net-block

#!/bin/bash

# Use this script to block one or more Akka cluster nodes network access.
# The command line parameters must be from 1 to 9.
# Root user (sudo) is required to create blocking rules.

usage() {
  echo "Usage: $0 nodes - Block cluster nodes network access, node numbers must be 1 through 9." ; exit 1
}

block() {
  node=$1

  if hash pfctl 2>/dev/null; then
    (pfctl -sr 2>/dev/null; echo "block drop quick on lo0 proto tcp to port 255$node") | pfctl -f - 2>/dev/null
    echo "blocked node $node, port 255$node (OSX)"
  elif hash iptables 2>/dev/null; then
    iptables -A INPUT -p tcp --dport 255$node -j DROP
    echo "blocked node $node, port 255$node (Linux)"
  else
    echo "This command is currently only available on OSX or Linux systems."
  fi
}

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

[ $# -eq 0 ] && usage

while [[ $# -gt 0 ]]; do
  node=$1
  shift

  if [[ $node =~ ^[1-9]$ ]] ; then
    block $node
  else
    echo "Cluster node number $node is invalid. The node number must be 1 through 9."
    usage
  fi

done