Scott at 17:41, 31 January 2011

2011-01-31T17:41:32Z

New page

<source lang="bash">
#!/bin/bash
# find all known dns entries for a class C subnet
# subnet (e.g. 123.45.67)
subnet=123.45.67
host=/usr/bin/host
if [[ $host == "" ]]; then
echo "host program not found"
echo "aborting..."
exit 1
fi
if [[ ! -x $host ]]; then
echo "host program $host not executable"
echo "aborting..."
exit 1
fi

echo "Known DNS entries for subnet $subnet on `date`"

# main loop
for (( i=1; i <= 254; i++))
do
ip=${subnet}.$i
output=`$host $ip 2> /dev/null`
#echo "output is \"$output\""
notfound=`echo $output | grep "not found"`
if [[ -z $notfound ]]; then
hostname=`echo $output | awk '{print $5}'`
echo -e "${ip}\t${hostname}"
fi
done

exit 0
</source>

Dns subnet - Revision history

Scott at 17:41, 31 January 2011