How do I check if a TCP port is open online?

Enter your server's IP address or domain followed by a colon and the port number (e.g. 1.1.1.1:80 or example.com:443) and run a TCP check. The tool attempts a TCP handshake from 65+ global nodes and reports whether each connection succeeded, was refused, or timed out.

What is the difference between a port being refused versus timing out?

A refused connection (TCP RST) means the port is actively closed — the server replied to reject the connection. A timeout means no reply was received at all, which typically indicates a firewall is silently dropping packets before they reach the server or application.

Which TCP ports can I test?

Any valid TCP port from 1 to 65535. Common examples include port 80 (HTTP), 443 (HTTPS), 22 (SSH), 25 (SMTP), 3306 (MySQL), 5432 (PostgreSQL), and 3389 (RDP). No login or special permissions required — the check only verifies whether the TCP handshake completes.

My port is open locally but fails from external nodes — why?

If a port works locally but fails from external nodes, something between the internet and your server is blocking it — commonly a cloud security group, iptables rule, upstream ISP filter, or geoblocking policy. Running the check from multiple regions helps identify whether the block is global or specific to certain countries or ASNs.

Rapport pour 8.8.8.8:53

Info Ping HTTP TCP UDP MTR DNS

Vérifier TCP 8.8.8.8:53

Vérifié le Oct 23, 2026 07:55:53 UTC |

| Revérifier |

Emplacement	Résultat	Temps	Adresse IP
Australia, Sydney	Connected	1.0 ms	8.8.8.8
Bosnia and Herzegovina, Novi Travnik	Connected	15.0 ms	8.8.8.8
Bulgaria, Sofia	Connected	1.0 ms	8.8.8.8
Canada, Montreal	Connected	2.0 ms	8.8.8.8
Switzerland, Bern	Connected	1.0 ms	8.8.8.8
Switzerland, Zurich	Connected	27.0 ms	8.8.8.8
China, Hohhot	Connected	211.0 ms	8.8.8.8
Cyprus, Larnaca	Connected	9.0 ms	8.8.8.8
Germany, Nuernberg	Connected	5.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	1.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	0.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	1.0 ms	8.8.8.8
Germany, Koblenz	Connected	16.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	5.0 ms	8.8.8.8
Denmark, Glostrup Municipality	Connected	29.0 ms	8.8.8.8
Spain, Bilbao	Connected	46.0 ms	8.8.8.8
Spain, Barcelona	Connected	24.0 ms	8.8.8.8
Finland, Helsinki	Connected	4.0 ms	8.8.8.8
Finland, Helsinki	Connected	12.0 ms	8.8.8.8
France, Gravelines	Connected	5.0 ms	8.8.8.8
France, Paris	Connected	10.0 ms	8.8.8.8
United Kingdom, London	Connected	8.0 ms	8.8.8.8
Hong Kong, Hong Kong	Connected	1.0 ms	8.8.8.8
Croatia, Zagreb	Connected	28.0 ms	8.8.8.8
Hungary, Budapest	Connected	82.0 ms	8.8.8.8
Israel, Petach Tikwa	Connected	2.0 ms	8.8.8.8
Israel, Netanja	Connected	2.0 ms	8.8.8.8
Iran, Tehran	Connected	1.0 ms	8.8.8.8
Iran, Tehran	Connected	1.0 ms	8.8.8.8
Iceland, Reykjavik (Miðborg)	Connected	22.0 ms	8.8.8.8
Italy, Como	Connected	1.0 ms	8.8.8.8
Japan, Tokyo	Connected	2.0 ms	8.8.8.8
South Korea, Seoul	Connected	35.0 ms	8.8.8.8
Kazakhstan, Almaty	Connected	92.0 ms	8.8.8.8
Lithuania, Pilaite	Connected	70.0 ms	8.8.8.8
Latvia, Riga	Connected	68.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	0.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	3.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	1.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	1.0 ms	8.8.8.8
Netherlands, Eygelshoven	Connected	6.0 ms	8.8.8.8
Norway, Oslo	Connected	32.0 ms	8.8.8.8
Poland, Warsaw	Connected	41.0 ms	8.8.8.8
Romania, Bacău	Connected	39.0 ms	8.8.8.8
Romania, Bucharest	Connected	8.0 ms	8.8.8.8
Serbia, Belgrade	Connected	11.0 ms	8.8.8.8
Russia, Moscow	Connected	29.0 ms	8.8.8.8
Singapore, Singapore	Connected	1.0 ms	8.8.8.8
Tor, Onion	Connected	55.0 ms	8.8.8.8
Tor, Onion	Connected	41.0 ms	8.8.8.8
Tor, Onion	Connected	99.0 ms	8.8.8.8
Turkey, Istanbul	Connected	10.0 ms	8.8.8.8
Ukraine, Khmelnytskyi	Connected	28.0 ms	8.8.8.8
United States, Dallas	Connected	0.0 ms	8.8.8.8
United States, Los Angeles	Connected	30.0 ms	8.8.8.8
United States, Houston	Connected	7.0 ms	8.8.8.8
United States, Miami	Connected	1.0 ms	8.8.8.8
South Africa, Johannesburg	Connected	2.0 ms	8.8.8.8