[SOLVED] Ip scanner script no worky work

NSH · 04-11-2022, 06:59 AM

Hi
I'm trying to understand why this bash script
<CODE>

#!/bin/bash

is_alive_ping()
{
ping -c 1 $1 > /dev/null
[ $? -eq 0 ] && echo Node with IP: $i is up.
}

for i in 192.168.2.{1..255}
do
is_alive_ping $i & disown
done
exit

</CODE>

dosn't return anything as it does in the the tutorial

<link> https://duckduckgo.com/?q=bash+scrip...%3DGtovwKDemnI </link>
at 1:00:00

Don't understand ip protocols that well.

michaelk · 04-11-2022, 07:50 AM

I did not watch the video.

What is your LAN IP address network? You can find out by looking at the output of the command:
ip a

Under the section starting with 2: like

Code:

2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:d9:b9:26 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.224/24 brd 192.168.1.255

The IP address is 192.168.1.244 and the network is 192.168.1.1 - 192.168.1.255, the loop should be

Code:

for i in 192.168.1.{1..254}

192.168.1.255 is the broadcast address and not assigned to a device. If yours is not /24 you can search for a IPv4 calculator to figure out your subnet. If it is an IPv6 address then the script needs to be changed a bit.

NSH · 04-11-2022, 11:36 AM

Cool! find an inet adress starting with 100. Thank you.

michaelk · 04-11-2022, 12:27 PM

Quote:

inet 100.xx.xx.xx/21

Your IP address is 100.xx.xx.xx with a 21 subnet which means the valid IP addresses are:
100.xx.xx.1 - 100.xx.xx.254 for a possible number of 2046 hosts.

One way to iterate the entire range would be to use two loops.

Code:

for x in 100.xx.{xx..yy}; do
  for y in {0..255}; do

  done
done

Using the loops as posted will ping some invalid addresses but it is the quickest. I did not watch the video and I'm not sure what the ultimate goal you are trying to achieve but some devices are configured to ignore icmp requests and I would be annoyed if I discovered someone trying to constantly ping me on my network.