Common Network Ports Reference — TCP/UDP Port Numbers Explained

Free Tools

🔐

JWT Decoder

Decode JSON Web Tokens securely in your browser with header/payload highlighting and expiration check.

#️⃣

Hash Generator

SHA-256, SHA-512, and SHA-1 cryptographic hashing using browser SubtleCrypto API.

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Password Generator

Cryptographic high-entropy passwords, API tokens, and secure passphrases.

🛡️

Password Strength Checker

Test password security privately. Calculates entropy bits, estimated crack time, and weakness flags.

🕸️

Subnet & CIDR Calculator

Calculate IPv4 subnet masks, CIDR notation, network address, broadcast address, and host ranges.

🌍

What is My IP?

Find your public IP address, ISP details, geographic location, and user-agent string.

⚡

cURL to Code Converter

Convert cURL commands to Python Requests, JavaScript Fetch, Axios, Go, and PHP code.

🌐

REST API Tester

Lightweight, browser-based HTTP client. Send GET, POST, PUT, DELETE requests and inspect JSON responses.

🔍

Regex Tester & Explainer

Test, debug, and break down Regular Expressions (Regex) in real-time with regex match highlighting.

🔍

Error Analyzer

Paste an error message and get a deterministic diagnosis with likely causes and next steps. No AI, nothing sent to a server.

📚

HTTP Status Codes Directory

Searchable dictionary of HTTP status codes (1xx - 5xx) with troubleshooting guides and RFC standards.

🛡️

Chmod Calculator

Interactive Linux file permission calculator. Converts octal (755, 644) and symbolic permissions.

⏰

Cron Parser & Visualizer

Translate crypted cron expressions into human-readable English with next run schedule preview.

✨

JSON Formatter & Validator

Beautify, validate, format, sort keys, and minify JSON strings with real-time error syntax markers.

💾

SQL Formatter

Format and indent messy SQL queries across PostgreSQL, MySQL, SQLite, and Transact-SQL.

🔄

YAML ↔ JSON Converter

Convert configuration files seamlessly between YAML and JSON with instant syntax validation.

⚛️

SVG to React JSX / TSX

Clean inline SVG code and convert to React JSX, TypeScript TSX, or Vue 3 components.

📦

Base64 Codec

Convert UTF-8 text and binary to Base64 or Hex encoding and decode back in real-time.

🔗

URL Codec & Query Parser

Percent-encode and decode URIs with an interactive query-parameter key/value breakdown table.

🆔

UUID / GUID Generator

Generate cryptographically secure UUID v4 (Random) and v7 (Time-Ordered) IDs in bulk.

🎨

Code to Image Converter

Export code snippets into gorgeous dark-mode screenshots for presentation slides and LinkedIn.

⏱️

Unix Timestamp Converter

Convert Unix epoch timestamps to human-readable dates, local time, and UTC standard.

🌍

Timezone Converter

Coordinate global team meeting hours across timezones with an interactive slider control.

🎨

Color Converter

Convert colors instantly between HEX, RGB, HSL, and CMYK format strings for web styling.

🧮

Scientific Calculator

Browser-based calculator supporting trigonometric functions, logarithms, powers, and roots.

🎂

Age Calculator

Calculate exact age in years, months, and days from any birth date, plus total days lived and days to your next birthday.

％

Percentage Calculator

Find what percent X is of Y, calculate percentage increase/decrease, or find a value from a percentage.

📐

Unit Converter

Convert length, weight, temperature, and digital storage units (bytes to GB/TB) instantly.

📝

Word & Character Counter

Count words, characters, sentences, paragraphs, and reading time in real-time.

🔠

Text Case Converter

Convert text strings to UPPERCASE, lowercase, Title Case, camelCase, snake_case, and Kebab-Case.

⚖️

Text Diff Checker

Compare two text files or code snippets to highlight line-by-line additions, deletions, and changes.

📈

Meta Tag Generator

Generate optimized HTML meta tags for Google Search, Facebook Open Graph, and Twitter Cards.

🤖

Robots.txt Generator

Build valid robots.txt files to manage search engine crawler access and allow/block specific bots.

🗺️

XML Sitemap Generator

Generate structured XML sitemaps ready for Google Search Console submission.

📝

Schema Markup Generator

Generate valid JSON-LD schema markup for Articles, FAQs, Organizations, and Products.

Blog

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The Complete AI Prompt Engineering Guide: Master ChatGPT, Claude & Gemini

Master prompt engineering with proven frameworks: Chain-of-Thought, Few-Shot, CARE, and RTF. Copy high-impact prompts for coding, debugging, SEO writing, and learning.

📝

What is Artificial Intelligence? A Complete Beginner's Guide

Learn what AI is, how it works, types of AI, real-world examples, and how AI is changing every industry.

📝

Python Tutorial for Beginners: Learn Python (Step-by-Step)

The ultimate Python tutorial for absolute beginners. Syntax, data types, functions, OOP, and real projects.

📝

What is Cloud Computing? Types, Examples & Benefits Guide)

Understand IaaS, PaaS, SaaS, public vs private vs hybrid clouds, top providers, and real-world use cases.

📝

Top 50 Git Commands Every Developer Must Know

The complete Git cheat sheet — branching, merging, rebasing, stashing, undoing mistakes, and advanced workflows.

📝

What is Docker? Containers Explained for Beginners

Learn Docker from scratch — containers vs VMs, Dockerfile, Docker Compose, key commands, and production best practices.

📝

Cybersecurity Basics: How to Protect Yourself Online

Common threats, password security, 2FA, VPNs, encryption, phishing, and developer security best practices.

📝

How to Learn Web Development: Complete Roadmap

Step-by-step roadmap from HTML/CSS/JS beginner to full-stack developer with React, Node.js, and deployment.

📝

20 Hidden Windows Features You're Probably Not Using

20 real, built-in Windows 10/11 features hiding in plain sight — God Mode, Snap Layouts, Clipboard History, Storage Sense, PowerToys, and more.

📝

25 Free Websites Every Student Should Bookmark

25 genuinely free, well-known websites for students — learning platforms, research tools, productivity apps, and more.

📝

30 Keyboard Shortcuts That Will Save You Hours

30 real, verifiable keyboard shortcuts for Windows, macOS, and browsers that noticeably speed up everyday computer use.

Linux Course

🐧

Linux: Linux Fundamentals

What Linux actually is, the kernel, distributions, and how a command becomes hardware activity.

⌨️

Linux: Command Line

The shell, navigation, environment variables, and how command syntax actually works.

📁

Linux: Filesystem

The Linux directory hierarchy, links, inodes, and everyday file operations.

🔐

Linux: Users & Permissions

Users, groups, sudo, and the permission model that protects every file on the system.

⚙️

Linux: Processes & Services

PIDs, signals, systemd units, and keeping services alive.

📦

Linux: Package Management

apt/dpkg on Debian-family systems, dnf/rpm on RHEL-family systems — never treated as identical.

🌐

Linux: Networking

TCP/IP, routing, DNS, ports, and the tools to inspect and fix all of it.

💽

Linux: Storage & LVM

Disks, partitions, filesystems, and Logical Volume Management end to end.

🔑

Linux: SSH & Remote Administration

Key-based auth, sshd hardening, and administering machines you can’t touch.

🧱

Linux: Firewalls

firewalld and ufw, zones, ports, and nftables underneath both.

🛡️

Linux: SELinux & AppArmor

Mandatory access control on RHEL and Ubuntu, and why "just disable it" is the wrong fix.

📊

Linux: Logging & Monitoring

journald, rsyslog, log rotation, and reading logs to find the actual root cause.

📜

Linux: Bash Scripting

Variables, loops, functions, and error handling — building real automation, not one-liners.

🖥️

Linux: Web Servers

Nginx and Apache: virtual hosts, reverse proxying, and production configuration.

🔒

Linux: TLS/SSL

Certificates, keys, CSRs, and OpenSSL — how HTTPS actually gets built.

📦

Linux: Containers

Docker and Podman: images, namespaces, cgroups, and what isolation really means.

🌿

Linux: Git

Version control for the configuration and scripts a sysadmin actually owns.

🤖

Linux: Ansible

Inventories, playbooks, and automating many servers instead of SSHing into each one.

☁️

Linux: Cloud Linux Administration

Running and administering Linux on Azure and AWS — where cloud services end and Linux begins.

🔏

Linux: Linux Security & Hardening

A practical, distro-aware hardening checklist for real production servers.

🧭

Linux: Troubleshooting

Symptom → cause → command → fix → verify → prevent, for the failures you’ll actually hit.

🏗️

Linux: Real-World Projects

End-to-end builds: web servers, storage architecture, monitoring, hardened bastion hosts.

🎓

Linux: RHCSA Preparation

Mapping general Linux knowledge to current RHCSA objectives — practice, not a guarantee.

💼

Linux: Linux Interview Preparation

Real operational interview questions across admin, cloud, DevOps, and security roles.

Error Encyclopedia

🛑

Cloudflare Error 520: Web Server Returns an Unknown Error

Cloudflare received an empty, reset, or otherwise unparseable response from your origin server.

🛑

Cloudflare Error 521: Web Server Is Down

Cloudflare cannot establish a connection to your origin server at all — it's actively refusing connections.

🛑

Cloudflare Error 522: Connection Timed Out

Cloudflare's connection attempt to your origin server timed out — the server is reachable at the network level but not responding in time.

🛑

Cloudflare Error 525: SSL Handshake Failed

Cloudflare could not complete an SSL/TLS handshake with your origin server.

🛑

Cloudflare Error 526: Invalid SSL Certificate

Cloudflare completed the SSL handshake but the origin's certificate failed validation under "Full (strict)" mode.

🛑

Windows Error 0x80070005: Access Denied

A permissions error — Windows denied access to a file, registry key, or service needed to complete the operation.

🛑

Windows Error 0x8007000E: Out of Memory or System Resources

Windows Update (or another operation) ran out of memory or system resources mid-process.

🛑

Windows Error 0x80070643: Update Installation Failed

A generic Windows Update or MSI installer failure, most commonly tied to .NET Framework updates.

🛑

Windows Error 0x80070002: The System Cannot Find the File Specified

Windows Update (or another process) couldn't find a file it expected to exist.

🛑

Git Error: Permission denied (publickey)

The remote Git server (GitHub, GitLab, etc.) rejected your SSH key — either none was offered, or the one offered isn't authorized.

🛑

Git Error: refusing to merge unrelated histories

Git detected two branches with no common commit ancestor and, by default, refuses to merge them without explicit confirmation.

🛑

Git Error: failed to push some refs (non-fast-forward)

The remote branch has commits your local branch doesn't have — Git refuses to push until you incorporate them first.

🛑

Git: You Are in "Detached HEAD" State

You've checked out a specific commit directly instead of a branch — new commits here won't belong to any branch unless you create one.

🛑

Docker Error: Cannot Connect to the Docker Daemon

The docker CLI can't reach the Docker daemon (dockerd) — usually because it isn't running, or your user lacks permission to access its socket.

🛑

Docker Error: Port Is Already Allocated

A container failed to start because the host port you're trying to map is already in use by another process or container.

🛑

Docker Error: No Space Left on Device

Docker has run out of disk space — usually from accumulated unused images, stopped containers, and build cache, not the disk itself being full.

🛑

Kubernetes Error: CrashLoopBackOff

A container in the pod is starting, crashing, and being restarted repeatedly, with Kubernetes applying an increasing delay between attempts.

🛑

Kubernetes Error: ImagePullBackOff

Kubernetes cannot pull the container image specified in the pod spec — usually a wrong image name/tag, or missing registry credentials.

🛑

Kubernetes Pod Stuck in Pending State

The pod has been accepted by the cluster but the scheduler can't find a node with enough resources (or matching constraints) to place it on.

🛑

DNS Error: NXDOMAIN (Non-Existent Domain)

The DNS server successfully responded, but confirmed the requested domain name does not exist in DNS at all.

🛑

DNS Error: SERVFAIL

The DNS server encountered an internal error and could not process the query — distinct from NXDOMAIN, which is a definitive "doesn't exist" answer.

AI Tools Directory

🤖

ChatGPT

OpenAI's general-purpose conversational AI assistant — writing, brainstorming, coding help, image generation (DALL-E), and data analysis in one interface.

🤖

Claude

Anthropic's conversational AI assistant, commonly used for long-form writing, document analysis, and coding assistance with a focus on careful, structured responses.

🤖

Google Gemini

Google's conversational AI assistant, integrated with Google's search and Workspace ecosystem for research, writing, and productivity tasks.

🤖

Perplexity

An AI-powered answer engine that searches the web in real time and provides cited, sourced answers rather than a single unsourced response.

🤖

GitHub Copilot

An AI pair-programming tool integrated into code editors (VS Code, JetBrains, and others) that suggests code completions and can answer questions about your codebase.

🤖

Cursor

An AI-native code editor (a fork of VS Code) built around AI-assisted editing, multi-file code generation, and codebase-aware chat.

🤖

Midjourney

An AI image generation tool known for stylized, artistic output, historically accessed primarily through Discord and now also via a web interface.

🤖

Adobe Firefly

Adobe's generative AI image and design tool, integrated into Photoshop, Illustrator, and available as a standalone web app, trained with a focus on commercially-safe usage.

🤖

Canva (Magic Studio)

Canva's suite of AI-assisted design features — including AI image generation, background removal, and text-to-design tools — built into its existing design platform.

🤖

ElevenLabs

An AI voice generation platform for realistic text-to-speech, voice cloning, and dubbing, commonly used for narration, audiobooks, and video voiceovers.

🤖

Otter.ai

An AI meeting assistant that transcribes conversations in real time and generates searchable notes and summaries.

🤖

Runway

An AI video generation and editing platform, including text-to-video and image-to-video generation alongside more traditional AI-assisted editing tools.

🤖

Synthesia

An AI video generation platform focused on AI avatar presenters — turning a text script into a video of a talking AI avatar, commonly used for training and explainer videos.

🤖

Grammarly

An AI-powered writing assistant that checks grammar, spelling, tone, and clarity, integrated as a browser extension and app across many writing surfaces.

🤖

Notion AI

AI features built directly into the Notion workspace app — drafting, summarizing, translating, and Q&A over your own Notion pages.

Certifications

🎩

RHCSA — Red Hat Certified System Administrator

An entry-to-intermediate Linux administration certification focused on genuinely being able to configure and troubleshoot a RHEL system, not recognize terminology.

🎩

RHCE — Red Hat Certified Engineer

A more advanced Red Hat certification that requires holding RHCSA first (or passing it as a prerequisite alongside), with a strong focus on automating system administration tasks using Ansible.

☸️

CKA — Certified Kubernetes Administrator

Validates the ability to administer a Kubernetes cluster — installation, configuration, troubleshooting, and day-to-day cluster operations.

☸️

CKAD — Certified Kubernetes Application Developer

Validates the ability to design, build, and deploy applications for Kubernetes, from a developer's perspective rather than a cluster administrator's.

☸️

CKS — Certified Kubernetes Security Specialist

An advanced, security-focused Kubernetes certification requiring CKA as a prerequisite, covering hardening a cluster and its workloads against real attack scenarios.

☁️

AZ-900 — Microsoft Certified: Azure Fundamentals

An entry-level, vendor-neutral-in-spirit certification covering core cloud concepts and how they map to Azure specifically — no hands-on lab component.

☁️

AZ-104 — Microsoft Certified: Azure Administrator Associate

A role-based certification for administrators who manage Azure resources day to day — identity, storage, compute, and networking.

☁️

AZ-500 — Microsoft Certified: Azure Security Engineer Associate

A security-focused Azure certification covering identity/access, platform protection, security operations, and data/application security within Azure.

☁️

AWS Cloud Practitioner — AWS Certified Cloud Practitioner

AWS's entry-level, foundational certification covering core AWS concepts, services, and billing — the AWS equivalent of Azure's AZ-900 in scope and audience.

☁️

AWS SAA — AWS Certified Solutions Architect – Associate

One of the most widely recognized cloud certifications, focused on designing well-architected, cost-effective, resilient solutions on AWS.

🔐

Security+ — CompTIA Security+

A widely recognized, vendor-neutral entry point into cybersecurity, covering security fundamentals across networks, threats, cryptography, and governance.

🌐

Network+ — CompTIA Network+

A vendor-neutral networking fundamentals certification, commonly paired with or taken before Security+.

Network Ports

🔌

Port 20 — FTP (Data)

File Transfer Protocol data channel, used alongside port 21 for the actual file transfer in active mode.

🔌

Port 21 — FTP (Control)

File Transfer Protocol control channel, used to establish and manage an FTP session.

🔌

Port 22 — SSH

Secure Shell — encrypted remote login, command execution, and file transfer (via SCP/SFTP) to a server.

🔌

Port 23 — Telnet

Unencrypted remote terminal protocol, largely obsolete for security reasons.

🔌

Port 25 — SMTP

Simple Mail Transfer Protocol — used for mail servers to relay email to each other.

🔌

Port 53 — DNS

Domain Name System — resolves domain names to IP addresses. UDP is used for most queries; TCP for larger responses (like zone transfers).

🔌

Port 67 — DHCP (Server)

Dynamic Host Configuration Protocol — server side, assigns IP addresses to devices joining a network.

🔌

Port 68 — DHCP (Client)

Dynamic Host Configuration Protocol — client side, used by a device requesting an IP address.

🔌

Port 80 — HTTP

Hypertext Transfer Protocol — unencrypted web traffic.

🔌

Port 110 — POP3

Post Office Protocol v3 — downloads email from a mail server to a client, typically removing it from the server.

🔌

Port 123 — NTP

Network Time Protocol — synchronizes system clocks across a network.

🔌

Port 143 — IMAP

Internet Message Access Protocol — manages email on the server, keeping it synced across multiple devices (unlike POP3, which downloads and often removes it).

🔌

Port 161 — SNMP

Simple Network Management Protocol — monitors and manages network devices (routers, switches, servers).

🔌

Port 389 — LDAP

Lightweight Directory Access Protocol — queries and modifies directory services (like user directories).

🔌

Port 443 — HTTPS

HTTP Secure — web traffic encrypted with TLS/SSL.

🔌

Port 445 — SMB

Server Message Block — Windows file and printer sharing protocol.

🔌

Port 465 — SMTPS

SMTP over implicit TLS — encrypted mail submission.

🔌

Port 587 — SMTP (Submission)

The standard port for mail clients to submit outgoing email to their mail server, typically with STARTTLS encryption.

🔌

Port 993 — IMAPS

IMAP over implicit TLS — encrypted email synchronization.

🔌

Port 995 — POP3S

POP3 over implicit TLS — encrypted email download.

🔌

Port 1433 — Microsoft SQL Server

Default port for Microsoft SQL Server database connections.

🔌

Port 3306 — MySQL / MariaDB

Default port for MySQL and MariaDB database connections.

🔌

Port 3389 — RDP

Remote Desktop Protocol — Windows remote graphical desktop access.

🔌

Port 5432 — PostgreSQL

Default port for PostgreSQL database connections.

🔌

Port 5900 — VNC

Virtual Network Computing — cross-platform remote desktop access.

🔌

Port 6379 — Redis

Default port for Redis, an in-memory data store commonly used for caching and message queues.

🔌

Port 8080 — HTTP (Alternate)

A common alternate port for HTTP traffic, often used for development servers, proxies, or secondary web services.

🔌

Port 8443 — HTTPS (Alternate)

A common alternate port for HTTPS traffic, often used for admin panels or secondary secure services.

🔌

Port 27017 — MongoDB

Default port for MongoDB database connections.

Guides & Resources

🏠

Home

Free developer & network tools, AI course, Linux course

🛠️

Free Tools Directory

Browse all free tools by category: security, networking, generators, formatters, and more

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AI Course

Free practical AI course for developers

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Linux Administration Course

24-level structured curriculum with labs

🐧

Linux Tutorial Handbook

Quick one-page Linux command reference

📱

iPhone Duo

Price, specs, camera, buying guide

🖥️

PC Builder

Build your PC with estimated pricing

🚀

IT Career Paths

Network, SysAdmin, DevOps, Cloud & more roadmaps

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IT Troubleshooting

Common IT problems and step-by-step fixes

🪟

Windows Help Center

Windows fixes, error codes, and related tools in one place

🤖

Android Help Center

Battery, storage, and WiFi fixes for Android

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iPhone Help Center

Battery, charging, and boot loop fixes for iPhone

📲

Apps Help Center

WhatsApp, Chrome, and ChatGPT troubleshooting

🛑

Error Code Encyclopedia

Cloudflare, Windows, Git, Docker, Kubernetes, and DNS error codes explained

🤖

AI Tools Directory

Curated AI tools across writing, image, video, coding, and more

⚖️

Compare

Side-by-side comparisons of popular AI, browser, and productivity tools

🎮

Tech Brain Games

Free trivia, memory match, reaction time, and sequence games

📅

Daily Challenge

One tech trivia question a day — same for everyone, build a streak

🌐

Free Websites Directory

Genuinely free websites across education, productivity, design, dev tools, research, privacy, media, and career

🎓

IT Certification Hub

RHCSA, CKA, Azure, AWS, Security+, Network+ and more

ℹ️

Affiliate Disclosure

How affiliate/commercial links work on this site

🔌

Common Network Ports Reference

What every common TCP/UDP port is used for

🧠

Tech Trivia Quiz

Linux, Networking, Cybersecurity, AI, and Coding trivia

🧩

Memory Match Game

Tech-icon pairs matching game

⚡

Reaction Time Test

Test your reflexes in milliseconds

🔢

Sequence Memory Game

Simon-style pattern memory game

📋

DevOps Cheatsheets

HTTP codes, ports, Linux commands

💻

Laptops & Mobiles Buying Guide

What to check before buying a laptop or phone

📝

Tech Blog (all posts)

Developer guides & tutorials

Port	Protocol	Service
20	TCP	FTP (Data)
21	TCP	FTP (Control)
22	TCP	SSH
23	TCP	Telnet
25	TCP	SMTP
53	TCP/UDP	DNS
67	UDP	DHCP (Server)
68	UDP	DHCP (Client)
80	TCP	HTTP
110	TCP	POP3
123	UDP	NTP
143	TCP	IMAP
161	UDP	SNMP
389	TCP	LDAP
443	TCP	HTTPS
445	TCP	SMB
465	TCP	SMTPS
587	TCP	SMTP (Submission)
993	TCP	IMAPS
995	TCP	POP3S
1433	TCP	Microsoft SQL Server
3306	TCP	MySQL / MariaDB
3389	TCP	RDP
5432	TCP	PostgreSQL
5900	TCP	VNC
6379	TCP	Redis
8080	TCP	HTTP (Alternate)
8443	TCP	HTTPS (Alternate)
27017	TCP	MongoDB