Install Sentinel Runtime

Objectives

  • Setting up a Horizon Sentinel running on one of the following Operating Systems

  • Secure access with encrypted passwords to the Karaf shell

  • Sentinel can be configured with the Karaf Shell from the server via ssh admin@localhost -p 8301

  • Sentinel is running as user sentinel without root permissions

Requirements

  • Linux physical server or a virtual machine running a supported Linux operating system

  • Internet access to download the installation packages

  • Ensure DNS is configured so that localhost and your server’s host name are resolved properly

  • Horizon Core instance runs on latest stable release

  • Java OpenJDK 11 or 17 is installed

  • System user with administrative permissions (sudo) to perform the installation tasks

    If you run Debian, you may have to install and configure sudo yourself. See Debian Wiki for guidance.
Time synchronization is a critical part of operating a monitoring system. Ensure you have a functional time synchronization process running with your operating system. If you are not familiar with this topic, the knowledgebase article Ensure time synchronization for your OpenNMS components is a good starting point.

Installing the Sentinel package

  • CentOS/RHEL 9

  • CentOS/RHEL 8

  • CentOS/RHEL 7

  • Ubuntu

  • Debian

Install OpenJDK 11 JRE runtime
sudo dnf -y install java-11-openjdk-headless
Add repository and import GPG key
sudo dnf -y install https://yum.opennms.org/repofiles/opennms-repo-stable-rhel9.noarch.rpm
sudo rpm --import https://yum.opennms.org/OPENNMS-GPG-KEY
Install Horizon Sentinel
sudo dnf -y install {package-prefix}-sentinel
Disable the OpenNMS Horizon repository after installation to prevent unwanted upgrades when upgrading other packages on the server. After upgrading, Horizon requires manual steps to upgrade configuration files or migrate database schemas to a new version. For this reason, it is recommended to exclude the Horizon packages from updates except when you are planning on performing an upgrade.
Disable auto updates for Horizon Sentinel
sudo dnf config-manager --disable opennms-repo-stable-*
Verify directory structure with the tree command
sudo dnf -y install tree
tree /opt/sentinel -L 1
Directory structure after successful installation
/opt/sentinel
├── bin
├── COPYING
├── deploy
├── etc
├── lib
└── system
Enable Horizon Sentinel on system boot and start immediately
sudo systemctl enable --now sentinel
Install OpenJDK 11 JRE runtime
sudo dnf -y install java-11-openjdk-headless
Add repository and import GPG key
sudo dnf -y install https://yum.opennms.org/repofiles/opennms-repo-stable-rhel8.noarch.rpm
sudo rpm --import https://yum.opennms.org/OPENNMS-GPG-KEY
Installing the of Horizon Sentinel
sudo dnf -y install {package-prefix}-sentinel
Disable the OpenNMS Horizon repository after installation to prevent unwanted upgrades when upgrading other packages on the server. After upgrade, Horizon requires manual steps to upgrade configuration files or migrate database schemas to a new version. For this reason, it is recommended to exclude the Horizon packages from update except when you are planning on performing an upgrade.
Disable auto updates for Horizon Sentinel
sudo dnf config-manager --disable opennms-repo-stable-*
Verify directory structure with the tree command
sudo dnf -y install tree
tree /opt/sentinel -L 1
Directory structure after successful installation
/opt/sentinel
├── bin
├── COPYING
├── deploy
├── etc
├── lib
└── system
Enable Horizon Sentinel on system boot and start immediately
sudo systemctl enable --now sentinel
Install OpenJDK 11 JRE runtime
sudo yum -y install java-11-openjdk-headless
Add repository and import GPG key
sudo yum -y install https://yum.opennms.org/repofiles/opennms-repo-stable-rhel7.noarch.rpm
sudo rpm --import https://yum.opennms.org/OPENNMS-GPG-KEY
Installing the of Horizon Sentinel
sudo yum -y install {package-prefix}-sentinel
Disable the OpenNMS Horizon repository after installation to prevent unwanted upgrades when upgrading other packages on the server. After upgrade, Horizon requires manual steps to upgrade configuration files or migrate database schemas to a new version. For this reason, it is recommended to exclude the Horizon packages from update except when you are planning on performing an upgrade.
Disable auto updates for Horizon Sentinel
sudo yum -y install yum-utils
sudo yum-config-manager --disable opennms-repo-stable-*
Verify directory structure with the tree command
sudo yum -y install tree
tree /opt/sentinel -L 1
Directory structure after successful installation
/opt/sentinel
├── bin
├── COPYING
├── deploy
├── etc
├── lib
└── system
Enable Horizon Sentinel on system boot and start immediately
sudo systemctl enable --now sentinel
Add OpenNMS repository GPG key
curl -fsSL https://debian.opennms.org/OPENNMS-GPG-KEY | sudo gpg --dearmor -o /usr/share/keyrings/opennms.gpg
Add and update apt repository
echo "deb [signed-by=/usr/share/keyrings/opennms.gpg] https://debian.opennms.org stable main" | sudo tee /etc/apt/sources.list.d/opennms.list
sudo apt update
You can safely ignore the message about conflicting distributions (expected stable but got opennms-xx).
Installing the of Horizon Sentinel
sudo apt -y install opennms-sentinel
Disable the OpenNMS Horizon repository after installation to prevent unwanted upgrades when upgrading other packages on the server. After upgrade, Horizon requires manual steps to upgrade configuration files or migrate database schemas to a new version. For this reason, it is recommended to exclude the Horizon packages from update except when you are planning on performing an upgrade. 
sudo apt-mark hold opennms-sentinel
Verify directory structure with the tree command
sudo apt -y install tree
tree /usr/share/sentinel -L 1
Directory structure after successful installation
/usr/share/sentinel
├── bin
├── data -> /var/lib/sentinel/data
├── deploy -> /var/lib/sentinel/deploy
├── etc -> /etc/sentinel
├── lib
└── system
Enable Horizon Sentinel on system boot and start immediately
sudo systemctl enable --now sentinel
Install GnuPG and add OpenNMS repository GPG key
sudo apt -y install curl gnupg ca-certificates
curl -fsSL https://debian.opennms.org/OPENNMS-GPG-KEY | sudo gpg --dearmor -o /usr/share/keyrings/opennms.gpg
Add and update apt repository
echo "deb [signed-by=/usr/share/keyrings/opennms.gpg] https://debian.opennms.org stable main" | sudo tee /etc/apt/sources.list.d/opennms.list
sudo apt update
You can safely ignore the message about conflicting distributions (expected stable but got opennms-xx).
Installing the of Horizon Sentinel
sudo apt -y install opennms-sentinel
Disable the OpenNMS Horizon repository after installation to prevent unwanted upgrades when upgrading other packages on the server. After upgrade, Horizon requires manual steps to upgrade configuration files or migrate database schemas to a new version. For this reason, it is recommended to exclude the Horizon packages from update except when you are planning on performing an upgrade. 
sudo apt-mark hold opennms-sentinel
Verify directory structure with the tree command
sudo apt -y install tree
tree /usr/share/sentinel -L 1
Directory structure after successful installation
/usr/share/sentinel
├── bin
├── data -> /var/lib/sentinel/data
├── deploy -> /var/lib/sentinel/deploy
├── etc -> /etc/sentinel
├── lib
└── system
Enable Horizon Sentinel on system boot and start immediately
sudo systemctl enable --now sentinel

Secure Access to Karaf Shell

Change the default user/password admin/admin for the Karaf shell and encrypt it.

  • CentOS/RHEL 7/8/9

  • Debian/Ubuntu

Enable password encryption
sudo vi /opt/sentinel/etc/org.apache.karaf.jaas.cfg
#
# Boolean enabling / disabling encrypted passwords
#
encryption.enabled = true(1)
#...
encryption.algorithm = SHA-512(2)
1 Enable password encryption from false to true
2 Set a secure encryption algorithm like SHA-512

As soon the file is saved, Karaf will immediately encrypt the password in users.properties.

Set a secure admin password for Karaf
sudo vi /opt/sentinel/etc/users.properties
# All users, groups, and roles entered in this file are available after Karaf startup
# and modifiable via the JAAS command group. These users reside in a JAAS domain
# with the name "karaf".
#
# OPENNMS: Change the admin user from 'karaf' to 'admin'
admin = {CRYPT}C7AD...{CRYPT},_g_:admingroup(1)
1 Replace the whole string {CRYPT}C7AD…​{CRYPT} with your new password in plaintext. As soon you save the file the password will be SHA-512 encrypted.
Set restrictive file permissions
sudo chmod 600 /opt/sentinel/etc/users.properties
Enable password encryption
sudo vi /usr/share/sentinel/etc/org.apache.karaf.jaas.cfg
#
# Boolean enabling / disabling encrypted passwords
#
encryption.enabled = true(1)
#...
encryption.algorithm = SHA-512(2)
1 Enable password encryption from false to true
2 Set a secure encryption algorithm like SHA-512

As soon the file is saved, Karaf will immediately encrypt the password in users.properties.

Set a secure admin password for Karaf
sudo vi /usr/share/sentinel/etc/users.properties
# All users, groups, and roles entered in this file are available after Karaf startup
# and modifiable via the JAAS command group. These users reside in a JAAS domain
# with the name "karaf".
#
# OPENNMS: Change the admin user from 'karaf' to 'admin'
admin = {CRYPT}C7AD...{CRYPT},_g_:admingroup(1)
1 Replace the whole string {CRYPT}C7AD…​{CRYPT} with your new password in plaintext. As soon you save the file the password will be SHA-512 encrypted.
Set restrictive file permissions
sudo chmod 600 /usr/share/sentinel/etc/users.properties
Password or encryption algorithm changes happen immediately. It is not required to restart the Sentinel.
By default the Karaf Shell is restricted to 127.0.0.1. If you want enable remote access, set sshHost=0.0.0.0 in org.apache.karaf.shell.cfg. The change is applied immediately and a Sentinel restart is not required. If you have a firewall running on your host, allow 8301/tcp to grant access to the Karaf Shell.

Set up flow processing

Once you have Sentinel installed, see scale flows data to setup flow processing.