FD_SOCK.startServerSocket() calls Util.createServerSocket(), which does not take into account a port_range. The docs for FD_SOCK state that port_range applies both for client and server socket ports. The configured value should be used instead of incrementing the port number until a free port can be bound to.

Also, the port number keeps incrementing - there's no check for MAX_PORT i.e. 65535 which could mean this could loop forever, unless an IOException is thrown before because of an invalid port number, but I don't know whether this is specified anywhere.