Getting Started

After setup, logs that would typically appear in /var/log/messages will be forwarded to the Nagios Log Server R2, allowing centralized monitoring and alerting.

Automatic Setup Using a Script

The easiest way to configure log forwarding is by using the provided script. This method requires rsyslog to be installed on your CentOS 8 machine.

Steps to Run the Script:

1. Ensure Rsyslog is Installed:

sudo dnf install rsyslog -y
sudo systemctl enable --now rsyslog

sudo dnf install rsyslog -y
sudo systemctl enable --now rsyslog

2. Download the Script from the Nagios Log Server R2:

curl -sS -O http://192.168.1.49/nagioslogserver/scripts/setup-linux.sh

curl -sS -O http://192.168.1.49/nagioslogserver/scripts/setup-linux.sh

3. Execute the Script to Configure Rsyslog:

sudo bash setup-linux.sh -s 192.168.1.49 -p 5544

sudo bash setup-linux.sh -s 192.168.1.49 -p 5544

• Replace 192.168.1.49 with your Nagios Log Server R2’s IP address.
• The -p 5544 option specifies the port for log transmission.

Manual Setup Using Rsyslog Configuration

If you prefer manual setup or need more control over configurations, follow these steps:

1. Edit Rsyslog Configuration:

sudo nano /etc/rsyslog.d/99-nagios.conf

sudo nano /etc/rsyslog.d/99-nagios.conf

2. Add the Following Configuration:

*.* @@192.168.1.49:5544

*.* @@192.168.1.49:5544

• Replace 192.168.1.49 with the IP address of your Nagios Log Server R2.
• The @@ symbol indicates TCP transmission; use @ for UDP if needed.

3. Restart Rsyslog to Apply Changes:

sudo systemctl restart rsyslog

sudo systemctl restart rsyslog

4. Check Status to Ensure it’s Running:

sudo systemctl status rsyslog

sudo systemctl status rsyslog

Receiving Logs in Log Server

On your Log Server’s GUI, click Add Log Source.

Click Linux.

Type in your machine’s IP address to see if you are receiving logs. If it’s working, the interface will confirm that logs are being received.

Conclusion

Whether using the automatic script or manual setup, forwarding logs from CentOS 8 to Nagios Log Server R2 ensures centralized log management for better monitoring and alerting. Use the method that best fits your deployment needs.

Step 1: Install SNMP and Utilities

CentOS 8 uses dnf as the default package manager. Install SNMP packages with:

sudo dnf install net-snmp net-snmp-utils -y

sudo dnf install net-snmp net-snmp-utils -y

Step 2: Start and Enable the SNMP Service

Once installed, start and enable the SNMP service so that it runs at boot:

sudo systemctl enable --now snmpd

sudo systemctl enable --now snmpd

Step 3: Configure SNMP

The main configuration file for SNMP is located at:

/etc/snmp/snmpd.conf

/etc/snmp/snmpd.conf

Before making changes, back up the original file:

sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak

sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak

Now, edit the configuration file:

sudo nano /etc/snmp/snmpd.conf

sudo nano /etc/snmp/snmpd.conf

Modify or add the following lines to set up SNMPv2c with a community string (replace YourCommunity with a strong name):

com2sec readonly  default  YourCommunity
group   MyROGroup v2c        readonly
view    all    included   .1
access  MyROGroup ""      any       noauth    exact  all    none   none
syslocation "Data Center"
syscontact "Admin <admin@example.com>"

com2sec readonly  default  YourCommunity
group   MyROGroup v2c        readonly
view    all    included   .1
access  MyROGroup ""      any       noauth    exact  all    none   none
syslocation "Data Center"
syscontact "Admin <admin@example.com>"

Save and exit the file, then restart the SNMP service:

sudo systemctl restart snmpd

sudo systemctl restart snmpd

Step 4: Adjust Firewall Rules

To allow SNMP traffic, open the necessary UDP port (161):

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

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

Step 5: Verify SNMP Functionality

Test if SNMP is working correctly with:

snmpwalk -v2c -c YourCommunity -O e 127.0.0.1

snmpwalk -v2c -c YourCommunity -O e 127.0.0.1

If you see output with system information, SNMP is working correctly.

Step 6: Open Firewall for SNMP

If you want to allow SNMP traffic from remote machines, open the firewall to allow SNMP traffic:

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

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

This command opens port 161 (the default SNMP port) for UDP traffic, allowing SNMP queries from remote systems.

Step 7: Test SNMP from a Remote System

Finally, to ensure SNMP is accessible remotely, test it from another system using snmpwalk:

snmpwalk -v2c -c YourCommunityString

snmpwalk -v2c -c YourCommunityString

Replace <server-ip> with the IP address of your CentOS server. If SNMP is correctly configured, you will receive SNMP data from the remote server.

Monitoring with Nagios XI

On Nagios XI navigate to Run a Wizard and click on the SNMP wizard

Add your Host Name and type in the SNMP Community string that you created.

Pick the SNMP Services that you want to monitor and then click Next and Finish with Defaults.

Conclusion

You have successfully installed and configured SNMP on CentOS 8. This setup allows your server to be monitored remotely, enhancing network management capabilities. You also configured SNMP monitoring with Nagios XI, which provides a powerful interface for tracking system performance and network activity. By adding your SNMP-enabled server to Nagios XI, you can gain deeper insights into system health, set up alerts, and optimize network monitoring for better performance.

Prerequisites

• A CentOS 8 system with root or sudo privileges
• Access to the internet
• A running Nagios server

Step 1: Update System Packages

Before installing any software, it’s best to update your system:

sudo dnf update -y

sudo dnf update -y

Step 2: Download NCPA Package

The official NCPA package for CentOS 8 is available on the Nagios website. You can download it using wget:

wget https://assets.nagios.com/downloads/ncpa/ncpa-latest.el8.x86_64.rpm

wget https://assets.nagios.com/downloads/ncpa/ncpa-latest.el8.x86_64.rpm

Step 3: Install NCPA

Use the dnf package manager to install the downloaded RPM package:

sudo dnf install -y ncpa-latest.el8.x86_64.rpm

sudo dnf install -y ncpa-latest.el8.x86_64.rpm

This command installs NCPA along with its dependencies.

Step 4: Configure NCPA

The main configuration file for NCPA is located at:

/etc/ncpa/ncpa.cfg

/etc/ncpa/ncpa.cfg

Open the file with a text editor, such as nano:

sudo nano /etc/ncpa/ncpa.cfg

sudo nano /etc/ncpa/ncpa.cfg

Set the api_token value to a secure string, as it is required for communication between NCPA and the Nagios server:

api_token = YOUR_SECURE_API_TOKEN

api_token = YOUR_SECURE_API_TOKEN

Save the file and exit.

Step 5: Start and Enable NCPA Service

Once configured, start the NCPA services and enable them to run at boot:

sudo systemctl enable --now ncpa_listener
sudo systemctl enable --now ncpa_passive

sudo systemctl enable --now ncpa_listener
sudo systemctl enable --now ncpa_passive

Step 6: Configure Firewall Rules (If Applicable)

If you have firewalld enabled, allow NCPA through the firewall:

sudo firewall-cmd --permanent --add-port=5693/tcp
sudo firewall-cmd --reload

sudo firewall-cmd --permanent --add-port=5693/tcp
sudo firewall-cmd --reload

Step 7: Verify NCPA Installation

To check if NCPA is running, use the following command:

sudo systemctl status ncpa_listener ncpa_passive

sudo systemctl status ncpa_listener ncpa_passive

Additionally, you can test API access via curl:

curl https://localhost:5693/api --insecure

curl https://localhost:5693/api --insecure

If everything is set up correctly, you should receive a JSON response.

Monitoring with Nagios

On your Nagios web GUI, click Run a wizard and find the NCPA wizard.

Type in the Address of your machine running NCPA. You can leave the Port as default. Enter the Token that you created earlier and click Next, and Finish with Defaults.

Conclusion

You have successfully installed and configured NCPA on CentOS 8. This agent allows you to monitor system performance and services using Nagios. Want Nagios notifications in Slack or Discord? Click to find out how.