create new lines when you press ‘enter’ and it instead jumps to the beginning of the current line, tell minicom to add linefeeds by pressing ‘Ctrl-a a’.


A step-by-step guide to using the FRDM-KL25Z in Linux with GCC and the mbed library 2

Freescale FRDM-KL25Z

By Viswesr (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

I recently bought a Freescale FRDM-KL25Z to experiment with ARM and embedded systems programming, and I thought I should share my experiences with using it in a completely open source Linux environment so that others may learn from my (many) mistakes. The FRDM-KL25Z is an inexpensive development platform built around an ARM Cortex M0+ based microcontroller.  It has support from several commercial development environments, but there is a lack of documentation for how to make it work on Linux using nothing but open source software. After some research, trial and error, and almost bricking the thing, I finally got everything to work.

This post will show you how to set up a development environment around the FRDM-KL25Z using the GCC toolchain and mbed library. To make it more general I will not use any IDE. This will all be by hand. Once you have it working it should not be a problem

I had to buy a freedom board for a school class, and I was frustrated at first to find that there was no support for the linux platform. I'm personally a fan of the teensy ARM microprocessors which are supported by GCC or the Arduino IDE, now I can add the new micro to my growing collection. Thanks again for the great article!

to set up an IDE around it as well, but that is left as an exercise to the reader.

Getting everything to work will require a few steps.

  1. Install the mbed firmware
  2. Install the GCC ARM toolchain
  3. Set up debugging tools
  4. Download and build the mbed library
  5. Create a simple program

Installing the mbed firmware

There are several firmware variants you can install on your FRDM-KL25Z. You can use whichever version you like as long as it supports the CMSIS-DAP debugging interface (i.e. any firmware other than what came pre-installed). The one I have chosen to use is the mbed firmware. It is easy to use and performs a sanity check on any binaries you give it to make sure that you don’t accidentally brick your device (which you very well might do if you are not careful).

To install the mbed firmware first download the newest version. At the moment  (2014-08-13) that would be this one.

Start the board in bootloader mode by holding down the reset button while plugging in the board using the SDA USB port.https://mbed.org/handbook/CMSIS-DAP

A mass-storage device named BOOTLOADER will appear. If you were using Windows it would be enough to copy the firmware file to this device and restart the board, but since you are using Linux it isn’t quite that simple. You first have to mount it using the ‘msdos’ file system type.

sudo mount -t msdos /dev/sdd /mnt

In my case the board shows up as /dev/sdd. This may, of course, be different in your case. Copy the firmware file to /mnt and restart the board. You should now see a mass-storage device named MBED.

To test that everything is working you can try one of mbed’s example programs. Sign in or create an account and click “Import Program”. This will take you to their online IDE where you can export the program to a ‘.bin’. Copy this file to the MBED  device and press the reset button. If everything is working then the led will probably start blinking (depending on the example you chose).

You could stop here and just use mbed’s online IDE. The rest of this guide will show you how to compile your own programs offline with GCC and the mbed library, and how to get the USB debugging interface to work.

Install the GCC ARM toolchain

The next step is to install the tools needed to compile your own programs. For this you want the gcc-arm-none-eabi from launchpad. Download the one ending with linux.tar.bz2, unless you want to compile it from source.

Just extract it somewhere, add the bin directory to you path variable, and you are done.

Set up debugging tools

With any new firmware the FRDM-KL25Z will support USB debugging using the CMSIS-DAP debugging interface. To use it we need to install OpenOCD and hidapi.

First you must download and install hidapi.

git clone http://github.com/signal11/hidapi.git
cd hidapi
./bootstrap
./configure
make
sudo make install

Next, do the same for OpenOCD.

git clone http://openocd.zylin.com/openocd
cd openocd
./bootstrap
./configure --enable-maintainer-mode --enable-cmsis-dap --enable-hidapi-libusb

Open ‘tcl/target/kl25.cfg’ and add the following text to the end.

adapter_khz 50
$_TARGETNAME configure -event gdb-attach {
    halt
}
make
sudo make install

Permissions

By default only the root user has access to the device files used for debugging. If you want to give a normal user permission to use the debugging tools you will have to set up some udev rules.

Create the file ‘/etc/udev/rules.d/45-mbed_debugger.rules’ and add the following to it.

SUBSYSTEM=="usb", ATTR{idVendor}=="0d28", ATTR{idProduct}=="0204", MODE="0660", GROUP="plugdev"

Similarly, create the file ‘/etc/udev/rules.d/99-hidraw-permissions.rules’ and add the following to it.

KERNEL=="hidraw*", SUBSYSTEM=="hidraw", MODE="0664", GROUP="plugdev"

This will give all users in the ‘plugdev’ group read and write access to all relevant device files. You could use any group you want, or just a specific user.

To test that it is working run the following command as a non-privileged user with the FRDM-KL25Z plugged in.

openocd -c "interface cmsis-dap" -f /usr/local/share/openocd/scripts/target/kl25.cfg

If it complains about not finding the libhidapi-hidraw.so.0 library check that ‘/usr/local/lib’ is in ‘/etc/ld.so.conf’, run ‘ldconfig’, and try again.

If you now open a second terminal you should be able to connect to the device with GDB.

arm-none-eabi-gdb --eval-command "target remote localhost:3333"

Download and build the mbed library

The mbed development platform consists of an online browser based IDE and compiler (as you saw earlier), and an open source library that simplifies the development of embedded systems code by hiding low level details from the programmer. This is part we want. To use the library offline without the IDE you will have to  download and compile the source code.

git clone https://github.com/mbedmicro/mbed.git
cd mbed/workspace_tools

In addition to the main mbed library, the repository contains a number of other useful libraries that can be installed.

–rtos Real Time Operating System
–usb USBDevice
–dsp Digital Signal Processing
–fat SDFileSystem

The following command will build the mbed library and all the optional libraries that are compatible with the FRDM-KL25Z.

python build.py -m KL25Z -t GCC_ARM --rtos --usb --dsp --fat

When it is done you can find the compiled libraries in ‘build’. Move them to where you want the mbed libraries to be located.

Create a simple program

Finally everything that you need to build your own programs is in place, but before you can start programming we will have to pull all of the pieces together and show how to compile a program from source code. For this example we will, of course, create a simple program that turns the three LEDs on and off.

Most of the work needed to build a program for the FRDM-KL35Z has already been taken care of for you by the mbed library. All you must do is link everything together and compile it. You could set this up by hand, but I recommend you start out by using this makefile. It will set up all the paths and include directories for you. What is left is to set the path to the mbed libraries in MBED_PATH, set the program name in TARGET,  add any local source and header folders to SRC_DIRS and INC_DIRS, and to tell it which mbed libraries to use.

Next, create the file ‘src/main.cpp’ and add the following to it.

#include <mbed.h>

Ticker tick;

DigitalOut led1(LED_RED);
DigitalOut led2(LED_GREEN);
DigitalOut led3(LED_BLUE);

void flip() {
    led3 = !led3;
}

int main()
{
    led3 = true;

    //Flip the blue LED every 5 seconds
    tick.attach(&flip, 5.0);

    //Flip the red and green LED once every second
    while (true) {
        led1 = true;
        led2 = false;
        wait (1.0);
        led1 = false;
        led2 = true;
        wait (1.0);
    }
}

Don’t forget to add the ‘src’ folder to SRC_DIRS in the makefile, then compile with ‘make’.

If everything is working as it should it should now create a ‘build’ directory with the file ‘mbed.bin’ in it (assuming you did not change TARGET). Copy this file to the MBED device, wait for it to load it, and then press the reset button. The LED should now start blinking in different colors.

That’s all. You are now ready to start programming your own programs. Build something interesting.

Some helpful tips on how not to lock your FRDM-KL25Z and save yourself much pain

Unless you are careful you will sooner or later manage to “lock” your FRDM-KL25Z. This happens when you accidentally enable the security bits. If you have not set up the mbed library (in particular the *.ld files) correctly then this could happen very easily. The mbed firmware will protect you from this mistake by refusing to flash binaries with the security bits enabled, but there are ways to bypass it using the debugger and OpenOCD.

To check if you have set the security bits open the binary in a hex editor and look at the contents of address 0x0000040C. The last two bits should be “10”. If it isn’t, something is wrong and you should NOT attempt to flash this binary to the board. Seriously, don’t do it!

If you ignored my advice and flashed the board with a binary that had the security bits enabled then you will have to unsecure it. This can be a little complicated, but if you read these instructions and still didn’t follow my advice then it’s your own fault. Supposedly there are tools you can use to unsecure the device, but I have not found any that are free and works in Linux. Fortunately, some variants of the FRDM-KL25Z firmware will unset the security bits when they are installed. You can then reinstall the firmware you want to use. This can require some trial and error, but I have had success with the MSD-DEBUG-FRDM-KL25Z_Pemicro_v114.SDA firmware.

Save yourself a lot of trouble and make sure that you don’t do this in the first place. Unless you know what you are doing only program the device by copying binaries to the MBED mass-storage device.

Sources

http://mbed.org/handbook/Firmware-FRDM-KL25Z
http://karibe.co.ke/2013/08/setting-up-linux-opensource-build-and-debug-tools-for-freescale-freedom-board-frdm-kl25z/
http://embeddedworldweb.blogspot.se/2013/08/mbed-gcc-with-eclipse-kl25z-part-1.html
http://mcuoneclipse.com/2012/11/04/how-not-to-secure-my-microcontroller/


How to use setxkbmap to rebind Caps Lock

Caps Lock must be the second most useless key on my keyboard (what does Scroll Lock even do?) and one of the first things I usually do after installing a new Linux system is to rebind it to something useful, such as backspace. This is very easy to do (in X11 at least). Just call this script on login.

#!/bin/sh

#Set the keyboard layout to "Swedish" 
setxkbmap -layout se

#Replace Caps Lock with Backspace
setxkbmap -option caps:backspace

#Required to allow key repeat
xmodmap -e "clear Lock"

You can replace Caps Lock with other keys by changing ‘caps:backspace’ to whatever you want.

Replace Caps lock with escape:

setxkbmap -option caps:escape

Replace Caps Lock with Ctrl:

setxkbmap -option ctrl:nocaps

Reset all options and bindings:

setxkbmap -option

How to paste text when copy/paste is disabled

It is sometimes the case that an application will not allow you to paste in text, forcing you to write it out by hand (either because it is poorly written or because of perceived security risks). These instructions are the results of having to manually enter long and complex passwords for virtual Windows machines one time too many, and will show you how to bypass such restrictions using a simple script.

Dependencies

Klipper

xdotool

typeclipboard

#!/bin/sh
 
#This script will type out the content of the Klipper clipboard as if the user had typed it themself.
 
#Copy the content of the KDE clipboard
to_write=$(qdbus org.kde.klipper /klipper getClipboardContents)

#Clear the clipboard. Uncomment this line if you will be copying anything sensitive.
#qdbus org.kde.klipper /klipper clearClipboardHistory

#Wait for one second to give the user time to release any keys that may have been pressed.
sleep 1
 
#Type out the content of the clipboard
xdotool type --clearmodifiers "$to_write"

Common problems

If the output does not match the content of the clipboard it is possible that xdotool is using the wrong keyboard layout. This can be fixed by adding ‘setxkbmap -layout LAYOUT’ to your shell profile, where LAYOUT is the keyboard layout you want (e.g. ‘se’ for Swedish).

Try not to press down any modifier keys (Ctrl, Shift, Alt, etc.) when running the script. With ‘–clearmodifiers’  xdotool will attempt to unset all modifiers, but this will not always work. The script will type out anything you give it as if you had typed it out yourself. This includes things like keyboard shortcuts. Strange and dangerous things can happen if you are not careful. The script will wait for one second before doing anything to give you time to take your hands of the keyboard.

Create a shortcut

To create a keyboard shortcut for the script in KDE4, go to ‘System Settings -> Shortcuts and Gestures -> Custom Shortcuts’, then ‘Edit -> New -> Command/URL’. Under ‘Trigger’, select the keyboard shortcut you want, and under ‘Action’, give it the path to the script.

Pasting passwords to Windows machines running in VirtualBox

This was the reason why I wrote the script in the first place. To paste a password, simply copy it and click on the Windows password field, then press the host key (right Ctrl) so that VirtualBox does not capture the keyboard, followed by the keyboard shortcut you chose. The script will then type out the password as if you had typed it out yourself, bypassing the disabled copy/paste functionality.