Quarantine Foods

The year 2020 started normal. Every weekday, I go to office. Three times a week, I pump those muscles at the gym. Every four days, I visit the grocery store to pick up a loaf of bread, along with other ingredients. Every Friday evening, I have a video chat with my family.

🕒 12 Timezones Away — 3 Timezones Away — Oops, It's Here

The first sign of problem occurred on Chinese New Year's Day. Traditionally, my mother's extended family would have an annual gathering during the holidays. However, my mother informed me that their gathering has been canceled, because there's a Coronavirus outbreak in parts of China. I thought, well, this doesn't affect me, because I live in Maryland USA, 12 timezones away from China.

The next week, China entered a lock down due to the spreading virus. My father found himself relying more on grocery delivery services. A difference from what I observed in 2017 is that, the gated community is not allowing delivery persons to enter the neighborhood, and my father has to collect his deliveries at the neighborhood entrance. At the same time, I heard on Twitter that the Coronavirus has reached the Chinese community in Seattle, 3 timezones from me.

In early March, the Coronavirus reached Maryland. A week later, public schools are being closed. This is when things started to get serious.

Getting Started with NDNts in Node.js

This article shows how to get started with NDNts, Named Data Networking (NDN) libraries for the modern web. In particular, it demonstrates how to write a producer and a consumer application in Node.js using JavaScript programming language, and transmit a few Interest and Data packets via NFD forwarder on the local machine.

Prepare the System

This guide is written for Ubuntu 18.04 operating system. If you have a Windows PC, you can enable Windows Subsystem for Linux and install Ubuntu 18.04 from the Microsoft Store. If you have a Macbook or a Linux machine other than Ubuntu 18.04, you can install Vagrant, and create a virtual machine using bento/ubuntu-18.04 template. All steps below should be executed inside Ubuntu 18.04 environment.

To use NDNts, you must have Node.js. As of this writing, NDNts works best with Node.js 14.x, and you should install that version. The easiest way to install Node.js is through Node Version Manager (nvm). To install nvm and then install Node.js, type the following commands in Ubuntu 18.04 terminal:

$ wget -qO- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.3/install.sh | bash
$ nvm install 14
Now using node v14.2.0 (npm v6.14.4)

Introducing NDNph and New Version of esp8266ndn

NDNph is my latest Named Data Networking (NDN) client library. This article gives an overview of this library.

History and Motivation

In 2016, I started esp8266ndn. It contains a copy of ndn-cpp-lite, UCLA REMAP's C++ library that does not use dynamic memory allocations. I then added integrations with ESP8266's network stack and crypto functions, making esp8266ndn the first NDN library that works on the ESP8266 microcontroller. Using this library, I built several projects, including a wearable jewelry and a call button. University of Memphis also deployed several sensor nodes using esp8266ndn.

Over the years, esp8266ndn gained many new features, and widened platform support to include ESP32 and nRF52. However, using ndn-cpp-lite as the core is becoming problematic:

  • New protocol features show up slowly, because ndn-cpp-lite author would not add a feature until ndn-cxx has it, and design discussions for ndn-cxx sometimes take several years.
  • There is no generic TLV encoder/decoder, making it difficult to support TLV structures in application layer.
  • ndn-cpp-lite is bloated with obsolete features, due to their backwards compatibility guarantees. Consequently, binary code size is unnecessarily large.
  • Although I can add patches to ndn-cpp-lite during importing into esp8266ndn, it has been difficult to test these patches. This isn't ndn-cpp-lite's fault, but is still an issue.

Thought Provoker #3

The title comes from a geocache named Thought Provoker #3. Inside the container there is a thought provoking question:

If you could travel across the United States of America (and had no other obligations, financial or time constraints) what mode of transportation would you use and why? Walk/run, ride a bike, ride a motorcycle, hitchhike, drive a car, drive a RV/motorhome, take trains, or something else?

Here are my answers.

First Choice: Geocaching Express 6000

The Geocaching Express 6000 GPS Receiver is a powerful GPS receiver, as shown in Geocaching International Film Festival (GIFF) 2019:


Geo-snatching is the act of finding loopholes instead of geocaches.

This includes:

  • armchair geocaching;
  • hacking your smartphone's location so you can log Adventure Labs or solve Whereigo cartridges without visiting the location;
  • logging an FTF on a friend's cache that you helped place;
  • finding your own caches by adopting it to a sock puppet account (aka rule 52612);
  • other general tomfoolery.

The term geo-snatching was invented by gsmX2 on this Facebook post. This article explains what geo-snatching or geosnatching means in geocaching, and how a geo-snatcher or geosnatcher differs from an honest geocacher. Content of this article does not necessarily reflect blog owner's views.

Introducing NDNts, Named Data Networking libraries for the Modern Web

I'm creating a new Named Data Networking (NDN) client library, NDNts. The initial NPM release, v0.0.20191223-beta.1, was uploaded yesterday. This article explains why I'm doing this, and why you should consider using my library.


I've been developing Named Data Networking (NDN) for several years. Although my specialty is in the forwarding plane, I occasionally build NDN applications, such as a home surveillance camera. A common ingredient of every NDN application is some sort of client libraries, which provides APIs that allow the application to encode/decode NDN packets and communicate over NDN networks in accordance with the NDN protocol. One of these client libraries is the NDN Common Client Libraries (NDN-CCL), which provide a consistent API across several programming languages.

I adopted ndn-js, the JavaScript variant of NDN-CCL, in several projects, and was unhappy about it:

  • The API feels like Java, not JavaScript.
  • Callbacks everywhere, leading to callback hell.
  • The library inserts over 50 symbols to the browser's global scope, causing name conflicts.
  • All features are bundled into a single file that weighs over 500KB.
  • There's no unit testing for the most part, let alone continuous integration.

Bye, C.H.I.P

In 2015, I backed CHIP - The World's First Nine Dollar Computer on Kickstarter. Since then,

In 2018, Next Thing Co went out of business. Disappearing along with them is the software updates. Debian Buster was released in July 2019, but CHIPs are stuck with now two-generation old Debian Jessie, along with a 3-year-old Linux 4.4 kernel. Without software updates, running C.H.I.P computers on the Internet is increasingly risky.

This week, I have decided to sell my collection of C.H.I.P single board computers. They were sold for $77 (equals Kickstarter pricing) within two days of listing on eBay.

my C.H.I.P computers

Show Omega2 Battery Voltage in OpenWrt LuCI

Sometime ago, I bought an Onion Omega2 Pro and flashed it with OpenWrt 18.06. I plan to take my Omega on the road, so I installed a Li-Po battery on the device, so that it does not need to depend on USB power input. One big question is: what's the remaining power level?

Install power-dock2 to View Battery Voltage

The standalone Power Dock has a set of battery indicator LEDs that visually tells how much juice is left. However, the Omega2 Pro that I have does not have battery indicators. Instead, I need to use power-dock2 command to read battery level. Let me try it:

root@Omega2:~# power-dock2
-ash: power-dock2: not found

It does not work, because I flashed my Omega with OpenWrt 18.06, and power-dock2 command is not included in the standard OpenWrt distribution. The command comes from OnionIoT's OpenWrt feed (package source). I must add the OpenWrt feed before I can install the power-dock2 package.


2019年6月,我前往美国俄勒冈州度假7天,租车自驾旅行。 英文游记已经陆续发表,这篇文章是其中一个精彩景点的中文介绍。

波特兰是俄勒冈州最大的城市,也是我俄勒冈旅游的必经之地。 我在查询波特兰旅游信息时,找到了一个名叫“Shanghai Tunnels (上海隧道)”的旅游项目。 景点介绍称,导游将带领大家参观波特兰进行shanghai贸易的地方。 我来自中国上海(Shanghai),一看到“shanghai”这个名字,我就毫不犹豫的报了名。

本着“松紧结合”的原则,我将波特兰市区的游览安排在马特诺玛瀑布之后一天,可以在爬山后稍稍放松一下。 6月11日星期二一大早,我驾车到达密尔沃基轻轨车站,然后搭乘轻轨列车前往波特兰。 虽说这是“自驾游”,我这天选择了乘坐公共交通,以抛弃市区停车的烦恼。 我在市区游览了一整天,参观了国际玫瑰试验园、波特兰日本花园、皮托克豪宅三个著名景点,并在波特兰州立大学校区漫步。 傍晚六点半,我来到位于波特兰中国城的霍博饭店,与导游会合。 我同导游聊起了我决定参加这个旅游项目的原因,导游却告诉我,这个隧道很有意思,但是与上海这座城市没有任何关系。 呃,好吧。

导游让十几位游客在饭店的后院集合,给大家讲解隧道的历史。 他说,我们将要参观的隧道,并不是市政下水道,而是波特兰老建筑的地下室。 在19世纪波特兰建市的时候,每幢建筑都设有地下室,而且这些地下室都是互相连通的,形成了隧道。 1850年代,掮客在隧道里设立了据点,绑架街上游手好闲的人员,将他们临时关押在隧道里,然后拐卖到远洋轮船上。 由于不少远洋轮船的目的地是中国上海,英文“shanghai”就有了另一层意思:强制或诱骗某人去轮船上当水手。

根据网站说明,隧道的入口就在霍博饭店。 我一边听导游讲解,一边四处观望,想看看隧道的入口在什么地方。 我看到有人在使用一部看上去有些年头的电梯,就盯着看电梯是否钻入地下层。 这时,导游仿佛看出了我的心思,介绍道,那是波特兰的第一部液压电梯,安装于1880年代,但是并不通地下室。

Mystery at the Museum - Plan a Trip

Geocaching.com's newest promotion, Mystery at the Museum, is online today. To qualify for the first three souvenirs, you must find and log a number of geocaches, in a certain order.

Geocaching.com offers a filter function that shows which geocaches to find and log next. However, it only allows me to select the clue tiers that I currently qualify for. Since I haven't found any geocaches since the promotion started, I can only search for the Detective clue, but cannot search for any other clue types.

CLUES filter disabled except for Detective

This is inconvenient for me, because I prefer to go geocaching offline. I usually download a number of geocaches to my phone, go out to find them, and then log them at end of the day. I want to be able to search for clue types beyond Detective, even if I don't currently qualify for them. Then, I can go out, find enough geocaches to complete two or three souvenirs together, and then log them into the correct order.

I poked around the URI parameters in the address bar, and found two methods. I thought I'd share them, in case anyone needs it.