mtr,traceroute,pathping,tracert,ping

netstat -ntu | tail -n +3|awk '{ print $5}' | cut -d : -f 1 | sort | uniq -c| sort -n -r | head -n 5

tcpdump -i eth0 -tnn dst port 80 -c 1000|awk -F "." '{print $1 "." $2 "." $3 "." $4}'| sort | uniq -c | sort -nr | head -20