On Debian 13:
sudo apt update
sudo apt install -y apt-transport-https wget gnupg
curl -fsSL https://packages.icinga.com/icinga.key | sudo gpg --dearmor -o /usr/share/keyrings/icinga.gpg
echo \"deb [signed-by=/usr/share/keyrings/icinga.gpg] https://packages.icinga.com/debian icinga-$(lsb_release -cs) main\" | sudo tee /etc/apt/sources.list.d/icinga.list
sudo apt update
sudo apt install icinga2
On RHEL 10:
sudo dnf install -y https://packages.icinga.com/epel/icinga-rpm-release-10-latest.noarch.rpm
sudo dnf install icinga2
sudo systemctl enable --now icinga2
Icinga Web 2 requires a web server and database. If you want the UI:
sudo apt install icingaweb2 icingacli
On RHEL:
sudo dnf install icingaweb2 icingacli
Then follow the web setup wizard at http://SERVER_IP/icingaweb2/setup.
On UFW:
sudo ufw allow 80/tcp
On firewalld:
sudo firewall-cmd --permanent --add-service=http
sudo firewall-cmd --reload
See Icinga Hardening.