TCP connections usage

Command: sar -n TCP

      active/s
	     The number of times TCP connections have made  a  direct
	     transition  to  the SYN-SENT state from the CLOSED state
	     per second [tcpActiveOpens].

      passive/s
	     The number of times TCP connections have made  a  direct
	     transition  to  the SYN-RCVD state from the LISTEN state
	     per second [tcpPassiveOpens].