Using a Different System?
Monitor Your Devices Using LibreNMS on Ubuntu 16.04
LibreNMS is a full-featured open source network monitoring system. It uses
SNMP to obtain the data from different devices. A variety of devices are supported in LibreNMS such as Cisco, Linux, FreeBSD, Juniper, Brocade, Foundry, HP and many more. It supports multiple authentication mechanisms and supports two-factor authentication. It has a customizable alerting system which can alert the network admin via email, IRC or slack.
- A Vultr CentOS 7 server instance.
- A sudo user.
For this tutorial, we will use
nms.example.com as the domain name pointed towards the Vultr instance. Please make sure to replace all occurrences of the example domain name with the actual one.
Update your base system using the guide How to Update CentOS 7. Once your system has been updated, proceed to install the dependencies.
Install Nginx and PHP
The front end of LibreNMS is basically written in PHP, thus we will need to install a web server and PHP. In this tutorial, we will install Nginx along with PHP 7.2 to obtain maximum security and performance.
sudo yum -y install nginx
Start Nginx and enable it to start at boot automatically.
sudo systemctl start nginx sudo systemctl enable nginx
Add and enable the Remi repository, as the default YUM repository contains an older version of PHP.
sudo rpm -Uvh http://rpms.remirepo.net/enterprise/remi-release-7.rpm sudo yum -y install yum-utils sudo yum-config-manager --enable remi-php72
Install PHP version 7.2 along with the modules required by LibreNMS.
sudo yum -y install php php-cli php-common php-curl php-fpm php-gd php-mcrypt php-mysql php-process php-snmp php-xml php-zip
Open the loaded configuration file by PHP in an editor.
sudo nano /etc/php.ini
Find the following lines, uncomment and change their value as shown.
;cgi.fix_pathinfo=1 memory_limit = 128M ;date.timezone =
Use these values instead, replace
Asia/Kolkata with your local timezone.
cgi.fix_pathinfo=0 memory_limit = -1 date.timezone = Asia/Kolkata
You will also need to change the system timezone by running the following command.
sudo ln -sf /usr/share/zoneinfo/Asia/Kolkata /etc/localtime
Now open the PHP-FPM configuration file.
sudo nano /etc/php-fpm.d/www.conf
Find the following line.
listen = 127.0.0.1:9000
Replace it with the following line.
listen = /var/run/php-fpm/php-fpm.sock
By default, PHP-FPM is configured for Apache web server user. Change the user to
user = nginx group = nginx
Further, uncomment the following lines.
listen.owner = nobody listen.group = nobody
Save the file and exit from the editor. Restart PHP-FPM and enable it to start at boot time.
sudo systemctl restart php-fpm sudo systemctl enable php-fpm
Set the appropriate ownership to the socket file.
sudo chown nginx:nginx /var/run/php-fpm/php-fpm.sock
MariaDB is a fork of MySQL. Add the MariaDB repository into your system. The default
yum repository contains an older version of MariaDB.
echo "[mariadb] name = MariaDB baseurl = http://yum.mariadb.org/10.2/centos7-amd64 gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB gpgcheck=1" | sudo tee /etc/yum.repos.d/mariadb.repo
sudo yum -y install mariadb mariadb-server
Now, open the MySQL configuration file.
sudo nano /etc/my.cnf
Add the following lines at the end of the block.
[mysqld] innodb_file_per_table=1 sql-mode="" lower_case_table_names=0
Restart MariaDB and enable it to automatically start at boot time.
sudo systemctl restart mariadb sudo systemctl enable mariadb
Before configuring the database, you will need to secure MariaDB first.
You will be asked for the current MariaDB root password. By default, there is no root password in a fresh MariaDB installation. Press the “
Enter” key to proceed. Set a strong password for the
root user of your MariaDB server and answer “
Y” to all of the other questions that are asked. The questions asked are self-explanatory.
Log into the MySQL shell as root.
mysql -u root -p
Provide the password for the MariaDB root user to log in.
Run the following queries to create a database and a database user for the LibreNMS installation.
CREATE DATABASE librenms CHARACTER SET utf8 COLLATE utf8_general_ci; CREATE USER 'librenms'@'localhost' IDENTIFIED BY 'StrongPassword'; GRANT ALL PRIVILEGES ON librenms.* TO 'librenms'@'localhost'; FLUSH PRIVILEGES; EXIT;
You can replace the database name
librenms and username
librenms according to your choice. Please make sure to change
StrongPassword to a very strong password.
Apart from the dependencies above, LibreNMS needs few more dependencies. Install them by running.
sudo yum -y install cronie fping git ImageMagick jwhois mtr MySQL-python net-snmp net-snmp-utils nmap python-memcached rrdtool
Add a new unprivileged user for LibreNMS application.
sudo useradd librenms -d /opt/librenms -M -r sudo usermod -a -G librenms nginx
LibreNMS can be installed directly by cloning its Github repository.
cd /opt sudo git clone https://github.com/librenms/librenms.git librenms
Fix the ownership.
sudo chown librenms:librenms -R /opt/librenms
LibreNMS relies on SNMP for many tasks. Since we have already installed SNMP, copy the example configuration file to its location.
sudo cp /opt/librenms/snmpd.conf.example /etc/snmp/snmpd.conf
Open the configuration file in the editor.
sudo nano /etc/snmp/snmpd.conf
Find this line.
com2sec readonly default RANDOMSTRINGGOESHERE
Edit the text
RANDOMSTRINGGOESHERE and replace the community string with any string of your choice. For example.
com2sec readonly default my-org
Remember the string as it will be required later when we add the first SNMP device.
SNMP also needs information about the distribution version. Download and install the script to find the distribution version.
sudo curl -o /usr/bin/distro https://raw.githubusercontent.com/librenms/librenms-agent/master/snmp/distro sudo chmod +x /usr/bin/distro
Start the SNMP daemon service and enable it to automatically start at boot time.
sudo systemctl enable snmpd sudo systemctl restart snmpd
Now you will need to add some crontab entries to run the scheduled tasks. Create a new cron job file.
sudo nano /etc/cron.d/librenms
Populate the file with the following text.
33 */6 * * * librenms /opt/librenms/cronic /opt/librenms/discovery-wrapper.py 1 */5 * * * * librenms /opt/librenms/discovery.php -h new >> /dev/null 2>&1 */5 * * * * librenms /opt/librenms/cronic /opt/librenms/poller-wrapper.py 16 15 0 * * * librenms /opt/librenms/daily.sh >> /dev/null 2>&1 * * * * * librenms /opt/librenms/alerts.php >> /dev/null 2>&1 */5 * * * * librenms /opt/librenms/poll-billing.php >> /dev/null 2>&1 01 * * * * librenms /opt/librenms/billing-calculate.php >> /dev/null 2>&1 */5 * * * * librenms /opt/librenms/check-services.php >> /dev/null 2>&1
Restart the cron daemon service.
sudo systemctl restart crond
logrotate so that the log files are automatically refreshed over time.
sudo cp /opt/librenms/misc/librenms.logrotate /etc/logrotate.d/librenms
Finally, set the appropriate ownership and permissions.
sudo chown -R librenms:nginx /opt/librenms sudo chmod g+w -R /opt/librenms sudo setfacl -d -m g::rwx /opt/librenms/rrd /opt/librenms/logs sudo setfacl -R -m g::rwx /opt/librenms/rrd /opt/librenms/logs
SSL and Nginx VHost configurations
Logins and other information sent through the web interface of LibreNMS are not secured if the connection is not encrypted with SSL. We will configure Nginx to use SSL generated with Let’s Encrypt free SSL.
Install Certbot, which is the client application for Let’s Encrypt CA.
sudo yum -y install certbot
Before you can request the certificates, you will need to allow port
443, or standard
HTTPS services through the firewall.
sudo firewall-cmd --zone=public --add-service=http --permanent sudo firewall-cmd --zone=public --add-service=https --permanent sudo firewall-cmd --reload
Note: To obtain certificates from Let’s Encrypt CA, the domain for which the certificates are to be generated must be pointed towards the server. If not, make the necessary changes to the DNS records of the domain and wait for the DNS to propagate before making the certificate request again. Certbot checks the domain authority before providing the certificates.
Generate the SSL certificates:
sudo certbot certonly --webroot -w /usr/share/nginx/html -d nms.example.com
The generated certificates are likely to be stored in the
/etc/letsencrypt/live/nms.example.com/ directory. The SSL certificate will be stored as
fullchain.pem and private key will be stored as
Let’s Encrypt certificates expire in 90 days, hence it is recommended to set up auto-renewal for the certificates using a cron job.
Open the cron job file.
sudo crontab -e
Add the following line at the end of the file.
30 5 * * 1 /usr/bin/certbot renew --quiet
The above cron job will run every Monday at 5:30 AM local time. If the certificate is due for expiry, it will automatically be renewed.
Create a new virtual host.
sudo nano /etc/nginx/conf.d/nms.example.com.conf
Populate the file.
nms.example.com with your actual domain in the above configuration.
sudo chown nginx:nginx /var/lib/php/session sudo systemctl restart nginx
Installation using WebUI
To finish the installation, open
https://nms.example.com on your favorite browser. You will see the requirements are satisfied. Provide your database details and create a new administrative account. Once installed, you will get a message to validate the installation. Click on the link and log in using the administrator account. You will see that everything except the “
Poller” has an “
Now, click on the link to add a device. On the “
Add Device” interface, provide the hostname as the localhost and leave everything as it is. Provide your community string in community field. It must be the exact same string which you have provided in
snmpd.conf during the configuration of SNMP.
Once the device has been added, you can see the details by going to the “
Similarly, you can add more devices into the LibreNMS application for “around the clock” monitoring.
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