Install Let's Encrypt SSL with Certbot (Apache) on Debian 12

Step 1 – Install

apt update && apt upgrade -y
apt install -y certbot python3-certbot-apache

Step 2 – Obtain and install

certbot --apache -d example.com -d www.example.com

Step 3 – Verify

apachectl configtest && systemctl reload...

Install Let's Encrypt SSL with Certbot (Nginx) on Debian 12

Step 1 – Install Certbot + Nginx plugin

apt update && apt upgrade -y
apt install -y certbot python3-certbot-nginx

Step 2 – Obtain certificate

certbot --nginx -d example.com -d www.example.com

Certbot modifies Nginx config and opti...

Install MariaDB on Debian 12

Step 1 – Install and secure

apt update && apt upgrade -y
apt install -y mariadb-server
systemctl enable --now mariadb
mysql_secure_installation

Step 2 – Create database and user

CREATE DATABASE appdb CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
CREATE USER '...

Install Memcached on Debian 12

Step 1 – Install

apt install -y memcached libmemcached-tools
systemctl enable --now memcached

Step 2 – Configure (/etc/memcached.conf)

-l 127.0.0.1   # listen on localhost only
-m 256         # memory (MB)
-c 1024        # max connections
-t 4           # thr...

Install ModSecurity WAF on Apache – Debian 12

Step 1 – Install

apt install -y libapache2-mod-security2
a2enmod security2
systemctl restart apache2

Step 2 – Enable detection mode

cp /etc/modsecurity/modsecurity.conf-recommended /etc/modsecurity/modsecurity.conf 2>/dev/null || \
   cp /usr/sha...

Install MySQL on Debian 12

Step 1 – Install and secure

apt update && apt upgrade -y
apt install -y mysql-server
systemctl enable --now mysql
mysql_secure_installation

Step 2 – Connect

mysql -u root -p

Step 3 – Create database and user

CREATE DATABASE appdb CHARACTER SET utf8mb4 COLLATE u...

Install Nginx on Debian 12

Step 1 – Update packages

apt update && apt upgrade -y

Step 2 – Install Nginx

apt install -y nginx

Step 3 – Enable and start

systemctl enable --now nginx

Step 4 – Firewall

ufw allow 'Nginx Full'
ufw reload

Step 5 – Verify

nginx -v
curl -I http://localhos...

Install Node.js on Debian 12

Step 1 – Install

curl -fsSL https://deb.nodesource.com/setup_20.x | bash -
apt install -y nodejs

Step 2 – Verify

node --version && npm --version

Step 3 – Simple HTTP server

// app.js
const http = require('http');
http.createServer((req, res) => {
  res.writeH...

Install Percona XtraDB Cluster (PXC) on Debian 12

PXC provides synchronous multi-master MySQL replication using the Galera library.

Step 1 – Install

wget https://repo.percona.com/apt/percona-release_latest.$(lsb_release -sc)_all.deb
dpkg -i percona-release_latest.$(lsb_release -sc)_all.deb
per...

Install PHP-FPM on Debian 12

Step 1 – Install

apt update && apt upgrade -y
apt install -y php8.2-fpm php8.2-cli php8.2-opcache php8.2-mysql php8.2-mbstring php8.2-xml php8.2-gd
systemctl enable --now php8.2-fpm

Step 2 – Verify

php --version
php-fpm -v 2>/dev/null || php-fpm8.3 -v 2>/dev/null...

Install PostgreSQL on Debian 12

Step 1 – Install

apt update && apt upgrade -y
apt install -y postgresql postgresql-contrib
systemctl enable --now postgresql

Step 2 – Connect as superuser

sudo -u postgres psql

Step 3 – Create database and user

CREATE USER appuser WITH PASSWORD 'StrongPass...

Install Prometheus on Debian 12

Step 1 – Install

apt install -y prometheus prometheus-node-exporter

Step 2 – Create user and directories

useradd -r -s /sbin/nologin prometheus 2>/dev/null || useradd -r -s /usr/sbin/nologin prometheus
mkdir -p /etc/prometheus /var/lib/prometheus
chown prometh...

Install Redis on Debian 12

Step 1 – Install

apt update && apt upgrade -y
apt install -y redis-server
systemctl enable --now redis-server

Step 2 – Verify

redis-cli ping   # PONG

Step 3 – Bind and password (/etc/redis/redis.conf)

bind 127.0.0.1 ::1
requirepass StrongRedisPass!

Restart,...

Install Varnish Cache on Debian 12

Step 1 – Install

apt update && apt upgrade -y
apt install -y varnish
systemctl enable --now varnish

Step 2 – Basic /etc/varnish/default.vcl

vcl 4.1;

backend default {
    .host = "127.0.0.1";
    .port = "8080";
    .connect_timeout = 5s;
    .first_byte_...

Install WordPress on Debian 12 (Nginx + PHP-FPM + MySQL)

Prerequisites

• Nginx · PHP-FPM · MySQL

Step 1 – Database

CREATE DATABASE wordpress CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
CREATE USER 'wpuser'@'localhost' IDENTIFIED BY 'WPStrongPass!';
GRANT ALL PRIVILEGES ON wordpre...

Integrate PHP-FPM with Nginx on Debian 12

Prerequisites

PHP-FPM installed and running. See PHP-FPM install guide.

Socket path: /run/php/php8.2-fpm.sock

Step 1 – Nginx server block

server {
    listen 80;
    server_name example.com;
    root /var/www/example.com/html;
    index index.ph...

MariaDB Backup and Restore on Debian 12

mariadb-dump (logical)

mariadb-dump -u root -p appdb > /backups/appdb_$(date +%F).sql
mariadb-dump -u root -p --all-databases --single-transaction > /backups/all_$(date +%F).sql

Restore

mariadb -u root -p appdb < /backups/appdb_2026-05-07.sql

Mariaba

MariaDB Galera Cluster on Debian 12

Nodes: 192.168.1.10 · 192.168.1.11 · 192.168.1.12

Step 1 – Install Galera on all nodes

apt install -y galera-4 mariadb-server

Step 2 – Configure Node 1 (/etc/mysql/conf.d/galera.cnf)

[mysqld]
binlog_format            = ROW
default-storage-engine...

Memcached Distributed Setup on Debian 12

Memcached itself has no cluster mode — distribution is handled by the client using consistent hashing.

Run multiple instances

memcached -d -l 192.168.1.10 -p 11211 -m 512 -t 4 -u memcache
memcached -d -l 192.168.1.11 -p 11211 -m 512 -t 4 -u memcache

s

Monitor Percona XtraDB Cluster on Debian 12

Key wsrep variables

SHOW STATUS LIKE 'wsrep_%';

MySQL Backup and Restore on Debian 12

mysqldump

# Single database
mysqldump -u root -p appdb > /backups/appdb_$(date +%F).sql

# All databases
mysqldump -u root -p --all-databases > /backups/all_$(date +%F).sql

# Compressed
mysqldump -u root -p appdb | gzip > /backups/appdb_$(date +%F).sql.gz

MySQL Primary-Replica Replication on Debian 12

Primary: 192.168.1.10   Replica: 192.168.1.11

Primary – my.cnf

[mysqld]
server-id   = 1
log_bin     = /var/log/mysql/mysql-bin
binlog_format = ROW
binlog_expire_logs_seconds = 604800

CREATE USER 'replicator'@'192.168.1.11' IDENTIFIED WITH my...

Nginx Load Balancing on Debian 12

Round-robin (default)

upstream myapp {
    server 192.168.1.10:8080;
    server 192.168.1.11:8080;
    server 192.168.1.12:8080;
}
server {
    listen 80;
    server_name lb.example.com;
    location / { proxy_pass http://myapp; }
}

Least connections

upstrea...

Nginx Rate Limiting on Debian 12

Define zones in http block

http {
    limit_req_zone $binary_remote_addr zone=api:10m     rate=10r/s;
    limit_req_zone $binary_remote_addr zone=login:10m   rate=5r/m;
}

Apply to locations

location /api/ {
    limit_req zone=api burst=20 nodelay;
    limit...