python subprocess issue with Nmap

Question

Im trying to get a linux binary to send its standard output to a variable by using subprocess. But just keep getting tracebacks.

>>> import subprocess
>>>nmap -sn -Pn todd.ns.cloudflare.com --script dns-check-zone --script-args='dns-check-zone.domain=www.macmonster.com

Any Ideas (oh and Im using Python2.7).

Ideally I would like to avoid using Shell=true to avoid any security concerns.

Thanks,

Answer 1

shlex to the rescue!

The module shlex will take a string containing the whole shell command and split it up exactly how Popen and check_output expect it. Like this:

import shlex, subprocess
cmd = "/usr/bin/nmap -sn -Pn todd.ns.cloudflare.com --script dns-check-zone --script-args='dns-check-zone.domain=www.macmonster.com'"
args = shlex.split(cmd)
output = subprocess.check_output(args)

When you look at contents of args you'll see:

>>> print args
['/usr/bin/nmap', '-sn', '-Pn', 'todd.ns.cloudflare.com', '--script', 'dns-check-zone', '--script-args=dns-check-zone.domain=www.macmonster.com']

Note that shlex split up the option "--script dns-check-zone" into two tokens. On the other hand it kept "--script-args='dns-check-zone.domain=www.macmonster.com'", but removed the single-quotes.

Answer 2

import subprocess
output = subprocess.check_output(["/usr/bin/nmap", "-sP", "-n", "172.16.1.0/24"])

output = subprocess.check_output(["/usr/bin/nmap", "-sP", "-n", "172.16.1.0/24"], stderr=subprocess.STDOUT)

Answer 3

Have you tried this:

p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
var = p.stdout.read()
print var

I would have used communicate, but it returns an odd list-type thing.