Building a Dedicated Jitsi Meet Video Conferencing Station on Raspberry Pi 4

Using a Raspberry Pi 4 connected directly to an HDMI living room TV with an external USB webcam creates a dedicated, affordable family video-conferencing terminal. However, running WebRTC in standard Chromium on ARM without optimizations often causes CPU throttling, audio noise, and meeting lag.

Optimal Hardware Choices: Raspberry Pi 4 (4GB) • Logitech C920 / C922 / C270 USB Webcam • Micro-HDMI to HDMI audio

Critical Hardware & Audio Points

• Microphone Input: The Raspberry Pi 4's 3.5mm onboard jack is output only (no microphone input pin). Connecting standard headset microphones requires either an external USB audio dongle or a webcam with integrated noise-cancelling microphones (e.g. Logitech C920).
• Audio Routing: Configure ALSA/PulseAudio to output conference sound through HDMI to your TV speakers while capturing voice from the USB webcam microphone.

Chromium Performance Optimizations for WebRTC

Launch Chromium in kiosk mode with hardware GPU acceleration flags:

chromium-browser --kiosk --start-fullscreen   --enable-accelerated-video-decode   --use-gl=egl   --ignore-gpu-blocklist   --autoplay-policy=no-user-gesture-required   "https://meet.jit.si/YourPrivateRoom#config.startWithVideoMuted=false"

How to Install Asterisk 18 and FreePBX 15 on Ubuntu (Raspberry Pi 4)

Running a full-featured IP-PBX telephony server on a Raspberry Pi 4 provides small offices and lab environments with an enterprise telephone system at negligible power consumption. This comprehensive guide covers compiling Asterisk 18 LTS with DAHDI/libpri and configuring the FreePBX 15 web administration portal on Ubuntu Server (ARM64).

Hardware: Raspberry Pi 4 (4GB / 8GB recommended) • OS: Ubuntu 20.04 LTS aarch64 • Stack: Asterisk 18 LTS, FreePBX 15, MariaDB, Node.js

1. Installing Build Prerequisites and MariaDB

sudo apt-get update && sudo apt-get upgrade -y
sudo apt-get install -y build-essential linux-headers-generic libssl-dev libncurses5-dev   libnewt-dev libxml2-dev linux-headers-$(uname -r) libsqlite3-dev uuid-dev   mariadb-server mariadb-client libjansson-dev libedit-dev sox libsox-fmt-all

# Configure database
sudo mysql_secure_installation

2. Compiling Asterisk 18 LTS

cd /usr/src
sudo wget http://downloads.asterisk.org/pub/telephony/asterisk/asterisk-18-current.tar.gz
sudo tar -zxf asterisk-18-current.tar.gz
cd asterisk-18.*

sudo contrib/scripts/get_mp3_source.sh
sudo contrib/scripts/install_prereq install

sudo ./configure --with-pjproject-bundled --with-jansson-bundled
sudo make menuselect.makeopts
sudo menuselect/menuselect --enable format_mp3 menuselect.makeopts
sudo make -j$(nproc)
sudo make install
sudo make samples
sudo make config
sudo ldconfig

3. Installing FreePBX 15

Install Node.js, Apache, PHP modules, and run the FreePBX install script pointing to Asterisk:

cd /usr/src
sudo wget http://mirror.freepbx.org/modules/packages/freepbx/freepbx-15.0-latest.tgz
sudo tar -zxf freepbx-15.0-latest.tgz
cd freepbx
sudo ./install -n

[Solved] Proxmox 6.3 DHCP Error on Huawei RH2288 V3 Servers: No Working Lease in Persistent Database

When booting the Proxmox VE 6.x installer on enterprise Huawei FusionServer RH2288 V3 rack servers, the graphical installation aborts and drops into a debug shell with the error: No working lease in persistent database.

Root Cause: Kernel framebuffer conflict with Huawei integrated server graphics (BMC) and IOMMU initialization.

Step-by-Step Resolution

1. At the Proxmox GRUB boot menu, press e to edit the boot entry.
2. Locate the linux kernel line and append the following kernel parameters:

   modprobe.blacklist=nouveau amd_iommu=on video=efifb:off

3. Press Ctrl+X or F10 to boot.

Assigning Static IP in Debug Shell (If DHCP is Unavailable)

If your datacenter environment does not offer DHCP on the management network, configure network parameters directly in the debug prompt:

ip addr add 192.168.1.50/24 dev enp2s0f0
ip route add default via 192.168.1.1 dev enp2s0f0
echo "nameserver 1.1.1.1" > /etc/resolv.conf

How to Install Matching Linux Kernel Headers on Sangoma OS (FreePBX Distro)

When running the FreePBX Sangoma OS distro inside a VirtualBox virtual machine, installing VirtualBox Guest Additions fails with "Kernel headers not found for target kernel" even after installing kernel-devel and kernel-headers via yum.

Root Cause: In FreePBX Sangoma OS installations, the build directory symlink /lib/modules/$(uname -r)/build is missing from the active kernel directory.

The 1-Line Fix

Create the missing build symlink pointing to the kernel source directory:

# 1. Install development packages
yum install dkms gcc kernel-devel kernel-headers -y

# 2. Fix the missing module build symlink
ln -s /usr/src/kernels/$(uname -r) /lib/modules/$(uname -r)/build

# 3. Mount and build Guest Additions
mount /dev/cdrom /media/cdrom
cd /media/cdrom
./VBoxLinuxAdditions.run

The kernel module compilation will complete cleanly, enabling dynamic display resizing and shared folders.

How to Compile and Install the Latest Tesseract OCR 4/5 on Debian 11 (Bullseye)

Tesseract OCR is Google's optical character recognition engine. Compiling the latest upstream release directly on Debian 11 ensures access to LSTM neural network model improvements and enhanced UTF-8 language model accuracy.

Prerequisites: Leptonica image processing library • Autotools • C++17 compiler

Build and Installation Commands

# 1. Install build headers and Leptonica
sudo apt-get update
sudo apt-get install g++ autoconf automake libtool pkg-config   libpng-dev libjpeg62-turbo-dev libtiff5-dev zlib1g-dev libleptonica-dev -y

# 2. Download and compile Tesseract
VERSION="4.1.1" # Or latest 5.x release
cd /usr/src
wget https://github.com/tesseract-ocr/tesseract/archive/${VERSION}.tar.gz
tar -zxf ${VERSION}.tar.gz
cd tesseract-${VERSION}

./autogen.sh
./configure --prefix=/usr/local
make -j$(nproc)
sudo make install
sudo ldconfig

# 3. Download traineddata language models (e.g., English and Persian/Arabic)
cd /usr/local/share/tessdata
sudo wget https://github.com/tesseract-ocr/tessdata_fast/raw/main/eng.traineddata
sudo wget https://github.com/tesseract-ocr/tessdata_fast/raw/main/fas.traineddata

Connecting USB GSM / 3G / 4G Dongles to Raspberry Pi 4 (Huawei E303, usb-modeswitch, and Gammu)

USB cellular modems (such as the ubiquitous Huawei E303, E173, and E3372) enable Raspberry Pi 4 projects to send SMS notifications, handle emergency alerts, and provide cellular backup connectivity. However, modern USB modems initially boot into a virtual CD-ROM storage mode (ZeroCD) to deliver Windows drivers, requiring usb-modeswitch to toggle them into serial modem mode.

Hardware: Raspberry Pi 4 • Huawei E303 USB Dongle • usb-modeswitch • Gammu SMS Gateway

1. Installing usb-modeswitch and Gammu

sudo apt-get update
sudo apt-get install usb-modeswitch usb-modeswitch-data gammu minicom -y

2. Switching from Mass Storage to Modem Mode

Check lsusb to identify your device vendor and product ID:

# Example: ID 12d1:1f01 (Mass Storage Mode)
lsusb | grep Huawei

# Mode-switch into serial modem mode (12d1:1001 or 12d1:14db):
sudo usb_modeswitch -v 12d1 -p 1f01 -M '55534243123456780000000000000011062000000100000000000000000000'

Confirm the modem serial nodes are created under /dev/ttyUSB0, /dev/ttyUSB1, and /dev/ttyUSB2.

3. Sending a Test SMS via Gammu

Configure ~/.gammurc:

[gammu]
port = /dev/ttyUSB0
connection = at115200

Send an automated test message:

echo "Alert: Raspberry Pi online!" | gammu sendsms TEXT +1234567890

How to Install and Configure Munin Monitoring with Nginx and CGI on CentOS 8

Setting up Munin on CentOS 8 via EPEL 8 provides turnkey server performance graphs. This guide walks through configuring systemd timer units, fastcgi spawners for dynamic graph generation, and integrating the dashboard into an Nginx virtual host.

Packages: munin • munin-node • munin-cgi • spawn-fcgi

1. Installing Packages from EPEL 8

dnf install epel-release -y
dnf install munin munin-cgi munin-node spawn-fcgi nginx -y

2. Enabling Node and Systemd Services

systemctl enable --now munin-node
systemctl enable --now munin-cgi-graph.socket
systemctl enable --now munin-cgi-html.socket

3. Nginx Server Block (/etc/nginx/conf.d/munin.conf)

server {
    listen 80;
    server_name munin.example.com;

    location / {
        root /var/www/html/munin;
        index index.html;
    }

    location ^~ /munin-cgi/munin-cgi-graph/ {
        fastcgi_split_path_info ^(/munin-cgi/munin-cgi-graph)(.*);
        fastcgi_param PATH_INFO $fastcgi_path_info;
        fastcgi_pass unix:/run/munin/fcgi-graph.sock;
        include fastcgi_params;
    }
}