Crontab entry to check for bad actors attempting 100+ incorrect password attempts in a day from a given IP address and ban that IP address from trying to connect to the server

crontab

# Continuously check for bad actors and ban them!
0 */2 * * * zgrep "Failed password for root from"  /var/log/auth.log | sed "s_.*Failed password for root from \([0-9][^ ]*\).*_\1_"  | sort | uniq -c  | sort -n |  while read x ; do export IP=`echo $x | sed 's_^[ ]*[0-9]* \([0-9].*\)_\1_'`; export TEST=`echo $x | sed 's_^[ ]*\([0-9]*\) [0-9].*_\1_'`; test $TEST -gt 100 && (grep -qxF "ALL: $IP" /etc/hosts.deny || sudo bash -c "echo 'ALL: $IP' >> /etc/hosts.deny ")   ; done