Who is hammering FTP on our server?
sudo grep “no such user”  /var/log/syslog | cut -d[ -f 3 | cut -d] -f 1 | sort | uniq -c | less
What firewall rules do we have in place?

sudo iptables –numeric  –line-numbers -L INPUT | less

How do we add to the rules immediately?
sudo iptables –insert INPUT 3 -s [...]