Bash script to list all IPs in prefix

Question

I\'m trying to create script that I can input a set of prefixes, which will then list all IP addresses within the prefixes (including network/host/broadcast).

An ex

Answer 1

This script should do. It's (almost) pure Bash. The seq part can be replaced if a completely pure bash is required.

Since Bash apparently uses signed two-complement 4-byte integers, the script is limited to /8 mask maximum. I found ranges larger than /16 impractical anyway so this doesn't bother me at all. If someone knows a simple way to overcome this, please share :)

#!/usr/bin/env bash

base=${1%/*}
masksize=${1#*/}

[ $masksize -lt 8 ] && { echo "Max range is /8."; exit 1;}

mask=$(( 0xFFFFFFFF << (32 - $masksize) ))

IFS=. read a b c d <<< $base

ip=$(( ($b << 16) + ($c << 8) + $d ))

ipstart=$(( $ip & $mask ))
ipend=$(( ($ipstart | ~$mask ) & 0x7FFFFFFF ))

seq $ipstart $ipend | while read i; do
    echo $a.$(( ($i & 0xFF0000) >> 16 )).$(( ($i & 0xFF00) >> 8 )).$(( $i & 0x00FF ))
done 

Usage:

./script.sh 192.168.13.55/22

Tested with Bash version 4.4.23. YMMV.