random_scripts/check_ptr.sh

#!/bin/bash

# Test if any IP4 and IP6 addresses of a hostname blocked on a DNSBL
# 2024-02-23
# by Sandros

# Parameter check
if [[ $# -ne 1 ]]; then
    echo "Usage: ./${0##*/} <hostname>"
    exit 1
fi

DNS="84.2.44.1"

# Get IPs
IPS="$(dig +short $1 A @$DNS | sort -u) $(dig +short $1 AAAA @$DNS | sort -u)"

# Loop through IPs
fails=0
for IP in $IPS; do
        # Performs the actual lookup against blacklists
        RESULT=$(host $IP $DNS | tail -1 | rev | cut -d" " -f1 | rev | sed 's/.$//')
        if [ "$RESULT" != "$1" ]; then
                ((fails++))
        fi
done

echo $fails
exit 0