Oct 132021
 October 13, 2021  Posted by at 11:46 am Tutorial Tagged with: , ,  No Responses »

This is a concise tutorial, it is not meant to be a hand holding step by step guide. Please comment or contact me if you find errors.

Setup a domain/sub domain with an A record to the ip of the server or a CNAME to a “dynamic DNS” hostname. I recommend https://freedns.afraid.org.
The server needs to have ports 80 and 443 reachable to the public. The DNS must be propagated for letsencrypt to be successful.

Start the install

apt-get install apache2 mariadb-server libapache2-mod-php php-gd php-json php-mysql php-curl php-mbstring php-intl php-imagick php-xml php-zip php-bz2 python3-certbot-apache redis-server php-redis php-bcmath php-gmp ffmpeg curl coreutils

Download Nextcloud

wget https://download.nextcloud.com/server/releases/latest-22.tar.bz2

Make sure the md5 matches
md5sum latest-22.tar.bz2
curl https://download.nextcloud.com/server/releases/latest-22.tar.bz2.md5

Extract the tar file and change permissions
tar xfv nextcloud-22.x.tar.bz2
mv nextcloud/ /var/www/example.com/
chown www-data:www-data -R /var/www/example.com/

Setup Apache

Create a apache virtual site
cp /etc/apache2/sites-available/000-default.conf /etc/apache2/sites-available/example.com.conf

edit /etc/apache2/sites-available/example.com.conf
uncomment and change
ServerName example.com
change log location if you would like
ErrorLog ${APACHE_LOG_DIR}/example.com_error.log
CustomLog ${APACHE_LOG_DIR}/example.com_access.log combined

a2ensite example.com

a2enmod php7.4 rewrite headers env dir mime userdir dav ssl

service apache2 restart

Setup Letsencrypt

certbot --apache -d example.com

tell it to redirect http to https

Edit /etc/apache2/sites-enabled/example.com-le-ssl.conf

  <Directory /var/www/example.com/>
    Require all granted
    AllowOverride All
    Options FollowSymLinks MultiViews
    <IfModule mod_dav.c>
      Dav off

Configure php
edit /etc/php/7.4/apache2/php.ini

memory_limit = 768M
upload_max_filesize = 1024M
post_max_size = 1024M
max_execution_time = 300

Create a database, user and password for nextcloud

mariadb -uroot

CREATE USER 'nextcloud'@'localhost' IDENTIFIED BY 'PASSWORD';
FLUSH privileges;

run the installer at https://example.com/

Now we can setup Redis

edit /etc/redis/redis.conf
Under the # Unix socket. section add the following

port 0
unixsocket /var/run/redis/redis-server.sock
unixsocketperm 770

add www-data to redis group

usermod -a -G redis www-data
/etc/group will now have an entry like this “redis:x:119:www-data”

systemctl enable redis-server

Add the following to /var/www/example.com/config/config.php

'memcache.local' => '\\OC\\Memcache\\Redis',
  'memcache.distributed' => '\\OC\\Memcache\\Redis',
  'memcache.locking' => '\\OC\\Memcache\\Redis',
  'redis' =>
  array (
    'host' => '/var/run/redis/redis-server.sock',
    'port' => 0,
    'dbindex' => 0,
    'timeout' => 1.5,

edit /etc/php/7.4/apache2/php.ini

  opcache.revalidate_freq = 1

systemctl restart redis-server
systemctl restart apache2
Setup cron for Nextcloud

crontab -u www-data -e
*/5 * * * * php -f /var/www/example.com/cron.php


Jan 202020
 January 20, 2020  Posted by at 11:36 pm Tutorial Tagged with: , ,  6 Responses »

The reason I use x11vnc is that it connects to the existing graphical session. Most other vnc servers will spawn an entirely new graphical session. While that is super cool, I don’t want that feature. This is for remote support, where I want the user and the supporter to share the same session. I use the ‘-auth guess’ to have x11vnc guess the XAUTHORITY file‐name and use it appropriately. This avoids the annoying hard coding of gdm, lightdm, xdm or specific users .Xauthority.

Install x11vnc
# apt-get install x11vnc

The following should work for any distro that uses systemd, just the apt bits are Debian specific.

Generate the password and store it under etc so no users can change this password, only root. You can do this under your users home so that its not managed by root. In my case I didn’t want the user to be able to change or accidentally delete the password.
# x11vnc -storepasswd /etc/x11vnc.pwd

edit (create new) the following file
use whatever text editor you prefer, here I use vi
# vi /etc/systemd/system/x11vnc.service

And add the following, making any changes you want to the x11vnc ExecStart
See the man page for explanations of the switches

Description=Start x11vnc at startup.

ExecStart=/usr/bin/x11vnc -auth guess -forever -loop -noxdamage -repeat -rfbauth /etc/x11vnc.pwd -rfbport 5900 -shared -o /var/log/x11vnc.log


Now enable the above, start it and verify its running and listening properly
# systemctl enable x11vnc
# systemctl start x11vnc
# netstat -pat
tcp 0 0* LISTEN 2806/x11vnc

Now that the server is all setup lets move onto the client
apt-get install tigervnc-viewer
vncviewer [remote host ip or hostname]


Oct 112009
 October 11, 2009  Posted by at 2:48 pm documentation, music Tagged with: , , , , , , , , ,  No Responses »

I wanted to share some notes on patching the Linux Libre kernel with realtime capabilities. The Linux-Libre project pulls out all the un-free bits from standard Linux. Contrary to popular belief, Linux has many non-free parts, small binary or obfuscated pieces of code for various hardware. I have a Lenovo T61 laptop. I removed the Intel wireless pci express card and put in a Atheros AR5008 wifi card using ath9k completely free wireless driver. Now my system (as far as I can tell:-) is completely free.

I make music and the realtime patch makes the latency of my system and soundcard very low. This is a unique advantage that the gnu/linux operating system gives its users. I highly recommend a realtime patch for anyone working with audio and video on gnu/linux.

Start by getting the rt patch http://www.kernel.org/pub/linux/kernel/projects/rt/ for the kernel version you want to compile.
Then get the corresponding Linux-Libre version http://www.linux-libre.fsfla.org/pub/linux-libre/releases/

tar xfvj linux-
cd linux-
bzcat ../patch- | patch -p1

Now Linux is patched with realtime
now its time for

make menuconfig

from the RT How to:
* activated the High-Resolution-Timer Option (Attention, the amount of supported platforms by the HR timer is still very limited. Right now the option is only supported on x86 systems, PowerPC and ARM Support are however in queue.)
* disabled all Power Management Options like ACPI or APM (not all ACPI functions are “bad”, but you will have to check very carefully to find out which function will affect your real time system. Thus it’s better to simply disable them all if you don’t need them. APM, however, is a no-go.) NOTE: Since rt patch 2.6.18-rt6 you will probably have to activate ACPI option to activate high resolution timer. Since the TSC timer on PC platforms, as used in the previous versions, are now marked as unsuitable for hrt mode due to many lacks of functionalities and reliabilties, you will need i.E. pm_timer as provided by ACPI to use as clock source. To activate the pm_timer, you can just activate the ACPI_SUPPORT in menuconfig and deactivate all other sub modules like “fan”, “processor” or “button”. If you have an old pc, which lacks ACPI support, you migh have problems using the high resolution timer.

I personally have not removed my power management options, as I use a laptop and want these features. I don’t notice any problems but have not tried it without them to know what I’m missing.

then compile the kernel, the debian way

fakeroot make-kpkg kernel_image
sudo dpkg -i linux-image-

Here is my latest config and the debian package for libre realtime for lenovo t61

~ May your kernel build and your modules have your back ~