Check if a port is open, closed, or filtered on any IP address or domain name.
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View your current public IP address
Calculate subnet masks and network ranges
Convert between IPv4 and IPv6 addresses
Find Autonomous System Number information
Check if an IP is listed in spam databases
Check if a domain supports IPv6
Resolve domain names to IP addresses
Convert IP addresses to domain names
Scan ports on any IP address or domain
Test your internet connection speed
Detect if you're using a proxy or VPN
Verify if links are accessible
Ping any host to test connectivity
Validate SPF records for email security
Validate DMARC records for email protection
Check DKIM records for email authentication
Analyze email headers to trace sender
Check HTTP response headers of any URL
Familiarize yourself with frequently used network ports to effectively manage your network infrastructure, resolve connection problems, and maintain security. These ports serve as standard communication channels for web services, applications, and server systems.
| Name | Description | |
|---|---|---|
| 80 - HTTP (Hypertext Transfer Protocol) | Primary port for unencrypted web browsing. Web servers typically use this port for standard HTTP connections. Visiting sites without encryption uses this port. | |
| 443 - HTTPS (HTTP Secure) | Encrypted web communication using TLS/SSL protocols. Required for secure e-commerce, login pages, and any site handling sensitive information. | |
| 22 - SSH (Secure Shell) | Encrypted protocol for secure remote server access. Enables administrators to log in and execute commands on remote systems safely. | |
| 21 - FTP (File Transfer Protocol) | Legacy protocol for file transfers between systems. Lacks encryption, making it vulnerable. Prefer SFTP (port 22) or FTPS (port 990) for secure transfers. | |
| 25 - SMTP (Simple Mail Transfer Protocol) | Standard port for email transmission between mail servers. Frequently blocked by ISPs to reduce spam. Contemporary email systems prefer ports 587 or 465. | |
| 53 - DNS (Domain Name System) | Converts human-readable domain names to numeric IP addresses. Fundamental internet service. Typically uses UDP for standard queries, TCP for extended data transfers. | |
| 110 - POP3 (Post Office Protocol v3) | Email retrieval protocol that downloads messages to your device and deletes them from the server. For encrypted access, use POP3S on port 995. | |
| 143 - IMAP (Internet Message Access Protocol) | Email protocol that maintains messages on the server, enabling access from multiple devices. For encrypted connections, use IMAPS on port 993. | |
| 993 - IMAPS (IMAP over SSL/TLS) | Encrypted IMAP implementation with SSL/TLS protection. The preferred method for accessing IMAP email in current email applications. | |
| 995 - POP3S (POP3 over SSL/TLS) | POP3 with SSL/TLS encryption for secure email retrieval. The recommended approach for POP3 connections in today's email software. | |
| 3389 - RDP (Remote Desktop Protocol) | Microsoft's protocol enabling remote desktop control of Windows machines. Requires robust password protection and ideally VPN access for security. | |
| 3306 - MySQL | Standard MySQL database connection port. Requires strict security measures and should never be publicly accessible without firewall protection. | |
| 5432 - PostgreSQL | Default PostgreSQL database connection port. Must be properly secured and restricted to prevent unauthorized database access. | |
| 6379 - Redis | Redis in-memory database default port. Popular for caching and session management. Requires authentication and should remain private, not publicly exposed. | |
| 27017 - MongoDB | MongoDB NoSQL database default connection port. Widely adopted in contemporary web development. Needs authentication and strict network access restrictions. |
Understanding how port checking works helps you diagnose network connectivity issues, verify firewall configurations, and ensure your services are accessible. Our tool provides a simple, fast way to test port accessibility from external networks.
You enter a public IP address or domain name and the specific port number you want to test. Common ports like 21 (FTP), 22 (SSH), 80 (HTTP), and 443 (HTTPS) are available for quick selection.
The tool attempts to initiate a TCP connection from its server to the entered IP/domain and port. This request simulates an external connection trying to access that port from the internet.
The tool analyzes the response and displays whether the port is open, closed, or filtered. Open ports accept connections, closed ports reject them, and filtered ports are blocked by firewalls.
Port checker tools serve a wide range of users from IT professionals to home network enthusiasts. Whether you're managing enterprise infrastructure, deploying web applications, or troubleshooting connectivity problems, port checking helps verify network accessibility, identify blocked ports, and maintain secure network configurations.
Port checker tools are essential for maintaining network security, troubleshooting connectivity issues, and ensuring proper service configuration. Whether you're a professional managing enterprise infrastructure or a home user setting up personal services, understanding port status helps prevent security vulnerabilities and resolve connection problems efficiently.
Our port checker tool provides a comprehensive, user-friendly solution for all your port checking needs. Built with performance and reliability in mind, it offers advanced features that make network diagnostics fast, accurate, and accessible to everyone.
Find answers to common questions about port checking, network diagnostics, and how to use our port checker tool effectively.
Start the service you want reachable, then test your public IP and target port from outside your network using our Port Checker. If it shows closed, verify firewall rules, router port forwarding, and that the service is actively listening on the correct port.
Open the Port Checker, enter a domain or IP, add the port number, and run a check. Read the result as open, closed, or filtered. For accurate troubleshooting, test after each firewall or router change and confirm the target service is running.
A port checker attempts a network connection to a specific host and port, then reports whether access is open, closed, or filtered. Our Port Checker helps you validate firewall rules, confirm service availability, and quickly isolate connectivity issues during deployment or troubleshooting.
Port knocking is a security technique that keeps a service port closed until a client sends a specific sequence of connection attempts. It reduces visible attack surface but is not a replacement for authentication, encryption, and proper firewall policy. You can verify exposure changes with our Port Checker.
A port is usually considered bad when it is unexpectedly open, blocked when required, or tied to suspicious traffic. Compare expected service behavior with real checks from our Port Checker. Unexpected state, repeated failures, or unknown listeners are signs to investigate immediately.
TCP is connection-based and prioritizes reliable, ordered delivery, making it ideal for web, mail, and file transfer. UDP is connectionless and faster, often used for streaming, gaming, DNS, and voice traffic where low latency matters more than guaranteed delivery. Test TCP exposure quickly with our Port Checker.
TCP is a transport protocol that moves data reliably between systems. HTTP is an application protocol that defines how browsers and servers exchange web content. In practice, HTTP usually runs on top of TCP, commonly on ports 80 or 443. You can verify those ports with our Port Checker.
Port 80 remains widely used for default HTTP traffic, health checks, redirects to HTTPS, and compatibility with older systems and constrained environments. Even secure sites often listen on 80 to forward users to encrypted pages on 443. You can test both paths quickly with our Port Checker.