Server Infrastructure Project

Assigned static IPs on the VirtualBox internal network. Configured the gateway server with two NICs (NAT for internet, internal for the lab subnet) and enabled IP forwarding with iptables MASQUERADE.

# On gateway: /etc/netplan/00-installer-config.yaml
network:
  version: 2
  ethernets:
    enp0s3:          # NAT adapter (internet)
      dhcp4: true
    enp0s8:          # Internal network
      addresses: [10.0.0.1/24]
      nameservers:
        addresses: [8.8.8.8]

sudo netplan apply

# Enable IP forwarding
echo "net.ipv4.ip_forward=1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

# NAT rule — masquerade internal subnet out enp0s3
sudo iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -o enp0s3 -j MASQUERADE
sudo iptables -A FORWARD -i enp0s8 -o enp0s3 -j ACCEPT
sudo iptables -A FORWARD -i enp0s3 -o enp0s8 -m state --state RELATED,ESTABLISHED -j ACCEPT

# Persist iptables rules
sudo apt install -y iptables-persistent
sudo netfilter-persistent save

Configured the app server as the NFS host for shared home directories. All three nodes mount /srv/homes so users have a consistent home directory across the infrastructure.

# On app server — NFS server setup
sudo apt install -y nfs-kernel-server
sudo mkdir -p /srv/homes
sudo chown nobody:nogroup /srv/homes

# Export the share
echo "/srv/homes  10.0.0.0/24(rw,sync,no_subtree_check,no_root_squash)" \
  | sudo tee -a /etc/exports
sudo exportfs -arv
sudo systemctl enable --now nfs-kernel-server

# On gateway and monitor nodes — mount NFS
sudo apt install -y nfs-common
sudo mkdir -p /srv/homes
echo "10.0.0.2:/srv/homes  /srv/homes  nfs  defaults,_netdev  0  0" \
  | sudo tee -a /etc/fstab
sudo mount -a
df -h /srv/homes

Deployed a LAMP stack on the app server, created a test database with a web-accessible PHP info page, and locked down MariaDB to localhost only.

sudo apt install -y apache2 php libapache2-mod-php php-mysql mariadb-server

# Secure MariaDB
sudo mysql_secure_installation
# Remove anon users, disallow root remote login, remove test DB

# Create app database and user
sudo mysql -u root -p <<'SQL'
CREATE DATABASE appdb CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
CREATE USER 'appuser'@'localhost' IDENTIFIED BY 'SecurePass123!';
GRANT ALL PRIVILEGES ON appdb.* TO 'appuser'@'localhost';
FLUSH PRIVILEGES;
SQL

# Test PHP-MySQL connection
cat > /var/www/html/info.php <<'EOF'
<?php phpinfo(); ?>
EOF

# Verify from gateway
curl -s http://10.0.0.2/info.php | grep -i "php version"

Installed Node Exporter on all three servers and Prometheus + Grafana on the monitoring server. Configured Prometheus scrape jobs and imported a Node Exporter dashboard in Grafana.

# Install Node Exporter on ALL nodes (gateway, app, monitor)
wget https://github.com/prometheus/node_exporter/releases/download/v1.7.0/node_exporter-1.7.0.linux-amd64.tar.gz
tar xvf node_exporter-*.tar.gz
sudo cp node_exporter-*/node_exporter /usr/local/bin/

# Create systemd service
sudo tee /etc/systemd/system/node_exporter.service <<'EOF'
[Unit]
Description=Prometheus Node Exporter
[Service]
User=nobody
ExecStart=/usr/local/bin/node_exporter
[Install]
WantedBy=multi-user.target
EOF
sudo systemctl enable --now node_exporter

# On monitor server: install Prometheus
wget https://github.com/prometheus/prometheus/releases/download/v2.48.0/prometheus-2.48.0.linux-amd64.tar.gz
# ... extract and configure

# /etc/prometheus/prometheus.yml
scrape_configs:
  - job_name: 'gateway'
    static_configs:
      - targets: ['10.0.0.1:9100']
  - job_name: 'appserver'
    static_configs:
      - targets: ['10.0.0.2:9100']
  - job_name: 'monitor'
    static_configs:
      - targets: ['10.0.0.3:9100']

Installed Grafana, added Prometheus as a data source, imported the official Node Exporter Full dashboard (ID 1860), and configured an alert rule for disk usage above 80%.

sudo apt install -y apt-transport-https
wget -q -O - https://packages.grafana.com/gpg.key | sudo apt-key add -
echo "deb https://packages.grafana.com/oss/deb stable main" \
  | sudo tee /etc/apt/sources.list.d/grafana.list
sudo apt update && sudo apt install -y grafana
sudo systemctl enable --now grafana-server

# Grafana accessible at http://10.0.0.3:3000
# Default: admin/admin → change immediately

# Add Prometheus datasource via UI:
# Configuration → Data Sources → Add → Prometheus
# URL: http://localhost:9090

# Import dashboard ID 1860 (Node Exporter Full)
# Dashboards → Import → Enter 1860 → Load → Select Prometheus DS

# Verify all three nodes appear in dashboard dropdowns