NaGIOS 4: UBUNTU 20.04 instalasi NaGIOS
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.
Kebutuhan
- 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 username@your_nagios_server_ip
Instalasi aplikasi pendukung,
sudo apt update sudo apt -y install autoconf gcc libc6 make wget unzip apache2 php libapache2-mod-php 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/ wget -O nagioscore.tar.gz https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.6.tar.gz tar xzf nagioscore.tar.gz cd /usr/local/src/nagioscore-nagios-4.4.6/
Run script & specify Apache config directory:
sudo su cd /usr/local/src/nagioscore-nagios-4.4.6/ sudo ./configure --with-httpd-conf=/etc/apache2/sites-enabled
Catatan: jika kita menggunakan email server postfix, ada baiknya di tambah --with-mail=/usr/sbin/sendmail
Compile & install Nagios,
cd /usr/local/src/nagioscore-nagios-4.4.6/ sudo make all sudo make install-groups-users sudo make install sudo make install-daemoninit sudo make install-commandmode sudo make install-config
Konfigurasi apache
sudo make install-webconf sudo a2enmod rewrite sudo a2enmod cgi sudo usermod -a -G nagios www-data
Konfigurasi & masukan _PASSWORD_ untuk user nagiosadmin (untuk user lain, nagiosadmin bisa di ganti)
sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
Catatan: edit /usr/local/nagios/etc/cgi.cfg ubah nagiosadmin ke useranda jika tidak menggunakan nagiosadmin.
Restart Apache,
sudo systemctl restart apache2
Step 2 — Installing 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,
sudo su cd /usr/local/src curl -L -O https://nagios-plugins.org/download/nagios-plugins-2.3.3.tar.gz tar zxf nagios-plugins-2.3.3.tar.gz cd /usr/local/src/nagios-plugins-2.3.3
Konfigurasi & instalasi:
cd /usr/local/src/nagios-plugins-2.3.3 ./configure sudo make sudo make install
Step 3 — Installing the check_nrpe Plugin
Nagios me-monitor remote host menggunakan Nagios Remote Plugin Executor (NRPE). NRPE terdiri dari dua bagian,
- check_nrpe plugin (di admin console) yang digunakan di Nagios server.
- NRPE daemon, di remote host dan mengirimkan data ke Nagios server.
Download,
cd /usr/local/src curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-4.0.3/nrpe-4.0.3.tar.gz tar zxf nrpe-4.0.3.tar.gz cd nrpe-4.0.3
Konfigurasi dan install check_nrpe plugin:
./configure make check_nrpe sudo make install-plugin
Step 4 — Konfigurasi Nagios server
Konfigurasi awal Nagios, meliputi proses editing beberapa file konfigurasi. Kita hanya perlu melakukannya satu kali di Nagios server.
Edit nagios.cfg
sudo vi /usr/local/nagios/etc/nagios.cfg
Temukan,
/usr/local/nagios/etc/nagios.cfg ... #cfg_dir=/usr/local/nagios/etc/servers ...
Buang # di depan cfg_dir, menjadi
cfg_dir=/usr/local/nagios/etc/servers
Buat directory tersebut. Ini akan menyimpan file konfigurasi untuk setiap server yang kita monitor,
sudo mkdir -y /usr/local/nagios/etc/servers
Edit contact
sudo vi /usr/local/nagios/etc/objects/contacts.cfg
Ubah email dengan email kita,
/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 ******
...
Edit commands.cfg'
Untuk menambahkan new command ke konfigurasi Nagios.
sudo vu /usr/local/nagios/etc/objects/commands.cfg
Tambahkan,
/usr/local/nagios/etc/objects/commands.cfg
...
define command{
command_name check_nrpe
command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
}
Restart Nagios
sudo systemctl start nagios
Step 5 — Akses Nagios Web
Akses ke
http://nagios_server_public_ip/nagios.
username nagiosadmin password yangkitasetsebelumnya
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 Plugin & NRPE Daemon di Server yang di monitor
Untuk memonitor sebuah server, kita perlu menginstalasi Nagios Remote Plugin Executor (NRPE) di remote host tersebit, install plugin, dan konfigurasi Nagios server.
Login server yang akan di monitor,
ssh onno@your_monitored_server_ip
Buat user nagios yang akan menjalankan NRPE agent,
sudo useradd nagios
Install aplikasi pendukung,
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-2.3.3.tar.gz tar zxf nagios-plugins-2.3.3.tar.gz cd nagios-plugins-2.3.4
Compile & install
./configure make sudo make install
Install NRPE daemon,
cd /usr/local/src curl -L -O https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-4.0.3/nrpe-4.0.3.tar.gz tar zxf nrpe-4.0.3.tar.gz cd nrpe-4.0.3
Configure & Install NRPE:
./configure make nrpe sudo make install-daemon sudo make install-config sudo make install-init
Untuk ujicoba kita akan monitor penggunan harddisk. Contoh,
df -h /
Akan keluar,
Output Filesystem Size Used Avail Use% Mounted on /dev/vda1 25G 1.4G 23G 6% /
Edit /usr/local/nagios/etc/nrpe.cfg
sudo vi /usr/local/nagios/etc/nrpe.cfg
Kita perlu menembukan dan mengubah,
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 ...
Start NRPE,
sudo systemctl start nrpe.service
Pastikan running,
sudo systemctl status nrpe.service
output kira2,
... 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
Buka port 5666 di firewall,
sudo ufw allow 5666/tcp
Cek komunikasi ke remote NRPE server dari Admin Console (Nagios Server),
/usr/local/nagios/libexec/check_nrpe -H second_ubuntu_server_ip
Output,
NRPE v4.0.3
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.
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