What is a Network Monitoring System (NMS)?

A Network Monitoring System (NMS) is software that continuously monitors the health, availability, and performance of your IT infrastructure. Rather than manually checking every switch, router, firewall, or server, an NMS automatically collects metrics, stores historical data, and can alert you when something goes wrong.

Typical benefits include:

• Detecting outages before users report them.
• Monitoring CPU, memory, storage, and network utilisation.
• Tracking performance trends over time.
• Receiving alerts when thresholds are exceeded.
• Building dashboards and reports for operational visibility.
• Identifying potential capacity or hardware issues before they become critical.

Popular Open Source Monitoring Platforms

There are several excellent monitoring solutions available. Three of the most popular are:

Each platform has its strengths, and the right choice depends on your environment and operational requirements.

Why I Chose Zabbix

I chose Zabbix because it offers enterprise-grade functionality while remaining completely open source.

Some of the features that stood out to me include:

• Free to download and use.
• No licensing costs.
• No limits on monitored devices.
• Powerful dashboards and alerting.
• Excellent scalability.
• Large community with hundreds of templates.

For organisations requiring commercial assistance, Zabbix also offers:

• Technical support subscriptions
• Consulting services
• Training
• Implementation and migration assistance
• Integration services
• Template development
• Custom development

This doesn’t mean LibreNMS or Checkmk are inferior products they’re both excellent. Zabbix simply aligns better with my requirements for both home lab environments and enterprise deployments.

Zabbix Server Installation

This guide installs Zabbix 8.0 on a Debian 13 virtual machine using PostgreSQL and Nginx.

Create the Virtual Machine

• Name: ZABBIX
• CPU: 8 vCPU
• RAM: 16 GB
• Storage: 512 GB
• Root account: Locked
• Username: zabbix
• Do not install a desktop environment
• Add SSH Server and standard system utilities

Choose a strong password during installation.

After the first boot, update the operating system.

sudo apt update && sudo apt full-upgrade -y

Installing Zabbix 8.0

Install PostgreSQL

sudo apt install postgresql postgresql-client postgresql-contrib

Install the Zabbix Repository

wget https://repo.zabbix.com/zabbix/8.0/release/debian/pool/main/z/zabbix-release/zabbix-release_latest_8.0+debian13_all.deb

sudo dpkg -i zabbix-release_latest_8.0+debian13_all.deb

sudo apt update

Install Zabbix

sudo apt install \
    zabbix-server-pgsql \
    zabbix-frontend-php \
    php8.4-pgsql \
    zabbix-nginx-conf \
    zabbix-sql-scripts \
    zabbix-agent2

Allow PHP-FPM to Write the Zabbix Configuration

During the initial web setup, Zabbix needs permission to write its configuration file.

Create a systemd override:

sudo systemctl edit php-fpm

Add:

[Service]
ReadWritePaths=/etc/zabbix/web

Reload systemd:

sudo systemctl daemon-reload

Create the PostgreSQL Database

Create the database user:

sudo -u postgres createuser --pwprompt zabbix

Choose a strong database password.

Create the database:

sudo -u postgres createdb \
    -E Unicode \
    -T template0 \
    -O zabbix \
    zabbix

Import the initial schema:

zcat /usr/share/zabbix/sql-scripts/postgresql/server.sql.gz | sudo -u zabbix psql zabbix

Configure Zabbix

Edit:

/etc/zabbix/zabbix_server.conf

Set the database password:

DBPassword=<your_database_password>

Configure Nginx

Remove the default site:

sudo rm /etc/nginx/sites-enabled/default

sudo systemctl reload nginx

Edit:

/etc/nginx/conf.d/zabbix.conf

Uncomment the first two lines and configure your hostname.

For environments without DNS, use:

server {
    listen 80;
    server_name _;

Start Services

sudo systemctl restart \
    zabbix-server \
    zabbix-agent2 \
    nginx \
    php8.4-fpm

Enable services to start automatically:

sudo systemctl enable \
    zabbix-server \
    zabbix-agent2 \
    nginx \
    php8.4-fpm

Complete the Web Installation

Open your browser and navigate to:

http://<server-ip>/

Log in using:

Immediately change the administrator password after logging in.

Installing Webmin

Although optional, I find Webmin useful for managing Linux servers through a web interface.

Install curl:

sudo apt install curl

Download the repository setup script:

curl -o webmin-setup-repo.sh https://raw.githubusercontent.com/webmin/webmin/master/webmin-setup-repo.sh

sudo sh webmin-setup-repo.sh

Install Webmin:

sudo apt update

sudo apt install webmin --install-recommends

Access Webmin:

https://<server-ip>:10000

Once logged in, navigate to System > Software Package Updates> Scheduled Upgrades.

Configure automatic security updates as appropriate for your environment.

Post-Installation Tweaks

Increase the Zabbix Cache Size

For larger environments, increasing the cache improves performance.

Edit:

/etc/zabbix/zabbix_server.conf

Uncomment the CacheSize=32M and change it to:

CacheSize=256M

Restart Zabbix:

sudo systemctl restart zabbix-server

Troubleshooting

Test SNMP Connectivity

The snmpwalk utility is invaluable when troubleshooting SNMP devices.

snmpwalk -v2c -c <community> <device_ip_or_hostname>

ArubaOS-CX SNMP

On ArubaOS-CX switches, SNMP must be enabled on the VRF servicing the monitoring server (typically the default VRF).

Without this configuration, the switch will not respond to SNMP requests.

snmp-server vrf default