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Screenshots… These days, we all have literally THOUSANDS of them. Although each image is usually small because screenshot resolutions tend to be much lower than those of photos taken with your rear camera, once you have thousands of them, the collection can be, uhhh, quite large. 
 
 Problems 
 Deleting them is most people’s choice, I suppose. But it always upsets me to…
Intro 
 Raspberry Pis have always been the go-to platform for geeks to tinker with, but there’s a crucial problem. 
 For many years, microSD cards were the only storage medium for Raspberry Pis, and, as you may know, they are pretty darn slow. Even the fastest cards, say, SanDisk Extreme Pro, perform better than average cards, but they are still nowhere near even those DRAM-less QLC…
Wow… It has literally been nearly a year (July 31, 2025) since I last wrote. I believe many of you were wandering where have I been. Don’t worry, I was doing perfectly well in real life and was purely because I was busy and didn’t have time to write. 😂 
 Where have I been 
 Study. If you know me well, you should know that I was a senior student of a senior high school.…
As the era passes, we are in serious need of encrypting our disks. Built-in encryption software, such as BitLocker in Microsoft Windows and FileVault in macOS, is both amazing. 
 
 Though BitLocker has been proven to be vulnerable. 
 In GNU/Linux, we have some great alternatives. The best and most popular one must be LUKS, aka cryptsetup . 
 So today I’m going to share how to…
It’s been a long time since my last post about eUICCs . A lot things have changed since then. 
 Major changes 
 5ber.eSIM has gone bankrupt and it’s said that their employees’ insurance was in debt for months before the entire company went collapsed. However, the technical team has started a new company called XeSIM . It’s fundamentally the exact same thing as…
Generating cryptographic keys is the most important* part in the cryptography world. 
 Why and How? 
 random numbers 
 I’m not going to talk about the theories and principles of cryptography, but there’s one thing you need to know that, for asymmetric cryptography, the keys are everything. Your private keys take the responsibility of authenticating, decrypting and signing…
Wow it’s been another year. This year, a lot of things have changed. 
 Life 
 This year, I’ve finally reached my age of 16! I’ve gone to Nanjing twice, visited a lot of places of interest; I’ve also met some of my friends which we originally met online offline :), which is a big step forward towards my relationship circle. 
 There aren’t really many things…
This post has some updates! Available at: here 
 eSIM, aka embedded SIM cards, a new form of SIM cards. The traditional SIM cards are essentially a Java Card with customized applet on it. You need to use this card in order to connect to the cellular network. But as time goes by, these little plastic SIM cards seem to be out-of-fashion. That’s when eSIM comes into play. You can straight…
S/MIME, our old friend, usually used to sign and encrypt emails. Essentially it’s a standard to ensure the authenticity and security of your communications, especially emails. However, it can also be used to sign regular data. You guessed it, we are going to use it to sign Git commits. 
 The difference between PGP signatures and S/MIME signatures is that the latter requires a central…
OpenSSL is one of those tools that accompanies us all the time while still being ignored by almost everyone. It is powerful, but it is also complicated and sometimes confusing. 
 This guide demonstrates two different operations: 
 
 Signing: prove that data was signed by the holder of a private key and that it has not been modified. 
 Encryption: keep data confidential for a…
Wow, it’s been 2 years since I wrote the last storage-related posts (and that was actually my first blog post ever, learn more ) 
 So, two years have passed, and it’s time to write another one. 
 Briefly introduction 
 Despite that I started to focus on privacy and security, the cloud storage is still my main storage medium. But don’t panic just yet, I now have decent…
If you haven’t known what a GPG key is, please close this tutorial. 
 As we all know, GPG keys have their ID s, they are essentially 40 hexadecimal characters that are used to identify your keys. 
 Your ID may look like this. 
 9684 79A1 AFF9 27E3 7D1A 566B B569 0EEE BB95 2194 // GitHub web-flow signing
 Usually we just memorize the last 16 characters because it is enough in…
If you have a lab like me, you will probably need to serve some of your services through Web. And speaking of web, we cannot ignore one critical aspect – Security. 
 The easiest way to secure your websites is to use TLS. However, most easy-to-get certificates for websites are meant for public domains, not for IPs, not to mention internal IPs. Furthermore, you might not feel comfortable…
So, many of you may know that I am a long-time Linux user. 
 However, recently many of my friends tried REALLY HARD to convince me to try BSD-based systems. 
 At first glance, my opinion was a solid NO . I mean, one of the most important thing for me is software ecosystem. Of course, Linux (GNU/Linux) absolutely crushed most operating systems in terms of ecosystems. 
 Later, as I was…
So, as you start to jump down the rabbit hole of cryptography, you will start to face another question: 
 
 How can I take care of my keys? 
 Well, it’s a long story for everyone, and here’s mine. 
 Asymmetric 
 There are symmetric and asymmetric cryptography, and I will walk you through. 
 OpenPGP Keys 
 If you have followed my blog for a long time, you…
If you have caught up with my blog for a long time, you may know what OpenPGP is. And you probably know what a YubiKey is, which can act as a smartcard . 
 Traditional OpenPGP stores your private key on your computer, generally in ~/.gnupg , which is nowhere near safe. Storing your private keys to a OpenPGP smartcard has following benefits. 
 
 
 
 Safe, only people who…
It’s been another year. The final review has been delayed on my calendar for like two months. But hey better late than never. It’s time to summarize the past year. 
 Unlike last year, I wouldn’t explain which month happened which event, but in general. 
 Study 
 It’s been a year, and this year I have been admitted to the high school which I was looking forward…
If you have ever seen my previous posts, you might know that I have two YubiKeys and a bunch of Linux servers. 
 Passwords are far from secure when comparing them with a pair of keys. 
 
 Technically not a pair of keys , just because I’m talking about asymmetric keys, so a pair of . 
 But if you decide to switch to Keys instead of Passwords, it’s highly possible that…
What is Parchive? 
 Parchive is redundant file format. If you lose part of your file in transmission or in storage, you can use a Parchive file to repair it. It’s like RAID for files instead of a whole file system. – parchive.github.io 
 It uses a codec called Reed-Solomon Codes. Yes, the same codec that is used by RAID-5. 
 Parchive is essentially parity files for files.…
Introduction 
 In today’s digital age, safeguarding our personal information and communications is of utmost importance. One effective solution to ensure privacy and security is GnuPG (GNU Privacy Guard). In this blog post, we’ll explore what GnuPG is and how it can help you protect your sensitive data from prying eyes. 
 What is GnuPG? 
 GnuPG, also known as GNU Privacy…
Recently I have purchased an HK Mobi prepaid SIM card. The card is essentially a Prepaid HKCSL SIM . My plan includes 12 GB of local data, 12 GB of Greater China Roaming data, 2000 minutes of local call, as well as 38 HK$ of balance . 
 This post focuses on the roaming experience in mainland China, my primary residence. 
 Test environment 
 The test machine is a OnePlus 8 , the phone…
What is SHA & What is the problem 
 SHA , also Secure Hashing Algorithm , is a widely used hash algorithm. It is used to validate the integrity of your files and messages. However, your hash may looks like this. 
 e35386cfc8311b630a29da909dff48d3334caf2ee85c6318a86d1496afa5ed14 
 This is a SHA256sum , it is a 64-byte long string constructed with HEX . It is hard to remember and if you…
After the careful consideration, we decided to switch to static blog eventually.
That’s right, we are ditching WordPress!
Originally, we used Neve with WordPress , running on OVHcloud . It works fine, but we all know WordPress is very heavy and slow, especially for low-end machines like the OVH one.
Now, we changed a lot. We used Hugo as our static site generator, and used Poison…
Proxmox Backup Server/Client is software that helps you protect and secure your important data. It creates and manages backups of your computer systems, files, and virtual machines. It schedules regular backups, stores them safely, and allows easy restoration. It also supports virtual machine backups, making it a comprehensive backup solution. 
 However, you may find no ARM support for Proxmox…
Disclaimer 
 No brands nor manufacturers paid me to write this blog post. It is entirely based on my own experiences. 
 Introduction 
 In the ever-evolving landscape of the digital era, our lives have become intricately intertwined with the vast realm of the internet. From streaming our favorite movies and music to capturing precious moments through high-resolution photographs, our…
A few months ago, I posted a tutorial on how to install Proxmox VE on the ARM instance of OCI, and this is a follow-up. Original Post 
 Goal 
 The goal is to create a container that has NAT IPv4 (only for IPv4 connection, no ports opened, and with PVE, it is not possible to do that, at least with no official methods), and has a dedicated IPv6 address. 
 Requirements 
 You need to…
In the modern era, where our lives are increasingly intertwined with technology, the need for robust digital security has become more crucial than ever. One of the fundamental aspects of securing our online presence lies in the effective management of passwords. With the multitude of online accounts and services we use on a daily basis, it has become almost impossible to remember unique and strong…
LiteServer started as a small byte on the big internet back in October 2007, which is now 15 years ago. During the first years of their business, they covered the hosting market in The Netherlands and Belgium. 
 During the 2022 Black Friday, they offered 60% OFF for all their VPSes. The base model of the HDD VPS is 1 vCPU, 1 GB RAM, 500 GB cached HDD, and 15 TB@1 Gbps network, hosted in…
ServaRICA is a VPS merchant established back in 2010. Their campus is in Montreal, Canada currently. 
 Their Summer Deal and Black Friday deal is very attractive and I purchased one for benchmarking. 
 Their best seller is obviously, their “Opossum” tier. A year ago, the tier only had IPv6 addresses. That’s right, no IPv4, not even NAT. However, starting from the Black…
After two months’ suspension, everything is back on track and this blog will continue to update as normal. 
 两个月后的今天，一切回到了正轨，一切都会像往常一样运作。 
 -- Frank Ruan, 18:57 Jun. 20, 2023 (China Standard Time)
This notice is bilingual. (Simplified Chinese & English) 
 Due to some unexpected and unpreventable reasons, me (@orwtmc), and my blog (frank-ruan.com) won’t update until Jun. 20, 2023 . Sorry for the inconveniences. 
 因不可抗力原因，本人（@orwtmc）以及我的博客（frank-ruan.com）将暂停更新，直到 2023年6月20日晚间 （中国标准时间）。为您带来的不便敬请谅解。 
 -- Frank Ruan, 19:02 on May 3, 2023 (China Standard Time).
Vultr is a cloud computing company established back in 2014. Although they entered the industry for just less than 10 years, they really have dominated the “bang for the buck” market along with DigitalOcean and Linode. 
 However, they recently (a few months ago) announced a Free Tier . Users need to debit their account 5$ via Credit Card and enable two-factor authentication . 
…
Proxmox Virtual Environment is a great virtualization platform. And Oracle Cloud Infrastructure seems to provide virtual machines for free forever. The regular x86_64 instance has only 1/8 OCPU and 1 GB RAM . However, the new Ampere instance is aarch64 (arm64) architecture. With 4 Neoverse N1 Cores and 24 GB RAM , we can fire up some decent containers on it. 
 However, Proxmox doesn’t…
In the modern era, cryptography has become one of the most important part of our digital life. We all know, cryptography is used to encrypt, sign, authenticate. Above all, the most important is of course, the security. We would never want anyone except ourselves (or the recipients, if applicable). So here are some advices based on my own experience. 
 1. Use proper algorithm. 
 It depends…
KURUN Cloud is a VPS company established back in 2019. They are an LIR of ARIN. From the website, I would guess that a group of Chinese people launches it, but headquartered in California, US. 
 They have a great deal, you get 1 vCPU core, 1 GB RAM, 10 GB Disk for just 3$/month, and very good networking to China (it’s very obvious that this machine is the best choice for proxy.
OVHcloud is a European cloud computing and hosting company. It was founded in 1999 in France and has since expanded to operate globally, with locations in Europe, North America, and Asia. OVHcloud offers a wide range of services, including cloud infrastructure, dedicated servers, web hosting, and domain name registration. The company is known for its innovative technology and commitment to privacy…
A S/MIME (Secure/Multipurpose Internet Mail Extensions) certificate is a type of digital certificate that is used to encrypt and sign email messages. It allows the recipient of the email to verify the identity of the sender, and to ensure that the message has not been tampered with during transit. 
 There are multiple companies that offer S/MIME certificates, such as DigiCert, GlobalSign,…
2022 Final Review 
 This is December 31, 2022, 23:06 PM CST now. 
 2022 is a pretty terrible year for us, but there were still some noticable events which are worth noting. 
 January: 
 
 Nothing serious, took final exam of 8A, I remembered that it wasn’t too good. 
 February: 
 
 Get Chinese New Year, bought Google Workspace for the first time (and then got…
Yubico is famous for its excellent hardware keys, and somehow they have become the industry standard. But unfortunately, for unknown reasons*, they don’t offer services to China (mainland), not even sell to China. That sucks since I live in China. (oof, don’t worry, but that’s how the story starts) 
 How did I make up my mind to buy a YubiKey? 
 It’s a long story,…
Kimsufi is an affiliated company with one of the biggest providers in France – OVH. A couple of months ago, all of Kimsufi’s services are migrated to OVH and everything is now OVH’s. 
 For 4.99€ (before tax, more on that later), you will get the following spec. 
 Intel ATOM N2800 @ 1.86 GHz - 2 Cores / 4 Threads;
4 GB DDR3 1066 MHz;
1 x 1 TB SATA…
Friendhosting is a VDS provider established back on April 20, 2009. So pretty old merchant. 
 They offer Web Hosting, SSD VDS and HDD VDS for storage. 
 The location for HDD VPS is only Bulgaria and Netherlands. Since they are all DMCA-ignored, it will be nice for torrenting. (Ignoring the disk speed, more on that later.) 
 The base model is 2 vCPU, 512 MB RAM, and 100 GB HDD. I bought…
Nacsshost is a VDS provider located in Turkey. Currently they are not providing any further information, so be careful when you are purchasing. 
 They use PayTR as their payment gateway, just like most Turkish merchants would do. They only supports Credit Card/Debit Card payment with 3D-Secure. So no PayPal whatsoever. But your credit card info is still safe since PayTR is widely used. 
 I…
This post will be Q&A formed, just see if this is great. 
 Q1: Where does penguins live? 
 A1: Antarctica. 
 Q2: Who owns Antarctica? 
 A2: …? Nope. 
 Q3: Does any countries or any people own Antarctica? 
 A3: No. 
 Q4: So does any of above own penguins? 
 A4: No. 
 Q5: Move back to Linux, what’s Linux’s avatar? 
 A5: Penguin. 
 Q6:…
Speaking of instant messaging, you may think about WhatsApp, Telegram, Signal, etc. But those apps are stealing your privacy for business reasons, which is sad, especially when you are discussing some indescribable topics with your friends. You may run into trouble at any time. So that’s when Matrix comes in! 
 According to their website, 
 Matrix is an open-source project that…
We’ve heard a lot about Web3.0, Blockchain, Distributed Web, etc. But most of them are just in concept and a bunch of essays. Did you know that there’s a real-life example, which powers the distributed web? I’m talking about IPFS, the InterPlanetary File System . 
 WARNING: IPFS Website & default Gateway are blocked in the People’s Republic of China, so make sure your…
Gullo is a one-man virtual server provider. Further information is unknown. They didn’t provide any information, so be careful when buying their services, 
 I’ve seen their offers in the forum LowEndTalk, so I’ve ordered a few months ago (March 2022). 
 The setup is really bad. 1 ancient Xeon CPU, 256 MB DDR3 RAM, 5 GB HDD… For $10 bucks, please no… 
…
idc.wiki (formerly 50network) is a virtual private service provider, established in 2016 ( unsure, seen from domain RDAP data ). They’ve been famously known for their great optimized network connection between Los Angeles and mainland China. 
 The network is provided by China Unicom. 
 There are two kinds of network, one is the China Unicom Backbone ( AS4837 ), and the other is China…
Interserver is an ancient cloud service provider which is established back in 1999 ! So the reliability is ensured. 
 Their Storage VPS is famously known as the best in the LowEndTalk forum. Yesterday (Aug. 3, 2022) was a guy in the LET forum’s birthday. The Interserver guy has posted a coupon code to celebrate his birthday—code happybirthdaylala. It is a 50% off recurring discount,…
Kuroit has been a British-established hosting provider since 2018. They initially provide virtual hosting which only allows users to upload their website to servers. But now things changed. They are now providing virtual private servers to users. 
 They posted a thread in the forum LowEndTalk a few days ago and many users rushed into them. 
 They provide two data centers now and one is…
To be clear, I am poor. So the only thing I can do is to install Hackintosh to my ancient Compotato (Computer + Potato cuz it’s even “sicker” than Ubisoft’s server XD). 
 Here’s my neofetch . 
 
 Just for lol. Time Machine & Homebrew absolutely slain Windows.