Bash Random Private IPv4 Address

randomPrivateIpv4.sh

#!/bin/bash
privateIpv4Prefixes=(10
                     172
                     192)
# There should be 6 for every prefix
# One for each octet

#                  10.0.0.0/8 - 10.0.0.0 - 10.255.255.255
privateIpv4Ranges=(0 255 0 255 0 255
#                  172.16.0.0/12 - 172.16.0.0 - 172.31.255.255
                   16 31 0 255 0 255
#                  192.168.0.0/16 - 192.168.0.0 - 192.168.255.255
                   168 168 0 255 0 255)
function randomPrivateIp() {
  prefixIndex=$(shuf -i 0-$(( ${#privateIpv4Prefixes[@]} - 1 )) -n 1)

  echo -n "${privateIpv4Prefixes[prefixIndex]}"

  (( rangeStartingIndex = prefixIndex * 6 ))

  for _ in {0..2};
  do
    rangeStart=${privateIpv4Ranges[$rangeStartingIndex]}
    rangeEnd=${privateIpv4Ranges[$rangeStartingIndex + 1]}

    echo -n ".$(shuf -i "$rangeStart"-"$rangeEnd" -n 1)"

    ((rangeStartingIndex+=2))
  done
}

randomPrivateIp

Went over it with shellcheck