What does it mean when a port is open?

An **open port** means that a specific application or service on your device is actively listening for connections and is accessible from the internet. This is the desired status for hosting game servers, web servers, or remote access tools. It confirms that your **port forwarding** rules and firewall settings are correctly configured to allow external traffic to reach your service.

Why is my port showing as closed?

A **closed port** indicates that while the connection reached your device, no application was listening on that specific port. This often happens if the server software (like a Minecraft server) isn't running. If the status is 'filtered' or 'timeout', it usually means a **firewall** or router is blocking the connection entirely before it even reaches your device.

What is the difference between TCP and UDP ports?

**TCP (Transmission Control Protocol)** is connection-oriented and reliable, ensuring all data arrives in order (used for web, email, file transfers). **UDP (User Datagram Protocol)** is connectionless and faster but doesn't guarantee delivery (used for gaming, streaming, VoIP). Our scanner can check both, but UDP scanning is more complex as it doesn't always send a response.

How do I open a port on my router?

To open a port, you need to log into your router's admin panel (usually via 192.168.1.1) and find the **Port Forwarding** section. Create a new rule specifying the **port number** (e.g., 25565), the protocol (TCP/UDP), and the **local IP address** of the device running the server. Save the settings and restart the router if necessary.

What are the most commonly used ports?

Some of the most frequently checked ports include **80** (HTTP Web), **443** (HTTPS Secure Web), **21** (FTP File Transfer), **22** (SSH Remote Login), **25** (SMTP Email), **3389** (RDP Remote Desktop), and **25565** (Minecraft). Knowing these standard port numbers helps in quickly configuring services and diagnosing network issues.

Is port scanning legal?

Yes, **port scanning** your own network or a network you have permission to test is completely legal and a standard security practice. However, scanning networks or IP addresses that you do not own or have authorization for can be considered a hostile act and may violate laws or ISP terms of service. Always use this tool responsibly.

Can I check multiple ports at once?

Yes, our tool supports **port range scanning** and batch checking. You can enter a range like '20-25' to check consecutive ports, or use our 'Popular Ports' preset to scan a group of common services simultaneously. This is useful for quickly auditing your network's security posture or verifying multiple services.

What is port forwarding?

**Port forwarding** is a router configuration that directs incoming internet traffic from a specific port to a specific device on your local network. Without it, your router rejects unsolicited external requests. It is essential for allowing friends to connect to your game server, accessing security cameras remotely, or hosting a website from home.

Why do I need to check my external IP?

Your **external IP address** is how the internet sees your network. When setting up a server or port forwarding, external users must connect to this public IP, not your local one (like 192.168.x.x). Our tool automatically detects your public IP so you can accurately test if your services are reachable from the outside world.

What does 'filtered' port status mean?

A **filtered** status means that our scanner sent a request but received no reply at all. This typically indicates that a **firewall** (on your router, computer, or ISP level) is silently dropping the packets to hide the port's existence. To fix this, you usually need to adjust your firewall settings to explicitly allow traffic on that port.

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What is a Port Checker?

A port checker is a simple online utility that tests whether a specific communication channel (port) on your computer or network is open and accessible from the internet. Think of ports as virtual doors on your device; some need to be open for specific applications to work, while others should remain closed for security. This tool attempts to connect to a specific port on your IP address, just like an external visitor would, and reports back whether the connection was successful (open port) or blocked (closed port).

Users often need to check if ports are open to ensure that port forwarding rules are correctly configured on their router. This is essential for various activities, such as hosting a game server, running a web server, or using peer-to-peer applications. If a port is closed, external users won't be able to connect to your service, leading to network connectivity issues. Conversely, checking for open ports is also a vital security step to ensure you aren't accidentally exposing vulnerable services to the web.

This tool is widely used by a diverse group of people, from gamers setting up multiplayer servers for Minecraft or Call of Duty, to IT professionals and server admins troubleshooting firewall configurations. Even home users setting up security cameras or smart home devices rely on a port checker to verify their setup. By providing instant feedback on your network's accessibility, our tool helps you diagnose connection problems and secure your digital environment with ease.

How to Use the Port Checker

Enter Target Address

Start by entering the IP address or domain name you wish to scan. You can manually type it in, or use the 'Use My IP' button to automatically detect and fill in your current public IP address.

Specify Port Number

Input the specific port number you want to test (e.g., 80 for Web). You can also select from our list of popular presets for common services.

Initiate Check

Click the 'Check Port' button to start the scan. Our tool will attempt to establish a connection to the specified port on the target address.

Interpret Results

Review the port status. 'Open' means accessible. 'Closed' means reachable but not listening. 'Filtered' usually indicates a firewall block.

Troubleshoot

If your port is closed, check your router's port forwarding settings and firewall configuration to resolve network connectivity issues.

Common Use Cases for Port Checking

Gaming Server Setup

Essential for hosting multiplayer games like Minecraft, FiveM, or CS:GO. You need to verify that your port forwarding is correctly configured so friends can connect to your server. Common ports include 25565 for Minecraft and 30120 for FiveM.

Remote Desktop Access

When setting up Remote Desktop Protocol (RDP) or VNC to access your computer from away, you must ensure the specific port is open. Checking port 3389 (default for RDP) confirms that your remote connection tunnel is accessible through your firewall.

Web Server Configuration

Running a personal website or web application requires HTTP port 80 and HTTPS port 443 to be open to the public. Our tool helps developers verify that their web server is reachable from the internet and not blocked by an ISP or router.

File Transfer Servers

For sharing files securely, you might set up an FTP or SFTP server. Use our scanner to check if port 21 (FTP) or port 22 (SFTP) is open, ensuring that authorized users can upload and download files without connection errors.

Security Cameras & NVR

Accessing your home security cameras or Network Video Recorder (NVR) remotely often requires forwarding specific ports. A port check ensures that your external request can reach your camera system, allowing you to view live feeds from anywhere.

VoIP Services

Voice over IP (VoIP) services and IP phones rely on specific ports like SIP port 5060 to establish calls. Checking these ports helps diagnose one-way audio issues or registration failures, ensuring clear and reliable communication.

Understanding Network Ports

What are Network Ports?

Think of your IP address as a building's street address, and network ports as the individual apartment numbers within that building. While the IP address ensures data reaches the correct device, the port number directs that data to the specific application or service waiting for it. Without ports, your computer wouldn't know if incoming data was meant for your web browser, email client, or game.

Port Number Ranges

There are 65,535 available ports, categorized into three ranges:

• Well-Known Ports (0-1023): Reserved for core system services like web browsing (80) and email (25).

• Registered Ports (1024-49151): Assigned to specific applications like Minecraft (25565) or SQL databases.

• Dynamic/Private Ports (49152-65535): Used temporarily for private or custom connections.

TCP vs UDP Protocols

Ports use two main protocols to transport data:

• TCP (Transmission Control Protocol): Reliable and ordered. It guarantees data delivery, making it perfect for web browsing (HTTP), email, and file transfers where accuracy matters.

• UDP (User Datagram Protocol): Fast but less reliable. It sends data without checking if it arrives, making it ideal for real-time applications like online gaming, streaming, and VoIP where speed is critical.

Common Ports Reference

A quick reference guide to the most frequently used TCP ports and UDP ports.

Port	Service	Protocol	Description
20	FTP-Data	TCP	FTP uses a separate data channel (port 20) for transferring file content in active mode. The control connection on port 21 negotiates the transfer, while port 20 carries the raw data stream. FTP-Data traffic is unencrypted — file contents travel in plain text. Use SFTP (port 22) or FTPS for secure file transfers.
21	FTP	TCP	FTP (File Transfer Protocol) enables uploading and downloading files between a client and a server over TCP. It uses separate control (port 21) and data (port 20) channels. FTP transmits usernames, passwords, and file data in plain text, making it vulnerable to network interception. SFTP (port 22) or FTPS are the secure alternatives recommended for all modern deployments.
22	SSH	TCP	SSH (Secure Shell) provides an encrypted tunnel for remote login, command execution, and file transfer over untrusted networks. SSH version 2, defined by RFC 4251–4254, replaced the original SSH-1 protocol after critical security flaws were discovered. It supports key-based authentication as a more secure alternative to password login. Common implementations include OpenSSH (default on Linux and macOS), Dropbear (embedded devices), and Bitvise (Windows).
23	Telnet	TCP	Telnet was the original standard for remote terminal access before SSH existed. It transmits all data — including usernames and passwords — in plain text over the network. Any attacker with packet-sniffing access can capture Telnet credentials instantly. Telnet was deprecated in favour of SSH and should never be used on any modern system.
25	SMTP	TCP	SMTP (Simple Mail Transfer Protocol) is the standard protocol for routing email between mail servers on the internet. Port 25 is used for server-to-server (MTA) delivery and is blocked by most ISPs on residential connections to prevent spam. Authenticated submission from mail clients uses port 587 (STARTTLS) or port 465 (implicit TLS). SMTP servers must implement anti-relay protections to prevent being used as open spam relays.
53	DNS	UDP	DNS (Domain Name System) translates human-readable domain names into IP addresses. DNS uses UDP for queries under 512 bytes and falls back to TCP for larger responses. A recursive resolver queries multiple authoritative servers to resolve a domain on the client's behalf. Open DNS resolvers can be abused in amplification DDoS attacks.
80	HTTP	TCP	HTTP (HyperText Transfer Protocol) is the application-layer protocol for transmitting web pages and APIs between browsers and servers. HTTP transfers all data including form inputs and session cookies in plain text, making it vulnerable to interception on shared or public networks. Modern web standards require HTTPS (port 443) for all sites that handle user data. Redirect all port 80 traffic to port 443.
110	POP3	TCP	POP3 (Post Office Protocol v3) allows email clients to download messages from a mail server to a local device. Unlike IMAP, POP3 typically deletes messages from the server after download. POP3 in plain-text mode sends credentials unencrypted — use POP3S (port 995) with TLS instead. For multi-device access, IMAPS (port 993) is generally preferred.
143	IMAP	TCP	IMAP (Internet Message Access Protocol) lets email clients access and sync messages stored on a mail server, keeping messages available across multiple devices. Unlike POP3, IMAP leaves messages on the server and synchronises folder organisation and read/unread states. IMAP in plain-text mode (port 143) should be upgraded to STARTTLS or replaced with IMAPS (port 993), which uses TLS from connection start.
443	HTTPS	TCP	HTTPS is HTTP secured with TLS (Transport Layer Security), providing encryption, server authentication, and data integrity for web communications. It became the web standard after Let's Encrypt made free TLS certificates widely available in 2016. TLS 1.3 (RFC 8446) is the current recommended version, with TLS 1.0 and 1.1 officially deprecated. Browsers display security warnings for any site without HTTPS.
465	SMTPS	TCP	SMTPS wraps SMTP in implicit TLS from the moment a connection is established, originally assigned to port 465. This port was briefly deprecated in 1998 but restored by RFC 8314 in 2018 as a modern alternative to STARTTLS on port 587. Major providers including Gmail and Microsoft 365 support port 465 with implicit TLS.
587	SMTP Submission	TCP	SMTP Submission (port 587) is the current standard for authenticated email submission from mail clients to their outgoing mail server. It mandates STARTTLS to encrypt the connection before credentials are transmitted. Unlike port 25, port 587 requires authentication, preventing unauthorised relay. All major email providers recommend port 587 for client SMTP configuration.
993	IMAPS	TCP	IMAPS is IMAP secured with TLS applied immediately at connection start, before any credentials are exchanged. This eliminates the risk of credential interception present in plain-text IMAP. IMAPS on port 993 is the recommended configuration for all modern mail servers. Disable plain IMAP (port 143) once all clients support IMAPS.
995	POP3S	TCP	POP3S is POP3 with TLS applied from the very start of the connection, encrypting messages and authentication tokens. POP3S on port 995 is the secure alternative to plain POP3 (port 110). For multi-device access with server-side message retention, IMAPS (port 993) is generally preferred over POP3S.
1194	OpenVPN	UDP	OpenVPN is an open-source VPN protocol that creates encrypted tunnels using TLS. It defaults to UDP port 1194 for performance but can operate over TCP for firewall traversal. OpenVPN supports certificate-based authentication and strong cipher suites including AES-256-GCM. It is supported by major router firmware distributions including pfSense, OPNsense, and DD-WRT.
1433	MSSQL	TCP	Microsoft SQL Server uses port 1433 as its default TCP port for client connections, implementing the Tabular Data Stream (TDS) protocol. It supports both Windows Authentication and SQL Server Authentication, with Windows Authentication preferred in domain environments. Exposing port 1433 directly to the internet is a critical security risk — use a VPN or SSH tunnel for remote access.
3306	MySQL	TCP	MySQL is one of the world's most widely deployed open-source relational databases, listening on port 3306 by default. MariaDB, a community fork, also uses port 3306 and is compatible with MySQL clients. Both support SSL/TLS connections, but these must be explicitly configured. Bind port 3306 to localhost in my.cnf and use an SSH tunnel for remote database management.
3389	RDP	TCP	RDP (Remote Desktop Protocol) is Microsoft's protocol for graphical remote control of Windows systems over port 3389. It provides full desktop access including audio, clipboard, and drive redirection. Exposed port 3389 is a primary ransomware attack vector — operators use brute-force and credential stuffing to gain access. Always use a VPN instead of exposing RDP directly and enable Network Level Authentication (NLA).
5432	PostgreSQL	TCP	PostgreSQL is a powerful open-source relational database listening on port 5432 by default. It supports advanced SQL with JSONB, full-text search, PostGIS extensions, and complex queries. PostgreSQL uses pg_hba.conf to control host and user access, and supports TLS for encrypted connections. Set listen_addresses to localhost and use an SSH tunnel or VPN for remote access.
5900	VNC	TCP	VNC (Virtual Network Computing) implements the RFB protocol (RFC 6143) to share and control a graphical desktop remotely over port 5900. It transmits screen pixels, mouse, and keyboard input. Standard VNC sessions are unencrypted — always tunnel VNC over SSH (ssh -L 5900:localhost:5900) or use a VPN before connecting. Implementations include RealVNC, TigerVNC, and macOS Screen Sharing.
6379	Redis	TCP	Redis is an in-memory key-value store used for caching, session management, pub/sub messaging, and real-time leaderboards. It has no authentication by default in older versions. Exposed Redis instances have been repeatedly abused for data theft and cryptomining. Always bind Redis to 127.0.0.1, enable requirepass, and never expose port 6379 to the internet.
8080	HTTP-Alt	TCP	Port 8080 is the most common alternative HTTP port, used when port 80 is unavailable or requires elevated OS privileges. It is the default for Apache Tomcat, Jetty, and many development web servers. HTTP proxy and caching servers also commonly listen on port 8080. Users must specify the port explicitly in the URL since browsers do not assume port 8080.
8443	HTTPS-Alt	TCP	Port 8443 serves as an alternative HTTPS port when port 443 is in use or restricted. It is commonly used by control panels (Plesk, cPanel), Kubernetes API servers, and Java application servers with TLS enabled. Apply the same TLS security standards as port 443: valid certificate, TLS 1.2 minimum, strong cipher suites.
25565	Minecraft	TCP	Port 25565 is the default TCP port for Minecraft Java Edition dedicated servers. Players connect by entering the server IP in the Minecraft client. Server software variants include the official Mojang server, Paper, Spigot, Fabric, and Velocity. Open port 25565 only when actively hosting a server and use a whitelist to control who may join.
27015	Source Engine	UDP	Port 27015 is the default UDP port for Valve's Source engine dedicated server software, used by Counter-Strike 2, Team Fortress 2, Left 4 Dead 2, and Garry's Mod. The Source engine also uses this port for Steam Server Browser queries. Keep the server binary updated via SteamCMD and set a strong RCON password.
27017	MongoDB	TCP	MongoDB is a document-oriented NoSQL database storing data in BSON format, listening on port 27017 by default. It shipped with no authentication enabled by default in early versions, leading to mass data exposures. Enable authentication (security.authorization: enabled in mongod.conf), bind to localhost, and use TLS for any remote connection. Never expose port 27017 to the internet.

Troubleshooting Closed Ports

If your port status shows as closed or filtered, it means the connection couldn't be established. Here are the most common reasons and how to fix them.

Firewall Blocking

Problem: Your computer's firewall (like Windows Defender) or a third-party security suite is blocking incoming connections.

Solution: Create an inbound rule in your firewall settings to allow traffic on the specific port you are testing.

Router Configuration

Problem: Your router doesn't know which device to send the traffic to.

Solution: Log into your router's admin panel and configure port forwarding to direct traffic for that port to your computer's local IP address.

ISP Blocking

Problem: Some Internet Service Providers (ISPs) block common ports like 80, 443, or 25 to prevent customers from hosting servers.

Solution: Check your ISP's documentation or contact support. You may need to use a non-standard port (e.g., 8080 instead of 80).

Service Not Running

Problem: The application (game server, web server) isn't actually running or listening on that port.

Solution: Ensure your software is started and configured to listen on the correct port and IP address (0.0.0.0 usually covers all interfaces).

Incorrect IP Address

Problem: You might be checking the wrong IP, or your local IP has changed (DHCP).

Solution: Verify you are scanning your public IP (use our 'My IP' tool) and that your port forwarding rule points to your current local IP.

Double NAT

Problem: You have two routers connected (e.g., ISP modem + personal router), creating two layers of Network Address Translation.

Solution: Set your ISP modem to 'Bridge Mode' or configure port forwarding on both devices to chain the connection through.