nc-proxy.sh

#!/bin/sh -e

if [ $# != 3 ]
then
    echo "usage: $0 <src-port> <dst-host> <dst-port>"
    exit 0
fi

TMP=`mktemp -d`
PIPE=$TMP/pipe
SENT=$TMP/pipe.sent
RCVD=$TMP/pipe.rcvd
trap 'rm -rf "$TMP"' EXIT
#mkfifo -m 0600 "$PIPE"
mkfifo -m 0600 "$PIPE" "$SENT" "$RCVD"
#TIMESTAMP=$(date "+%Y-%m-%d %H:%M:%S")
sed 's/^/=> /' <"$SENT" &
sed 's/^/<=  /' <"$RCVD" &
nc -v -k -l -p "$1" <"$PIPE" | tee "$SENT" | nc "$2" "$3" | tee "$RCVD" >"$PIPE"