AlmaLinux – Nagios Library https://library.nagios.com Complete Nagios monitoring resources and documentation Tue, 10 Feb 2026 18:46:46 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 https://library.nagios.com/wp-content/uploads/2024/11/Nagios-Blue-N.svg AlmaLinux – Nagios Library https://library.nagios.com 32 32 Comprehensive SNMP Monitoring of AlmaLinux 8 with Nagios XI https://library.nagios.com/tutorials/comprehensive-snmp-monitoring-of-almalinux-8-with-nagios-xi/ Thu, 27 Mar 2025 14:51:04 +0000 https://library.nagios.com/?p=53512 Ensuring the health and performance of Linux servers is crucial for maintaining a stable and efficient IT environment. Simple Network Management Protocol (SNMP) provides a lightweight, agentless solution for monitoring AlmaLinux 8 with Nagios XI, allowing administrators to track critical system metrics without installing additional software.

This guide will take you through the complete process of setting up SNMP on AlmaLinux 8, integrating it with Nagios XI, and enabling real-time monitoring for proactive issue resolution and improved system reliability.

Prerequisites

Before proceeding, ensure the following:

  • An AlmaLinux 8 system with root or sudo privileges
  • Nagios XI installed and accessible, with the SNMP Wizard enabled
  • A stable internet connection for package downloads

Step 1: Install SNMP on AlmaLinux 8

  1. To install SNMP and the required libraries, run:
sudo dnf install net-snmp net-snmp-utils -y
  1. After installation, verify the installed version:
snmpd -v

Step 2: Configure SNMP Access

SNMP v2c Configuration

  1. Create a backup of the existing configuration:
sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak
  1. Edit the SNMP configuration file:
sudo nano /etc/snmp/snmpd.conf
  1. Replace or update the line with your community string and Nagios XI IP:
rocommunity Str0ngC0mmunity 10.25.5.12
  1. Save the file and restart SNMP:
sudo systemctl restart snmpd.service

SNMP v3 Configuration (More Secure)

  1. Stop the SNMP service temporarily:
sudo systemctl stop snmpd.service
  1. Create an SNMP user with authentication and encryption:
sudo net-snmp-create-v3-user -ro -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy nagios
  1. Restart the SNMP service:
sudo systemctl restart snmpd.service

Step 3: Configure Firewall Rules

  1. If firewalld is active, allow SNMP traffic on UDP port 161:
sudo firewall-cmd --zone=public --add-port=161/udp --permanent
sudo firewall-cmd --reload
  1. Confirm firewall rules:
sudo firewall-cmd --list-ports

Step 4: Enable SNMP Service on Boot

To ensure SNMP starts automatically at boot:

sudo systemctl enable snmpd.service

Step 5: Test SNMP Communication

From your Nagios XI server:

For SNMP v2c:

snmpwalk -v2c -c Str0ngC0mmunity 10.25.5.12

For SNMP v3:

snmpwalk -v3 -u nagios -l authPriv -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy 10.25.5.12

Expected Output (Example):

iso.3.6.1.2.1.1.1.0 = STRING: "Linux almalinux8 ..."

If the command does not return data, review SNMP configuration and firewall settings.

Step 6: Add AlmaLinux 8 Host to Nagios XI Using SNMP Wizard

1. Log in to Nagios XI

2. Navigate to Configure > Run a configuring wizard

Screenshot 2025 03 12 083824 10
configuration wizard

3. Search for and select Linux SNMP wizard

Linux SNMP 8
Linux SNMP

4. Enter the AlmaLinux 8 server’s IP address and SNMP credentials

Linux SNMP step 1 8
AlmaLinux 8 credentials

5. Click Next, select the system metrics to monitor (CPU, memory, disk, etc.)

6. Apply the configuration and verify that Nagios XI is collecting SNMP data

Common Issues & Fixes

SNMP Service is Not Running

Check logs for errors:

sudo journalctl -u snmpd --no-pager | tail -20

Restart SNMP if necessary:

sudo systemctl restart snmpd.service

Host Appears “Down” in Nagios XI

Check firewall rules:

sudo firewall-cmd --list-ports

Ensure SNMP is running:

sudo systemctl status snmpd

Verify Nagios XI configuration

Incorrect SNMP Credentials Error

Confirm the correct community string (SNMP v2c) or authentication details (SNMP v3) Restart the SNMP service after changes

Conclusion

You’ve successfully configured SNMP on AlmaLinux 8 for agentless monitoring with Nagios XI, providing real-time system insights. For advanced setups, explore custom SNMP OIDs or additional Nagios XI plugins.

For support:

]]> Monitoring AlmaLinux 9 with SNMP in Nagios XI: A Step-by-Step Guide https://library.nagios.com/tutorials/monitoring-almalinux-9-with-snmp-in-nagios-xi-a-step-by-step-guide/ Wed, 26 Mar 2025 19:16:57 +0000 https://library.nagios.com/?p=53476 Effective Linux server monitoring is essential for ensuring performance and reducing downtime. Simple Network Management Protocol (SNMP) provides an agentless solution to monitor AlmaLinux 9 servers using Nagios XI.

This guide walks you through the process of installing and configuring SNMP on AlmaLinux 9 and integrating it with Nagios XI for centralized, real-time system visibility.

Prerequisites

Before proceeding, make sure you have:

  • AlmaLinux 9 with root or sudo privileges
  • A running Nagios XI server with the SNMP wizard enabled
  • Network connectivity between AlmaLinux and Nagios XI

Step 1: Install SNMP on AlmaLinux 9

  1. Install the SNMP daemon and utilities:
sudo dnf install net-snmp net-snmp-utils -y
  1. Verify SNMP installation:
snmpd -v

Step 2: Configure SNMP Access

SNMP v2c Configuration

  1. Backup the default config:
sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak
  1. Edit the configuration file:
sudo nano /etc/snmp/snmpd.conf
  1. Add the following line (replace with your Nagios XI server IP):
rocommunity Str0ngC0mmunity 10.25.5.12
  1. Restart SNMP:
sudo systemctl restart snmpd.service

SNMP v3 Configuration (More Secure)

  1. Stop SNMP temporarily:
sudo systemctl stop snmpd.service
  1. Create a secure SNMP v3 user:
sudo net-snmp-create-v3-user -ro -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy nagios
  1. Restart SNMP:
sudo systemctl restart snmpd.service

Step 3: Configure Firewall Rules

If firewalld is active:

sudo firewall-cmd --zone=public --add-port=161/udp --permanent
sudo firewall-cmd --reload

Confirm the rule:

sudo firewall-cmd --list-ports

Step 4: Enable SNMP on Boot

sudo systemctl enable snmpd.service

Step 5: Test SNMP Communication

Run from Nagios XI server:

For SNMP v2c:

snmpwalk -v2c -c Str0ngC0mmunity 10.25.5.12

For SNMP v3:

snmpwalk -v3 -u nagios -l authPriv -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy 10.25.5.12

Expected output:

iso.3.6.1.2.1.1.1.0 = STRING: "Linux almalinux 9 ..."

If no output appears, verify SNMP configuration and firewall.

Step 6: Add AlmaLinux Host to Nagios XI Using SNMP Wizard

1. Log into Nagios XI.

2. Go to Configure > Run a configuring wizard.

Screenshot 2025 03 12 083824 9
configuring wizard

3. Select Linux SNMP wizard.

Linux SNMP 7
Linux SNMP

4. Enter AlmaLinux 9 IP and SNMP settings (community string or SNMP v3 credentials).

Linux SNMP step 1 7
AlmaLinux 9 credentials

5. Choose metrics (CPU, memory, disk, processes).

6. Apply configuration and verify monitoring.

Common Issues & Fixes

SNMP Not Running

sudo journalctl -u snmpd --no-pager | tail -20
sudo systemctl restart snmpd.service

Host Appears “Down” in Nagios XI

sudo firewall-cmd --list-ports
sudo systemctl status snmpd

SNMP Credential Errors

  • Confirm SNMP version and credentials in both AlmaLinux and Nagios XI
  • Restart SNMP after any changes

Conclusion

You’ve successfully configured AlmaLinux 9 for SNMP monitoring in Nagios XI. This setup allows for secure, agentless tracking of system metrics in real-time. For advanced use, explore custom SNMP OIDs or additional Nagios XI plugins.

For support:

]]> Comprehensive Guide: Monitoring AlmaLinux 9 with NCPA in Nagios XI https://library.nagios.com/tutorials/comprehensive-guide-monitoring-almalinux-9-with-ncpa-in-nagios-xi/ Wed, 26 Mar 2025 18:46:52 +0000 https://library.nagios.com/?p=53465 The Nagios Cross-Platform Agent (NCPA) is a lightweight, flexible agent that enables centralized monitoring of AlmaLinux 9 from Nagios XI. Whether you’re monitoring CPU, memory, disk, or services, NCPA supports both active checks (pulled by Nagios) and passive checks (pushed via NRDP).

This guide outlines how to install, configure, and connect AlmaLinux 9 with Nagios XI using NCPA 3.x as of March 2025.

Prerequisites

  • A Nagios XI instance (latest version)
  • AlmaLinux 9 system (fully updated with sudo dnf update)
  • Root/sudo access
  • Port 5693 open between AlmaLinux and Nagios XI
  • firewalld installed and running

Step 1: Install NCPA on AlmaLinux 9

Option 1: Install via Nagios Repository (Recommended)

sudo rpm -Uvh https://repo.nagios.com/nagios/9/nagios-repo-9-1.el9.noarch.rpm
sudo dnf install ncpa -y

Option 2: Manual RPM Installation

cd /tmp
wget https://assets.nagios.com/downloads/ncpa/ncpa-latest-1.x86_64.rpm
sudo rpm -ivh ncpa-latest-1.x86_64.rpm

Ensure dependencies like python3 are installed if needed.

Step 2: Configure NCPA Token

sudo nano /usr/local/ncpa/etc/ncpa.cfg

Edit:

community_string = Str0ngT0k3n2025

Save and exit.

Step 3: Start and Enable NCPA

sudo systemctl restart ncpa
sudo systemctl enable ncpa
sudo systemctl status ncpa

Ensure status is active (running).

Step 4: Open Firewall Port 5693

sudo firewall-cmd --zone=public --add-port=5693/tcp --permanent
sudo firewall-cmd --reload
sudo firewall-cmd --list-ports

Confirm 5693/tcp is listed.

Step 5: Verify NCPA Installation

Access the web interface:

https://<AlmaLinux-IP>:5693

Accept the certificate warning and log in using your token Str0ngT0k3n2025. The dashboard should show system stats.

Step 6: Add Host to Nagios XI

1. Log in to Nagios XI.

2. Go to Configure > Configuration Wizards > NCPA.

NCPA 6
NCPA

3. Enter:

  • IP: AlmaLinux IP
  • Port: 5693
  • Token: Str0ngT0k3n2025
rhel 2
NCPA Config step 1

4. Choose desired checks (CPU, memory, disk, processes).

5. Finish wizard and apply configuration.

Step 7: Optional – Setup Passive Checks (NRDP)

  1. In Nagios XI, go to Admin > Inbound Transfers > NRDP to get the URL and token.
  2. Edit ncpa.cfg:
[passive checks]
%HOSTNAME%|CPU Usage = cpu/percent --warning 60 --critical 80
  1. Restart NCPA:
sudo systemctl restart ncpa

Step 8: Troubleshooting Tips

  • Check service status:
sudo systemctl status ncpa
journalctl -u ncpa
  • Test connectivity:
nc -zv <AlmaLinux-IP> 5693
  • View logs:
cat /usr/local/ncpa/var/log/ncpa.log
  • Ensure token/IP match in Nagios XI wizard

Conclusion

With NCPA installed and configured on AlmaLinux 9, you’re now monitoring key system metrics in real time from Nagios XI. For advanced setups, explore encrypted transport or plugin-based checks via the NCPA API.

For help, visit:

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