Forward traffic from a local port to an onion address.

onionport.sh

#!/bin/sh
## Bind a local port and forward its traffic to an onion address.
## Requires socat to be installed, and a tor proxy to be running.

###############################################################################
# Environment
###############################################################################

SOCKS_HOST="127.0.0.1"
SOCKS_PORT="9050"
LOG_PATH="/var/log/onionport"

###############################################################################
# Methods
###############################################################################

usage() {
  printf "
    Bind a local port and forward its traffic to an onion address.
    Requires socat to be installed, and a tor proxy to be running.

    Usage: 
      $0 localport onionaddress.onion:port
      (start a new forwarding service)

      $0 localport stop
      (stop an existing service)

    Arguments:
      localport    - The local port that you will be sending traffic to (i.e 127.0.0.1:port).
      onionaddress - The onion address (and port) destination to forward traffic.

    Default tor proxy configuration is set to $SOCKS_HOST:$SOCKS_PORT.
    This must be changed in the script file to match your tor configuration.

    You can bring up this help screen by using '$0 --help'
  \n"
}

kill_existing_pid() {
  EXIST_PID="$(ps aux | grep socat | grep tcp-listen:$1 | awk '{print $2}')"
  if [ ! -z $EXIST_PID ]; then
    kill -9 $EXIST_PID
    echo "Killed existing process for port $1 at pid $EXIST_PID."
  else
    echo "No existing onionport detected on port $1."
  fi
}

###############################################################################
# Script
###############################################################################

set -e

## Check if socat is installed.
if [ -z "$(which socat)" ]; then
  echo "Socat is not detected! Make sure socat is installed and visible in your PATH."
fi

## Check if help has been invoked.
if [ "$1" = "--help" ]; then usage && exit 0; fi

## Check if a valid number has been given.
if [ -z "$1" ] || [ -z "$(echo $1 | grep -P '^[0-9]+$')" ]; then
  echo "Invalid port number!" && usage && exit 1
fi

## Check if a valid address or option has been given.
if [ "$2" = "stop" ]; then
  kill_existing_pid $1 && exit 0
elif [ -z "$2" ] || [ -z "$(echo $2 | grep .onion)" ]; then
  echo "Invalid onion address!" && usage && exit 1
fi

## If log path does not exist, create it.
if [ ! -d "$LOG_PATH" ]; then mkdir -p "$LOG_PATH"; fi

## Check if an onionport is already in use.
kill_existing_pid $1

## Start the socat program as a daemon service.
socat tcp-listen:$1,reuseaddr,fork \
  socks4a:$SOCKS_HOST:$2,socksport=$SOCKS_PORT > $LOG_PATH/$1.log &
printf "Socat tunnel with pid $! created on port $1 and redirecting to:\nhttp://$2\n"