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.

Report for nl-eyg-vmheaven.check-host.eu:80

Name: Check-Host nl-eyg-vmheaven.check-host.eu:80 TCP Port Connectivity Test
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

Check TCP nl-eyg-vmheaven.check-host.eu:80

Checked Oct 23, 2026 15:03:58 UTC |

| Check again |

Location	Result	Time	IP Address
Albania, Tirana	ERROR	-	192.109.200.172
Australia, Sydney	ERROR	-	192.109.200.172
Bosnia and Herzegovina, Novi Travnik	ERROR	-	192.109.200.172
Bulgaria, Sofia	ERROR	-	192.109.200.172
Canada, Montreal	ERROR	-	192.109.200.172
Switzerland, Bern	ERROR	-	192.109.200.172
Switzerland, Zurich	ERROR	-	192.109.200.172
China, Hohhot	ERROR	-	192.109.200.172
Cyprus, Larnaca	ERROR	-	192.109.200.172
Germany, Nuernberg	ERROR	-	192.109.200.172
Germany, Frankfurt am Main	ERROR	-	192.109.200.172
Germany, Frankfurt am Main	ERROR	-	192.109.200.172
Germany, Frankfurt am Main	ERROR	-	192.109.200.172
Germany, Koblenz	ERROR	-	192.109.200.172
Germany, Frankfurt am Main	ERROR	-	192.109.200.172
Denmark, Glostrup Municipality	ERROR	-	192.109.200.172
Spain, Bilbao	ERROR	-	192.109.200.172
Spain, Barcelona	ERROR	-	192.109.200.172
Finland, Helsinki	ERROR	-	192.109.200.172
Finland, Helsinki	ERROR	-	192.109.200.172
France, Gravelines	ERROR	-	192.109.200.172
France, Paris	ERROR	-	192.109.200.172
United Kingdom, London	ERROR	-	192.109.200.172
Hong Kong, Hong Kong	ERROR	-	192.109.200.172
Croatia, Zagreb	ERROR	-	192.109.200.172
Hungary, Budapest	ERROR	-	192.109.200.172
Israel, Petach Tikwa	ERROR	-	192.109.200.172
Israel, Netanja	ERROR	-	192.109.200.172
Iran, Tehran	ERROR	-	192.109.200.172
Iran, Tehran	ERROR	-	192.109.200.172
Iceland, Reykjavik (Miðborg)	ERROR	-	192.109.200.172
Italy, Como	ERROR	-	192.109.200.172
Japan, Tokyo	ERROR	-	192.109.200.172
South Korea, Seoul	ERROR	-	192.109.200.172
Kazakhstan, Almaty	ERROR	-	192.109.200.172
Lithuania, Pilaite	ERROR	-	192.109.200.172
Latvia, Riga	ERROR	-	192.109.200.172
Moldova, Chisinau	ERROR	-	192.109.200.172
Netherlands, Amsterdam	ERROR	-	192.109.200.172
Netherlands, Amsterdam	ERROR	-	192.109.200.172
Netherlands, Amsterdam	ERROR	-	192.109.200.172
Netherlands, Amsterdam	ERROR	-	192.109.200.172
Netherlands, Eygelshoven	ERROR	-	192.109.200.172
Norway, Oslo	ERROR	-	192.109.200.172
Poland, Warsaw	ERROR	-	192.109.200.172
Romania, Bacău	ERROR	-	192.109.200.172
Romania, Bucharest	ERROR	-	192.109.200.172
Serbia, Belgrade	ERROR	-	192.109.200.172
Russia, Moscow	ERROR	-	192.109.200.172
Singapore, Singapore	ERROR	-	192.109.200.172
Tor, Onion	ERROR	-	nl-eyg-vmheaven.check-host.eu
Tor, Onion	ERROR	-	nl-eyg-vmheaven.check-host.eu
Tor, Onion	ERROR	-	nl-eyg-vmheaven.check-host.eu
Turkey, Istanbul	ERROR	-	192.109.200.172
Ukraine, Khmelnytskyi	ERROR	-	192.109.200.172
United States, Dallas	ERROR	-	192.109.200.172
United States, Los Angeles	ERROR	-	192.109.200.172
United States, Houston	ERROR	-	192.109.200.172
United States, Miami	ERROR	-	192.109.200.172
South Africa, Johannesburg	ERROR	-	192.109.200.172