Difference between revisions of "NaGIOS 4: UBUNTU 20.04 instalasi NaGIOS"

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==Prerequisit==
  
Prerequisites
+
* Dua Ubuntu 20.04 server dengan user root privige. Firewall dengan ufw.
 +
** Server dengan Nagios akan di sebut Nagios server.
 +
** Server tanpa Nagios akan di sebut Ubuntu server.
 +
* Nagios Server akan menjalakan Apache dan PHP.
  
To follow this tutorial, you will need:
+
Nagios Server biasanya di jalankan di belakang Firewall atau VPN. Jika di jalankan di IP Public anda harus lebih serius menginstalasi TLS/SSL dll. Tutorial ini berasumsi, Nagios server di belakang Firewall.
  
    Two Ubuntu 18.04 servers set up by following our Initial Server Setup Guide for Ubuntu 18.04, including a non-root user with sudo privileges and a firewall configured with ufw. On one server, you will install Nagios; this tutorial will refer to this as the Nagios server. It will monitor your second server; this second server will be referred to as the second Ubuntu server.
+
==Step 1 — Installing Nagios 4==
    The server that will run the Nagios server needs Apache and PHP installed. Follow this guide to configure those on one of your servers. You can skip the MySQL steps in that tutorial.
 
  
Typically, Nagios runs behind a hardware firewall or VPN. If your Nagios server is exposed to the public internet, you should secure the Nagios web interface by installing a TLS/SSL certificate. This is optional but strongly encouraged. You can follow the Let’s Encrypt on Ubuntu 18.04 guide to obtain the free TLS/SSL certificate.
+
Login ke Nagios server,
 
 
This tutorial assumes that your servers have private networking enabled so that monitoring happens on the private network rather than the public network. If you don’t have private networking enabled, you can still follow this tutorial by replacing all the references to private IP addresses with public IP addresses.
 
Step 1 — Installing Nagios 4
 
 
 
There are multiple ways to install Nagios, but you’ll install Nagios and its components from source to ensure you get the latest features, security updates, and bug fixes.
 
 
 
Log in to your server that runs Apache. In this tutorial, we’ll call this the Nagios server:
 
  
 
     ssh sammy@your_nagios_server_ip
 
     ssh sammy@your_nagios_server_ip
  
Because you’re building Nagios and its components from source, you must install a few development libraries to complete the build, including compilers, development headers, and OpenSSL.
+
Instalasi aplikasi pendukung,
 
 
Update your package lists to ensure you can download the latest versions of the prerequisites:
 
 
 
    sudo apt update
 
 
 
Then install the required packages:
 
  
 
  sudo apt update
 
  sudo apt update
Line 38: Line 28:
 
  # sudo apt -y install autoconf gcc make unzip libgd-dev libmcrypt-dev libssl-dev dc snmp libnet-snmp-perl gettext
 
  # sudo apt -y install autoconf gcc make unzip libgd-dev libmcrypt-dev libssl-dev dc snmp libnet-snmp-perl gettext
  
With the prerequisites installed, you can install Nagios itself. Download the source code for the latest stable release of Nagios Core. Go to the Nagios downloads page, and click the Skip to download link below the form. Copy the link address for the latest stable release so you can download it to your Nagios server.
+
Download source code terakhir Nagios (misalnya),
 
 
Download the release to your home directory with the curl command:
 
  
     cd ~
+
     cd /usr/local/src/
 
     curl -L -O https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.4.tar.gz
 
     curl -L -O https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.4.tar.gz
 
Extract the Nagios archive:
 
 
 
     tar zxf nagios-4.4.4.tar.gz
 
     tar zxf nagios-4.4.4.tar.gz
 
Then change to the extracted directory:
 
 
 
     cd nagioscore-nagios-4.4.4
 
     cd nagioscore-nagios-4.4.4
  
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Now compile Nagios with this command:
 
Now compile Nagios with this command:
  
    make all
+
make all
  
 
Next create a nagios user and nagios group. They will be used to run the Nagios process:
 
Next create a nagios user and nagios group. They will be used to run the Nagios process:
  
    sudo make install-groups-users
+
sudo make install-groups-users
  
 
Now run these make commands to install Nagios binary files, service files, and its sample configuration files:
 
Now run these make commands to install Nagios binary files, service files, and its sample configuration files:
  
    sudo make install
+
sudo make install
    sudo make install-daemoninit
+
sudo make install-daemoninit
    sudo make install-commandmode
+
sudo make install-commandmode
    sudo make install-config
+
sudo make install-config
  
 
You’ll use Apache to serve Nagios’ web interface, so run the following to install the Apache configuration files and configure its settings:
 
You’ll use Apache to serve Nagios’ web interface, so run the following to install the Apache configuration files and configure its settings:
  
    sudo make install-webconf
+
sudo make install-webconf
  
 
Enable the Apache rewrite and cgi modules with the a2enmod command:
 
Enable the Apache rewrite and cgi modules with the a2enmod command:
  
    sudo a2enmod rewrite
+
sudo a2enmod rewrite
    sudo a2enmod cgi
+
sudo a2enmod cgi
  
 
In order to issue external commands via the web interface to Nagios, add the web server user, www-data, to the nagios group:
 
In order to issue external commands via the web interface to Nagios, add the web server user, www-data, to the nagios group:
  
    sudo usermod -a -G nagios www-data
+
sudo usermod -a -G nagios www-data
  
 
Use the htpasswd command to create an admin user called nagiosadmin that can access the Nagios web interface:
 
Use the htpasswd command to create an admin user called nagiosadmin that can access the Nagios web interface:
  
    sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
+
sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
  
 
Enter a password at the prompt. Remember this password, as you will need it to access the Nagios web interface.
 
Enter a password at the prompt. Remember this password, as you will need it to access the Nagios web interface.
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Restart Apache to load the new Apache configuration:
 
Restart Apache to load the new Apache configuration:
  
    sudo systemctl restart apache2
+
sudo systemctl restart apache2
  
 
You’ve now installed Nagios. But for this to work, it is necessary to install the Nagios Plugins, which you’ll cover in the next step.
 
You’ve now installed Nagios. But for this to work, it is necessary to install the Nagios Plugins, which you’ll cover in the next step.
Step 2 — Installing the Nagios Plugins
 
 
Nagios needs plugins to operate properly. The official Nagios Plugins package contains over 50 plugins that allow you to monitor basic services such as uptime, disk usage, swap usage, NTP, and others.
 
 
Let’s install the the plugins bundle.
 
 
You can find the latest version of the Nagios Plugins on the official site.
 
 
Download it to your home directory with curl:
 
  
    cd ~
+
==Step 2 — Installing the Nagios Plugins==
    curl -L -O https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz
 
  
Extract the NRPE archive and navigate into the extracted directory:
+
Kita perlu menginstalasi Nagios plugin, ada sekitar 50 plugin untuk memonitor berbagai hal seperti uptime, disk usage, swap usage, NTP dll. Download plugin,
  
    tar zxf nagios-plugins-2.2.1.tar.gz
+
cd /usr/local/src
    cd nagios-plugins-2.2.1
+
curl -L -O https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz
 +
tar zxf nagios-plugins-2.2.1.tar.gz
 +
cd nagios-plugins-2.2.1
  
 
Next configure their installation:
 
Next configure their installation:
  
    ./configure
+
./configure
 +
make
 +
sudo make install
  
Now build and install the plugins:
+
Now the plugins are installed, but you need one more plugin for monitoring remote servers. Let’s install it next.
  
    make
+
==Step 3 — Installing the check_nrpe Plugin==
    sudo make install
 
 
 
Now the plugins are installed, but you need one more plugin for monitoring remote servers. Let’s install it next.
 
Step 3 — Installing the check_nrpe Plugin
 
  
 
Nagios monitors remote hosts using the Nagios Remote Plugin Executor, or NRPE. It consists of two pieces:
 
Nagios monitors remote hosts using the Nagios Remote Plugin Executor, or NRPE. It consists of two pieces:
  
    The check_nrpe plugin that the Nagios server uses.
+
* The check_nrpe plugin that the Nagios server uses.
    The NRPE daemon, which runs on the remote hosts and sends data to the Nagios server.
+
* The NRPE daemon, which runs on the remote hosts and sends data to the Nagios server.
 
 
Let’s install the check_nrpe plugin on our Nagios server.
 
 
 
Find the download URL for the latest stable release of NRPE at the GitHub page.
 
 
 
Download it to your home directory with curl:
 
 
 
    cd ~
 
    curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-3.2.1/nrpe-3.2.1.tar.gz
 
 
 
Extract the NRPE archive:
 
 
 
    tar zxf nrpe-3.2.1.tar.gz
 
  
Then change to the extracted directory:
+
Download,
  
    cd nrpe-3.2.1
+
cd /usr/local/src
 +
curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-3.2.1/nrpe-3.2.1.tar.gz
 +
tar zxf nrpe-3.2.1.tar.gz
 +
cd nrpe-3.2.1
  
 
Configure the check_nrpe plugin:
 
Configure the check_nrpe plugin:
  
    ./configure
+
./configure
 +
make check_nrpe
 +
sudo make install-plugin
  
Now build and install check_nrpe plugin:
+
Let’s configure the Nagios server next.
  
    make check_nrpe
+
==Step 4 — Configuring Nagios==
    sudo make install-plugin
 
 
 
Let’s configure the Nagios server next.
 
Step 4 — Configuring Nagios
 
  
 
Now let’s perform the initial Nagios configuration, which involves editing some configuration files. You only need to perform this section once on your Nagios server.
 
Now let’s perform the initial Nagios configuration, which involves editing some configuration files. You only need to perform this section once on your Nagios server.
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Find this line in the file:
 
Find this line in the file:
/usr/local/nagios/etc/nagios.cfg
+
/usr/local/nagios/etc/nagios.cfg
 +
 +
...
 +
#cfg_dir=/usr/local/nagios/etc/servers
 +
...
  
...
+
Uncomment this line by deleting the # character from the front of the line:
#cfg_dir=/usr/local/nagios/etc/servers
 
...
 
  
Uncomment this line by deleting the # character from the front of the line:
+
/usr/local/nagios/etc/nagios.cfg
/usr/local/nagios/etc/nagios.cfg
 
  
cfg_dir=/usr/local/nagios/etc/servers
+
cfg_dir=/usr/local/nagios/etc/servers
  
 
Save and close nagios.cfg by pressing CTRL+X, followed by Y, and then ENTER (if you’re using nano).
 
Save and close nagios.cfg by pressing CTRL+X, followed by Y, and then ENTER (if you’re using nano).
Line 217: Line 178:
 
Now create the directory that will store the configuration file for each server that you will monitor:
 
Now create the directory that will store the configuration file for each server that you will monitor:
  
    sudo mkdir /usr/local/nagios/etc/servers
+
sudo mkdir /usr/local/nagios/etc/servers
  
 
Open the Nagios contacts configuration in your text editor:
 
Open the Nagios contacts configuration in your text editor:
  
    sudo nano /usr/local/nagios/etc/objects/contacts.cfg
+
sudo nano /usr/local/nagios/etc/objects/contacts.cfg
  
 
Find the email directive and replace its value with your own email address:
 
Find the email directive and replace its value with your own email address:
/usr/local/nagios/etc/objects/contacts.cfg
 
  
...
+
/usr/local/nagios/etc/objects/contacts.cfg
define contact{
+
 
        contact_name                   nagiosadmin             ; Short name of user
+
...
        use                             generic-contact         ; Inherit default values from generic-contact template (defined above)
+
define contact{
         alias                          Nagios Admin           ; Full name of user
+
        contact_name nagiosadmin     ; Short name of user
         email                          your_email@your_domain.com       ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
+
        use           generic-contact ; Inherit default values from generic-contact template (defined above)
...
+
        alias         Nagios Admin   ; Full name of user
 +
        email         your_email@your_domain.com ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
 +
...
  
 
Save and exit the editor.
 
Save and exit the editor.
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Next, add a new command to your Nagios configuration that lets you use the check_nrpe command in Nagios service definitions. Open the file /usr/local/nagios/etc/objects/commands.cfg in your editor:
 
Next, add a new command to your Nagios configuration that lets you use the check_nrpe command in Nagios service definitions. Open the file /usr/local/nagios/etc/objects/commands.cfg in your editor:
  
    sudo nano /usr/local/nagios/etc/objects/commands.cfg
+
sudo nano /usr/local/nagios/etc/objects/commands.cfg
  
 
Add the following to the end of the file to define a new command called check_nrpe:
 
Add the following to the end of the file to define a new command called check_nrpe:
 
/usr/local/nagios/etc/objects/commands.cfg
 
/usr/local/nagios/etc/objects/commands.cfg
  
...
+
...
define command{
+
define command{
        command_name check_nrpe
+
        command_name check_nrpe
        command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
+
        command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
}
+
}
  
 
This defines the name and specifies the command-line options to execute the plugin.
 
This defines the name and specifies the command-line options to execute the plugin.
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Then start Nagios and enable it to start when the server boots:
 
Then start Nagios and enable it to start when the server boots:
  
    sudo systemctl start nagios
+
sudo systemctl start nagios
  
 
Nagios is now running, so let’s log in to its web interface.
 
Nagios is now running, so let’s log in to its web interface.
Step 5 — Accessing the Nagios Web Interface
+
 
 +
==Step 5 — Accessing the Nagios Web Interface==
  
 
Open your favorite web browser, and go to your Nagios server by visiting http://nagios_server_public_ip/nagios.
 
Open your favorite web browser, and go to your Nagios server by visiting http://nagios_server_public_ip/nagios.
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Let’s monitor our other server with Nagios,
 
Let’s monitor our other server with Nagios,
Step 6 — Installing Nagios Plugins and NRPE Daemon on a Host
+
 
 +
==Step 6 — Installing Nagios Plugins and NRPE Daemon on a Host==
  
 
Let’s add a new host so Nagios can monitor it. You’ll install the Nagios Remote Plugin Executor (NRPE) on the remote host, install some plugins, and then configure the Nagios server to monitor this host.
 
Let’s add a new host so Nagios can monitor it. You’ll install the Nagios Remote Plugin Executor (NRPE) on the remote host, install some plugins, and then configure the Nagios server to monitor this host.
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Log in to the second server, which we’ll call the second Ubuntu server:
 
Log in to the second server, which we’ll call the second Ubuntu server:
  
    ssh sammy@your_monitored_server_ip
+
ssh sammy@your_monitored_server_ip
  
 
First create a nagios user which will run the NRPE agent:
 
First create a nagios user which will run the NRPE agent:
  
    sudo useradd nagios
+
sudo useradd nagios
  
 
You’ll install NRPE from source, which means you’ll need the same development libraries you installed on the Nagios server in Step 1. Update your package sources and install the NRPE prerequisites:
 
You’ll install NRPE from source, which means you’ll need the same development libraries you installed on the Nagios server in Step 1. Update your package sources and install the NRPE prerequisites:
  
    sudo apt update
+
sudo apt update
    sudo apt install autoconf gcc libmcrypt-dev make libssl-dev wget dc build-essential gettext
+
sudo apt install autoconf gcc libmcrypt-dev make libssl-dev wget dc build-essential gettext
  
 
NRPE requires that Nagios Plugins is installed on the remote host. Let’s install this package from source.
 
NRPE requires that Nagios Plugins is installed on the remote host. Let’s install this package from source.
Line 294: Line 258:
 
Download Nagios Plugins to your home directory with curl:
 
Download Nagios Plugins to your home directory with curl:
  
    cd ~
+
cd /usr/local/src
    curl -L -O https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz
+
curl -L -O https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz
 
+
tar zxf nagios-plugins-2.2.1.tar.gz
Extract the Nagios Plugins archive and change to the extracted directory:
+
cd nagios-plugins-2.2.1
 
 
    tar zxf nagios-plugins-2.2.1.tar.gz
 
    cd nagios-plugins-2.2.1
 
  
 
Before building Nagios Plugins, configure them with the following command:
 
Before building Nagios Plugins, configure them with the following command:
  
    ./configure
+
./configure
 
+
make
Now compile the plugins:
+
sudo make install
 
 
    make
 
 
 
Then install them by running:
 
 
 
    sudo make install
 
  
 
Next, install NRPE daemon. Find the download URL for the latest stable release of NRPE at the GitHub page just like you did in Step 3. Download the latest stable release of NRPE to your monitored server’s home directory with curl:
 
Next, install NRPE daemon. Find the download URL for the latest stable release of NRPE at the GitHub page just like you did in Step 3. Download the latest stable release of NRPE to your monitored server’s home directory with curl:
  
    cd ~
+
cd /usr/local/src
    curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-3.2.1/nrpe-3.2.1.tar.gz
+
curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-3.2.1/nrpe-3.2.1.tar.gz
 
+
tar zxf nrpe-3.2.1.tar.gz
Extract the NRPE archive with this command:
+
cd nrpe-3.2.1
 
 
    tar zxf nrpe-3.2.1.tar.gz
 
 
 
Then change to the extracted directory:
 
 
 
    cd nrpe-3.2.1
 
 
 
Configure NRPE:
 
 
 
    ./configure
 
  
Now build and install NRPE and its startup script with these commands:
+
Configure & Install NRPE:
  
    make nrpe
+
./configure
    sudo make install-daemon
+
make nrpe
    sudo make install-config
+
sudo make install-daemon
    sudo make install-init
+
sudo make install-config
 +
sudo make install-init
  
 
Now, let’s update the NRPE configuration file and add some basic checks that Nagios can monitor.
 
Now, let’s update the NRPE configuration file and add some basic checks that Nagios can monitor.
Line 342: Line 288:
 
First, let’s monitor the disk usage of this server. Use the df -h command to look for the root filesystem. You’ll use this filesystem name in the NRPE configuration:
 
First, let’s monitor the disk usage of this server. Use the df -h command to look for the root filesystem. You’ll use this filesystem name in the NRPE configuration:
  
    df -h /
+
df -h /
  
 
You’ll see output similar to this:
 
You’ll see output similar to this:
  
Output
+
Output
Filesystem      Size  Used Avail Use% Mounted on
+
Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        25G  1.4G  23G  6% /
+
/dev/vda1        25G  1.4G  23G  6% /
  
 
Now open /usr/local/nagios/etc/nrpe.cfg file in your editor:
 
Now open /usr/local/nagios/etc/nrpe.cfg file in your editor:
  
    sudo nano /usr/local/nagios/etc/nrpe.cfg
+
sudo nano /usr/local/nagios/etc/nrpe.cfg
  
 
The NRPE configuration file is very long and full of comments. There are a few lines that you will need to find and modify:
 
The NRPE configuration file is very long and full of comments. There are a few lines that you will need to find and modify:
Line 361: Line 307:
  
 
Locate these settings and alter them appropriately:
 
Locate these settings and alter them appropriately:
/usr/local/nagios/etc/nrpe.cfg
+
/usr/local/nagios/etc/nrpe.cfg
  
...
+
...
server_address=second_ubuntu_server_private_ip
+
server_address=second_ubuntu_server_private_ip
...
+
...
allowed_hosts=127.0.0.1,::1,your_nagios_server_private_ip
+
allowed_hosts=127.0.0.1,::1,your_nagios_server_private_ip
...
+
...
command[check_vda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/vda1
+
command[check_vda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/vda1
...
+
...
  
 
Save and exit the editor. Now you can start NRPE:
 
Save and exit the editor. Now you can start NRPE:
  
    sudo systemctl start nrpe.service
+
sudo systemctl start nrpe.service
  
 
Ensure that the service is running by checking its status:
 
Ensure that the service is running by checking its status:
  
    sudo systemctl status nrpe.service
+
sudo systemctl status nrpe.service
  
 
You’ll see the following output:
 
You’ll see the following output:
  
 
Output
 
Output
...
+
...
Aug 01 06:28:31 client systemd[1]: Started Nagios Remote Plugin Executor.
+
Aug 01 06:28:31 client systemd[1]: Started Nagios Remote Plugin Executor.
Aug 01 06:28:31 client nrpe[8021]: Starting up daemon
+
Aug 01 06:28:31 client nrpe[8021]: Starting up daemon
Aug 01 06:28:31 client nrpe[8021]: Server listening on 0.0.0.0 port 5666.
+
Aug 01 06:28:31 client nrpe[8021]: Server listening on 0.0.0.0 port 5666.
Aug 01 06:28:31 client nrpe[8021]: Server listening on :: port 5666.
+
Aug 01 06:28:31 client nrpe[8021]: Server listening on :: port 5666.
Aug 01 06:28:31 client nrpe[8021]: Listening for connections on port 5666
+
Aug 01 06:28:31 client nrpe[8021]: Listening for connections on port 5666
Aug 01 06:28:31 client nrpe[8021]: Allowing connections from: 127.0.0.1,::1,165.22.212.38
+
Aug 01 06:28:31 client nrpe[8021]: Allowing connections from: 127.0.0.1,::1,165.22.212.38
  
 
Next, allow access to port 5666 through the firewall. If you are using UFW, configure it to allow TCP connections to port 5666 with the following command:
 
Next, allow access to port 5666 through the firewall. If you are using UFW, configure it to allow TCP connections to port 5666 with the following command:
  
    sudo ufw allow 5666/tcp
+
sudo ufw allow 5666/tcp
  
 
You can learn more about UFW in How To Set Up a Firewall with UFW on Ubuntu 18.04.
 
You can learn more about UFW in How To Set Up a Firewall with UFW on Ubuntu 18.04.
Line 398: Line 344:
 
Now you can check the communication with the remote NRPE server. Run the following command on the Nagios server:
 
Now you can check the communication with the remote NRPE server. Run the following command on the Nagios server:
  
    /usr/local/nagios/libexec/check_nrpe -H second_ubuntu_server_ip
+
/usr/local/nagios/libexec/check_nrpe -H second_ubuntu_server_ip
  
 
You’ll see the following output:
 
You’ll see the following output:
  
 
Output
 
Output
NRPE v3.2.1
+
NRPE v3.2.1
  
 
Repeat the steps in this section for each additional server you want to monitor.
 
Repeat the steps in this section for each additional server you want to monitor.
  
 
Once you are done installing and configuring NRPE on the hosts that you want to monitor, you will have to add these hosts to your Nagios server configuration before it will start monitoring them. Let’s do that next.
 
Once you are done installing and configuring NRPE on the hosts that you want to monitor, you will have to add these hosts to your Nagios server configuration before it will start monitoring them. Let’s do that next.
Step 7 — Monitoring Hosts with Nagios
+
==Step 7 — Monitoring Hosts with Nagios==
  
 
To monitor your hosts with Nagios, you’ll add configuration files for each host specifying what you want to monitor. You can then view those hosts in the Nagios web interface.
 
To monitor your hosts with Nagios, you’ll add configuration files for each host specifying what you want to monitor. You can then view those hosts in the Nagios web interface.
Line 414: Line 360:
 
On your Nagios server, create a new configuration file for each of the remote hosts that you want to monitor in /usr/local/nagios/etc/servers/. Replace the highlighted word, monitored_server_host_name with the name of your host:
 
On your Nagios server, create a new configuration file for each of the remote hosts that you want to monitor in /usr/local/nagios/etc/servers/. Replace the highlighted word, monitored_server_host_name with the name of your host:
  
    sudo nano /usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
+
sudo nano /usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
  
 
Add the following host definition, replacing the host_name value with your remote hostname, the alias value with a description of the host, and the address value with the private IP address of the remote host:
 
Add the following host definition, replacing the host_name value with your remote hostname, the alias value with a description of the host, and the address value with the private IP address of the remote host:
/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
+
/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
  
define host {
+
define host {
        use                            linux-server
+
        use                            linux-server
        host_name                      your_monitored_server_host_name
+
        host_name                      your_monitored_server_host_name
        alias                          My client server
+
        alias                          My client server
        address                        your_monitored_server_private_ip
+
        address                        your_monitored_server_private_ip
        max_check_attempts              5
+
        max_check_attempts              5
        check_period                    24x7
+
        check_period                    24x7
        notification_interval          30
+
        notification_interval          30
        notification_period            24x7
+
        notification_period            24x7
}
+
}
  
 
With this configuration, Nagios will only tell you if the host is up or down. Let’s add some services to monitor.
 
With this configuration, Nagios will only tell you if the host is up or down. Let’s add some services to monitor.
  
 
First, add this block to monitor load average:
 
First, add this block to monitor load average:
/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
 
  
define service {
+
/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
        use                            generic-service
+
 
        host_name                      your_monitored_server_host_name
+
define service {
        service_description            Load average
+
        use                            generic-service
        check_command                  check_nrpe!check_load
+
        host_name                      your_monitored_server_host_name
}
+
        service_description            Load average
 +
        check_command                  check_nrpe!check_load
 +
}
  
 
The use generic-service directive tells Nagios to inherit the values of a service template called generic-service, which is predefined by Nagios.
 
The use generic-service directive tells Nagios to inherit the values of a service template called generic-service, which is predefined by Nagios.
  
 
Next, add this block to monitor disk usage:
 
Next, add this block to monitor disk usage:
/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
+
/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
  
define service {
+
define service {
        use                            generic-service
+
        use                            generic-service
        host_name                      your_monitored_server_host_name
+
        host_name                      your_monitored_server_host_name
        service_description            /dev/vda1 free space
+
        service_description            /dev/vda1 free space
        check_command                  check_nrpe!check_vda1
+
        check_command                  check_nrpe!check_vda1
}
+
}
  
 
Now save and quit. Restart the Nagios service to put any changes into effect:
 
Now save and quit. Restart the Nagios service to put any changes into effect:
  
    sudo systemctl restart nagios
+
sudo systemctl restart nagios
  
 
After several minutes, Nagios will check the new hosts and you’ll see them in the Nagios web interface. Click on the Services link in the left navigation bar to see all of your monitored hosts and services.
 
After several minutes, Nagios will check the new hosts and you’ll see them in the Nagios web interface. Click on the Services link in the left navigation bar to see all of your monitored hosts and services.
  
 
Nagios Services Page
 
Nagios Services Page
Conclusion
+
 
 +
==Conclusion==
  
 
You’ve installed Nagios on a server and configured it to monitor load average and disk usage of at least one remote machine.
 
You’ve installed Nagios on a server and configured it to monitor load average and disk usage of at least one remote machine.

Revision as of 11:41, 14 May 2020

Sumber: https://www.digitalocean.com/community/tutorials/how-to-install-nagios-4-and-monitor-your-servers-on-ubuntu-18-04


Nagios adalah sistem pemantauan open-source yang populer. Nagios menjaga inventory server anda dan memonitor mereka sehingga anda tahu layanan penting anda sudah up dan running. Menggunakan sistem pemantauan seperti Nagios adalah tool penting untuk lingkungan produksi apa pun, karena dengan memantau waktu kerja, penggunaan CPU, atau disk space, anda dapat mencegah masalah sebelum terjadi, atau sebelum pengguna anda menghubungi anda.

Disini kita akan menginstalasi Nagios 4 dan mengkonfigurasinya agar kita dapat memonitor resource host di interface web Nagios. Kita juga akan mensetup Nagios Remote Plugin Executor (NRPE), yang akan berjalan sebagai agent remote host sehingga kita dapat memonitor resource-nya.


Prerequisit

  • Dua Ubuntu 20.04 server dengan user root privige. Firewall dengan ufw.
    • Server dengan Nagios akan di sebut Nagios server.
    • Server tanpa Nagios akan di sebut Ubuntu server.
  • Nagios Server akan menjalakan Apache dan PHP.

Nagios Server biasanya di jalankan di belakang Firewall atau VPN. Jika di jalankan di IP Public anda harus lebih serius menginstalasi TLS/SSL dll. Tutorial ini berasumsi, Nagios server di belakang Firewall.

Step 1 — Installing Nagios 4

Login ke Nagios server,

   ssh sammy@your_nagios_server_ip

Instalasi aplikasi pendukung,

sudo apt update
sudo apt -y install autoconf gcc libc6 make wget unzip apache2 php libapache2-mod-php7.2 libgd-dev
# sudo apt -y install autoconf gcc make unzip libgd-dev libmcrypt-dev libssl-dev dc snmp libnet-snmp-perl gettext

Download source code terakhir Nagios (misalnya),

   cd /usr/local/src/
   curl -L -O https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.4.tar.gz
   tar zxf nagios-4.4.4.tar.gz
   cd nagioscore-nagios-4.4.4

Before building Nagios, run the configure script and specify the Apache configs directory:

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

Note: If you want Nagios to send emails using Postfix, you must install Postfix and configure Nagios to use it by adding --with-mail=/usr/sbin/sendmail to the configure command. We won’t cover Postfix in this tutorial, but if you choose to use Postfix and Nagios later, you’ll need to reconfigure and reinstall Nagios to use Postfix support.

You’ll see the following output from the configure command:

Output

      • Configuration summary for nagios 4.4.4 2019-07-29 ***:
General Options:
-------------------------
       Nagios executable:  nagios
       Nagios user/group:  nagios,nagios
      Command user/group:  nagios,nagios
            Event Broker:  yes
       Install ${prefix}:  /usr/local/nagios
   Install ${includedir}:  /usr/local/nagios/include/nagios
               Lock file:  /run/nagios.lock
  Check result directory:  /usr/local/nagios/var/spool/checkresults
          Init directory:  /lib/systemd/system
 Apache conf.d directory:  /etc/apache2/sites-enabled
            Mail program:  /bin/mail
                 Host OS:  linux-gnu
         IOBroker Method:  epoll
Web Interface Options:
------------------------
                HTML URL:  http://localhost/nagios/
                 CGI URL:  http://localhost/nagios/cgi-bin/
Traceroute (used by WAP):


Review the options above for accuracy. If they look okay, type 'make all' to compile the main program and CGIs.

Now compile Nagios with this command:

make all

Next create a nagios user and nagios group. They will be used to run the Nagios process:

sudo make install-groups-users

Now run these make commands to install Nagios binary files, service files, and its sample configuration files:

sudo make install
sudo make install-daemoninit
sudo make install-commandmode
sudo make install-config

You’ll use Apache to serve Nagios’ web interface, so run the following to install the Apache configuration files and configure its settings:

sudo make install-webconf

Enable the Apache rewrite and cgi modules with the a2enmod command:

sudo a2enmod rewrite
sudo a2enmod cgi

In order to issue external commands via the web interface to Nagios, add the web server user, www-data, to the nagios group:

sudo usermod -a -G nagios www-data

Use the htpasswd command to create an admin user called nagiosadmin that can access the Nagios web interface:

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

Enter a password at the prompt. Remember this password, as you will need it to access the Nagios web interface.

Warning: If you create a user with a name other than nagiosadmin, you will need to edit /usr/local/nagios/etc/cgi.cfg and change all the nagiosadmin references to the user you created.

Restart Apache to load the new Apache configuration:

sudo systemctl restart apache2

You’ve now installed Nagios. But for this to work, it is necessary to install the Nagios Plugins, which you’ll cover in the next step.

Step 2 — Installing the Nagios Plugins

Kita perlu menginstalasi Nagios plugin, ada sekitar 50 plugin untuk memonitor berbagai hal seperti uptime, disk usage, swap usage, NTP dll. Download plugin,

cd /usr/local/src
curl -L -O https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz
tar zxf nagios-plugins-2.2.1.tar.gz
cd nagios-plugins-2.2.1

Next configure their installation:

./configure
make
sudo make install

Now the plugins are installed, but you need one more plugin for monitoring remote servers. Let’s install it next.

Step 3 — Installing the check_nrpe Plugin

Nagios monitors remote hosts using the Nagios Remote Plugin Executor, or NRPE. It consists of two pieces:

  • The check_nrpe plugin that the Nagios server uses.
  • The NRPE daemon, which runs on the remote hosts and sends data to the Nagios server.

Download,

cd /usr/local/src
curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-3.2.1/nrpe-3.2.1.tar.gz
tar zxf nrpe-3.2.1.tar.gz
cd nrpe-3.2.1

Configure the check_nrpe plugin:

./configure
make check_nrpe
sudo make install-plugin

Let’s configure the Nagios server next.

Step 4 — Configuring Nagios

Now let’s perform the initial Nagios configuration, which involves editing some configuration files. You only need to perform this section once on your Nagios server.

Open the main Nagios configuration file in your preferred text editor. Here, you’ll use nano:

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

Find this line in the file:

/usr/local/nagios/etc/nagios.cfg

...
#cfg_dir=/usr/local/nagios/etc/servers
...

Uncomment this line by deleting the # character from the front of the line:

/usr/local/nagios/etc/nagios.cfg
cfg_dir=/usr/local/nagios/etc/servers

Save and close nagios.cfg by pressing CTRL+X, followed by Y, and then ENTER (if you’re using nano).

Now create the directory that will store the configuration file for each server that you will monitor:

sudo mkdir /usr/local/nagios/etc/servers

Open the Nagios contacts configuration in your text editor:

sudo nano /usr/local/nagios/etc/objects/contacts.cfg

Find the email directive and replace its value with your own email address:

/usr/local/nagios/etc/objects/contacts.cfg
...
define contact{
        contact_name  nagiosadmin     ; Short name of user
        use           generic-contact ; Inherit default values from generic-contact template (defined above)
        alias         Nagios Admin    ; Full name of user
        email         your_email@your_domain.com  ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
...

Save and exit the editor.

Next, add a new command to your Nagios configuration that lets you use the check_nrpe command in Nagios service definitions. Open the file /usr/local/nagios/etc/objects/commands.cfg in your editor:

sudo nano /usr/local/nagios/etc/objects/commands.cfg

Add the following to the end of the file to define a new command called check_nrpe: /usr/local/nagios/etc/objects/commands.cfg

...
define command{
        command_name check_nrpe
        command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
}

This defines the name and specifies the command-line options to execute the plugin.

Save and exit the editor.

Then start Nagios and enable it to start when the server boots:

sudo systemctl start nagios

Nagios is now running, so let’s log in to its web interface.

Step 5 — Accessing the Nagios Web Interface

Open your favorite web browser, and go to your Nagios server by visiting http://nagios_server_public_ip/nagios.

Enter the login credentials for the web interface in the popup that appears. Use nagiosadmin for the username, and the password you created for that user.

After authenticating, you will see the default Nagios home page. Click on the Hosts link in the left navigation bar to see which hosts Nagios is monitoring:

Nagios Hosts Page

As you can see, Nagios is monitoring only “localhost”, or itself.

Let’s monitor our other server with Nagios,

Step 6 — Installing Nagios Plugins and NRPE Daemon on a Host

Let’s add a new host so Nagios can monitor it. You’ll install the Nagios Remote Plugin Executor (NRPE) on the remote host, install some plugins, and then configure the Nagios server to monitor this host.

Log in to the second server, which we’ll call the second Ubuntu server:

ssh sammy@your_monitored_server_ip

First create a nagios user which will run the NRPE agent:

sudo useradd nagios

You’ll install NRPE from source, which means you’ll need the same development libraries you installed on the Nagios server in Step 1. Update your package sources and install the NRPE prerequisites:

sudo apt update
sudo apt install autoconf gcc libmcrypt-dev make libssl-dev wget dc build-essential gettext

NRPE requires that Nagios Plugins is installed on the remote host. Let’s install this package from source.

Find the latest release of Nagios Plugins from the downloads page.

Download Nagios Plugins to your home directory with curl:

cd /usr/local/src
curl -L -O https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz
tar zxf nagios-plugins-2.2.1.tar.gz
cd nagios-plugins-2.2.1

Before building Nagios Plugins, configure them with the following command:

./configure
make
sudo make install

Next, install NRPE daemon. Find the download URL for the latest stable release of NRPE at the GitHub page just like you did in Step 3. Download the latest stable release of NRPE to your monitored server’s home directory with curl:

cd /usr/local/src
curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-3.2.1/nrpe-3.2.1.tar.gz
tar zxf nrpe-3.2.1.tar.gz
cd nrpe-3.2.1

Configure & Install NRPE:

./configure
make nrpe
sudo make install-daemon
sudo make install-config
sudo make install-init

Now, let’s update the NRPE configuration file and add some basic checks that Nagios can monitor.

First, let’s monitor the disk usage of this server. Use the df -h command to look for the root filesystem. You’ll use this filesystem name in the NRPE configuration:

df -h /

You’ll see output similar to this:

Output
Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        25G  1.4G   23G   6% /

Now open /usr/local/nagios/etc/nrpe.cfg file in your editor:

sudo nano /usr/local/nagios/etc/nrpe.cfg

The NRPE configuration file is very long and full of comments. There are a few lines that you will need to find and modify:

   server_address: Set to the private IP address of the monitored server.
   allowed_hosts: Add the private IP address of your Nagios server to the comma-delimited list.
   command[check_hda1]: Change /dev/hda1 to whatever your root filesystem is called.

Locate these settings and alter them appropriately:

/usr/local/nagios/etc/nrpe.cfg
...
server_address=second_ubuntu_server_private_ip
...
allowed_hosts=127.0.0.1,::1,your_nagios_server_private_ip
...
command[check_vda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/vda1
...

Save and exit the editor. Now you can start NRPE:

sudo systemctl start nrpe.service

Ensure that the service is running by checking its status:

sudo systemctl status nrpe.service

You’ll see the following output:

Output

...
Aug 01 06:28:31 client systemd[1]: Started Nagios Remote Plugin Executor.
Aug 01 06:28:31 client nrpe[8021]: Starting up daemon
Aug 01 06:28:31 client nrpe[8021]: Server listening on 0.0.0.0 port 5666.
Aug 01 06:28:31 client nrpe[8021]: Server listening on :: port 5666.
Aug 01 06:28:31 client nrpe[8021]: Listening for connections on port 5666
Aug 01 06:28:31 client nrpe[8021]: Allowing connections from: 127.0.0.1,::1,165.22.212.38

Next, allow access to port 5666 through the firewall. If you are using UFW, configure it to allow TCP connections to port 5666 with the following command:

sudo ufw allow 5666/tcp

You can learn more about UFW in How To Set Up a Firewall with UFW on Ubuntu 18.04.

Now you can check the communication with the remote NRPE server. Run the following command on the Nagios server:

/usr/local/nagios/libexec/check_nrpe -H second_ubuntu_server_ip

You’ll see the following output:

Output

NRPE v3.2.1

Repeat the steps in this section for each additional server you want to monitor.

Once you are done installing and configuring NRPE on the hosts that you want to monitor, you will have to add these hosts to your Nagios server configuration before it will start monitoring them. Let’s do that next.

Step 7 — Monitoring Hosts with Nagios

To monitor your hosts with Nagios, you’ll add configuration files for each host specifying what you want to monitor. You can then view those hosts in the Nagios web interface.

On your Nagios server, create a new configuration file for each of the remote hosts that you want to monitor in /usr/local/nagios/etc/servers/. Replace the highlighted word, monitored_server_host_name with the name of your host:

sudo nano /usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg

Add the following host definition, replacing the host_name value with your remote hostname, the alias value with a description of the host, and the address value with the private IP address of the remote host:

/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
define host {
        use                             linux-server
        host_name                       your_monitored_server_host_name
        alias                           My client server
        address                         your_monitored_server_private_ip
        max_check_attempts              5
        check_period                    24x7
        notification_interval           30
        notification_period             24x7
}

With this configuration, Nagios will only tell you if the host is up or down. Let’s add some services to monitor.

First, add this block to monitor load average:

/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
define service {
        use                             generic-service
        host_name                       your_monitored_server_host_name
        service_description             Load average
        check_command                   check_nrpe!check_load
}

The use generic-service directive tells Nagios to inherit the values of a service template called generic-service, which is predefined by Nagios.

Next, add this block to monitor disk usage:

/usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg
define service {
        use                             generic-service
        host_name                       your_monitored_server_host_name
        service_description             /dev/vda1 free space
        check_command                   check_nrpe!check_vda1
}

Now save and quit. Restart the Nagios service to put any changes into effect:

sudo systemctl restart nagios

After several minutes, Nagios will check the new hosts and you’ll see them in the Nagios web interface. Click on the Services link in the left navigation bar to see all of your monitored hosts and services.

Nagios Services Page

Conclusion

You’ve installed Nagios on a server and configured it to monitor load average and disk usage of at least one remote machine.

Now that you’re monitoring a host and some of its services, you can start using Nagios to monitor your mission-critical services. You can use Nagios to set up notifications for critical events. For example, you can receive an email when your disk utilization reaches a warning or critical threshold, or a notification when your main website is down. This way you can resolve the situation promptly, or even before a problem occurs.



Referensi


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