dnsbl-check.sh



    1 #!/usr/bin/env bash
    2 # Script to check if specified IP is on common known dns blacklists
    3 # Copyright (C) 2018  Aaron Ball <nullspoon@oper.io>
    4 # 
    5 # This program is free software: you can redistribute it and/or modify
    6 # it under the terms of the GNU General Public License as published by
    7 # the Free Software Foundation, either version 3 of the License, or
    8 # (at your option) any later version.
    9 # 
   10 # This program is distributed in the hope that it will be useful,
   11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   13 # GNU General Public License for more details.
   14 # 
   15 # You should have received a copy of the GNU General Public License
   16 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
   17 
   18 # Default to opendns main nameserver if the NS variable isn't set
   19 export NS=${NS:-208.67.220.220}
   20 
   21 # Pertinent color escape sequences
   22 export CGREEN=$'\e[32m'
   23 export CRED=$'\e[31m'
   24 export CRESET=$'\e[0m'
   25 
   26 export LIST=${LIST:-dnsbls.txt}
   27 
   28 # is_ipv4:
   29 # Checks if the provided string is a valid IPv4 address.
   30 #
   31 # @str   String to check
   32 # @return (stdout) 1 == valid ip, 0 == invalid ip
   33 is_ipv4() {
   34   local str="${1}"
   35   local match
   36   match=$(printf "${str}" | grep -E '^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$')
   37   if [ "${match}" = "${str}" ]; then
   38     printf 1
   39     return 0;
   40   fi
   41   printf 0;
   42   return 1;
   43 }
   44 
   45 
   46 # main:
   47 # Ye olde' main.
   48 #
   49 # @ip   IP address to check for blacklist
   50 main() {
   51   local ip="${1}" # IP address to check for blacklisting
   52   local rev       # IP address, reversed for dns lookup (dig)
   53   local resp      # Response from dns query
   54   local dnsbls    # Array of dns blacklist endpoints
   55   local found     # Number of times the ip was found in blacklists
   56 
   57   if [ -z "${ip}" ]; then
   58     printf "IP address required\n"
   59     return 1
   60   fi
   61 
   62   if [ ! -f "${LIST}" ]; then
   63     printf "ERROR: DNSBL manifest '%s' not accessible.\n" "${LIST}"
   64     printf "Please set LIST environment variable to file that exists\n"
   65     return 1
   66   else
   67     dnsbls=($(grep -v '^#' "${LIST}"))
   68   fi
   69 
   70   if [ $(is_ipv4 "${ip}") = 0 ]; then
   71     printf "Provided IP '%s' is not a valid IPv4 address\n" "${ip}"
   72     return 1
   73   fi
   74 
   75   # If the terminal is not a char terminal (eg: someone is using less, more,
   76   # cat, etc), we don't want to print escape codes because they will get
   77   # mangled by the tool most likely.
   78   if [ ! -t 1 ]; then
   79     unset CGREEN
   80     unset CRED
   81     unset CRESET
   82   fi
   83 
   84   # Reverse the ip address
   85   rev=$(printf '%s.' "${ip}" | tac -s.)
   86 
   87   # Some basic information
   88   printf "Checking %s\n" "${ip}"
   89   printf "Reverse DNS: %s\n\n" "$(dig @${NS} +short -x ${ip})"
   90 
   91   found=0
   92   for bl in ${dnsbls[@]}; do
   93     # I can dig it
   94     resp="$(dig @${NS} +short -t a ${rev}${bl})"
   95     printf "%-25s: " "${bl}"
   96     if [ -z "${resp}" ]; then
   97       printf "%bNot found%b\n" "${CGREEN}" "${CRESET}"
   98     else
   99       printf "%bFound%b\n" "${CRED}" "${CRESET}"
  100       found=$((found + 1))
  101     fi
  102   done
  103 
  104   printf "\nFound %s on %d lists\n" "${ip}" "${found}"
  105 }
  106 
  107 main ${@}