Alex Brown @lextech devisnotnull

Opening and closing an SSH tunnel in a shell script the smart way

I recently had the following problem:

From an unattended shell script (called by Jenkins), run a command-line tool that accesses the MySQL database on another host.
That tool doesn't know that the database is on another host, plus the MySQL port on that host is firewalled and not accessible from other machines.

We didn't want to open the MySQL port to the network, but it's possible to SSH from the Jenkins machine to the MySQL machine. So, basically you would do something like

ssh -L 3306:localhost:3306 remotehost

	#!/bin/bash
	# https://serverfault.com/questions/532569/how-to-do-port-forwarding-redirecting-on-debian

	IPTBL=/sbin/iptables

	IF_IN=eth0
	PORT_IN=40022

	IP_OUT=172.16.93.128
	PORT_OUT=22

	#!/usr/bin/env bash
	# Reset routing table on OSX

	# display current routing table
	echo "******** BEFORE **************************************"
	netstat -r
	echo "**********************************************************"

	for i in {0..4}; do
	sudo route -n flush # several times

	#!/bin/bash

	if [ $# -ne 1 ] ; then
	echo 'Please provide a name for the virtual machine '
	exit 1
	fi

	############################################

	function print_with_line_numbers {

	#!/bin/sh

	# Remote ARG1
	# Remote port $ARG2
	# Local port $ARG3

	if [ $# -ne 3 ] ; then
	echo 'Invalid aruments provided, Example ./cli.sh 192.158.1.1 5900 5900'
	exit 1
	fi

	const compose = (...fns) =>
	fns.reduce((prevFn, nextFn) =>
	(...args) => nextFn(prevFn(...args)),
	value => value
	);

	const compose2 = (fn, g) =>
	(...args) =>
	fn(g(...args))

	#!/bin/sh

	yum update -y
	yum install -y wget unzip openjdk-8-jre-headless xvfb libxi6 libgconf-2-4

	wget https://dl.google.com/linux/direct/google-chrome-stable_current_x86_64.rpm
	yum install -y ./google-chrome-stable_current_*.rpm

	curl https://chromedriver.storage.googleapis.com/73.0.3683.20/chromedriver_linux64.zip > ~/chromedriver.zip
	unzip -o ~/chromedriver.zip -d /usr/local/bin/chromedriver

	version: '3.1'

	services:

	db:
	image: postgres
	restart: always
	environment:
	POSTGRES_PASSWORD: example
	ports: