Quick check for a ddos via number of connections

A quick and usefull command for checking if a server is under ddos is:

netstat -anp |grep 'tcp\|udp' | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

That will list the IPs taking the most amount of connections to a server. It is important to

remember that the ddos is becoming more sophistcated and they are using fewer

connections with more attacking ips. If this is the case you will still get low number of

connections even while you are under a DDOS.