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.

Report for google.com:80

Location	Result	Time	IP Address
Albania, Tirana	Connected	80.0 ms	192.178.24.174
Australia, Sydney	Connected	0.0 ms	142.251.222.14
Bosnia and Herzegovina, Novi Travnik	Connected	48.0 ms	142.251.140.78
Bulgaria, Sofia	Connected	1.0 ms	192.178.24.78
Canada, Montreal	Connected	2.0 ms	64.233.178.101
Switzerland, Bern	Connected	2.0 ms	74.125.29.138
Chile, Santiago	Connected	1.0 ms	142.251.0.100
China, Hohhot	ERROR	-	142.250.69.174
Germany, Nuernberg	Connected	4.0 ms	142.251.20.139
Germany, Frankfurt am Main	Connected	0.0 ms	142.250.154.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.14.113
Germany, Limburg	Connected	2.0 ms	142.251.13.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.14.101
Germany, Duesseldorf	Connected	4.0 ms	142.251.39.142
Denmark, Glostrup Municipality	Connected	12.0 ms	192.178.25.14
Spain, Bilbao	Connected	37.0 ms	142.251.13.100
Finland, Helsinki	Connected	34.0 ms	192.178.25.78
Finland, Helsinki	Connected	8.0 ms	142.251.143.142
France, Gravelines	Connected	11.0 ms	192.178.183.139
France, Paris	Connected	18.0 ms	172.217.22.14
United Kingdom, London	Connected	7.0 ms	192.178.223.102
Georgia, Tbilisi	ERROR	-	google.com
Greece, Athens	ERROR	-	google.com
Hong Kong, Hong Kong	Connected	4.0 ms	216.58.198.14
Croatia, Zagreb	Connected	24.0 ms	142.251.110.113
Hungary, Budapest	Connected	15.0 ms	172.217.171.174
Indonesia, Jakarta	Connected	1.0 ms	74.125.24.100
Israel, Petach Tikwa	Connected	2.0 ms	142.250.75.110
Israel, Netanja	Connected	1.0 ms	142.250.75.46
India, New Delhi	Connected	1.0 ms	142.250.182.110
Iceland, Reykjavik (Miðborg)	Connected	22.0 ms	209.85.202.139
Italy, Como	Connected	30.0 ms	172.217.23.78
Kuwait, Kuwait City	ERROR	-	google.com
Lithuania, Pilaite	Connected	55.0 ms	172.217.19.238
Latvia, Riga	Connected	31.0 ms	142.250.102.138
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	142.250.180.14
Netherlands, Amsterdam	Connected	1.0 ms	172.217.23.238
Netherlands, Amsterdam	Connected	1.0 ms	172.217.17.206
Norway, Oslo	Connected	34.0 ms	209.85.203.139
Poland, Warsaw	ERROR	-	142.251.98.101
Romania, Bacău	Connected	46.0 ms	142.251.20.138
Romania, Bucharest	Connected	8.0 ms	192.178.24.14
Serbia, Belgrade	Connected	45.0 ms	142.251.110.113
Russia, St Petersburg	Connected	MIN23.0 AVG267.0 MAX511.0	173.194.221.139
Singapore, Singapore	Connected	1.0 ms	142.251.10.138
Turkey, Istanbul	Connected	10.0 ms	142.251.208.110
Taiwan, Taipei	Connected	2.0 ms	142.250.204.46
United States, Miami	Connected	1.0 ms	142.251.35.110
United States, Dallas	Connected	18.0 ms	142.250.113.113
United States, Kansas City	Connected	24.0 ms	209.85.145.101
United States, Dallas	Connected	2.0 ms	142.250.138.101
South Africa, Johannesburg	Connected	0.0 ms	192.178.54.46

Albania, Tirana

Connected

80.0 ms

192.178.24.174

Australia, Sydney

Connected

0.0 ms

142.251.222.14

Bosnia and Herzegovina, Novi Travnik

Connected

48.0 ms

142.251.140.78

Bulgaria, Sofia

Connected

1.0 ms

192.178.24.78

Canada, Montreal

Connected

2.0 ms

64.233.178.101

Switzerland, Bern

Connected

2.0 ms

74.125.29.138

Chile, Santiago

Connected

1.0 ms

142.251.0.100

China, Hohhot

ERROR

-

142.250.69.174

Germany, Nuernberg

Connected

4.0 ms

142.251.20.139

Germany, Frankfurt am Main

Connected

0.0 ms

142.250.154.138

Germany, Frankfurt am Main

Connected

0.0 ms

142.251.14.113

Germany, Limburg

Connected

2.0 ms

142.251.13.138

Germany, Frankfurt am Main

Connected

0.0 ms

142.251.14.101

Germany, Duesseldorf

Connected

4.0 ms

142.251.39.142

Denmark, Glostrup Municipality

Connected

12.0 ms

192.178.25.14

Spain, Bilbao

Connected

37.0 ms

142.251.13.100

Finland, Helsinki

Connected

34.0 ms

192.178.25.78

Finland, Helsinki

Connected

8.0 ms

142.251.143.142

France, Gravelines

Connected

11.0 ms

192.178.183.139

France, Paris

Connected

18.0 ms

172.217.22.14

United Kingdom, London

Connected

7.0 ms

192.178.223.102

Georgia, Tbilisi

ERROR

-

google.com

Greece, Athens

ERROR

-

google.com

Hong Kong, Hong Kong

Connected

4.0 ms

216.58.198.14

Croatia, Zagreb

Connected

24.0 ms

142.251.110.113

Hungary, Budapest

Connected

15.0 ms

172.217.171.174

Indonesia, Jakarta

Connected

1.0 ms

74.125.24.100

Israel, Petach Tikwa

Connected

2.0 ms

142.250.75.110

Israel, Netanja

Connected

1.0 ms

142.250.75.46

India, New Delhi

Connected

1.0 ms

142.250.182.110

Iceland, Reykjavik (Miðborg)

Connected

22.0 ms

209.85.202.139

Italy, Como

Connected

30.0 ms

172.217.23.78

Kuwait, Kuwait City

ERROR

-

google.com

Lithuania, Pilaite

Connected

55.0 ms

172.217.19.238

Latvia, Riga

Connected

31.0 ms

142.250.102.138

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

142.250.180.14

Netherlands, Amsterdam

Connected

1.0 ms

172.217.23.238

Netherlands, Amsterdam

Connected

1.0 ms

172.217.17.206

Norway, Oslo

Connected

34.0 ms

209.85.203.139

Poland, Warsaw

ERROR

-

142.251.98.101

Romania, Bacău

Connected

46.0 ms

142.251.20.138

Romania, Bucharest

Connected

8.0 ms

192.178.24.14

Serbia, Belgrade

Connected

45.0 ms

142.251.110.113

Russia, St Petersburg

Connected

MIN23.0

AVG267.0

MAX511.0

173.194.221.139

Singapore, Singapore

Connected

1.0 ms

142.251.10.138

Turkey, Istanbul

Connected

10.0 ms

142.251.208.110

Taiwan, Taipei

Connected

2.0 ms

142.250.204.46

United States, Miami

Connected

1.0 ms

142.251.35.110

United States, Dallas

Connected

18.0 ms

142.250.113.113

United States, Kansas City

Connected

24.0 ms

209.85.145.101

United States, Dallas

Connected

2.0 ms

142.250.138.101

South Africa, Johannesburg

Connected

0.0 ms

192.178.54.46

Check-Host.cc

Check TCP google.com:80