DEV Community: Md Asaduzzaman

Generate ssh-key, config and quick access server

Md Asaduzzaman — Mon, 16 Feb 2026 07:13:40 +0000

What we do?

Generate the New SSH Key
Copy the Public Key to the Server
Configure the SSH Client
Test the Connection

At a glance to see Diagram

To Do

1. Generate the New SSH Key (whithout passphrase)

ssh-keygen -t ed25519 -f ~/.ssh/id_rsa_deploy -N ""

2. Copy the Public Key to the Server

ssh-copy-id -i ~/.ssh/id_rsa_deploy.pub server-user@server-ip

Configure the SSH Client

Host deploy-server
    HostName server-ip
    User server-user
    IdentityFile ~/.ssh/id_rsa_deploy
    IdentitiesOnly yes

Test the Connection

ssh deploy-server

(Important): Fix permissions (if SSH refuses key)

Run these on your deployment machine:

chmod 700 ~/.ssh
chmod 600 ~/.ssh/deploy_key
chmod 644 ~/.ssh/deploy_key.pub
chmod 600 ~/.ssh/config

⭐ Bonus Point:

Securely copy file/folder from local to server

File copy from local to server:

scp file_name server_name_prod:/path_of_target_directory

// Example
scp index.html server_name1:/var/www/app1

Folder copy from local to server:

scp -r ./dist/* server_name_prod:/path_of_target_directory

HTTP STATUS CODE, you need to know for API Development

Md Asaduzzaman — Fri, 31 Oct 2025 01:54:21 +0000

HTTP status codes are 3-digit numbers returned by a web server to indicate the result of a client's request/response.

In API development choosing the right codes enhances clarity, debugging, and align with industry standard.

Why it Important?

Automated error handling in client applications
Proper caching behavior by intermediary servers
Meaningful monitoring and alerting in production systems
Better developer experience during integration

The Five Categories (1xx–5xx):

Informational responses (100 – 199)
Successful responses (200 – 299)
Redirection messages (300 – 399)
Client error responses (400 – 499)
Server error responses (500 – 599)

🟦 1xx – Informational

Code	Name	Description	Typical Use
100	Continue	Server has received the headers; client should continue.	Rarely used directly; used in chunked requests.
101	Switching Protocols	Server switches protocols as requested by the client.	WebSocket handshake upgrade.
102	Processing	WebDAV: server is processing but no response yet.	Long-running requests, WebDAV.
103	Early Hints	Suggests headers (like Link) before final response.	Performance optimizations (preload assets).

🟩 2xx – Success

Code	Name	Description	Typical Use
200	OK	Request succeeded; response depends on method.	GET returns resource; POST may return created resource.
201	Created	Resource successfully created.	POST /resources -> response includes Location header.
202	Accepted	Request accepted for processing, not completed.	Async operations queued.
203	Non-Authoritative Information	Returned meta-information modified from origin.	Proxy or transformation scenarios.
204	No Content	Success but no body returned.	Successful DELETE or PUT with no body response.
205	Reset Content	Client should reset the view.	HTML forms reset after a successful request.
206	Partial Content	Partial GET due to Range header.	Resuming downloads, media streaming.
207	Multi-Status	WebDAV; multiple separate responses.	Batch WebDAV operations.
208	Already Reported	WebDAV: members of a DAV binding already reported.	WebDAV multistatus optimization.
226	IM Used	Delta encoding; server fulfilled with a delta.	Rare: HTTP Delta encoding (RFC 3229).

🟨 3xx – Redirection

Code	Name	Description	Typical Use
300	Multiple Choices	Multiple representation options for the resource.	Content negotiation or choices page.
301	Moved Permanently	Resource moved permanently; update bookmarks.	Permanent redirects (SEO-friendly).
302	Found (Temporary Redirect)	Temporary redirect; user-agent may change method.	Temporarily redirecting resources.
303	See Other	Redirect using GET to retrieve result.	After POST, redirect to a GET-able result (PRG pattern).
304	Not Modified	Resource not modified; use cached copy.	Conditional GET with ETag/If-Modified-Since.
305	Use Proxy (deprecated)	Must use the proxy given in Location.	Deprecated — avoid using.
307	Temporary Redirect	Temporary redirect; method and body must not change.	Safer temporary redirect than 302 for non-GET methods.
308	Permanent Redirect	Permanent redirect; method and body preserved.	Permanent redirect that preserves method (replacement for 301).

🟥 4xx – Client Errors

Code	Name	Description	Typical Use
400	Bad Request	Malformed syntax or invalid request.	Validation errors, parse failures.
401	Unauthorized	Authentication required or failed.	Missing/invalid authentication token.
402	Payment Required	Reserved for future use.	Rarely used (some APIs use it for billing).
403	Forbidden	Server understood but refuses to authorize.	Valid auth but insufficient permissions.
404	Not Found	Resource not found.	Wrong URL, missing resource.
405	Method Not Allowed	Method not allowed for resource.	POST used where only GET allowed.
406	Not Acceptable	Content negotiation failed.	Requested content type not supported.
407	Proxy Authentication Required	Client must authenticate with proxy.	Requests through an authenticating proxy.
408	Request Timeout	Server timed out waiting for the request.	Large uploads interrupted or slow clients.
409	Conflict	Request could not be completed because of a conflict.	Versioning conflicts, duplicate unique fields.
410	Gone	Resource permanently removed.	Deleted resources that should not be requested again.
411	Length Required	Content-Length header required.	Servers requiring known-length requests.
412	Precondition Failed	One of the preconditions failed (If-Match, etc.).	Optimistic concurrency control (ETag mismatch).
413	Payload Too Large	Request entity too large.	Large file uploads exceeding limits.
414	URI Too Long	Request URI too long.	Overlong query strings or improperly built URLs.
415	Unsupported Media Type	Unsupported payload media type.	Sending XML to an API that accepts JSON only.
416	Range Not Satisfiable	Invalid Range header value.	Requesting byte ranges outside file length.
417	Expectation Failed	Server cannot meet Expect header.	Rare; related to Expect: 100-continue.
418	I'm a teapot	April Fools' joke (RFC 2324).	Easter-egg; not used in real APIs.
421	Misdirected Request	Server not able to produce response.	Requests routed incorrectly in multi-host setups.
422	Unprocessable Entity	Semantic errors in the request entity.	Validation errors with well-formed JSON.
423	Locked	Resource is locked (WebDAV).	Concurrency controls in WebDAV.
424	Failed Dependency	Operation failed due to earlier failure.	A step in a multi-step request failed.
425	Too Early	Server reluctant to process early data.	Protect against replay attacks (experimental).
426	Upgrade Required	Client should switch protocols.	Require TLS or a different protocol.
428	Precondition Required	Require preconditions (e.g., If-Match).	Prevent lost updates by requiring ETags.
429	Too Many Requests	Rate limiting; client should slow down.	API throttling; include Retry-After header.
431	Request Header Fields Too Large	Headers too large to process.	Oversized cookies or headers.
451	Unavailable For Legal Reasons	Resource unavailable due to legal reasons.	Geo-blocking or court-ordered takedown.

⛔ 5xx – Server Errors

Code	Name	Description	Typical Use
500	Internal Server Error	Generic server error.	Unhandled exceptions, server crashes.
501	Not Implemented	Server does not support requested functionality.	Feature not implemented on server.
502	Bad Gateway	Invalid response from upstream server.	Reverse proxy or gateway error.
503	Service Unavailable	Server overloaded or down for maintenance.	Temporary downtime; include Retry-After.
504	Gateway Timeout	Upstream server timed out.	Slow upstream service causing timeout.
505	HTTP Version Not Supported	HTTP version not supported by server.	Rare in modern APIs.
506	Variant Also Negotiates	Server configuration error in content negotiation.	Rare; indicates misconfiguration.
507	Insufficient Storage	WebDAV: insufficient storage.	Servers running out of storage for the request.
508	Loop Detected	WebDAV: infinite loop detected.	Misconfigured resource references.
509	Bandwidth Limit Exceeded (non-standard)	Informational; not an official status.	Some servers/providers use this for bandwidth caps.
510	Not Extended	Further extensions required to fulfill request.	Rare; extension negotiation needed.
511	Network Authentication Required	Client needs to authenticate to gain network access.	Captive portal or network auth required.

Conclusion:

HTTP status codes are not just numbers—they are a language between the front-end and back-end. A well-designed API should use them properly to communicate intent, success, or failure. This improves both developer experience and debuggability.

Why Angular? Kickstart Your Journey in 2025

Md Asaduzzaman — Thu, 02 Oct 2025 01:56:07 +0000

Why Angular? Kickstart Your Journey in 2025

Angular is not just another JavaScript framework—it’s a complete ecosystem for building modern web and mobile applications.

If you’re looking to level up as a developer in 2025, Angular gives you the tools, structure, and scalability you need.

What We’ll Cover

Why Angular is worth learning in 2025
How Angular sets you apart as a developer
The bonus: one skill for both web and mobile (Ionic)
A quick "Hello Angular" example

Why Angular?

Complete Framework: Everything you need—routing, forms, HTTP, state, testing—is built-in.
Enterprise Ready: Trusted by Google and used in large-scale apps worldwide.
Scalable by Design: From small projects to enterprise solutions, Angular’s modularity shines.
Consistent Updates: Angular 20 (latest version) brings modern features like zoneless apps and performance boosts.
One Skill, Two Platforms: Learn Angular once, and you can build web apps and hybrid mobile apps with Ionic.

Quick Example: Hello Angular Component

Here’s how simple it is to create your first Angular component:

import { Component } from '@angular/core';

@Component({
  selector: 'app-hello',
  template: `<h1>Hello Angular </h1>`
})
export class HelloComponent {}

Conclusion

Angular is more than a framework—it’s a career investment.
Whether you’re building enterprise web apps or mobile apps with Ionic, Angular keeps you future-proof in 2025 and beyond.

📌 Next article in the series: Project Setup & Clean Folder Structure

Deep learning about DNS records!

Md Asaduzzaman — Mon, 22 Sep 2025 09:21:56 +0000

🌍 DNS & VPS Setup Guide (Example: `plabonasad.xyz`)

When you purchase a domain and a VPS hosting, you need to connect them.

This is done using DNS records and configuring your VPS (like Nginx/Apache).

This guide is brief, step-by-step, and developer-friendly.

📖 Quick Overview: DNS Records

DNS is like the phonebook of the internet.

It tells the browser or mail server where to go when someone uses your domain.

Common DNS Records

Record	Purpose	Example
A	Points domain → IPv4 address	`plabonasad.xyz → 123.45.67.89`
AAAA	Points domain → IPv6 address	`plabonasad.xyz → 2606:4700:4700::1111`
MX	Directs emails → mail server	`@ MX 10 mail.google.com`
CNAME	Points domain → another domain	`www → plabonasad.xyz`
TXT	Stores text (for verification & security)	`"v=spf1 include:_spf.google.com ~all"`

👉 For website setup, the A record is the most important (connects your domain → VPS IP).

🚀 Step 1: Get Your VPS Public IP

Example: 123.45.67.89

🚀 Step 2: Set DNS Records

Go to your domain registrar DNS settings (where you bought plabonasad.xyz).

Add the following records:

Type	Name	Value	Purpose
A	@	123.45.67.89	Root domain → VPS
A	www	123.45.67.89	www → VPS

👉 This means:

plabonasad.xyz → goes to your VPS
www.plabonasad.xyz → goes to your VPS

🌍 Overview Flow (Diagram)

User Browser (plabonasad.xyz)
          |
          v
   DNS Lookup (A Record → 123.45.67.89)
          |
          v
       VPS Server
          |
          v
      Nginx/Apache
          |
          v
     Your Website

🚀 Step 3: Configure Nginx on VPS

SSH into your VPS:

ssh username@123.45.67.89

Create a config for your domain:

sudo nano /etc/nginx/sites-available/plabonasad.xyz

Copy nginx config code:

# Redirect everything to https://plabonasad.xyz
server {
    listen 80;
    server_name www.plabonasad.xyz;
    return 301 https://plabonasad.xyz$request_uri;
}

# Main site (canonical domain)
server {
    listen 80;
    server_name plabonasad.xyz;

    root /var/www/app1/public;
    index index.php index.html;

    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/run/php/php8.2-fpm.sock;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include fastcgi_params;
    }

    location ~ /\.ht {
        deny all;
    }
}

Enable the site by symlink:

sudo ln -s /etc/nginx/sites-available/plabonasad.xyz /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx

Step 4: Test DNS

Check if your domain points to the VPS:

dig plabonasad.xyz

Or use dnschecker.org

Step 5: Secure with SSL (Optional but Recommended)

Install Certbot:

sudo apt install certbot python3-certbot-nginx -y

Run:

sudo certbot --nginx -d plabonasad.xyz -d www.plabonasad.xyz

Now your site will load with HTTPS 🔒.

Final Notes

A record connects domain → server IP
Nginx/Apache serves the website from VPS
SSL (Certbot) secures with HTTPS
Other records (MX, CNAME, TXT) are useful for email & verification

Now when someone types plabonasad.xyz, they’ll reach your VPS-hosted site 🎉.

Redis Basics – Getting Started and Core Data Structures

Md Asaduzzaman — Thu, 18 Sep 2025 02:13:40 +0000

Redis is more than just a cache—it’s a powerful in-memory data store that supports real-time apps, queues, leaderboards, and more.

In this beginner-friendly guide, we’ll cover how to:
✅ Set up Redis locally or with Docker
✅ Use Redis CLI for quick testing
✅ Work with core data structures (Strings, Hashes, Lists, Sets, Sorted Sets)

🚀 Setup & Basics
Start Redis

Start Redis (local)

redis-server

Run with Docker
docker run --name redis -p 6379:6379 -d redis

Open Redis CLI
redis-cli

Test Connection

PING
# PONG

📦 Core Data Structures
🔹 Strings

SET name "Asad"
GET name
INCR counter

Use cases: counters, sessions, caching simple values.

Diagram:

key    →   value
----------------
name   →   "Asad"
counter →   1

🔹 Hashes

HSET user:1 name "Asad" age "25"
HGETALL user:1

Use cases: store JSON-like objects (e.g., user profiles).

Diagram:

user:1
 ├── name → "Asad"
 └── age  → "25"

🔹 Lists

LPUSH tasks "task1"
RPUSH tasks "task2"
LPOP tasks

Use cases: queues (FIFO), stacks (LIFO).

Diagram (FIFO Queue):

[ task1 ] → [ task2 ] → [ task3 ]

🔹 Sets
SADD tags "redis" "database" "cache"
SMEMBERS tags

Use cases: unique collections (tags, categories, followers).

Diagram:

tags = { "redis", "database", "cache" }

🔹 Sorted Sets
ZADD scores 100 "Asad" 200 "Plabon"
ZRANGE scores 0 -1 WITHSCORES

Use cases: leaderboards, rankings, priority queues.

Diagram:

+------+---------+
|User | Score |
+------+---------+
|Asad | 100 |
|Plabon| 200 |

✅ Wrap-Up

That’s the foundation of Redis. With just a few commands, you can build counters, queues, and ranking systems.

👉 In the next article, we’ll go deeper into advanced Redis concepts like Pub/Sub, Streams, persistence, clustering, and real-world AI use cases.

VPS Server Setup for Any Application (with Easy Deployment Flow)

Md Asaduzzaman — Thu, 18 Sep 2025 01:53:08 +0000

When you get a fresh VPS, the first question is: How do I set it up so I can deploy multiple apps easily?
In this guide, I’ll walk you through a full flow setup that works for Laravel, Node.js, Ruby on Rails, or almost any stack.

We’ll use:

OS: Ubuntu 22.04 LTS
Web Server: Nginx
Process Managers: php-fpm (for PHP), pm2 (for Node.js)
Database: MySQL/MariaDB or PostgreSQL
SSL: Let’s Encrypt (Certbot)
SSH Keys: For secure access

What You’ll Learn

By the end of this article, you’ll know how to:
✅ Add SSH access to your VPS
✅ Organize multiple apps on the same server
✅ Manage multiple PHP and Node.js versions
✅ Set up domains and subdomains with Nginx
✅ Secure apps with Let’s Encrypt SSL
✅ Deploy apps with a simple Git + build flow

Requirements

Before we start, make sure you have:

A VPS + a domain

Basic Linux knowledge (cd, nano, systemctl, etc.)

SSH key configured for secure login

Some familiarity with Nginx

At least one project (Laravel, Node.js, or Rails) to deploy

Directory Structure

We’ll keep all projects under /var/www/ for organization. This makes it easy to manage multiple apps on the same server.

/var/www/
   ├── laravel-app1/
   │     └── public/   # Laravel public folder
   ├── laravel-app2/
   │     └── public/
   ├── node-app1/
   ├── node-app2/

Version Management

Since different projects often require different versions, we’ll use:

php-fpm for multiple PHP versions

NVM for multiple Node.js versions

4.1 PHP

Install multiple PHP versions (7.4, 8.1, 8.2, etc.) with php-fpm.
Each app points to its own PHP socket:

Laravel App1 → PHP 8.1 → /run/php/php8.1-fpm.sock

Laravel App2 → PHP 8.2 → /run/php/php8.2-fpm.sock

Nginx will route each site to the right PHP version.

4.2 Node.js

Use NVM to install the Node.js version your project needs.

Use PM2 to keep apps running in the background.

Nginx will reverse-proxy to the correct port:

node-app1.yourdomain.com → localhost:3001

node-app2.yourdomain.com → localhost:3002

Domain & Subdomains

Point your DNS records to your VPS IP:

app1.yourdomain.com → VPS IP
app2.yourdomain.com → VPS IP
node1.yourdomain.com → VPS IP
node2.yourdomain.com → VPS IP

On the server, create Nginx configs for each app:

/etc/nginx/sites-available/
├── laravel-app1.conf
├── laravel-app2.conf
├── node-app1.conf
├── node-app2.conf

Then symlink them to sites-enabled/:

sudo ln -s /etc/nginx/sites-available/laravel-app1.conf /etc/nginx/sites-enabled/

SSL Certificates

Use Let’s Encrypt with Certbot:

Free SSL for each domain/subdomain

Auto-renew every 90 days

Works directly with Nginx

sudo certbot --nginx -d app1.yourdomain.com -d www.app1.yourdomain.com

Deployment Flow

Here’s the simple deployment workflow you can follow for each project:

Push your code to GitHub.

SSH into your VPS.

Clone or pull the project from GitHub.

Install dependencies:

Laravel → composer install && npm run build

Node.js → npm install && pm2 restart

Run migrations/seeds if needed.

Since Nginx + SSL are already set up, the app goes live instantly. 🚀

✅ Conclusion

With this setup, your VPS becomes a multi-app hosting machine.

PHP apps run side by side with Node.js apps.

Each project has its own domain/subdomain, SSL, and process manager.

Deployment is as easy as git pull && build.

This gives you the flexibility of a PaaS (like Heroku or Vercel) but with the full control of a VPS.

DEV Community: Md Asaduzzaman

Generate ssh-key, config and quick access server

What we do?

At a glance to see Diagram

To Do

1. Generate the New SSH Key (whithout passphrase)

2. Copy the Public Key to the Server

(Important): Fix permissions (if SSH refuses key)

⭐ Bonus Point:

Securely copy file/folder from local to server

HTTP STATUS CODE, you need to know for API Development

Why it Important?

🟦 1xx – Informational

🟩 2xx – Success

🟨 3xx – Redirection

🟥 4xx – Client Errors

⛔ 5xx – Server Errors

Conclusion:

Why Angular? Kickstart Your Journey in 2025

Why Angular? Kickstart Your Journey in 2025

What We’ll Cover

Why Angular?

Quick Example: Hello Angular Component

Conclusion

📌 Next article in the series: Project Setup & Clean Folder Structure

Deep learning about DNS records!

🌍 DNS & VPS Setup Guide (Example: plabonasad.xyz)

📖 Quick Overview: DNS Records

Common DNS Records

🚀 Step 1: Get Your VPS Public IP

🚀 Step 2: Set DNS Records

🌍 Overview Flow (Diagram)

🚀 Step 3: Configure Nginx on VPS

Step 4: Test DNS

Step 5: Secure with SSL (Optional but Recommended)

Final Notes

Redis Basics – Getting Started and Core Data Structures

Start Redis (local)

VPS Server Setup for Any Application (with Easy Deployment Flow)

🌍 DNS & VPS Setup Guide (Example: `plabonasad.xyz`)