XSystem252

How To Set Up a Raspberry Pi 4 with Archlinux 64-bit (AArch64) and Full Disk Encryption (+SSH unlock), USB Boot (No SD-Card) and btrfs

Written by: XSystem
First published on: 20 Dec 2020
Last updated on: 20 Dec 2020

[0] Introduction

Overview

markormesher

The Doubling Algorithm for Suffix Array Construction

I'll use x = "banana", m = 6 as an example. The suffixes are:

0:  banana
1:  anana
2:  nana
etc.

First, we'll work out R1, which is the rank of each suffix according to it's first letter only. Because we're just comparing single letters, we can do it in Theta(m) with a bucket sort. There will be some duplicates, and that's fine. We only have three different letters, so we give all of the A's a rank of 0, all of the B's a rank of 1, and all of the N's a rank of 2. We end up with this:

dump.csv

wernsey

/*
Java Datalog Engine with Stratified Negation

Copyright 2016 Werner Stoop

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

klzgrad

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