Determining IP address range from Subnet/CIDR

Script to find the IP address range from the given Subnet.

There are few functions which can be reused like
  1. Convert IP to Decimal ip_to_int()
  2. Convert Decimal to IP int_to_ip()
  3. Netmask to CIDR to_cidr()

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#!/bin/bash # http://linuxcalling.blogspot.in/ # Script to find the IP address range # Script : ip_range # Usage : ip_range <IP> <Subnet> [0|1 print range] # Ahamed (ahamed.en@gmail.com) usage() { EXE=${0#*/} echo "Usage: $EXE <IP> <Subnet> [0|1]<print range>" echo " eg: To display the IP address range" echo " $EXE 192.168.1.1 255.255.140.0" echo " eg: To display the IP address range with entire range" echo " $EXE 192.168.1.1 255.255.140.0 1" exit } [ $# -lt 2 ] && usage echo $1 $2 $3 | awk ' BEGIN{ BITS=8 mask_add[0]=valid_subnet[0]=0 for(i=BITS-1;i>=0;i--){ k=or(k,lshift(1,i)) mask_add[k]=BITS-i valid_subnet[BITS-i]=k } } function validate_subnet(input) { split(input, oc, ".") if(oc[4] > oc[3] || oc[3] > oc[2] || oc[2] > oc[1]){ print "Invalid Subnet: ",input exit } for(j=1; j<=BITS/2; j++){ for(i=0;i<=BITS;i++){ if(!xor(oc[j],valid_subnet[i])){ break; } err++ } if(err == (BITS+1)){ print "Invalid Subnet: ",input exit } err=0 } } function to_cidr(input) { split(input, oc, ".") ret=mask_add[oc[1]]+mask_add[oc[2]]+mask_add[oc[3]]+mask_add[oc[4]] return ret } function ip_to_int(input) { split(input, oc, ".") ip_int=(oc[1]*(256^3))+(oc[2]*(256^2))+(oc[3]*(256))+(oc[4]) return ip_int } function int_to_ip(input) { str="" num=input for(i=3;i>=0;i--){ octet = int (num / (256 ^ i)) str= i==0?str octet:str octet "." num -= (octet * 256 ^ i) } return str } { ip=$1 mask=$2 range=$3 validate_subnet(mask) cidr=to_cidr(mask) diff=32-cidr no_of_ip=2^diff ip_int=ip_to_int(ip) ip_mask=and(ip_int, (2^32 - 2^diff)) ip_start=ip_mask ip_end=ip_mask+no_of_ip-1 print "No of IPs\t"(no_of_ip-2) print "First IP\t" int_to_ip(ip_start+1) print "Last IP\t\t" int_to_ip(ip_end-1) print "Subnet\t\t" int_to_ip(ip_mask) print "Broadcast\t" int_to_ip(ip_end) if(range){ print "\nIP address range -- START --\n" curr=ip_start i=0 while(curr<=ip_end){ printf int_to_ip(curr)"\t" if(j++%4 == 0) printf "\n" curr+=1 } print "\nIP address range -- END --" } } '

Script Usage

[root@maximus] → ./ip_range 192.168.1.1 255.255.255.224
No of IPs       30
First IP        192.168.1.1
Last IP         192.168.1.30
Subnet          192.168.1.0
Broadcast       192.168.1.31


[root@maximus] → ./ip_range 192.168.1.1 255.255.255.224 1
No of IPs       30
First IP        192.168.1.1
Last IP         192.168.1.30
Subnet          192.168.1.0
Broadcast       192.168.1.31

IP address range -- START --

192.168.1.0     192.168.1.1     192.168.1.2     192.168.1.3
192.168.1.4     192.168.1.5     192.168.1.6     192.168.1.7
192.168.1.8     192.168.1.9     192.168.1.10    192.168.1.11
192.168.1.12    192.168.1.13    192.168.1.14    192.168.1.15
192.168.1.16    192.168.1.17    192.168.1.18    192.168.1.19
192.168.1.20    192.168.1.21    192.168.1.22    192.168.1.23
192.168.1.24    192.168.1.25    192.168.1.26    192.168.1.27
192.168.1.28    192.168.1.29    192.168.1.30    192.168.1.31

IP address range -- END --

[root@maximus] → ./ip_range 192.168.1.1 255.255.0.0
No of IPs       65534
First IP        192.168.0.1
Last IP         192.168.255.254
Subnet          192.168.0.0
Broadcast       192.168.255.255