jhsea3do jhsea3do

Update, September 2016

OK, you can pretty much ignore what I wrote below this update, because it doesn't really apply anymore.

I wrote this over a year ago, and at the time I had spent a couple of weeks trying to get Kafka 0.8 working with .NET and then Node.js with much frustration and very little success. I was rather angry. It keeps getting linked, though, and just popped up on Hacker News, so here's sort of an update, although I haven't used Kafka at all this year so I don't really have any new information.

In the end, we managed to get things working with a Node.js client, although we continued to have problems, both with our code and with managing a Kafka/Zookeeper cluster generally. What made it worse was that I did not then, and do not now, believe that Kafka was the correct solution for that particular problem at that particular company. What they were trying to achieve could have been done more simply with any number of other messaging systems, with a subscriber reading messages off and writing

朴素VPN：一个纯内核级静态隧道

由于路由管控系统的建立，实时动态黑洞路由已成为最有效的封锁手段，TCP连接重置和DNS污染成为次要手段，利用漏洞的穿墙方法已不再具有普遍意义。对此应对方法是多样化协议的VPN来抵抗识别。这里介绍一种太简单、有时很朴素的“穷人VPN”。

朴素VPN只需要一次内核配置（Linux内核），即可永久稳定运行，不需要任何用户态守护进程。所有流量转换和加密全部由内核完成，原生性能，开销几乎没有。静态配置，避免动态握手和参数协商产生指纹特征导致被识别。并且支持NAT，移动的内网用户可以使用此方法。支持广泛，基于L2TPv3标准，Linux内核3.2+都有支持，其他操作系统原则上也能支持。但有两个局限：需要root权限；一个隧道只支持一个用户。

朴素VPN利用UDP封装的静态L2TP隧道实现VPN，内核XFRM实现静态IPsec。实际上IP-in-IP隧道即可实现VPN，但是这种协议无法穿越NAT，因此必须利用UDP封装。内核3.18将支持Foo-over-UDP，在UDP里面直接封装IP，与静态的L2TP-over-UDP很类似。

创建一个朴素VPN

Unfortunately, the Cisco AnyConnect client for Mac conflicts with Pow. And by "conflicts", I mean it causes a grey-screen-of-death kernel panic anytime you connect to the VPN and Pow is installed.

As an alternative, there is OpenConnect, a command-line client for Cisco's AnyConnect SSL VPN.

Here's how to get it set up on Mac OS X:

OpenConnect can be installed via homebrew:
```
 brew update
```

brew install openconnect

	#include<algorithm>
	#include<iostream>
	template<typename T>
	class RingBuffer{
	T *array;
	size_t sum;
	int zero;
	bool rev;
	int Index(const int index) const;
	void Init();

	public class TopTags implements Processor<String, String> {

	private static final Logger LOG = LoggerFactory.getLogger(TopTags.class);
	// a Java Chronicle backed persistent map that auto delete on JVM shutdown for testing purposes
	// each update on the map will trigger subscriber signals
	MapStream<String, Integer> persistentMap;

	public TopTags() throws IOException {
	this.persistentMap = IOStreams.persistentMap("popularTags", true);
	}

	<html ng-app="dragTest">
	<head>
	<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js" type="text/javascript"></script>
	<script src="//ajax.googleapis.com/ajax/libs/jqueryui/1.10.3/jquery-ui.min.js" type="text/javascript"></script>
	<script src="http://code.angularjs.org/1.2.1/angular.min.js" type="text/javascript"></script>
	<script src="http://code.angularjs.org/1.2.1/angular-sanitize.min.js"></script>
	</head>
	<body class="container">

	<div ng-controller="dragCtrlr">

	# Dockerfile for Node-RED - pulls latest master code from git
	# Use the node.js v4 LTS engine
	FROM node:4-slim
	MAINTAINER ceejay

	RUN mkdir -p /root/.node-red
	WORKDIR /root/.node-red

	# download latest stable node-red
	RUN npm install -g --unsafe-perm node-red