This little snippet is for when you want to see new active connections per second, not concurrent established, as most tools show you:
C=0; while true; do echo "new connections: $C"; c1=`netstat -s -t|grep "active connections openings"|awk '{print $1;}'`; sleep 1; c2=`netstat -s -t|grep "active connections openings"|awk '{print $1;}'`; C=`expr $c2 - $c1` ; done
Enjoy!