CODEWITHSUNDEEP
linuxbashawk
soccerman stan
soccerman stan

Reputation: 121

Bash - Script to get port ids

I am trying to write a bash script that will take port id I retrieve from an nmap command, and then use those ports to send a file using netcat. So I got some basic knowledge using this link,

https://superuser.com/questions/590038/how-can-i-use-a-bash-script-to-run-nmap-and-capture-both-ip-and-hostname

and nmap man page. As a result I came up with the following script:

#! /bin/bash

FILE="input.txt"
sudo nmap -p1-20000 -sS 192.168.122.35 -oG - | awk '$4=="Status:" && $5=="Up" {cat $FILE | nc $2 $6}'

So the issue I am having has to do with the $6. It is suppose to be the port numbers retrieved from the nmap command but it actually is nothing at all. I was wondering if you guys would be able to help me retrieve the port ids.

Upvotes: 0

Views: 549

Answers (1)

tripleee
tripleee

Reputation: 189936

Awk is a separate language, you can't just plonk in external commands.

A simple fix is to use Awk's system function:

awk -v FILE="$FILE" '$4=="Status:" && $5=="Up" {
  system("nc " $2  " " $6 "<\"" FILE "\"")}'

(notice also the refactoring to avoid the useless cat, and the assignment to make the shell's FILE variable visible to Awk as a variable).

But perhaps it makes more sense to reroll this into a shell script with Awk as just a simple helper:

#! /bin/bash

FILE="input.txt"
sudo nmap -p1-20000 -sS 192.168.122.35 -oG - |
awk '$4=="Status:" && $5=="Up" { print $2, $6 }' |
while read host port; do
    nc "$host" "$port" <"$FILE"
done

This also avoids the complex quoting inside the system call.

Upvotes: 1

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