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 short script will print all the IP addresses in a CIDR range in a few lines of Bash. (I named it prips after the Ubuntu command of the same name. Obviously, if that command is available, use that.)

prips() {
  local cidr=$1 ; local lo hi a b c d e f g h

  # range is bounded by network (-n) & broadcast (-b) addresses.
  lo=$(ipcalc -n "$cidr" | cut -f2 -d=)
  hi=$(ipcalc -b "$cidr" | cut -f2 -d=)

  IFS=. read -r a b c d <<< "$lo"
  IFS=. read -r e f g h <<< "$hi"

  eval "echo {$a..$e}.{$b..$f}.{$c..$g}.{$d..$h}"
}

Note that I assume the RedHat Linux (Erik Troan, Preston Brown) version of ipcalc, not the Krischan Jodies version that is installed on some platforms (e.g. Mac OS X).

Examples:

$ prips 10.0.0.128/27
10.0.0.128 10.0.0.129 10.0.0.130 10.0.0.131 10.0.0.132 10.0.0.133 10.0.0.134 10.0.0.135 10.0.0.136 10.0.0.137 10.0.0.138 10.0.0.139 10.0.0.140 10.0.0.141 10.0.0.142 10.0.0.143 10.0.0.144 10.0.0.145 10.0.0.146 10.0.0.147 10.0.0.148 10.0.0.149 10.0.0.150 10.0.0.151 10.0.0.152 10.0.0.153 10.0.0.154 10.0.0.155 10.0.0.156 10.0.0.157 10.0.0.158 10.0.0.159

Calculates correct number of addresses in a /23 networks:

$ prips 10.0.0.0/23 | wc -w 
512

Inspecting a few of those addresses using cut:

$ prips 10.0.0.0/23 | cut -f1-10,256-266 -d' '
10.0.0.0 10.0.0.1 10.0.0.2 10.0.0.3 10.0.0.4 10.0.0.5 10.0.0.6 10.0.0.7 10.0.0.8 10.0.0.9 10.0.0.255 10.0.1.0 10.0.1.1 10.0.1.2 10.0.1.3 10.0.1.4 10.0.1.5 10.0.1.6 10.0.1.7 10.0.1.8 10.0.1.9

And maybe too slow but also correctly generates the 16 million addresses in a /8 network:

$ date ; prips 10.0.0.0/8 | wc -w ; date 
Sat May 20 18:06:00 AEST 2017
16777216
Sat May 20 18:06:41 AEST 2017