iptables rules are all lost when the PC is shutdown. This post shows how to permanently enable the added rules even after restarts. The post uses systemctl startup script introduced here. Suppose that you want to add this rule: -A INPUT -i docker0 -j ACCEPT -p tcp --dport 1234. Step

Sometimes you need to quickly fix an npm package without waiting for a new version to be published which usually takes time. In this post, I will show you how to do that with yarn 2, without using any additional tools. For yarn 1 users, please use the patch-package package

Problem Sometimes, the OS open a new VSCode instance when you want to open a directory (via xdg-open) with the default file manager (such as nautilus). Many users have claimed about this issue: #41037, #80499, #44344, archlinux, ... Background The OS chooses an application when opening a file (directory is a

This post includes the following content: * Create a certificate signing request (CSR) * Create your own certificate authority (CA) certificate to self-sign the CSR * Test the signed certificate with chrome and curl Part 1: Create a certificate signing request (CSR) Step 1: Create a private RSA key openssl genrsa -out server.

In this post, I will show 3 ways to use apt in a private server (a server that does not have direct internet access). Method 1: Download the .deb files and install them manually Adding  --print-uris to the apt command will print the URLs to download necessary .deb files. You

This post shows you how to SSH through a proxy server. Prerequisites The local client is required to have OpenBSD netcat installed. There are 2 versions of netcat. Traditional netcat and OpenBSD netcat. This tutorial explicitly requires OpenBSD netcat. Traditional netcat won't work. See their difference here. In macOS: # nc

Running (training) legacy machine learning models, especially models written for TensorFlow v1, is not a trivial task mostly due to the version incompatibility issue. This post will show the compatibility table with references to official pages. The general flow of the compatibility resolving process is * TensorFlow → Python * TensorFlow → Cudnn/Cuda

Initially, when you create a Kubernetes cluster in AWS (or we call EKS = Elastic Kubernetes Service), only the creator can have full access to the cluster. Other AWS users, even with the Administrator access of the AWS organization, can see the cluster name and several general configurations, but cannot access

You have your own AWS account (in your organization), and several accounts in client organizations. This post shows you how to manage all accesses in a single account. So that you do not have to log out and log in every time. Some values used in this post: * Your organization

Main entry: https://github.com/reactjs/rfcs/blob/react-18/text/0000-react-18.md (permanent link [https://github.com/reactjs/rfcs/blob/aa98d33b11b89461f310af244cee9a7bfbaff007/text/0000-react-18.md] ) To install: https://github.com/reactwg/react-18/discussions/9 Root API Main entry: https://github.com/reactwg/react-18/discussions/5 Legacy root exists for an easier

For security purposes, some browsers have a minimum font setting larger than zero by default in a specific condition. When your website has text with a font size smaller than 10px or 12px, you should expect that that text might be rendered as 10px (even you set it as smaller,

Server-side Mount new block storage to the server (optional) If you want to use existing storage in the server. This step can be skipped. # create new partition: # NOTE: this will erase existing data in the block storage parted -s /dev/vdb mklabel gpt parted -s /dev/vdb unit mib mkpart

There is a program running with the command python src/main.py (maybe in background). Now you want to find its PID and kill it in one command line. With pkill pkill -f "python src/main.py" By default, pkill / pgrep search for the process name (in this example, python)

TLDR; List all processes which are using any port. sudo netstat -tunlpa Sample output Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 127.0.0.1:42503 0.0.0.0:* LISTEN 867/containerd tcp 0 0 127.0.

Here are some facts regarding the specs of ES6 Promise (official specs doc) and the async/await (official doc) syntax, which comes with Quirk snippets. The Promise constructor 1. A promise can be resolved or rejected at most once. The subsequent calls to resolve/reject are no-op. console.log(await

It sometimes happens that although you have already set up your private/public key, you still cannot get connected to the remote server with ssh. In practice, there is an uncountable number of reasons: firewall, server configuration that restricts external access, ... The recommended method to find the reason is to

This article explains the order of the NULL value in the ORDER BY clause in sql, with reference to the official document for each dialect. The default behavior The following SQL dialects consider NULL as the largest value (the last position in ascending order of any value type): PostgreSQL, Oracle.

If you are using Python 3.9, you might get the following error when running the add-apt-repository command: Traceback (most recent call last): File "/usr/bin/add-apt-repository", line 191, in if not sp.add_source_from_shortcut(shortcut, options.enable_source): File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line

Many people have trouble with the AWS SDK for JavaScript v3's GetObjectCommand [https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-s3/classes/getobjectcommand.html] when trying to get Buffer output from s3. In this post, I will cover the reason why this happens, solutions and related information. This post

I summarize several useful Javascript/Typescript code snippets. * Get the last element from an array. Note: in the future, you can use Array Relative Indexing arr.at(-1) once the proposal is finalized. arr.slice(-1)[0] * Optional array element. [ cond && elm, // include elm only when cond is truthy elm1,

After releasing a website just within 2 weeks, my server is scanned with these URLs. I publish it here for my later reference and also hope that it helps others for a good beforehand protection. From a first server (hosted in AWS). /07-accessing-data/begin/vue-heroes/.env /07-accessing-data/end/vue-heroes/.env

I usually get confused when handling date datatype with databases, especially when connecting to the databases via libraries/drivers. In this post, I will summarize the results of their specification after my tests. Environment: * Node: v16.0.0. * Postgres nodejs driver: pg@8.6.0. * Mysqlite nodejs driver: sqlite3@5.

In this post, I will introduce how to create an Android application from the command line, without the help of any IDE such as Android Studio. If you are new to Android development, by following this post, I believe you will have a better understanding of how an Android application

To install KVM on Arch Linux, install the following packages: sudo pacman -S qemu virt-manager dnsmasq dmidecode vde2 Check if the qemu package added the kvm group. $ getent group | grep kvm kvm:x:992: Add your user to the kvm group with sudo usermod -aG kvm $USER. Then, reboot your

TLDR; Go to /Library/Developer/CoreSimulator/Profiles/Runtimes and delete your unused simulators. To quickly open the directory. There are 3 ways: * From the terminal, run open /Library/Developer/CoreSimulator/Profiles/Runtimes. * In Finder, press Cmd + shift + g, paste the directory path. * In Finder, select Go menu, select Go to