[[install-sentinel]]
= Install Sentinel Runtime
:description: Set up OpenNMS Sentinel (for scaling and streaming telemetry) on RHEL, CentOS, Debian, and Ubuntu.

[[objectives]]
== Objectives

* Setting up a {page-component-title} Sentinel running on one of the following <<minion/system-requirements.adoc#operating-systems-Core, Operating Systems>>
* Secure access with encrypted passwords to the xref:reference:karaf-shell/karaf-shell.adoc[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
* {page-component-title} Core instance runs on latest stable release
* Java {compatible-javajdk} is installed
* System user with administrative permissions (`sudo`) to perform the installation tasks
ifeval::["{page-component-title}" == "Horizon"]
+
NOTE: If you run Debian, you may have to install and configure `sudo` yourself.
See https://wiki.debian.org/sudo/[Debian Wiki] for guidance.
endif::[]

include::../../time-sync.adoc[]

== Installing the Sentinel package

[{tabs}]
====
CentOS/RHEL 9::
+
--
include::centos-rhel9/install-sentinel.adoc[]
--

ifeval::["{page-component-title}" == "Horizon"]
Ubuntu::
+
--
include::ubuntu/install-sentinel.adoc[]
--

Debian::
+
--
include::debian/install-sentinel.adoc[]
--
endif::[]
====

== Secure Access to Karaf Shell

IMPORTANT: Change the default user/password _admin/admin_ for the Karaf shell and encrypt it.

[{tabs}]
====
CentOS/RHEL 7/8/9::
+
--
include::centos-rhel/secure-karaf.adoc[]
--

ifeval::["{page-component-title}" == "Horizon"]
Debian/Ubuntu::
+
--
include::debian-ubuntu/secure-karaf.adoc[]
--
endif::[]
====

TIP: Password or encryption algorithm changes happen immediately.
It is not required to restart the Sentinel.

TIP: 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 xref:operation:deep-dive/flows/sentinel/sentinel.adoc#flows-scaling[scale flows data] to setup flow processing.
