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 50+ 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 google.com:80

Info Ping HTTP TCP UDP MTR DNS

TCP prüfen google.com:80

Geprüft am Apr 21, 2026 10:49:23 UTC |

| Erneut prüfen |

Standort	Ergebnis	Zeit	IP-Adresse
Albania, Tirana	Connected	47.0 ms	142.251.208.110
Australia, Sydney	Connected	0.0 ms	172.217.25.174
Bosnia and Herzegovina, Novi Travnik	Connected	48.0 ms	142.251.140.78
Bulgaria, Sofia	ERROR	-	172.217.21.238
Canada, Montreal	Connected	2.0 ms	64.233.178.100
Switzerland, Bern	Connected	3.0 ms	74.125.29.138
Chile, Santiago	Connected	1.0 ms	142.251.0.139
China, Hohhot	ERROR	-	142.250.73.142
Germany, Nuernberg	Connected	4.0 ms	142.251.20.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.143.110
Germany, Frankfurt am Main	Connected	1.0 ms	142.251.20.101
Germany, Limburg	Connected	2.0 ms	142.251.110.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.208.14
Germany, Duesseldorf	Connected	4.0 ms	172.217.23.238
Denmark, Glostrup Municipality	Connected	12.0 ms	142.251.143.142
Spain, Bilbao	Connected	36.0 ms	142.251.13.101
Finland, Helsinki	Connected	38.0 ms	142.251.38.78
Finland, Helsinki	Connected	16.0 ms	142.251.38.78
France, Gravelines	Connected	11.0 ms	142.251.14.101
France, Paris	Connected	9.0 ms	142.251.39.110
United Kingdom, London	Connected	6.0 ms	142.250.140.139
Georgia, Tbilisi	ERROR	-	google.com
Greece, Athens	ERROR	-	google.com
Hong Kong, Hong Kong	Connected	3.0 ms	216.58.198.14
Croatia, Zagreb	Connected	25.0 ms	142.251.20.101
Hungary, Budapest	Connected	15.0 ms	172.217.171.174
Indonesia, Jakarta	Connected	1.0 ms	142.250.4.139
Israel, Petach Tikwa	Connected	1.0 ms	142.250.75.46
Israel, Netanja	Connected	2.0 ms	142.250.75.46
India, New Delhi	Connected	1.0 ms	216.58.200.174
Iceland, Reykjavik (Miðborg)	Connected	36.0 ms	142.250.180.14
Italy, Como	Connected	30.0 ms	142.251.141.238
Kuwait, Kuwait City	ERROR	-	google.com
Lithuania, Pilaite	Connected	57.0 ms	172.217.19.238
Latvia, Riga	Connected	31.0 ms	142.250.102.113
Moldova, Chisinau	Connected	70.0 ms	192.178.24.174
Netherlands, Amsterdam	Connected	1.0 ms	142.251.142.206
Netherlands, Amsterdam	Connected	3.0 ms	192.178.25.206
Netherlands, Amsterdam	Connected	0.0 ms	172.217.23.238
Netherlands, Amsterdam	Connected	1.0 ms	172.217.23.238
Norway, Oslo	Connected	33.0 ms	209.85.203.100
Poland, Warsaw	Connected	15.0 ms	142.251.98.100
Romania, Bacău	Connected	33.0 ms	142.250.201.78
Romania, Bucharest	Connected	8.0 ms	172.217.21.206
Serbia, Belgrade	Connected	30.0 ms	142.251.20.102
Russia, St Petersburg	Connected	5.0 ms	173.194.222.138
Singapore, Singapore	Connected	1.0 ms	74.125.200.113
Turkey, Istanbul	Connected	11.0 ms	172.217.21.206
Taiwan, Taipei	Connected	1.0 ms	142.250.204.46
United States, Miami	Connected	60.0 ms	142.251.35.110
United States, Dallas	Connected	18.0 ms	172.253.135.102
United States, Kansas City	Connected	31.0 ms	142.250.152.113
United States, Dallas	Connected	2.0 ms	142.250.113.113
South Africa, Johannesburg	Connected	0.0 ms	142.251.47.142