net-localhost2

#!/bin/bash

# Use this to create or remove a localhost alias to IP address 127.0.0.2.

usage() {
  echo "Usage: $0 [create|remove] - Create or remove a localhost alias to IP 127.0.0.2." ; exit 1
}

localhost2Create() {
  if hash pfctl 2>/dev/null; then
    ifconfig lo0 alias 127.0.0.2
    echo "Create localhost alias on IP 127.0.0.2 (OSX)"
  elif hash ip 2>/dev/null; then
    ip address add 127.0.0.2/8 dev lo:2
    echo "Create localhost alias on IP 127.0.0.2 (Linux)"
  else
    echo "This command is currently only available on OSX or Linux systems."
    usage
  fi
}

localhost2Remove() {
  if hash pfctl 2>/dev/null; then
    ifconfig lo0 -alias 127.0.0.2
    echo "Remove localhost alias on IP 127.0.0.2 (OSX)"
  elif hash iptables 2>/dev/null; then
    ip address del 127.0.0.2/8 dev lo:2
    echo "Remove localhost alias on IP 127.0.0.2 (Linux)"
  else
    echo "This command is currently only available on OSX or Linux systems."
    usage
  fi
}

if ! [ $(id -u) = 0 ]; then
  echo "Root user (sudo) required."
  exit 1
fi

arg=$1

case $arg in
  "create")
    localhost2Create
    ;;
  "remove")
    localhost2Remove
    ;;
  *)
    echo "Invalid subcommand '$arg', must be 'create' or 'remove'"
    usage
    ;;
esac