This post describes how you can unblock port 10050 to allow Zabbix agent traffic through in the Fedora firewall.
Unblocking port 10050 so traffic can get through to Zabbix agent
By default Fedora 27 has a firewall which blocks traffic reaching port 10050. This stops Zabbix being able to contact the Zabbix agent and gather statistics.
To disable this permanently and reload the firewall configuration so it’s immediately available you can run the following command.
firewall-cmd --permanent --add-port=10050/tcp
systemctl restart firewalld
This adds an exception for the Zabbix agent service and unblocks port 10050 on a permanent basis.
This should ensure that even after reboots it should stay unblocked.