Enable port forwarding for Transmission

port_forward.sh

#! /bin/bash
######################################################################
# port_forward.sh
# ----------------
# Enable port forwarding for Transmission.
#
# Requirements:
#   Private Internet Access user and password as arguments
#
# Usage:
#  ./port_forward.sh <user> <password>
######################################################################

error( )
{
  echo "$@" 1>&2
  exit 1
}

error_and_usage( )
{
  echo "$@" 1>&2
  usage_and_exit 1
}

usage( )
{
  echo "Usage: `dirname $0`/$PROGRAM <user> <password>"
}

usage_and_exit( )
{
  usage
  exit $1
}

version( )
{
  echo "$PROGRAM version $VERSION"
}


port_forward_assignment( )
{
  echo 'Loading port forward assignment information..'
  if [ "$(uname)" == "Linux" ]; then
    local_ip=`ifconfig tun0|grep -oE "inet addr: *10\.[0-9]+\.[0-9]+\.[0-9]+"|tr -d "a-z :"|tee /tmp/vpn_ip`
    client_id=`head -n 100 /dev/urandom | md5sum | tr -d " -"`
  fi
  if [ "$(uname)" == "Darwin" ]; then
    local_ip=`ifconfig utun0 | grep "inet" | cut -d \  -f2|tee /tmp/vpn_ip`
    client_id=`head -n 100 /dev/urandom | md5 -r | tr -d " -"`
  fi
  json=`wget -q --post-data="user=$USER&pass=$PASSWORD&client_id=$client_id&local_ip=$local_ip" -O - 'https://www.privateinternetaccess.com/vpninfo/port_forward_assignment' | head -1`
  echo $json
  PORT=`echo $json | grep -oE "[0-9]+"`
}

EXITCODE=0
PROGRAM=`basename $0`
VERSION=1.0
USER=$1
PASSWORD=$2

while test $# -lt 2
do
  case $1 in
  --usage | --help | -h )
    usage_and_exit 0
    ;;
  --version | -v )
    version
    exit 0
    ;;
  *)
    error_and_usage "Unrecognized option: $1"
    ;;
  esac
  shift
done

port_forward_assignment

defaults write /Users/{username}/Library/Preferences/org.m0k.transmission BindPort $PORT

exit 0