A robot program called 'Hublist pinger' is running in the background which connects to the hubs from time to time and verifies the user count and other data. Finally it updates the hub in the hublist.
If you want, you can specify a user name and password here for the hublist pinger. It is not mandatory, but you may want to customize it if you have a minimum share requirement on your hub which would cause the pinger to be disconnected or if you registered a user for the pinger on your hub.
Important: If the pinger can't connect, the hub won't appear in the hublist.