Port Checker

Enter a hostname and port to check if the TCP port is open. Test firewall rules, verify services are running, and troubleshoot connectivity — instantly.

Common ports:

What does this tool check?

Port Reachability

Attempts a real TCP connection to verify whether the port is open and accepting connections from the internet.

Service Detection

Identifies the known service running on well-known ports — HTTP, HTTPS, SSH, SMTP, MySQL, PostgreSQL, Redis, and more.

Response Time

Measures how long the TCP handshake takes, helping you identify latency and connectivity issues.

Firewall Testing

Verify your server's firewall, security group, or cloud networking rules are allowing the right traffic through.

Got questions?

Frequently asked questions

Everything you need to know about Uptrue — no fluff.

How do I check if a port is open?
Enter the hostname or IP address and the port number in the tool above, then click "Check Port". The tool will attempt a TCP connection and tell you within seconds whether the port is open or closed.
A TCP port is a numbered endpoint (1–65535) on a server that allows specific types of network traffic. For example, port 80 handles HTTP web traffic, port 443 handles HTTPS, and port 22 is used for SSH remote access.
Ports can be blocked by a server-side firewall, a cloud provider's security group rules, or a network firewall between you and the server. A port may also appear closed if the service is not running or is configured to listen on a different port.
Common ports include: 21 (FTP), 22 (SSH), 25 (SMTP), 53 (DNS), 80 (HTTP), 143 (IMAP), 443 (HTTPS), 587 (SMTP Submission), 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis), and 27017 (MongoDB).
To open a port, you typically need to update your firewall rules. On Linux with UFW: `sudo ufw allow 443/tcp`. On AWS, update your Security Group inbound rules. On GCP, update your VPC firewall rules. Also ensure the service is running and listening on that port.

Monitor your ports 24/7

Uptrue's port check monitoring watches any TCP port every minute and alerts you instantly if it stops accepting connections. Pair it with ping/reachability monitoring so you can tell a port issue from a host outage at a glance.

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