BASH Proxy / Relay using NetCat

relay.sh

#!/bin/bash

# Adapted from the script on:
#   http://notes.tweakblogs.net/blog/7955/

TMP=$HOME/tmp
PREFIX=proxy
FIFO=`mktemp -u -p $TMP -t $PREFIX.XXXXXXXXXXX`


# Check arguments
if [ $# -lt 3 ]
then
    echo "Syntax: $0 <localport> <target_addr> <target_port>"
    exit 1
else
    LOCAL_PORT=$1
    TARGET_ADDR=$2
    TARGET_PORT=$3
fi


# Initialization
rm -v $TMP/$PREFIX.*

echo
echo "--> Running proxy:  *:$LOCAL_PORT => $TARGET_ADDR:$TARGET_PORT"

trap 'rm -f "$FIFO"' EXIT

mkfifo $FIFO
nc -l -k -p $LOCAL_PORT <$FIFO |nc $TARGET_ADDR $TARGET_PORT >$FIFO
rm $FIFO