netcat script to send a message to a marquee device

Question

I wrote a script that uses netcat to update the marquee in my office without knowing the ip address of the device. I used fping to calculate candidateIPs.

The script works. But, I still don't know the IP address of the device. Can someone help me understand how to update the script to narrow down the IP address that updated the text on the device?

#!/bin/bash

while read p; do
   echo "try $p"
   echo "\x00\x00\x00\x00\x00\x01\x5A\x30\x30\x02\x41\x41\x1B\x22\x61 Test message!\x04" | nc $p 3001 &
done < candidateIPs

wait

Answer 1

You can log your outputs an add verbosity e.g.

#!/bin/bash

while read p; do
   echo "try $p"
   echo "\x00\x00\x00\x00\x00\x01\x5A\x30\x30\x02\x41\x41\x1B\x22\x61 Test message!\x04" | nc -v "$p" 3001 2>&1 | tee "$p.log" &
done < candidateIPs

wait

You can examine either the ip-specific log files after that.