By default, CIUMon listens on port 5099. In order to connect to CIUMon from across a firewall, this port must be unblocked.
To limit the number of connections that must be allowed through the firewall, CIUMon can be run in relay mode on a computer outside the firewall. The relay mode CIUMon connects to the main CIUMon through the firewall, and live data users connect to the relay mode CIUMon.