nethserver-zabbix-agent integrates the Zabbix monitoring agent from Zabbix repo to NethServer
Install Zabbix repo:
rpm -ivh http://repo.zabbix.com/zabbix/3.4/rhel/7/x86_64/zabbix-release-3.4-2.el7.noarch.rpm
Install nethserver-zabbix-agent
https://www.zabbix.com/documentation/5.0/manual/concepts/agent