SSH to prevent brute force shell script

This is my first shell Script, write chaos, experiment, or is available, and now on my own Web server running up!! ~~

#!/bin/bash# this shell script  to prevent SSH brute force hack #auther:aaron guo#date:jan 8 2016#version:1.2#   Specifies the shell's log file logfile= "/var/log/blocked_ip" #  gets the current time, used for grep /var/log/secure.  (format: MM DD  HH) timenow=$ (date  ' +%b %e %h ') #  if 20 connections fail within the current hour, record rootip=$ (grep  "$timenow"  /var/log/secure|grep root.*because|awk  ' {print $9} ' |sort|uniq -c|sed s/[\. [a-za-z].*//g|awk  ' $1>20 {print $1 ":" $ $} ') anyip=$ (grep  "$timenow"  /var/log/secure| grep invalid| awk  ' {print $10} ' |sort|uniq -c|sed s/[\. [a-za-z].*//g|awk  ' $1>20 {print $1 ":" $ $} ') #  add hack root password to iptablesfor i in   $rootipdoip =$ (echo  $i |awk -f:  ' {print $2} ') #  check if an attacker's IP is present in Iptables no .         iptables-save|grep INPUT|grep DROP|grep  "$ip" >/dev/null#   If not present (that is, the previous command execution error, the variable $? > 0 ), then add to iptables.        if [ $? -gt 0 ];  then                 iptables -a input -s  "$ip"  -p tcp --dport 22 -j DROP                 now=$ (date  ' +% Y-%m-%d %h:%m ') # add to log file.                 echo -e  "$now  :  $ip"  >> $ logfile        fidone#  add those who try the name of the user to iptables.for i   in  $anyipdoip =$ (echo  $i |awk -f:  ' {print $2} ') # check crackers ip  exist or not.        iptables-save|grep input| grep drop|grep  "$ip" >/dev/null# do not exist , add to iptables.         if [ $? -gt 0 ]; then                 iptables -A INPUT -s  "$ip"  -p tcp --dport 22 -j DROP                 now=$ (date  ' +%y-%m-%d %h:%m ') # add to log  file.                 echo -e  "$now  :  $ip"  >>  $logfile          fidone

Finally add the script executable (x) permissions, and then add to/etc/crontab, I set the execution every 10 minutes (*/10)

# for details see Mans 4 crontabs# Example of Job definition:#.----------------minute (0-59) # |  .-------------Hour (0-23) # |  |  .----------Day of Month (1-31) # |  |  |  .-------month (1-12) OR jan,feb,mar,apr ... # |  |  |  |  .----Day of Week (0-6) (sunday=0 or 7) or sun,mon,tue,wed,thu,fri,sat# |  |  |  | |# * * * * * user-name command to be executed */10 * * * * root/root/blockip.sh

If there are errors, please correct me!!

This article is from "Lao Guo's Journal" blog, please be sure to keep this source http://laoguo.blog.51cto.com/11119466/1735478

SSH to prevent brute force shell script