Monitoring JDBC Connections

Hi all, I am looking for a way to monitor open remote connections (i.e., JDBC connections) and possibly to force close them. As far as I can tell, MonetDB restricts the number of simultaneous connections to 64 by default. Via select * from sys.queue I can monitor running queries but I haven't yet figured out a way to list all open connections. Consider e.g. the case that a JDBC connection is for some reason not properly closed. Any hints would be much appreciated. Best regards, Arno