Install telnet, 텔넷 설치하기

To install telnet on a Linux system, follow the steps based on the distribution you are using. Telnet is generally available in most distribution repositories but may need to be installed manually.

1. For Debian/Ubuntu-based systems

These instructions are for distributions such as Ubuntu, Debian, and Linux Mint.

  1. Update the package list:

    sudo apt update

  2. Install the telnet package:

    sudo apt install telnet

  3. Verify the installation:

    telnet --version

2. For CentOS/RHEL-based systems

These instructions apply to CentOS, Red Hat Enterprise Linux (RHEL), and Fedora.

  1. Update the package list:

    sudo yum update

  2. Install the telnet package:

    sudo yum install telnet

  3. Verify the installation:

    telnet

3. For Fedora

On Fedora systems, use the dnf package manager.

  1. Update the package list:

    sudo dnf update

  2. Install the telnet package:

    sudo dnf install telnet

  3. Verify the installation:

    telnet --version

4. For Arch-based systems

For Arch Linux or Manjaro, use the pacman package manager.

  1. Update the package list:

    sudo pacman -Sy

  2. Install the inetutils package, which includes telnet:

    sudo pacman -S inetutils

  3. Verify the installation:

    telnet

Usage Example

To use telnet, you can simply type:

telnet <hostname or IP> <port>

For example, to connect to a web server on port 80:

telnet example.com 80

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Using the MinIO API via curl

Using the MinIO API via curl is straightforward, as MinIO is compatible with Amazon S3 API, so most commands follow a similar syntax. Here’s a guide on how to use curl with the MinIO API for some common operations like uploading, downloading, and managing objects. Prerequisites Access Key and Secret Key : Obtain your MinIO Access Key and Secret Key. MinIO Endpoint : Know your MinIO server endpoint, e.g., http://localhost:9000 . Bucket : You may need an existing bucket name, or create a new one using the commands below. Authentication Header For requests to work with MinIO, you need to include authentication in the headers. MinIO uses AWS Signature Version 4 for signing requests. Common Examples 1. List Buckets To list all buckets in your MinIO account, use: curl -X GET \ - -url "http://localhost:9000/" \ - H "Authorization: AWS <AccessKey>:<Signature>" 2. Create a Bucket To create a new bucket, use: curl -X PUT \ - -url "htt...
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vsftpd default directory

The default directory for FTP users in vsftpd depends on how the FTP server is configured and the user’s home directory setup. Below are different configurations and their impact on the default directory that users are placed in when they connect to the server. 1. Default Directory Behavior with vsftpd When a user logs in via FTP, they are typically placed in their home directory . By default, the home directory is located at /home/<username> , where <username> is the name of the FTP user. For example: If the FTP user is ftpuser , the default login directory will be /home/ftpuser/ . 2. Changing the Default Directory for Users A. Using local_root Configuration You can specify a custom directory (other than the user’s home directory) for FTP users by setting the local_root parameter in the vsftpd configuration file. Open the vsftpd configuration file: sudo nano /etc/ vsftpd.conf Add the following line to specify a new directory for all FTP users: lo...
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[Ubuntu] *.deb 파일 설치 방법

확장자가 .deb 인 파일은 원래 Debian 리눅스에서의 설치파일입니다. Ubuntu 는 원래 Debian 리눅스에서 파생되었기 때문에, 많은 부분에서 서로 닮아 있습니다. 따라서 별다른 변환 절차 없이 아래와 같이 바로 설치가 가능합니다. [user@hostname]# sudo dpkg -i *.deb *.rpm 파일을 *.deb 파일로 변환 [user@hostname]$ sudo apt-get install alien [user@hostname]$ sudo alien -c *.rpm
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Offset out of range error in Kafka, 카프카 트러블슈팅

The "Offset out of range" error in Kafka typically occurs when a consumer tries to read an offset that no longer exists on the broker. This can happen for several reasons, such as: The offset is smaller than the earliest offset available for the topic partition (i.e., the messages have been deleted due to log retention policies). The offset is larger than the latest offset available for the topic partition (i.e., the consumer is trying to read beyond the latest message). Steps to Resolve "Offset Out of Range" Error 1. Check Current Offsets Before making changes, it's useful to understand the current offsets and the offset range available for the topic partitions. Use the kafka-consumer-groups.sh script to describe the consumer group: bin/kafka-consumer-groups.sh --bootstrap- server localhost: 9092 --describe -- group <consumer- group -id> This command will show the current offsets, log end offsets, and the lag for each partition. 2. Reset the...
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리눅스 (cron - 주기적 작업실행 데몬)

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리눅스 (하드링크&소프트링크)

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CDPEvents in puppeteer

In Puppeteer , CDPEvents refers to events emitted by the Chrome DevTools Protocol (CDP) . Puppeteer leverages CDP to interact with and control a Chromium-based browser. CDP provides detailed, low-level access to browser internals, such as network traffic, console logs, page lifecycle events, and more. You can listen to these CDP events through Puppeteer’s API to monitor or intercept browser activity. How to Listen for CDP Events in Puppeteer Enable the Required CDP Domain: Some events require enabling a particular domain (e.g., 'Network' , 'Page' , 'Runtime' ). Use page._client() to Access the CDP Session: Although it’s a bit lower-level, Puppeteer allows access to DevTools through the page._client() API. Example: Listening for Network Requests This example demonstrates how to intercept and log network requests using CDP. const puppeteer = require( 'puppeteer' ); ( async () => { const browser = await puppeteer.launch({ headless...
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Using venv in Python

Using venv in Python allows you to create a virtual environment, which is an isolated environment to manage dependencies for a specific project. Here's how you can use it step by step: 1. Create a Virtual Environment Open your terminal or command prompt. Navigate to the folder where you want to create the virtual environment. Run the following command: python -m venv myenv Replace myenv with the name you want for your virtual environment. This will create a directory named myenv containing the virtual environment. 2. Activate the Virtual Environment Activation depends on your operating system: On Windows : myenv \S cripts \a ctivate On macOS/Linux : source myenv /bin/ activate After activation, your terminal prompt will change, showing the name of the virtual environment (e.g., (myenv) ). 3. Install Dependencies With the virtual environment activated, you can now install packages using pip : pip install package _n ame For example: pip install req...
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