For reporting TCP ListenStats, users of older Linux kernels need to ensure that the the "inet_diag" and "tcp_diag" kernel modules are loaded as they do not autoload correctly. The inet_diag facilities of Raindrops is useful for periodic snapshot reporting of listen queue sizes.
Instead of snapshotting, Raindrops::Aggregate::LastDataRecv may be used to aggregate statistics from all accepted sockets as they arrive based on the last_data_recv field in Raindrops::TCP_Info