Extracting specific nmap output in bash

Question

I'm getting following nmap output from a scan:

PORT     STATE  SERVICE
113/tcp  closed ident
443/tcp  open   https
5060/tcp open   sip

I want to extract only open ports and save them into a variable while my script progress is below:

#!/bin/bash
echo Please enter your IP/domain address for nmap vulnerability scanning:
read IP
echo Your results against $ip will be output in sometime
nmap -sS -oG output.txt $ip

You can use --open to only show open ports – Raman Sailopal Feb 25 '21 at 09:11 — Raman Sailopal, Feb 25 '21 at 09:11

Ivan · Answer 1 · 2021-02-25T07:06:35.903

3

Grep them

nmap -sS -oG output.txt $ip | grep open

To store in var

open_ports=$(nmap -sS -oG output.txt $ip | grep open)
open_ports=${open_ports//[^0-9]/ } # remove text

Convert to an array

open_ports_arr=( $open_ports )

edited Feb 25 '21 at 07:06

answered Feb 25 '21 at 06:59

Ivan

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It is good except for your array variable, it is not how you fill an array. – Léa Gris Feb 25 '21 at 07:54
@LéaGris how should I? – Ivan Feb 25 '21 at 08:02
`mapfile -t arrayname < <(command)` or `IFS=$'\n' read -r -d '' -a arrayname < <(command)` (see my answer) – Léa Gris Feb 25 '21 at 08:17
Oh, yes `readarray` is certainly the right tool for creating arrays. I just like to keep it simple) – Ivan Feb 25 '21 at 08:36

score 2 · Answer 2 · answered Feb 25 '21 at 08:07

Here is how you can filter and extract open ports using awk and read the results into a bash array:

#!/usr/bin/env bash

# Read prompt ip address
read \
  -p 'Please enter your IP/domain address for nmap vulnerability scanning: ' \
  -r ip

# Print format info to user
printf 'Your results against %s will be output in sometime.\n' "$ip"

# Read the output of the nmap | awk commands into the ports array
IFS=$'\n' read -r -d '' -a ports < <(
  # Pipe the result of nmap to awk for processing
  nmap -sS -oG output.txt "$ip" |
    awk -F'/' '
      /[[:space:]]+open[[:space:]]+/{
        p[$1]++
      }
      END{
      for (k in p)
        print k
    }'
)

# If the resulting pors array is not empty iterate print format its content
if [ ${#ports[@]} -gt 0 ]; then
  printf 'List of open ports on host IP: %s\n' "$ip"
  for p in "${ports[@]}"; do
    printf '%d\n' "$p"
  done
fi

Why not just `nmap -sS -oG output.txt "$ip" | awk -F'/' '/open/{print $1}'`? — Ivan, Feb 25 '21 at 09:09
You can also use --open natively within nmap to show only open ports — Raman Sailopal, Feb 25 '21 at 09:11

Extracting specific nmap output in bash

2 Answers2