Some important netstat commands.

Sort by IP count

netstat -ntu | awk ' $5 ~ /^[0-9]/ {print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

12 164.68.xx.xx   
15 222.186.xx.xx   
18 87.76.xx.xx   
22 112.85.xx.xx   
25 173.249.xx.xx   
23 87.76.xx.xx   
10 208.86.xx.xx

Sort by Uniq IP

[arunlal@lintechops ~]# netstat -ntu | awk ' $5 ~ /^[0-9]/ {print $5}' | cut -d: -f1 | sort -u
 112.85.xx.xx
 173.249.xx.xx
 173.249.xx.xx
 208.86.xx.xx
 72.44.xx.xx
 87.76.xx.xx

List number of different connection types:

[arunlal@lintechops ~]# netstat -ant | awk '{print $6}' | sort | uniq -c | sort -n
       1 established)
       1 Foreign
       1 TIME_WAIT
       4 LISTEN
      19 ESTABLISHED