IP Abuse Detection for DreamHost

Alot of people have asked me about the best way to block specific IP addresses that are attacking their servers. No easy answer for sure. Here's what I came up with.

Per-domain Error.log and Access.log checks

This shell script analyzes a specific domains apache logs, both error and access, and then finds the IP address that hit your server the most. Then it checks for a a reverse DNS for each of the IP addresses, if it doesn't have a reverse DNS, AND it results in a positive to one of the 3 other tests its added to a bad IP list.

Generates .htaccess blocking code

Once the tests have concluded (on my machine it takes maybe 5 minutes) you have the choice to view an automatically generated .htaccess file that you can copy into your real .htaccess file, full of the correct code to Block the bad IP's. You can tell them bye bye with a 403 Forbidden.

IP Abuse / .htaccess Blocking Script

#!/bin/sh

# User-contributed script. Not sponsored by DreamHost.
# Script created 2008-01-16 by AskApache (www.askapache.com)


### SHELL OPTIONS
set +o noclobber  # allowed to clobber files
set +o noglob     # globbing on
set +o xtrace     # change to - to enable tracing
set +o verbose    # change to - to enable verbose debugging
set -e            # abort on first error


# directory where log files, reports, and generated .htaccess files will be saved
TMPDI="$HOME/ip_abuse"




function exitt(){
 case $TERM in
  xterm*|vt*|ansi|rxvt|gnome*) echo -e "33]0;$USER@`hostname`: $HOME07" ;;
 esac
}

function ok_continue()
{ echo -en "n33[?25l33[30;42m[ Press any key to continue ]33[0mn" ;read -n 1 ans;echo -en "33[?25h"; }

function test_title()
{ echo -en "nn33[0;32mn>>>"; echo -e "33[1;37m $1 33[0m n"; echo -e "nn[ ${1} ]n" >> $REPORT; }


function error_abuse(){
 clear; title
 case "$2" in
  connlimit|1*) test_title "CONCURRENT CONNECTION TEST"; future=2
   echo -e "Shows IP's making more than 20 requests concurrently.nn"
   cat $TMPDI/$YD/logs/e* |grep 'concurrent connection limit'|awk -F ']' '{print $3}' |
   awk '{print $2}'|sort|uniq -c |sort -nr|sed 's/^ *//'|egrep "[0-9]{2}+ " > $TMPDI/$YD/logs/out.txt ;;
  access|2*) test_title "TOP 50 IP TEST"; future=3
   echo -e "Displays the top 50 unique IP addresses that access your site."
   echo -e "If they don't have a reverse DNS maybe they should be blocked.nn"
   cat $TMPDI/$YD/logs/a* |awk '{print $1|"sort|uniq -dc|sort -nr"}' |egrep "[0-9]{3}+ "|
   awk '{print $1,$2}' > $TMPDI/$YD/logs/out.txt ;;
  internal|3*) test_title "INTERNAL RECURSION TEST"; future="report"
   echo -e "Shows the IP's that triggered an Internal Recursion Error,"
   echo -e "meaning that their is a looping problem on your server.n"
   cat $TMPDI/$YD/logs/e* |grep 'LimitInternalRecursion'|awk -F ']' '{print $3}'|awk '{print $2}' |
  sort|uniq -c|sort -nr|sed 's/^ *//'|egrep "[0-9]{2}+ " > $TMPDI/$YD/logs/out.txt ;;
 esac

 echo -e "33[?25l";t=0; h=0; cat $TMPDI/$YD/logs/out.txt |
 while read a
 do
 if [ $t -lt 50 ];then
  n=`echo "$a"|awk '{print $1}'`; ip=`echo "$a"|awk '{print $2}'`
  host=`nice -n 19 host -qQ -s 1 "${ip}" 2>&1|tr 'n' 't'|awk '{print $2}'`;
  case "$host" in
   does) echo -en "33[0;33m"; echo -e "$ip" >> $REPORT
    host=${host/does/!!!POSSIBLE-ABUSE!!!}; (( t++ )); (( h++ )); ips=" $ip$ips" ;;
   not) echo -en "33[0;33m"; echo -e "$ip" >> $REPORT
    host=${host/not/!!!POSSIBLE-ABUSE!!!}; (( t++ )); (( h++ )); ips=" $ip$ips" ;;
   PTR) echo -en "33[0;33m"; echo -e "$ip" >> $REPORT
    host=${host/PTR/!!!POSSIBLE-ABUSE!!!}; (( t++ )); (( h++ )); ips=" $ip$ips" ;;
   .) echo -en "33[0;33m"; echo -e "$ip" >> $REPORT
    host=${host/./!!!POSSIBLE-ABUSE!!!}; (( t++ )); (( h++ )); ips=" $ip$ips" ;;
  esac
  echo -en " ${n}t${ip}t${host}33[0mn"
  if [ $h -gt 3 ]; then
  echo -e "Deny from$ips" >> $TMPDI/$YD/.htaccess; h=0; ips=" ";
  fi
fi
done
[ $h -gt 0 ] && echo -e "Deny from$ips" >> $TMPDI/$YD/.htaccess
ok_continue; exec sh $0 "$1" "$future"
}





function menu(){
 PS3="`echo -e '33[0;36m'`Please Select a Domain To Test: `echo -e '33[0m'`"; echo -ne "33[0m"
 select v
 do
  YD="$v"
  mkdir -p -m 0755 $TMPDI/$YD/reports
  mkdir -p -m 0755 $TMPDI/$YD/logs
  echo "" > $TMPDI/$YD/logs/out.txt
  echo "" > $TMPDI/$YD/.htaccess
  echo -e "## IP-ABUSE-LOOKUPnOrder Allow,DenynAllow from All" > $TMPDI/$YD/.htaccess
  ELOG="$TMPDI/$YD/logs/error.log"
  ALOG="$TMPDI/$YD/logs/access.log"
  REPORT=$(echo -en "$TMPDI/$YD/reports/`date +%mx%dx%y`.txt");
  echo "" > $REPORT; echo -e "GENERATED REPORT FOR $YD n`date`n" >> $REPORT
  clear; title; cd ~/logs/$YD/http
  if [ ! -f $ELOG ]; then
   test_title "Creating Error log"
   `nice -n 19 gunzip -dc e*.gz | split -b 1m -a 4 -d - $TMPDI/$YD/logs/e.`; wait
   cp error.log $TMPDI/$YD/logs; echo -e "33[0;31m [ DONE ]nn"
  fi
  if [ ! -f $ALOG ]; then
   test_title "Creating access log"
   `nice -n 19 gunzip -dc a*.gz | split -b 5m -a 4 -d - $TMPDI/$YD/logs/a.`; wait
   cp access.log $TMPDI/$YD/logs; echo -e "33[0;31m [ DONE ]nn"
  fi
  cd $HOME; exec sh $0 "$YD" "1"
 done
}

function show_report(){
 clear; title;
 PS3="`echo -e '33[0;36m'`Please select a course of action: `echo -e '33[0m'`"; echo -ne "33[0m"
 select v in "View Report" "View .htaccess" "Quit"
 do
  case "$v" in
   *Report) clear; title; test_title "VIEWING $REPORT"; cat $REPORT ;;
   *htaccess) clear; title; test_title "VIEWING $TMPDI/$YD/.htaccess"; cat $TMPDI/$YD/.htaccess ;;
   Quit) break;;
  esac
 done
exit 0
}

function title(){
 # pretty sweet!
 echo -e "33[1;30m __________________________________________________________________________ "
 echo -e "|33[1;32m                 ___                     __ __         __                 33[1;30m|"
 echo -e "|33[1;32m                / _ _______ ___ ___ _  / // /__  ___ / /_                33[1;30m|"
 echo -e '|33[1;32m               / // / __/ -_) _ `/  ` / _  / _ (_-

Read more on the DreamHost wiki page: Block IP Abuse.