Python subprocess nmap output different from terminal command

Question

I'm trying to use the output of nmap command in linux (shell output):

sudo nmap -sn 192.168.1.0/24
------
Nmap scan report for 192.168.1.98
Host is up (0.094s latency).
MAC Address: B8:27:EB:CE:0A:9F (Raspberry Pi Foundation)

In a python script via subprocess:

import subprocess
p = subprocess.Popen(["nmap", "-sn", "192.168.1.0/24"], stdout=subprocess.PIPE)
output, err = p.communicate()
print ("*** Running nmap -sn 192.168.1.0/24 ***\n", output)

Which works pretty well except from the fact that I NEED the MAC line that shell output has and subprocess doesn't.

subprocess output:

\nNmap scan report for 192.168.1.98\nHost is up (0.015s latency).\n

I'm working on an idea of getting IP via MAC/Name and I can't see how to do it without that line...

I don't think it's writing to stderr. Have you tried prefixing with sudo? Although, using a package is a better approach. — edd
– edd, Commented Jul 9, 2020 at 14:48

mama · Accepted Answer · 2020-07-10 09:05:29Z

1

You don't need to run nmap as a subprocess in python, You can just install the nmap library and import it.

pip install python-nmap

Then write your code:

import json
import nmap

np = nmap.PortScanner()

target = '192.168.1.0/24'

# Scan the subnet 
results = np.scan(hosts=target, arguments='-sn')

# Clean the data nmap returns
results = results['scan']
output = {}
for result in results:
    output[result] = {}
    # Add the MAC addr to the IP
    try:
        output[result]['mac']       = results[result]['addresses']['mac']
    except:
        output[result]['mac']       = 'No MAC address avalible'
    # Add the vendor to the IP
    try:
        output[result]['vendor']    = list(results[result]['vendor'].values())[0]
    except:
        output[result]['vendor']    = 'No vendor info avalible'

print(json.dumps(output,indent=2))

When you run your code you have to run it as sudo or else you wont get the MAC addresses.

Output should look like this

{
  "192.168.1.1": {
    "mac": "16:91:82:xx:xx:xx",
    "vendor": "No vendor info avalible"
  },
  "192.168.1.10": {
    "mac": "44:39:C4:xx:xx:xx",
    "vendor": "Universal Global Scientific Industrial"
  },
  "192.168.1.50": {
    "mac": "No MAC address avalible",
    "vendor": "No vendor info avalible"
  }
}

I hope it was helpful :-)

edited Jul 10, 2020 at 9:05

answered Jul 9, 2020 at 14:45

mama

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6 Comments

Daniziz Over a year ago

Thanks @Mama. I was messing around with "python-nmap" version but it didn't solve my problem (Or I didn't figure how to solve it). I've used this version with this method nmap = nmap3.NmapHostDiscovery() results = nmap.nmap_no_portscan("192.168.1.0/24") The output works, but it does not gives me MAC addres or names, just IP and status.

Daniziz Over a year ago

This is the output:{'state': 'up', 'reason': 'conn-refused', 'reason_ttl': '0', 'addr': '192.168.1.98', 'addrtype': 'ipv4'} I need MAC and name in order to see IP Owners... maybe it's about conn-refused?

Daniziz Over a year ago

If I run my script as "sudo" I get this error:

[sudo] password for daniziz:  Traceback (most recent call last):   File "nmap_rb.py", line 2, in <module>     import nmap ModuleNotFoundError: No module named 'nmap'

Daniziz Over a year ago

Ok, I've done it with sudo pip install python-nmap since if I don't install it with sudo privileges I cant run .py script with sudo. Im going to play with JSON format in order to get my vendors, but this is better way than subprocess option.

Daniziz Over a year ago

Here is my solution:

for result in results:         try:             # View to list and append               vendor = list(results[result]["vendor"].values())[0]             vendors_check.append(vendor)         except IndexError as E:             print("Element scan error, not adding to list and continuing...")

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