Common Network Ports
The "Doors" of the Internet. Understand how TCP/UDP ports route traffic to the right service.
Port Scanner
Visualize how a firewall sees incoming traffic.
Select a port below or
run a scan to view details.
FTP Data
File Transfer Protocol (Data Transfer)
FTP Control
File Transfer Protocol (Command Control)
SSH
Secure Shell (Remote Login)
Telnet
Unencrypted Remote Login (Obsolete)
SMTP
Simple Mail Transfer Protocol (Sending Email)
DNS
Domain Name System (Resolves URLs into IP addresses)
HTTP
HyperText Transfer Protocol (Unsecured Web)
POP3
Post Office Protocol (Receiving Email)
NTP
Network Time Protocol (Syncs Clock)
IMAP
Internet Message Access Protocol (Syncing Email)
HTTPS
HTTP Secure (Encrypted Web Traffic)
SMB
Server Message Block (Windows File Sharing)
MySQL
MySQL Database Connection
RDP
Remote Desktop Protocol (Windows)
PostgreSQL
PostgreSQL Database Connection
HTTP-Alt
Alternative HTTP Port (Common for Dev)
MongoDB
MongoDB Database Connection
Minecraft
Minecraft Java Server
The Apartment Analogy
To understand ports, imagine a giant apartment building.
The building has a street address (The IP Address), which helps the mail carrier find the building. But once inside, how do they know which room to deliver the letter to?
That's the Port Number. Room 80 is the "Web Lobby". Room 25 is the "Mail Room". Room 22 is the "Security Office". When a data packet arrives at your computer, the Operating System looks at the port number to decide whether to send that data to Chrome (80/443), Discord (UDP), or Spotify.
The Firewall
A Firewall is simply a security guard who has a list of allowed Room Numbers.
- AllowPort 80/443 (Let people view the website)
- AllowPort 22 (Let admins log in to fix things)
- BlockEverything Else (Close unused doors to prevent Hackers)
TCP vs UDP
Data travels in two main ways:
TCP (Reliable): Like a certified letter. The sender waits for a signed receipt ("ACK") before sending the next page. Used for Websites, Emails, Files.
UDP (Fast): Like shouting across a room. You just throw the data as fast as possible. If a word gets lost, you don't repeat it. Used for Gaming, Video Chat, DNS.
Ports You Must Know
Web: HTTP (80) & HTTPS (443)
These connect browsers to web servers. 443 adds an SSL usage layer (Encryption), making it safe for credit cards and passwords.
Admin: SSH (22) & RDP (3389)
SSH is the standard CLI tool for managing Linux servers. RDP is the graphical equivalent for accessing a Windows PC remotely.
Databases: MySQL (3306) & Postgres (5432)
Backend code connects to these ports to read/write data. You typically do NOT expose these to the internet, only to your internal network.
Hosting a Game Server?
When you host a Minecraft server, it listens on port 25565. But your friends cannot see it because your Router blocks incoming connections.
Port Forwarding tells the router: "If anyone from the internet knocks on Door 25565, send them straight to my laptop's local IP (192.168.1.5)."
Frequently Asked Questions
What is Port 80 vs 443?
Port 80 is used for standard, unencrypted web traffic (HTTP). Port 443 is used for secure, encrypted web traffic (HTTPS). Modern websites should always force traffic to port 443.
Why is Port 22 important?
Port 22 is used for SSH (Secure Shell). It allows administrators to log in to servers remotely. It is a prime target for hackers, so many admins change it to a non-standard port for security.
What is the difference between TCP and UDP?
TCP (Transmission Control Protocol) guarantees delivery and order (used for Web, Email). UDP (User Datagram Protocol) is faster but does not guarantee delivery (used for Video Streaming, Gaming, DNS).
What is localhost?
Localhost corresponds to the IP address 127.0.0.1. It refers to "this computer". Developing a website on http://localhost:3000 means the server is running on your own machine at port 3000.
How do I check open ports?
On Windows, use "netstat -an". On Mac/Linux, use "lsof -i" or "netstat". For testing external servers, you can use port scanner tools like Nmap.
What is Port 25 used for?
Port 25 is the standard operator for SMTP (Simple Mail Transfer Protocol). It is used to SEND emails from server to server. Many residential ISPs block port 25 to prevent spam.
What is Port 53?
Port 53 handles DNS (Domain Name System) queries. It converts human-readable names like "google.com" into IP addresses. It primarily uses UDP for speed.
What port does Minecraft use?
Minecraft Java Edition servers run on TCP Port 25565 by default. Bedrock Edition runs on UDP Port 19132.
What is an Ephemeral Port?
Ephemeral ports (usually 49152 to 65535) are temporary ports assigned automatically by the OS for client-side outgoing connections. They are released once the connection ends.
Why do I need to Port Forward?
Your router acts as a firewall, blocking incoming connections. Port forwarding creates a rule that says "Any traffic knocking on Door 25565 should be sent to my gaming PC", allowing friends to join your server.
What is Port 3306?
Port 3306 is the default port for MySQL databases. It should generally NOT be open to the public internet for security reasons; connect via SSH tunnel or localhost instead.
What is Port 445 (SMB)?
Port 445 is used for Windows File Sharing (SMB). It is famous for being the vector of the WCry/WannaCry ransomware attack. It should arguably never be exposed to the internet.
What is Port 8080?
Port 8080 is an alternative HTTP port. It is commonly used by developers for testing web servers or for running secondary web services (like proxies) to avoid conflict with the main Port 80.
What is FTP (Port 20/21)?
FTP (File Transfer Protocol) uses two ports. Port 21 is for sending commands ("List files", "Login"). Port 20 is for actually sending the data. It is insecure; use SFTP (Port 22) instead.
What is port numbers range?
Ports range from 0 to 65535. 0-1023 are "Well-Known Ports" (system services). 1024-49151 are "Registered Ports" (user apps). 49152-65535 are "Dynamic/Private Ports".