Online Port Checker
Check if ports are open and accessible from multiple global locations.
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
Port checking verifies whether specific network ports are open and accepting connections—essential for confirming services are accessible, troubleshooting connectivity issues, and auditing server security. An open port means a service is listening; closed or filtered means it's not accessible.
Our multi-region port checker tests connectivity from 6+ global locations, revealing if ports are accessible worldwide or blocked in specific regions. This helps identify firewall misconfigurations, ISP-level blocking, and geo-restriction issues.
For comprehensive server diagnostics, also run traceroute to verify network path and latency test to measure response times once connectivity is confirmed.
**Methodology:** TCP connect to specified port from 6 regions with 10-second timeout, reporting open/closed/filtered status.
Common Errors & How to Fix Them
Click to expand troubleshooting stepsThe traceroute couldn't complete—no response received from destination. Packets may be blocked by a firewall, or the destination is unreachable.
1) Verify destination is reachable: ping target.com. 2) Try different protocols: traceroute -I (ICMP) vs traceroute -U (UDP) vs traceroute -T (TCP). 3) Check if destination firewall blocks traceroute. 4) Test from different source location. Some hosts simply block all traceroute traffic.
Traceroute shows hops up to a point, then only asterisks. Traffic is being blocked or dropped at that hop.
1) Identify the last responding hop—that's where blocking occurs. 2) Check if it's your ISP, a transit provider, or destination's network. 3) Try TCP traceroute: traceroute -T -p 443 target.com. 4) Contact the network operator if it's a provider issue. 5) If destination's network, firewall is blocking.
Traceroute shows the same IP addresses repeating. Packets are going in circles due to misconfigured routing tables.
1) Note the IPs involved in the loop. 2) If it's within your network: check router configurations for circular routes. 3) If it's external: report to ISP with traceroute output. 4) Try alternative route: use VPN to bypass problematic path. Routing loops are usually resolved within hours by network operators.
One or more hops show significantly higher latency than others. Could indicate congestion, distance, or router performance issues.
1) Check if high latency persists to destination or recovers. 2) If only that hop is slow: router may deprioritize ICMP (not a real problem). 3) If latency stays high: bottleneck identified. 4) For geographic hops (100ms+ jumps): expected for intercontinental links. 5) Persistent issues: contact ISP with evidence.
The port actively refused the connection. Either no service is listening on this port, or it's configured to reject connections.
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.
No response received—a firewall is silently dropping packets to this port. The port may or may not have a service listening.
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.
The connection attempt timed out. Server may be overloaded, port may be filtered, or there's network congestion.
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.
Cannot reach the host at all—not just the specific port. The server may be down, or there's a routing problem.
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.
Frequently Asked Questions
Common questions answeredTraceroute shows the path network packets take from source to destination, revealing each router (hop) along the way. It works by sending packets with increasing TTL (Time To Live) values—each router decrements TTL and returns a response when it reaches zero. This maps the complete route and measures latency at each hop.
Each line shows a hop number, router IP/hostname, and three response times (in milliseconds). Asterisks (*) mean the router didn't respond—this doesn't always indicate a problem, as some routers are configured not to respond to traceroute. Look for sudden latency increases between hops to identify bottlenecks.
Asterisks indicate the router at that hop didn't respond within the timeout period. Common reasons: firewall blocking ICMP/UDP, router configured to deprioritize or ignore traceroute packets, or rate limiting. If subsequent hops respond normally, it's not a problem—some routers simply don't respond to diagnostic traffic.
Network paths vary by geography. A traceroute from the US to a server in Germany takes a different route than from Asia. Multi-region traceroute reveals routing inefficiencies, identifies regional network issues, and helps diagnose "works from here but not there" problems. It's essential for global services.
Ping tests if a destination is reachable and measures round-trip time, but only shows the final result. Traceroute shows every hop along the path, helping you identify WHERE problems occur—not just that there IS a problem. Use ping for quick reachability checks; use traceroute to diagnose routing issues.
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