The FTS3 Web Monitoring allows peeking at the internal FTS3 state: active transfers, success rate, optimizer decisions...
It is not a tool for historical data, data aggregation, etc... For this sort of uses, better use the FTS Dashboard.
Firewalld is installed by default on some Linux distributions, including many images of CentOS 7.
In order to add the firwalled support for FTS Web Monitoring you need to install the fts-monitoring-firewalld package.
After the installation you can enable the firewalld service and reboot your server. Keep in mind that enabling firewalld will cause the service to start up at boot. It is best practice to create your firewall rules and take the opportunity to test them before configuring this behavior in order to avoid potential issues.
sudo systemctl enable firewalld
sudo reboot
When the server restarts, your firewall should be brought up, your network interfaces should be put into the zones you configured (or fall back to the configured default zone), and any rules associated with the zone(s) will be applied to the associated interfaces.
We can verify that the service is running and reachable by typing:
sudo firewall-cmd --state
output running
This indicates that our firewall is up and running with the default configuration.
When running FTS Web Monitorin, we can allow this traffic for interfaces in our "public" zone for this session by typing:
sudo firewall-cmd --zone=public --add-service=ftsmon
You can leave out the --zone= if you wish to modify the default zone. We can verify the operation was successful by using the --list-all or --list-services operations:
sudo firewall-cmd --zone=public --list-services