diff --git a/devices/acer.md b/devices/acer.md
new file mode 100644
index 0000000..f0a8fbd
--- /dev/null
+++ b/devices/acer.md
@@ -0,0 +1,12 @@
+# Acer Aspire 3820T
+
+* press the <> key to interrupt the start sequence
+* press the <> key to enter the BIOS setup
+* prepare USB stick for Debian installation like [this](../doc/bootable-usb-drive.md)
+* [Debian Installation](../doc/debian-install.md)
+* [Debian Configuration](../doc/debian-config.md)
+* [Debian Keyboard Layout](../doc/debian-keyboard-layout.md)
+* [Debian Lid Switch Configuration](../doc/debian-lid-switch-config.md)
+* [SSH Server](../doc/ssh-server.md)
+* [SSH Public Key Authentication](../doc/ssh-pub-key-auth.md)
+* [SSH Public Key Authentication](../doc/ssh-pub-key-auth.md)
diff --git a/devices/antje.md b/devices/antje.md
index 6459a98..5393ee5 100644
--- a/devices/antje.md
+++ b/devices/antje.md
@@ -1,4 +1,4 @@
 # Cloud Server
 
-* [SSH Server](doc/ssh-server.md)
-* [SSH Public Key Authentication](doc/ssh-pub-key-auth.md)
+* [SSH Server](../doc/ssh-server.md)
+* [SSH Public Key Authentication](../doc/ssh-pub-key-auth.md)
diff --git a/devices/cloud-server.md b/devices/cloud-server.md
index 9a92195..a18a08d 100644
--- a/devices/cloud-server.md
+++ b/devices/cloud-server.md
@@ -1,6 +1,6 @@
 # Cloud Server
 
-* [SSH Server](doc/ssh-server.md)
-* [SSH Public Key Authentication](doc/ssh-pub-key-auth.md)
-* [Docker](doc/docker.md)
-* [Static-gtfs-manager](doc/static-gtfs-manager.md)
+* [SSH Server](../doc/ssh-server.md)
+* [SSH Public Key Authentication](../doc/ssh-pub-key-auth.md)
+* [Docker](../doc/docker.md)
+* [Static-gtfs-manager](../doc/static-gtfs-manager.md)
diff --git a/doc/debian-config.md b/doc/debian-config.md
index 1821052..12a0bbf 100644
--- a/doc/debian-config.md
+++ b/doc/debian-config.md
@@ -1,8 +1,24 @@
 # Configure Debian
 
+* install sudo
+```
+su -
+apt install sudo --no-install-recommends
+exit
+```
+
 * add user <tbd> to sudoers using
 ```
-sudo usermod -a -G sudo <tbd>
+whereis usermod
+su -
+usermod -a -G sudo <tbd>
+exit
+exit
+```
+
+* logout and login user <tbd> and validate participation of the sudo group
+```
+sudo -l
 ```
 
 * update Debian
diff --git a/doc/ssh-pub-key-auth.md b/doc/ssh-pub-key-auth.md
index c7c31df..6411922 100644
--- a/doc/ssh-pub-key-auth.md
+++ b/doc/ssh-pub-key-auth.md
@@ -61,7 +61,7 @@ you may savely close the terminal/shell running the open password-based login
 * revert the password changes in ```ssh_config``` if you are srcurity conscious\
 ```
 sudo vi /etc/ssh/sshd_config
-PasswordAuthentication yes
+PasswordAuthentication no
 ```
 
 ## Links
diff --git a/doc/ssh-server.md b/doc/ssh-server.md
index 1f88653..200ea3a 100644
--- a/doc/ssh-server.md
+++ b/doc/ssh-server.md
@@ -16,7 +16,7 @@ systemctl list-unit-files | grep enabled | grep ssh
 sudo vi /etc/ssh/sshd_config
 sudo systemctl restart sshd
 ````
-* check port configuration
+* validate port configuration
 ```
 ss -tupln|grep <sshd port number>