This shows the active connections on port 80 right now / within the timeout parameter.

netstat -tupan | grep 80
or
netstat -a -n | grep :80 | cut -d : -f2 | awk '{print $2}' | sort | uniq -c | sort 

Monitor open connections for httpd including listen, count and sort it per IP

watch "netstat -plan | grep -v LISTEN | grep \":80 \" | awk {'print \$5'} | cut -d: -f 1 | uniq -c | sort -nk 1"
tail -50000 access_log | awk '{print $1}' | sort | uniq -c | sort -n | tail

Check what linux distro you are running.

cat /etc/*-release