harden-sshd

harden-sshd.sh

#!/bin/bash
if [ $UID -ne 0 ]; then
  echo "root only"
  exit 1
fi

restart=0
for i in $(grep "Failed password" /var/log/secure | grep -oE '((1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])\.){3}(1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])' | uniq)
do
  if [ `grep -c " $i\$" /etc/hosts.deny` -eq 0 ]; then
    echo "sshd: $i" >> /etc/hosts.deny
    echo "Added $i"
    restart=1
  fi
done

if [ $restart -gt 0 ]; then
  service sshd restart
fi