[REQUEST] Allow more than 1 dns resolver

[q2h1cg]

[REQUEST] Allow more than 1 dns resolver

[menzow]

I've been able to confirm that rate limiting indeed seems to be the issue. Using dnsblast it's easy to determine what the rate limits of a dns resolver is.

I've written a easy shell script that tries 10000 queries @ 1000 qps and outputs the stats. This helps checking a list of resolvers and find one with the lowest rate limit. I've shared it below incase it might help someone.

Save the following as scan.sh:

#!/bin/bash
IP=$1

TIMEOUT=3 # Timeout scan (in seconds). Lower for  faster results.
QUERIES=10000 # How many queries to send
QUERY_RATE=1000 # Queries per seconds

STATS=`timeout $TIMEOUT ~/misc/dnsblast/dnsblast $IP $QUERIES $QUERY_RATE 2>&1 | grep -E '^\S' | tail -n 1`

echo "$IP - $STATS"

Usage:

# Scan a single IP
$ ./scan.sh 8.8.8.8

# Check list of resolvers. Lower the amount of threads if you run out of buffer size.
$ cat resolvers.txt | parallel -j 4 './scan.sh {}'

[Q2h1Cg]

good job.

you can control the transmit rate with the parameter -rate, 10000 default. your ISP's dns server is better usually.

maybe I'll add a func to the program later.