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 gb-lon-abr.check-host.eu:80

Name: Check-Host gb-lon-abr.check-host.eu:80 TCP Port Connectivity Test
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

Check TCP gb-lon-abr.check-host.eu:80

Checked Apr 30, 2026 19:18:36 UTC |

| Check again |

ठिकाण	निकाल	वेळ	IP Address
Albania, Tirana	ERROR	-	31.59.122.194
Australia, Sydney	ERROR	-	31.59.122.194
Bosnia and Herzegovina, Novi Travnik	ERROR	-	31.59.122.194
Bulgaria, Sofia	ERROR	-	31.59.122.194
Canada, Montreal	ERROR	-	31.59.122.194
Switzerland, Bern	ERROR	-	31.59.122.194
Chile, Santiago	ERROR	-	31.59.122.194
China, Hohhot	ERROR	-	31.59.122.194
Germany, Nuernberg	ERROR	-	31.59.122.194
Germany, Frankfurt am Main	ERROR	-	31.59.122.194
Germany, Frankfurt am Main	ERROR	-	31.59.122.194
Germany, Limburg	ERROR	-	31.59.122.194
Germany, Frankfurt am Main	ERROR	-	31.59.122.194
Germany, Duesseldorf	ERROR	-	31.59.122.194
Denmark, Glostrup Municipality	Connected	13.0 ms	31.59.122.194
Spain, Bilbao	ERROR	-	31.59.122.194
Finland, Helsinki	ERROR	-	31.59.122.194
Finland, Helsinki	ERROR	-	31.59.122.194
France, Gravelines	ERROR	-	31.59.122.194
France, Paris	Connected	9.0 ms	31.59.122.194
United Kingdom, London	ERROR	-	31.59.122.194
Georgia, Tbilisi	ERROR	-	gb-lon-abr.check-host.eu
Hong Kong, Hong Kong	ERROR	-	31.59.122.194
Croatia, Zagreb	ERROR	-	31.59.122.194
Hungary, Budapest	Connected	15.0 ms	31.59.122.194
Indonesia, Jakarta	ERROR	-	31.59.122.194
Israel, Petach Tikwa	ERROR	-	31.59.122.194
Israel, Netanja	ERROR	-	31.59.122.194
India, New Delhi	ERROR	-	31.59.122.194
Iceland, Reykjavik (Miðborg)	ERROR	-	31.59.122.194
Italy, Como	ERROR	-	31.59.122.194
Lithuania, Pilaite	ERROR	-	31.59.122.194
Latvia, Riga	Connected	38.0 ms	31.59.122.194
Moldova, Chisinau	Connected	129.0 ms	31.59.122.194
Netherlands, Amsterdam	ERROR	-	31.59.122.194
Netherlands, Amsterdam	ERROR	-	31.59.122.194
Netherlands, Amsterdam	ERROR	-	31.59.122.194
Netherlands, Amsterdam	ERROR	-	31.59.122.194
Norway, Oslo	ERROR	-	31.59.122.194
Poland, Warsaw	Connected	22.0 ms	31.59.122.194
Romania, Bacău	ERROR	-	31.59.122.194
Romania, Bucharest	ERROR	-	31.59.122.194
Serbia, Belgrade	Connected	127.0 ms	31.59.122.194
Russia, Moscow	ERROR	-	31.59.122.194
Saudi Arabia, Riyadh	ERROR	-	31.59.122.194
Singapore, Singapore	ERROR	-	31.59.122.194
Tor, Onion	ERROR	-	gb-lon-abr.check-host.eu
Tor, Onion	ERROR	-	gb-lon-abr.check-host.eu
Tor, Onion	ERROR	-	gb-lon-abr.check-host.eu
Turkey, Istanbul	ERROR	-	31.59.122.194
Taiwan, Taipei	ERROR	-	31.59.122.194
United States, Miami	ERROR	-	31.59.122.194
United States, Dallas	ERROR	-	31.59.122.194
United States, Kansas City	ERROR	-	31.59.122.194
United States, Dallas	ERROR	-	31.59.122.194
South Africa, Johannesburg	ERROR	-	31.59.122.194