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.

Bericht für 1.1.1.1:80

Info Ping HTTP TCP UDP MTR DNS

TCP prüfen 1.1.1.1:80

Geprüft am Oct 23, 2026 16:11:18 UTC |

| Erneut prüfen |

Standort	Ergebnis	Zeit	IP-Adresse
Albania, Tirana	Connected	131.0 ms	1.1.1.1
Australia, Sydney	Connected	4.0 ms	1.1.1.1
Bosnia and Herzegovina, Novi Travnik	Connected	17.0 ms	1.1.1.1
Bulgaria, Sofia	Connected	31.0 ms	1.1.1.1
Canada, Montreal	Connected	13.0 ms	1.1.1.1
Switzerland, Bern	Connected	3.0 ms	1.1.1.1
Switzerland, Zurich	Connected	27.0 ms	1.1.1.1
China, Hohhot	Connected	270.0 ms	1.1.1.1
Cyprus, Larnaca	Connected	2.0 ms	1.1.1.1
Germany, Nuernberg	Connected	15.0 ms	1.1.1.1
Germany, Frankfurt am Main	Connected	1.0 ms	1.1.1.1
Germany, Frankfurt am Main	Connected	0.0 ms	1.1.1.1
Germany, Frankfurt am Main	Connected	1.0 ms	1.1.1.1
Germany, Koblenz	Connected	32.0 ms	1.1.1.1
Germany, Frankfurt am Main	Connected	7.0 ms	1.1.1.1
Denmark, Glostrup Municipality	Connected	42.0 ms	1.1.1.1
Spain, Bilbao	Connected	42.0 ms	1.1.1.1
Spain, Barcelona	Connected	18.0 ms	1.1.1.1
Finland, Helsinki	Connected	11.0 ms	1.1.1.1
Finland, Helsinki	Connected	19.0 ms	1.1.1.1
France, Gravelines	Connected	5.0 ms	1.1.1.1
France, Paris	Connected	18.0 ms	1.1.1.1
United Kingdom, London	Connected	16.0 ms	1.1.1.1
Hong Kong, Hong Kong	Connected	8.0 ms	1.1.1.1
Croatia, Zagreb	Connected	25.0 ms	1.1.1.1
Hungary, Budapest	Connected	70.0 ms	1.1.1.1
Israel, Petach Tikwa	Connected	1.0 ms	1.1.1.1
Israel, Netanja	Connected	1.0 ms	1.1.1.1
Iran, Tehran	Connected	1.0 ms	1.1.1.1
Iran, Tehran	Connected	1.0 ms	1.1.1.1
Iceland, Reykjavik (Miðborg)	Connected	2.0 ms	1.1.1.1
Italy, Como	Connected	1.0 ms	1.1.1.1
Japan, Tokyo	Connected	1.0 ms	1.1.1.1
South Korea, Seoul	Connected	2.0 ms	1.1.1.1
Kazakhstan, Almaty	Connected	2.0 ms	1.1.1.1
Lithuania, Pilaite	Connected	65.0 ms	1.1.1.1
Latvia, Riga	Connected	93.0 ms	1.1.1.1
Moldova, Chisinau	Connected	108.0 ms	1.1.1.1
Netherlands, Amsterdam	Connected	1.0 ms	1.1.1.1
Netherlands, Amsterdam	Connected	3.0 ms	1.1.1.1
Netherlands, Amsterdam	Connected	1.0 ms	1.1.1.1
Netherlands, Amsterdam	Connected	1.0 ms	1.1.1.1
Netherlands, Eygelshoven	Connected	8.0 ms	1.1.1.1
Norway, Oslo	Connected	0.0 ms	1.1.1.1
Poland, Warsaw	Connected	16.0 ms	1.1.1.1
Romania, Bacău	Connected	53.0 ms	1.1.1.1
Romania, Bucharest	Connected	11.0 ms	1.1.1.1
Serbia, Belgrade	Connected	10.0 ms	1.1.1.1
Russia, Moscow	Connected	24.0 ms	1.1.1.1
Singapore, Singapore	Connected	295.0 ms	1.1.1.1
Tor, Onion	Connected	114.0 ms	1.1.1.1
Tor, Onion	Connected	168.0 ms	1.1.1.1
Tor, Onion	Connected	88.0 ms	1.1.1.1
Turkey, Istanbul	Connected	12.0 ms	1.1.1.1
Ukraine, Khmelnytskyi	Connected	9.0 ms	1.1.1.1
United States, Dallas	Connected	1.0 ms	1.1.1.1
United States, Los Angeles	Connected	1.0 ms	1.1.1.1
United States, Houston	Connected	10.0 ms	1.1.1.1
United States, Miami	Connected	1.0 ms	1.1.1.1
South Africa, Johannesburg	Connected	2.0 ms	1.1.1.1