[Day 3] 6. Nagios Setup

Pre-requisites:

Configure Hostname:
- Set the hostname as
```
nag-server
```
  . To do the same follow these steps:
  1. open the
```
/etc/hostname
```
    file and change the name written to
```
nag-server
```
    .
  2. open the
```
/etc/hosts
```
    file and replace the name
```
debian
```
    with
```
nag-server
```
    or create a new entry below that line as:
```
shell
127.0.1.1       nag-server
  ```
```
Configure Static IP:
- Set a static IP for the server.
Network Connectivity:
- Ensure the server can ping both the local server and the internet.

Configure APT:

Update the APT sources list in
```
/etc/apt/sources.list
```
.

add

deb [trusted=1] http://sunbeam.shuharilabs.com/sw/repo/deb12/ bookworm main

Install sudo:
- Install
```
sudo
```
  by switching to the root user and running:
```
bash
apt install sudo
```

Set Time Zone:

Set the time zone using the following command:

bash
sudo dpkg-reconfigure tzdata

then select

Asia

and then

Kolkata

Install Nagios Core:

Install Pre-requisites / Dependencies:

Install required packages using the following command:

bash
sudo apt-get install -y apache2 apache2-utils autoconf gcc libc6 libgd-dev make php python3 tree unzip wget libkrb5-dev openssl libssl-dev

Download and Extract Nagios Source Code:

Download Nagios and extract it:

shell
wget http://192.168.0.52/sw/security_tools/nagios/nagios-4.5.0.tar.gz
tar -zxf nagios-4.5.0.tar.gz
cd nagios-4.5.0

Configure Nagios:

Navigate to the

nagios-4.5.0

directory and configure Nagios:

bash
sudo ./configure --with-httpd-conf=/etc/apache2/sites-enabled/

Compile and Install Nagios:
- Run the following command to compile Nagios:
```
bash
sudo make all
```

Create Nagios User and Group:

Create User and Group for Nagios:

Run the following command in the

nagios-4.5.0

directory:

bash
sudo make install-groups-users

Add Apache User to Nagios Group:

Ensure that the Apache user can access Nagios:

bash
sudo usermod -aG nagios www-data

Change Nagios User Password:

Set a password for the Nagios user:

bash
sudo passwd nagios

Install Nagios Executable:
- Run the following command to install the Nagios executable:
```
bash
sudo make install
```
- The Nagios binary will be located in
```
/usr/local/nagios/bin
```
  .
Enable Nagios Service to Start Automatically:
- Ensure Nagios starts automatically after the system boots:
```
bash
sudo make install-daemoninit
```

Enable Command Mode for Nagios:

Allow Nagios to execute commands:

bash
sudo make install-commandmode

Install Nagios Configuration Files:
- If there is no
```
/etc
```
  folder in Nagios, run the following command to install the configuration:
```
bash
sudo make install-config
```

Install Web Configuration:

Install the web configuration for Nagios:

bash
sudo make install-webconf

Configure Apache for Nagios:

Enable Apache Modules:

Enable the

rewrite

and

cgi

modules:

bash
sudo a2enmod rewrite
sudo a2enmod cgi

Set Up Authentication:

Set up password authentication for the Nagios web interface:

bash
sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

Verify Configuration:

Verify the Nagios configuration:

bash
sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

here we are calling the

nagios

and asking it to check the

nagios.conf

file.

Enable and Start Services:

Enable Apache and Nagios Services:

Enable and start both Apache and Nagios:

bash
sudo systemctl enable --now apache2 nagios

Check the Status of Services:

Verify the status of Apache:

bash
sudo systemctl status apache2

Restart and verify the status of Nagios:

bash
sudo systemctl status nagios

Access Nagios Web Interface:

Open a browser on your host machine and visit the following URL to access the Nagios web interface:
```
<your_ip>/nagios
```