Neeraj Kanhere neerajkanhere

Reverse Port Tunneling with EC2

Reverse port tunneling is used to give a user outside of a networks firewall accesst to a computer inside the firewall where direct SSH connections aren't allowed. It works by the in-firewall computer SSH'ing to a middleman computer that then forwards incomming SSH connections on a given port to the firewalled computer.

Setup the middleman

Get an ubuntu EC2 instance
Download it's security keys (both in-firewall and out-firewall computers will need the private key)
Setup the security group to allow connections on port 10002
SSH into the middleman and add: GatewayPorts yes to /etc/ssh/sshd_config

How to setup your own CA with OpenSSL

For educational reasons I've decided to create my own CA. Here is what I learned.

First things first

Lets get some context first.

JS REPL

There's not a good, simple embeddable REPL for JS out there that I could find. I wanted one for presentations on JavaScript concepts. The developer tools' console would be ideal, but bailing out of my presentation and opening a console brakes the flow. Tools like codepen.io et al. are great, but more overhead and set up than I need. I just want to type JS and show the result. This is a decent first step for my needs.

A Pen by Cory on CodePen.

License.

For those of you who want to try out systemd-networkd, you can read on, and find out in this tutorial how to switch from NetworkManager to systemd-networkd on Linux.

Requirement systemd-networkd is available in systemd version 210 and higher. Check the version of your systemd before proceeding.

$ systemctl --version

Switch from Network Manager to Systemd-Networkd

It is relatively straightforward to switch from Network Manager to systemd-networkd (and vice versa).

	[unix_http_server]
	file=/tmp/supervisor.sock ; path to your socket file

	[supervisord]
	logfile=/var/log/supervisord/supervisord.log ; supervisord log file
	logfile_maxbytes=50MB ; maximum size of logfile before rotation
	logfile_backups=10 ; number of backed up logfiles
	loglevel=error ; info, debug, warn, trace
	pidfile=/var/run/supervisord.pid ; pidfile location
	nodaemon=false ; run supervisord as a daemon

	/* curl_multi_test.c

	Clemens Gruber, 2013
	<[email protected]>

	Code description:
	Requests 4 Web pages via the CURL multi interface
	and checks if the HTTP status code is 200.

	Update: Fixed! The check for !numfds was the problem.

	import sys, os.path
	from xml.etree import ElementTree
	import xml.dom.minidom

	def process_vcxproj_file(fname):
	with open(fname, 'rb') as fin:
	proj = fin.read()

	add_optimize_after = ' <ItemDefinitionGroup Condition="'$(Configuration)\|$(Platform)'=='Debug\|Win32'">\r\n <ClCompile>'
	proj = proj.replace(add_optimize_after, add_optimize_after + '\r\n <Optimization>Disabled</Optimization>')

	# -- coding= utf-8 --
	import datetime
	import os
	import json
	import tornado.ioloop
	import tornado.web
	import tornado
	import tornado.httpclient
	import traceback
	import urllib2

	<powershell>

	# First we add our administrative user, replace username and password with your own
	$computer=$env:ComputerName
	$user="username" ## Change this!
	$password='password' ## And change this too!
	$objOu = [ADSI]"WinNT://$computer"
	$objGroup = [ADSI]"WinNT://$computer/Administrators,group"
	$objUser = $objOU.Create("User", $user)
	$objUser.setpassword($password)


	# the IP(s) on which your node server is running. I chose port 3000.
	upstream app_geoforce {
	server 127.0.0.1:3000;
	}

	upstream app_pcodes{
	server 127.0.0.1:3001;
	}