#!/bin/bash

####################################################
# blockauth: block auth connections using iptables #
# Author: q3aql@duck.com <q3aql>                   #
# License: GPL v2.0                                #
####################################################

# Check if process have root permissions
mkdir -p /etc/root &> /dev/null
administrador=$?
if [ ${administrador} -eq 0 ] ; then
  rm -rf /etc/root
else
  echo "blockauth: root permissions are required"
  exit
fi

# Check dependencies
path_check="/usr/bin /bin /usr/local/bin /sbin ${HOME}/.local/bin"
dependencies="iptables cat grep sort sed rm echo systemctl"
dependencies_found=""
dependencies_not_found=""
for checkPath in ${path_check} ; do
  for checkDependencies in ${dependencies} ; do
    if [ -f ${checkPath}/${checkDependencies} ] ; then
      dependencies_found="${dependencies_found} ${checkDependencies}"
    fi
  done
done
for notFound in ${dependencies} ; do
  check_found_one=$(echo ${dependencies_found} | grep " ${notFound}")
  check_found_two=$(echo ${dependencies_found} | grep "${notFound} ")
  if_not_found="${check_found_one}${check_found_two}"
  if [ -z "${if_not_found}" ] ; then
    dependencies_not_found="${dependencies_not_found} ${notFound}"
  fi
done
# Show if all dependencies are installed
if [ -z "${dependencies_not_found}" ] ; then
  echo > /dev/null
else
  echo "blockauth: some required tools are not installed:${dependencies_not_found}"
  echo "blockauth: process stopped"
  exit
fi

# Function for reduce log
function reduce_log() {
  if [ -z "${1}" ] ; then
    echo "blockauth: use: $0 <file.log>"
  else
    if [ -f "${1}" ] ; then
    num_tmp=${RANDOM}
    tail -4000 "${1}" > "${num_tmp}.tmp"
    cat "${num_tmp}.tmp" > "${1}"
    rm -rf "${num_tmp}.tmp"
    else
      echo "blockauth: file ${1} does not exist"
    fi
  fi
}

# Check auth.log
if [ ! -f /var/log/auth.log ] ; then
  echo "blockauth: file /var/log/auth.log does no exist"
  echo "blockauth: process stopped"
  exit
fi

# Read configuration file
if [ -f /etc/blockauth/blockauth.conf ] ; then
  source /etc/blockauth/blockauth.conf
else
  mkdir -p /etc/blockauth/
  echo "# Blockauth configuration file" > /etc/blockauth/blockauth.conf
  echo "valid_users=\"test1 test2\"" >> /etc/blockauth/blockauth.conf
  echo "always_ip_allowed=\"192.168.0.1 192.168.0.2\"" >> /etc/blockauth/blockauth.conf
  echo "blocklist=\"/etc/blockauth/blocklist.list\"" >> /etc/blockauth/blockauth.conf
  echo "filelog=\"/etc/blockauth/blockauth.log\"" >> /etc/blockauth/blockauth.conf
  echo "max_ip_blocklist=\"12500\"" >> /etc/blockauth/blockauth.conf
fi

# Check integrity of configuration file
if [ -z "${valid_users}" ] ; then
  echo "valid_users=\"test1 test2\"" >> /etc/blockauth/blockauth.conf
fi
if [ -z "${always_ip_allowed}" ] ; then
  echo "always_ip_allowed=\"192.168.0.1 192.168.0.2\"" >> /etc/blockauth/blockauth.conf
fi
if [ -z "${blocklist}" ] ; then
  echo "blocklist=\"/etc/blockauth/blocklist.list\"" >> /etc/blockauth/blockauth.conf
fi
if [ -z "${filelog}" ] ; then
  echo "filelog=\"/etc/blockauth/blockauth.log\"" >> /etc/blockauth/blockauth.conf
fi
if [ -z "${max_ip_blocklist}" ] ; then
  echo "max_ip_blocklist=\"12500\"" >> /etc/blockauth/blockauth.conf
fi
source /etc/blockauth/blockauth.conf

# Force edit configuration file
if [ "${valid_users}" == "test1 test2" ] ; then
  echo "blockauth: you must first configure the file /etc/blockauth/blockauth.conf"
  echo "blockauth: process stopped"
  exit
fi

echo "blockauth: running process"
blockauth=0
while [ ${blockauth} -eq 0 ] ; do
  sleep 60
  # Read auth.log file and select blocked IPs
  for user in ${valid_users} ; do
    echo "blockauth: allowing access for ${user}" 
    echo "blockauth: allowing access for ${user}" >> ${filelog} 
    sed -i "s/Failed password for ${user} from/blockauth\[allowed\]\: invalid pass for ${user} from/g" /var/log/auth.log
    sed -i "s/Failed password for invalid user ${user} from/blockauth\[allowed\]\: invalid pass for ${user} from/g" /var/log/auth.log
    systemctl restart rsyslog &> /dev/null
  done
  touch ${blocklist}
  cat ${blocklist} > ${blocklist}.temp
  echo "blockauth: creating blocklist"
  echo "blockauth: creating blocklist" >> ${filelog}
  cat /var/log/auth.log | grep "Failed password for" | grep -o -P '(?<=from).*(?=port)' >> ${blocklist}.temp
  sort -u ${blocklist}.temp > ${blocklist}
  rm -rf ${blocklist}.temp
  sed -i 's/Failed password for/blockauth\[blocked\]\: invalid pass for/g' /var/log/auth.log

  # Exclude allowed IPs
  if [ -z "${always_ip_allowed}" ] ; then
    echo "blockauth: running exclude allowed ips"
    echo "blockauth: running exclude allowed ips" >> ${filelog}
  else
    echo "blockauth: running exclude allowed ips"
    echo "blockauth: running exclude allowed ips" >> ${filelog}
    for allowed_ip in ${always_ip_allowed} ; do
      echo "blockauth: allowing ip ${allowed_ip}"
      echo "blockauth: allowing ip ${allowed_ip}" >> ${filelog}
      sed -i "/${allowed_ip}/d" ${blocklist}
    done
  fi

  # Block IPs using iptables
  for block_ip in $(cat ${blocklist}) ; do
    read_block_ip=$(iptables -n -L | grep "${block_ip}")
    if [ -z "${read_block_ip}" ] ; then
      echo "blockauth: blocking ip ${block_ip}"
      echo "blockauth: blocking ip ${block_ip}" >> ${filelog}
      iptables -A INPUT -d ${block_ip} -j DROP
      iptables -A OUTPUT -d ${block_ip} -j DROP
    fi
  done

  # Reduce log
  reduce_log ${filelog}
done