GNU cfengine
4.1.3 AllowMultipleConnectionsFrom
This variable should contain a list of IP wildcards to hosts which are
allowed simultaneous sessions on the server. Hosts which are not in this
list are allowed to connect only once, i.e. they must terminate and
reconnect in order to establish a new session. This is to prevent a
possible attacker from opening multiple sockets and never closing them,
resulting in a denial of service attack. Hosts IP's can be placed here
if they could have overlapping copy sessions (e.g. long backup transfers
which can run over time). This prevents the error message "Multiple
connections denied/spam shield".
