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 22, 2026 12:09:58 UTC |

| Erneut prüfen |

Standort	Ergebnis	Zeit	IP-Adresse
Albania, Tirana	Connected	49.0 ms	142.251.208.110
Australia, Sydney	Connected	1.0 ms	142.251.222.14
Bosnia and Herzegovina, Novi Travnik	Connected	48.0 ms	142.251.140.78
Bulgaria, Sofia	Connected	1.0 ms	192.178.25.238
Canada, Montreal	Connected	2.0 ms	64.233.178.100
Switzerland, Bern	Connected	3.0 ms	74.125.29.113
Chile, Santiago	Connected	1.0 ms	64.233.190.100
China, Hohhot	ERROR	-	142.250.73.110
Germany, Nuernberg	Connected	10.0 ms	142.251.127.102
Germany, Frankfurt am Main	Connected	1.0 ms	142.251.20.138
Germany, Frankfurt am Main	Connected	1.0 ms	142.251.14.101
Germany, Limburg	Connected	2.0 ms	142.251.13.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.20.138
Germany, Duesseldorf	Connected	3.0 ms	142.251.39.142
Denmark, Glostrup Municipality	Connected	12.0 ms	142.251.143.142
Spain, Bilbao	Connected	36.0 ms	142.251.13.102
Finland, Helsinki	Connected	39.0 ms	192.178.25.78
Finland, Helsinki	Connected	16.0 ms	142.251.38.78
France, Gravelines	Connected	12.0 ms	192.178.183.138
France, Paris	Connected	9.0 ms	172.217.22.14
United Kingdom, London	Connected	6.0 ms	142.250.151.101
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	24.0 ms	142.251.110.101
Hungary, Budapest	Connected	15.0 ms	172.217.171.174
Indonesia, Jakarta	Connected	1.0 ms	172.253.118.113
Israel, Petach Tikwa	Connected	2.0 ms	142.250.75.110
Israel, Netanja	Connected	2.0 ms	142.250.75.110
India, New Delhi	Connected	1.0 ms	142.251.43.174
Iceland, Reykjavik (Miðborg)	Connected	23.0 ms	209.85.202.138
Italy, Como	Connected	30.0 ms	142.250.181.174
Kuwait, Kuwait City	ERROR	-	google.com
Lithuania, Pilaite	Connected	57.0 ms	172.217.19.238
Latvia, Riga	Connected	31.0 ms	142.250.102.139
Moldova, Chisinau	Connected	36.0 ms	192.178.24.174
Netherlands, Amsterdam	Connected	1.0 ms	142.251.142.206
Netherlands, Amsterdam	Connected	3.0 ms	172.217.23.238
Netherlands, Amsterdam	Connected	1.0 ms	172.217.23.238
Netherlands, Amsterdam	Connected	1.0 ms	172.217.23.238
Norway, Oslo	Connected	34.0 ms	209.85.203.100
Poland, Warsaw	Connected	18.0 ms	142.251.98.100
Romania, Bacău	Connected	44.0 ms	142.251.20.139
Romania, Bucharest	Connected	8.0 ms	192.178.24.14
Serbia, Belgrade	Connected	30.0 ms	142.251.110.138
Russia, St Petersburg	Connected	4.0 ms	108.177.14.113
Singapore, Singapore	Connected	1.0 ms	74.125.200.101
Turkey, Istanbul	Connected	10.0 ms	142.251.208.110
Taiwan, Taipei	Connected	1.0 ms	142.250.204.46
United States, Miami	Connected	1.0 ms	192.178.50.46
United States, Dallas	Connected	18.0 ms	173.194.208.138
United States, Kansas City	Connected	26.0 ms	142.251.184.101
United States, Dallas	Connected	2.0 ms	142.251.116.101
South Africa, Johannesburg	Connected	0.0 ms	142.251.47.142