diff --git a/README b/README
new file mode 100644
index 0000000..02f6835
--- /dev/null
+++ b/README
@@ -0,0 +1,15 @@
+Yubikey login:
+^^^^^^^^^^^^^^
+
+-please create /etc/udev/rules.d/92-yubikey.rules with the following content:
+   ACTION=="add", ATTRS{idVendor}=="1050", ATTRS{idProduct}=="0010", RUN+="/etc/door/door.sh"
+
+
+
+SSH login:
+^^^^^^^^^^
+
+-in ~/.ssh/authorized_keys add to the first line:
+   no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty
+
+-in /etc/passwd change the the default shell to door_ssh_login.sh
diff --git a/door.sh b/door.sh
index 9661a2a..b24fc29 100755
--- a/door.sh
+++ b/door.sh
@@ -1,28 +1,106 @@
-#! /bin/sh
+#! /bin/bash
 
-cd /etc/door/
 export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
 OPEN_INDICATOR=/tmp/door_status_open
 CLOSED_INDICATOR=/tmp/door_status_closed
+GPIO_SWITCH=21
+WATCHDOG_PID=/tmp/door_watchdog_pid
 
+DELAY=10
+DATE_STRING="$(date +%s)#$(date +"%F %X")"
+TIMEOUT=30
+LOCKDIR="/var/lock"
+
+lock_file() {
+        OUTFILE=$1
+        OUTFILE_LOCK="${LOCKDIR}/$(readlink -f $OUTFILE | sed -e "s/\//\!/g").lock"
+        TIMEOUT_LOCK=$TIMEOUT
+        while [ $(mkdir "$OUTFILE_LOCK" 2> /dev/null; echo $? ) -ne 0 -a $TIMEOUT_LOCK -gt 0 ]; do
+                TIMEOUT_LOCK=$(($TIMEOUT_LOCK-1))
+                if [ -f "$OUTFILE_LOCK/lastaction" -a ! -d "$OUTFILE_LOCK/timeout"  ] >> /dev/null 2>&1; then
+                        FILEAGE=$(($(date +%s) - $(stat -c '%Y' "$OUTFILE_LOCK/lastaction" || echo $(date +%s) 2> /dev/null )))
+                        TIMEOUT_LOCK=$(($TIMEOUT-$FILEAGE))
+                fi
+                if [ $TIMEOUT_LOCK -le 0 ]; then
+                        if [ $(mkdir "$OUTFILE_LOCK/timeout" >> /dev/null 2>&1; echo $? ) -ne 0 ]; then
+                                TIMEOUTAGE_LOCK=$(($(date +%s) - $(stat -c '%Y' "$OUTFILE_LOCK/timeout")))
+                                if [ $TIMEOUTAGE_LOCK -gt $TIMEOUT ]; then
+                                        if [ $(rm -rf "$OUTFILE_LOCK/timeout" >> /dev/null 2>&1; echo $? ) -ne 0 ]; then
+                                                TIMEOUT_LOCK=$TIMEOUT
+                                        else
+                                                TIMEOUT_LOCK=1
+                                        fi
+                                else
+                                        TIMEOUT_LOCK=$(($TIMEOUT-$TIMEOUTAGE_LOCK))
+                                fi
+                        fi
+                fi
+                sleep 1
+        done
+        if [ $TIMEOUT_LOCK -le 0 ]; then
+                echo "Timeout! Ignoring old \"$OUTFILE_LOCK\"." >&2
+        fi
+        touch "$OUTFILE_LOCK/lastaction"
+}
+
+unlock_file() {
+        OUTFILE=${1}
+        OUTFILE_LOCK="${LOCKDIR}/$(readlink -f $OUTFILE | sed -e "s/\//\!/g").lock"
+        rm -rf "$OUTFILE_LOCK"
+}
+
+cd $(dirname $0) || {
+    echo "konnte verzeichniss nicht wechseln"
+    exit 1
+}
+
+if ! kill -0 $(cat $WATCHDOG_PID 2> /dev/null) > /dev/null 2>&1; then
+{
+	( while true; do
+		{
+		if [ $(cat /sys/class/gpio/gpio${GPIO_SWITCH}/value) -ne 1 -a -f $CLOSED_INDICATOR ]; then
+			{
+			lock_file $OPEN_INDICATOR
+			lock_file $CLOSED_INDICATOR
+			touch $OPEN_INDICATOR
+			rm -f $CLOSED_INDICATOR >> /dev/null 2>&1
+			unlock_file $OPEN_INDICATOR
+                        unlock_file $CLOSED_INDICATOR
+			}
+		fi
+		sleep .5
+		}
+	done ) &
+	echo $! > $WATCHDOG_PID
+	cat $WATCHDOG_PID
+}
+fi
+
+lock_file $OPEN_INDICATOR
+lock_file $CLOSED_INDICATOR
 if [ -f $OPEN_INDICATOR ]; then
 	LOCK_AGE=$(( $(date +%s)-$(stat -c %X $OPEN_INDICATOR) ))
 elif [ -f $CLOSED_INDICATOR ]; then
 	LOCK_AGE=$(( $(date +%s)-$(stat -c %X $CLOSED_INDICATOR) ))
 else
-	LOCK_AGE=15
+	LOCK_AGE=$DELAY
 fi
 
-if [ $LOCK_AGE -lt 15 ]; then
-	echo "please wait at least 15 seconds befor a second run of this script" >&2
+if [ $LOCK_AGE -lt $DELAY ]; then
+	echo "please wait at least $DELAY seconds before a second run of this script" >&2
+	unlock_file $OPEN_INDICATOR
+	unlock_file $CLOSED_INDICATOR
 	exit 1
 fi
 
-./door_verify.sh
-STATUS=$?
+if [ "$1" == "noverify" ]; then
+	STATUS=0
+else
+	./door_verify.sh
+	STATUS=$?
+fi
 if [ $STATUS -eq 0 ]; then
-	echo "opening door"
 	if [ -f $OPEN_INDICATOR ]; then
 		echo "closing door"
 		./door_lock.sh close
@@ -34,8 +112,17 @@ if [ $STATUS -eq 0 ]; then
 		rm $CLOSED_INDICATOR
 		touch $OPEN_INDICATOR	
 	fi
+	unlock_file $OPEN_INDICATOR
+	unlock_file $CLOSED_INDICATOR
 	exit 0
 else
 	echo "the lock won't move" >&2
+	if [ -f $OPEN_INDICATOR ]; then
+		touch $OPEN_INDICATOR
+	else
+		touch $CLOSED_INDICATOR
+	fi
+	unlock_file $OPEN_INDICATOR
+	unlock_file $CLOSED_INDICATOR
 	exit 1
 fi
diff --git a/door_lock.sh b/door_lock.sh
index 4884e5b..48d02d3 100755
--- a/door_lock.sh
+++ b/door_lock.sh
@@ -3,13 +3,18 @@
 GPIO_OPEN=23
 GPIO_CLOSE=24
 GPIO_CLIP=22
-SLEEP=2
+GPIO_SWITCH=21
+SLEEP=4
+CLOSE_TIMEOUT=15
 
 for i in $GPIO_OPEN $GPIO_CLOSE $GPIO_CLIP; do
 	echo "$i" > /sys/class/gpio/export
 	echo "out" > /sys/class/gpio/gpio${i}/direction
 done
 
+echo "$GPIO_SWITCH" > /sys/class/gpio/export
+echo "in" > /sys/class/gpio/gpio${GPIO_SWITCH}/direction
+
 case $1 in
 	open)
 		echo "1" > /sys/class/gpio/gpio${GPIO_OPEN}/value
@@ -17,9 +22,22 @@ case $1 in
 		echo "0" > /sys/class/gpio/gpio${GPIO_OPEN}/value
 		;;
 	close)
-		echo "1" > /sys/class/gpio/gpio${GPIO_CLOSE}/value
-		sleep $SLEEP
-		echo "0" > /sys/class/gpio/gpio${GPIO_CLOSE}/value
+		TIMER=$(($CLOSE_TIMEOUT*10))
+		while [ $TIMER -ge 0 ]; do
+		{
+			SWITCH=$(cat /sys/class/gpio/gpio${GPIO_SWITCH}/value)
+			if [ $SWITCH -eq 1 ]; then
+			{
+				echo "1" > /sys/class/gpio/gpio${GPIO_CLOSE}/value
+				sleep $SLEEP
+				echo "0" > /sys/class/gpio/gpio${GPIO_CLOSE}/value
+				break
+			}
+			fi
+			sleep .1
+			TIMER=$(($TIMER-1))
+		}
+		done
 		;;
 	clip)
 		echo "1" > /sys/class/gpio/gpio${GPIO_CLIP}/value
diff --git a/door_ssh_login.sh b/door_ssh_login.sh
new file mode 100755
index 0000000..5761eed
--- /dev/null
+++ b/door_ssh_login.sh
@@ -0,0 +1,10 @@
+#! /bin/bash --
+
+ping -c1 -t3  $(echo $SSH_CONNECTION | cut -d" " -f 1) >> /dev/null 2>&1
+STATUS=$?
+if [ $STATUS -ne 0 ]; then
+	echo "come closer... ;-)"
+	exit 1
+fi
+
+sudo $(dirname $0)/door.sh noverify
diff --git a/door_verify.sh b/door_verify.sh
index 2832cc2..c270aea 100755
--- a/door_verify.sh
+++ b/door_verify.sh
@@ -20,9 +20,7 @@ aes_decrypt() {
 echo "$1" | xxd -ps -r | openssl enc -aes256 -d -k "$2" >> /dev/null 2>&1
 DECRYPT_OK=$?
 DECRYPTED_TEXT="$(echo "$1" | xxd -ps -r | openssl enc -aes256 -d -k "$2" 2>&1)"
-if [ $DECRYPT_OK -ne 0 ]; then
-	DECRYPTED_TEXT="DEADBEEF"
-fi
+[ $DECRYPT_OK -ne 0 ] && DECRYPTED_TEXT="DEADBEEF"
 echo $DECRYPTED_TEXT
 }
 
@@ -35,7 +33,7 @@ if [ ! -f $KEYFILE ]; then
 	exit 1
 fi
 
-if [ ! -f $LOGFILE ]; then
+if [ ! -f "$LOGFILE" ]; then
         echo "generating new logfile" >&2
 	echo "# DATE:ID:SIGNED_DATE:STATUS" > $LOGFILE
 	chmod 600 $LOGFILE
diff --git a/etc_udev_rules.d_92-yubikey.rules b/etc_udev_rules.d_92-yubikey.rules
deleted file mode 100644
index 812f95a..0000000
--- a/etc_udev_rules.d_92-yubikey.rules
+++ /dev/null
@@ -1 +0,0 @@
-ACTION=="add", ATTRS{idVendor}=="1050", ATTRS{idProduct}=="0010", RUN+="/etc/door/door.sh"