Genx

Genx is a fast alternative domain name generator to help in generating potential subdomains of a target. Useful when starting recon on a domain.

Objectives of genx

Be a general purpose subdomain generation tool
Can generate large amounts of data very efficiently
Be as fast as possible
Allow for an array of cli commands
Have all the capabilities of altdns (great tool) and more
Finally: simply practice Rust

Compilation

To compile run:

A Makefile has been created so you can simply run:

make

Otherwise, compile manually:

rustc -O genx.rs

To cleanup:

make clean

Usage

./genx <domains> <wordlist.txt> <out_file> [-g]

Speed comparaison

This part contains speed comparaisons between genx and it’s python and c equivalents.

Simple keyword to domain concatenation

Comparaison with the current version of genx which reads input from a file, and outputs the combined keyword+domain to a file or stdout.

Lets compare the speed with a python program aimed at the same task:

import sys
import string
#./combine.py domain wordlist.txt output.txt
domain = sys.argv[3]
with open(sys.argv[2], 'w') as out:
    with open(sys.argv[1]) as f:
            for line in f:
                    out.write("{}.{}".format(line.rstrip(),domain))

We start by generating a file (tmp.txt) with 10,000,000 lines of 8 chars each which we will pass to both programs. (See generator at other/speed-test/random-str.py for source-code)

We run the program as such:

python3 other/speed-test/random-str.py 10000000 > tmp.txt

For this test we will use the domain name “example.com”.

We use time to record the time it takes for the program to execute and we run the program 10 times to get an average execution time.

Python Script

We run the script as such:

time for i in {1..10}; do python other/speed-test/combine.py "example.com" tmp.txt /dev/null; done

and get the following times:

bash-3.2$ time for i in {1..10}; do python other/speed-test/combine.py "example.com" tmp.txt /dev/null; done
real    1m18.426s
user    1m17.457s
sys     0m0.637s

Genx

We run the script as such:

time for i in {1..10}; do ./genx "example.com" tmp.txt /dev/null; done

and get the following times:

bash-3.2$ time for i in {1..10}; do ./genx "example.com" tmp.txt /dev/null; done
real    0m20.861s
user    0m20.271s
sys     0m0.468s

Result

78.426/20.861 = 3.759

This results in 276% faster subdomain generation when using genx vs its python equivalent.

Domain text list to keyword concatenation

For this second test we will use the same tools as in the previous test except we will run this python script as comparaison:

import sys
import string
with open(sys.argv[1]) as domains:
    with open(sys.argv[3], 'w') as out:
        for domain in domains:
            tmp = domain.rstrip()
            with open(sys.argv[2]) as keywords:
                for keyword in keywords:
                    out.write("{}.{}\n".format(keyword.rstrip(),tmp))

We reduce the number of keywords to 1,000,000 and setup a file with 10 domains:

example1.com
example2.com
example3.com
example4.com
example5.com
example6.com
example7.com
example8.com
example9.com
example0.com

Python Script

We used this command to run the script:

time for i in {1..10}; do python other/speed-test/combine-list.py other/speed-test/domains.txt tmp.txt /dev/null; done

and got the following total time:

bash-3.2$ time for i in {1..10}; do python other/speed-test/combine-list.py other/speed-test/domains.txt tmp.txt /dev/null; done
real    1m21.109s
user    1m18.348s
sys     0m1.154s

C program

We used this command to run the program:

time for i in {1..10}; do ./other/speed-test/genc other/speed-test/domains.txt tmp.txt /dev/null; done

and got the following times:

bash-3.2$ time for i in {1..10}; do ./other/speed-test/genc other/speed-test/domains.txt tmp2.txt /dev/null; done
real    0m24.739s
user    0m23.589s
sys     0m0.750s

Genx

We used this command to run the program:

time for i in {1..10}; do ./genx other/speed-test/domains.txt tmp.txt /dev/null; done

and got the following times:

bash-3.2$ time for i in {1..10}; do ./genx other/speed-test/domains.txt tmp.txt /dev/null; done
real    0m21.099s
user    0m20.373s
sys     0m0.552s

Results

Genx outperformed both C and Python at the same task.

With an increase of 284% over its Python equivalent and 17.3% faster than the C version.