How to Install Nagios on Arch Linux

Nagios is an open-source monitoring tool that helps IT professionals and system administrators to monitor their infrastructure and applications. It provides alerts when there is a problem with the system. In this tutorial, we will show you how to install Nagios on Arch Linux.

Prerequisites

Before you start, make sure that your Arch Linux system is up-to-date by running the following command in your terminal:

sudo pacman -Syu

Also, ensure that you have installed Apache, PHP, and other required packages by running the following command:

sudo pacman -S apache php php-cgi gd

Step 1: Download and Install Nagios Core

Download the Nagios Core package from the Nagios official website using the following command:
```
wget https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.6.tar.gz
```
Extract the Nagios Core package with the following command:
```
tar -xvf nagios-4.4.6.tar.gz
```
Go to the Nagios Core directory:
```
cd nagioscore-nagios-4.4.6/
```

Configure Nagios Core:

./configure --with-command-group=nagcmd

Now, compile and install Nagios Core:

make all
sudo make install
sudo make install-init
sudo make install-commandmode
sudo make install-config

Step 2: Install Nagios Plugins

Download the Nagios Plugins package from the Nagios official website:

wget https://github.com/nagios-plugins/nagios-plugins/archive/release-2.3.3.tar.gz

Extract the Nagios Plugins package:
```
tar -xvf release-2.3.3.tar.gz
```
Go to the Nagios Plugins directory:
```
cd nagios-plugins-release-2.3.3/
```

Configure Nagios Plugins:

./configure --with-nagios-user=nagios --with-nagios-group=nagios

Now, compile and install Nagios Plugins:
```
make
sudo make install
```

Step 3: Create a Nagios User and Group

Create a new user and group called nagios:

sudo useradd nagios
sudo groupadd nagios
sudo usermod -aG nagios nagios

Set a password for the Nagios user:
```
sudo passwd nagios
```
Add the Apache user (http) to the nagios group:
```
sudo usermod -aG nagios http
```

Step 4: Configure Apache Web server

Create a new Apache configuration file for Nagios:
```
sudo nano /etc/httpd/conf/extra/nagios.conf
```

Add the following lines to the file and save it:

ScriptAlias /nagios/cgi-bin "/usr/local/nagios/sbin"
<Directory "/usr/local/nagios/sbin">
    AllowOverride None
    Options ExecCGI
    Order allow,deny
    Allow from all
    Require all granted
</Directory>

Alias /nagios "/usr/local/nagios/share"
<Directory "/usr/local/nagios/share">
    AllowOverride None
    Options None
    Order allow,deny
    Allow from all
    Require all granted
</Directory>

Enable the Apache CGI module:
```
sudo a2enmod cgi
```
Restart the Apache service:
```
sudo systemctl restart httpd
```

Step 5: Verify Nagios Installation

Access Nagios web interface by typing the following URL in your web browser:
```
http://your_server_IP/nagios/
```
Login with the Nagios admin credentials (default username: nagiosadmin, default password: nagios).
You should see the Nagios dashboard.

Congratulations! You have successfully installed and configured Nagios on Arch Linux. You can start monitoring your infrastructure and applications using Nagios.