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 04:24:48 UTC |

| Revérifier |

Emplacement	Résultat	Temps	Adresse IP
Australia, Sydney	Connected	1.0 ms	8.8.8.8
Bosnia and Herzegovina, Novi Travnik	Connected	20.0 ms	8.8.8.8
Bulgaria, Sofia	Connected	4.0 ms	8.8.8.8
Canada, Montreal	Connected	5.0 ms	8.8.8.8
Switzerland, Bern	Connected	8.0 ms	8.8.8.8
Switzerland, Zurich	Connected	27.0 ms	8.8.8.8
China, Hohhot	Connected	200.0 ms	8.8.8.8
Cyprus, Larnaca	Connected	9.0 ms	8.8.8.8
Germany, Nuernberg	Connected	11.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	3.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	4.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	8.0 ms	8.8.8.8
Germany, Koblenz	Connected	26.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	6.0 ms	8.8.8.8
Denmark, Glostrup Municipality	Connected	44.0 ms	8.8.8.8
Spain, Bilbao	Connected	117.0 ms	8.8.8.8
Spain, Barcelona	Connected	27.0 ms	8.8.8.8
Finland, Helsinki	Connected	11.0 ms	8.8.8.8
Finland, Helsinki	Connected	33.0 ms	8.8.8.8
France, Gravelines	Connected	5.0 ms	8.8.8.8
France, Paris	Connected	15.0 ms	8.8.8.8
United Kingdom, London	Connected	16.0 ms	8.8.8.8
Hong Kong, Hong Kong	Connected	4.0 ms	8.8.8.8
Croatia, Zagreb	Connected	31.0 ms	8.8.8.8
Hungary, Budapest	Connected	40.0 ms	8.8.8.8
Israel, Petach Tikwa	Connected	6.0 ms	8.8.8.8
Israel, Netanja	Connected	17.0 ms	8.8.8.8
Iran, Tehran	Connected	4.0 ms	8.8.8.8
Iran, Tehran	Connected	9.0 ms	8.8.8.8
Iceland, Reykjavik (Miðborg)	Connected	36.0 ms	8.8.8.8
Italy, Como	Connected	15.0 ms	8.8.8.8
Japan, Tokyo	Connected	3.0 ms	8.8.8.8
South Korea, Seoul	Connected	49.0 ms	8.8.8.8
Kazakhstan, Almaty	Connected	86.0 ms	8.8.8.8
Lithuania, Pilaite	Connected	90.0 ms	8.8.8.8
Latvia, Riga	Connected	125.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	4.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	9.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	8.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	9.0 ms	8.8.8.8
Netherlands, Eygelshoven	Connected	9.0 ms	8.8.8.8
Norway, Oslo	Connected	32.0 ms	8.8.8.8
Poland, Warsaw	Connected	38.0 ms	8.8.8.8
Romania, Bacău	Connected	39.0 ms	8.8.8.8
Romania, Bucharest	Connected	27.0 ms	8.8.8.8
Serbia, Belgrade	Connected	14.0 ms	8.8.8.8
Russia, Moscow	Connected	40.0 ms	8.8.8.8
Singapore, Singapore	Connected	8.0 ms	8.8.8.8
Tor, Onion	ERROR	-	8.8.8.8
Tor, Onion	ERROR	-	8.8.8.8
Tor, Onion	ERROR	-	8.8.8.8
Turkey, Istanbul	Connected	14.0 ms	8.8.8.8
Ukraine, Khmelnytskyi	Connected	123.0 ms	8.8.8.8
United States, Dallas	Connected	60.0 ms	8.8.8.8
United States, Los Angeles	Connected	42.0 ms	8.8.8.8
United States, Houston	Connected	40.0 ms	8.8.8.8
United States, Miami	Connected	11.0 ms	8.8.8.8
South Africa, Johannesburg	Connected	3.0 ms	8.8.8.8