Build a Small Office Network Monitoring Stack with LibreNMS, Syslog, and Alert Routing

Expected Outcome

A working network monitoring system that provides visibility into network performance, logs network events, and routes alerts for proactive management.

Assumptions

• Basic knowledge of Linux command line
• A server or virtual machine (VM) running Ubuntu 20.04 or later
• Access to the office network and devices to monitor
• Administrative access to the router and switches

Bill of Materials

• Ubuntu 20.04 server or VM
• LibreNMS installation files
• Syslog server (e.g., rsyslog)
• Alert routing tool (e.g., Alertmanager)
• Network devices (routers, switches, etc.)

Build Steps

1. Prepare the Server

   Set up your Ubuntu server with the necessary updates and dependencies.

   Changes system state: review before running

   sudo apt update && sudo apt upgrade -y
   sudo apt install software-properties-common -y
   sudo add-apt-repository ppa:librenms/librenms -y
   sudo apt update

2. Install LibreNMS

   Install LibreNMS and its dependencies.

   Changes system state: review before running

   sudo apt install libapache2-mod-php php php-mysql php-mbstring php-xml php-curl php-gd php-zip php-json php-bcmath php-xmlrpc -y
   sudo apt install mariadb-server mariadb-client -y
   sudo mysql_secure_installation
   sudo mysql -u root -p -e "CREATE DATABASE librenms;"
   sudo mysql -u root -p -e "CREATE USER 'librenms'@'localhost' IDENTIFIED BY 'your_password';"
   sudo mysql -u root -p -e "GRANT ALL PRIVILEGES ON librenms.* TO 'librenms'@'localhost';"
   sudo mysql -u root -p -e "FLUSH PRIVILEGES;"
   sudo apt install git -y
   cd /opt && sudo git clone https://github.com/librenms/librenms.git
   cd librenms && sudo chown -R www-data:www-data . && sudo chmod -R 755 .

3. Configure LibreNMS

   Set up the LibreNMS configuration and web interface.

   Changes system state: review before running

   sudo cp /opt/librenms/config.php.default /opt/librenms/config.php
   sudo nano /opt/librenms/config.php
   sudo systemctl restart apache2
   sudo /opt/librenms/scripts/create_schema.php

4. Install and Configure Syslog

   Set up a syslog server to collect logs from network devices.

   Changes system state: review before running

   sudo apt install rsyslog -y
   sudo nano /etc/rsyslog.conf
   sudo systemctl restart rsyslog

5. Set Up Alert Routing

   Configure alert routing to manage notifications effectively.

   Changes system state: review before running

   sudo apt install prometheus-alertmanager -y
   sudo nano /etc/alertmanager/config.yml
   sudo systemctl restart alertmanager

6. Add Devices to LibreNMS

   Discover and add network devices to the LibreNMS monitoring stack.

   Changes system state: review before running

   /opt/librenms/addhost.php -h <device_ip> -d <device_description>
   sudo /opt/librenms/poller.php -h all

7. Validate the Setup

   Ensure that the monitoring stack is functioning correctly.

   Safe to run: read-only

   curl -I http://<your_librenms_url>
   sudo tail -f /var/log/syslog

Validation

• Check the LibreNMS web interface for device status.
• Verify that syslog is receiving logs from network devices.
• Test alert routing by simulating an alert.

Troubleshooting

• If a step fails, capture the exact command, exit code, and log line before retrying or changing the design.
• Check route tables, DNS resolution, firewall rules, and peer status from both sides of the connection.

Cleanup or Rollback

• Keep a copy of working configuration, compose files, scripts, and service credentials before removing containers, packages, or data directories.
• Export current network, DNS, VPN, and firewall settings before changing routes, peers, or resolver configuration.
• Rollback by restoring the prior route, peer, DNS, or firewall configuration and restarting only the affected service.

Next Improvements

• Explore additional features of LibreNMS such as VLAN-aware monitoring.
• Set up dashboards for visualizing network performance.
• Configure advanced alerting rules in Alertmanager.