install-portforwards.sh

#!/bin/bash

if [ $(dpkg-query -W -f='${Status}' socat 2>/dev/null | grep -c "ok installed") -eq 0 ]; then
  apt-get install socat;
else
  echo "*** Package socat already installed"
fi


MAPPINGS=("1231,10.0.12.1,123" "1232,10.0.12.2,123")

for MAPPING in ${MAPPINGS[@]}; do
	IFS="," read -r PORT_SRC IP PORT_DST <<< $MAPPING
	echo "*** Create mapping >>> SRC: ${PORT_SRC}, IP: ${IP}, DST: ${PORT_DST}"
	
	SERVICE_NAME="${IP}-${PORT_DST}.service"
	SERVICE_FILE="/etc/systemd/system/${SERVICE_NAME}"

	cat <<EOT > ${SERVICE_FILE}
[Unit]
Description=Forward port ${PORT_SRC} to ${IP}:${PORT_DST}

[Service]
User=root
WorkingDirectory=/opt
ExecStart=socat TCP-LISTEN:${PORT_SRC},fork TCP:${IP}:${PORT_DST}
Restart=always

[Install]
WantedBy=multi-user.target

EOT

	sudo systemctl daemon-reload
	sudo systemctl enable ${SERVICE_NAME}
	sudo systemctl start ${SERVICE_NAME}

	echo "*** Service ${SERVICE_NAME} created"

done