Open Port Checker

Check if ports are open from multiple global locations. Verify service accessibility and firewall configuration.

What This Checks

Multi-region port checkCommon port presetsSingle port verificationTCP connectivity testFirewall testing

About Port Checker

Test if specific TCP ports are open and accessible from multiple global locations. Check common ports like HTTP (80), HTTPS (443), SSH (22), and more.

Key Features

Multi-region port check

Common port presets

Single port verification

TCP connectivity test

Firewall testing

Also Available via API & MCP Server

Automate port checker checks in your CI/CD pipelines or run them directly from your AI coding agent.

REST API

Single endpoint, JSON response. Integrate into any language or platform.

cURL

curl -X POST https://probeops.com/api/v1/run \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"tool": "port_check", "target": "example.com"}'

Learn more about the API

MCP Server

Works with Claude Code, Cursor, Windsurf, and any MCP-compatible IDE.

Claude Code

> Check the port checker for example.com

Claude uses the probeops_port_check tool to run
the check from 6 global regions and returns
structured results.

Learn more about the MCP Server

Open port checking verifies whether specific ports on a server are accepting connections. This is essential for verifying service deployment, troubleshooting "service not accessible" issues, and confirming firewall rules are configured correctly.

Our multi-region port checker tests individual ports from 6+ global locations, helping you identify regional access differences caused by firewalls, security groups, or ISP blocking. Unlike port scanners that sweep ranges, this tool checks the specific ports you need—ideal for verifying deployments without triggering security alerts.

After confirming port accessibility, use latency testing to verify performance and SSL checking for ports running HTTPS services.

**Methodology:** TCP connect attempt from 6 global regions, distinguishing open (connection accepted), closed (refused), and filtered (timeout).

Common Errors & How to Fix Them

4 relevant issues

What This Means

The port actively refused the connection. Either no service is listening on this port, or it's configured to reject connections.

How to Fix

1) Verify service is running: systemctl status service-name. 2) Check service is on correct port: netstat -tlnp | grep PORT. 3) Ensure service binds to 0.0.0.0, not 127.0.0.1. 4) Check service configuration for listen address/port. 5) Restart service: systemctl restart service-name.

port closedconnection refusedservice not running

What This Means

No response received—a firewall is silently dropping packets to this port. The port may or may not have a service listening.

How to Fix

1) Check local firewall: ufw status, iptables -L -n. 2) For cloud: check security groups (AWS), firewall rules (GCP), NSG (Azure). 3) Check host-level firewall (Windows Firewall). 4) Verify ISP isn't blocking: test from different network. 5) Add firewall rule: ufw allow PORT/tcp.

port filteredfirewallblockedno response

What This Means

The connection attempt timed out. Server may be overloaded, port may be filtered, or there's network congestion.

How to Fix

1) Try with longer timeout: nc -vz -w 10 host port. 2) Check if server is overloaded: verify other services respond. 3) Test from different location to rule out network issues. 4) Check server resources: CPU, memory, connection limits. 5) Review firewall logs for dropped packets.

timeoutconnection timeoutslow response

What This Means

Cannot reach the host at all—not just the specific port. The server may be down, or there's a routing problem.

How to Fix

1) Verify hostname resolves: dig hostname A. 2) Try ping: ping hostname. 3) Check server status in cloud console if applicable. 4) Try traceroute to identify where connectivity breaks. 5) If server is up but unreachable: check network configuration, routing tables.

host unreachableserver downno route

See all errors →

Frequently Asked Questions

4 relevant questions

Ports are numbered endpoints (0-65535) that identify specific services on a server. Port 80 is HTTP, 443 is HTTPS, 22 is SSH. An "open" port accepts connections; a "closed" or "filtered" port doesn't. Checking ports helps verify services are accessible, diagnose connectivity issues, and audit security by finding unexpected open ports.

port-checkerbasics

Common ports: 80 (HTTP), 443 (HTTPS), 22 (SSH), 21 (FTP), 25/587 (SMTP email), 110/995 (POP3 email), 143/993 (IMAP email), 3306 (MySQL), 5432 (PostgreSQL), 3389 (RDP), 53 (DNS). For web servers, always check 80 and 443. For email servers, check 25, 587, 465, 110, 995, 143, 993.

port-checkercommon-ports

"Open" means a service is listening and accepting connections. "Closed" means no service is listening—the port actively rejects connections. "Filtered" means a firewall is blocking access—no response is received. From a security perspective, filtered is better than closed, as it doesn't confirm the port exists.

port-checkerstatus

Open ports themselves aren't insecure—the services behind them might be. Only expose necessary ports. Use firewalls to restrict access by IP when possible. Keep services updated to patch vulnerabilities. For admin services (SSH, databases), use non-default ports and require VPN/bastion access. Regularly audit which ports are open.

port-checkersecurity

See all FAQs →

How to Check if Ports are OpenStep-by-step guide with examples and troubleshooting tips