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

I recently wrote a function to generate all IP addresses from a given network address. The function takes the network address as argument and accepts CIDR and subnet masks. The script then stores all IPs in the array variable $ips.

Code

network_address_to_ips() {
  # create array containing network address and subnet
  local network=(${1//\// })
  # split network address by dot
  local iparr=(${network[0]//./ })
  # if no mask given it's the same as /32
  local mask=32
  [[ $((${#network[@]})) -gt 1 ]] && mask=${network[1]}

  # convert dot-notation subnet mask or convert CIDR to an array like (255 255 255 0)
  local maskarr
  if [[ ${mask} =~ '.' ]]; then  # already mask format like 255.255.255.0
    maskarr=(${mask//./ })
  else                           # assume CIDR like /24, convert to mask
    if [[ $((mask)) -lt 8 ]]; then
      maskarr=($((256-2**(8-mask))) 0 0 0)
    elif  [[ $((mask)) -lt 16 ]]; then
      maskarr=(255 $((256-2**(16-mask))) 0 0)
    elif  [[ $((mask)) -lt 24 ]]; then
      maskarr=(255 255 $((256-2**(24-mask))) 0)
    elif [[ $((mask)) -lt 32 ]]; then
      maskarr=(255 255 255 $((256-2**(32-mask))))
    elif [[ ${mask} == 32 ]]; then
      maskarr=(255 255 255 255)
    fi
  fi

  # correct wrong subnet masks (e.g. 240.192.255.0 to 255.255.255.0)
  [[ ${maskarr[2]} == 255 ]] && maskarr[1]=255
  [[ ${maskarr[1]} == 255 ]] && maskarr[0]=255

  # generate list of ip addresses
  local bytes=(0 0 0 0)
  for i in $(seq 0 $((255-maskarr[0]))); do
    bytes[0]="$(( i+(iparr[0] & maskarr[0]) ))"
    for j in $(seq 0 $((255-maskarr[1]))); do
      bytes[1]="$(( j+(iparr[1] & maskarr[1]) ))"
      for k in $(seq 0 $((255-maskarr[2]))); do
        bytes[2]="$(( k+(iparr[2] & maskarr[2]) ))"
        for l in $(seq 1 $((255-maskarr[3]))); do
          bytes[3]="$(( l+(iparr[3] & maskarr[3]) ))"
          printf "%d.%d.%d.%d\n" "${bytes[@]}"
        done
      done
    done
  done
}

Example

network_address_to_ips 10.0.1.0/255.255.255.240
network_address_to_ips 10.1.0.0/24