Check-Host.cc

Info Ping HTTP TCP UDP MTR DNS

Check TCP de-ffm-krk.check-host.eu:80

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Location Result Time IP Address
AL Albania, Tirana
AU Australia, Sydney
BA Bosnia and Herzegovina, Novi Travnik
BG Bulgaria, Sofia
CA Canada, Montreal
CH Switzerland, Bern
CL Chile, Santiago
CN China, Hohhot
DE Germany, Nuernberg
DE Germany, Frankfurt am Main
DE Germany, Frankfurt am Main
DE Germany, Limburg
DK Denmark, Glostrup Municipality
ES Spain, Madrid
FI Finland, Helsinki
FI Finland, Helsinki
FR France, Gravelines
FR France, Paris
GB United Kingdom, London
HK Hong Kong, Hong Kong
HR Croatia, Zagreb
HU Hungary, Budapest
ID Indonesia, Jakarta
IN India, New Delhi
IS Iceland, Reykjavik (Miðborg)
IT Italy, Como
LT Lithuania, Pilaite
LV Latvia, Riga
MD Moldova, Chisinau
NL Netherlands, Amsterdam
NL Netherlands, Amsterdam
NL Netherlands, Amsterdam
NL Netherlands, Eygelshoven
QA Qatar, Doha
RO Romania, Bacău
RO Romania, Bucharest
RS Serbia, Belgrade
SG Singapore, Singapore
TW Taiwan, Taipei
US United States, Miami
US United States, Dallas
US United States, Kansas City

Global TCP Port Checker & Network Connectivity Test

The Check-Host TCP port checker is a critical transport-layer diagnostic tool. It allows systems administrators to verify if a specific port is open, closed, or stealth-dropped by a firewall across more than 50 geographic locations by initiating a standard 3-way TCP handshake (SYN, SYN-ACK, ACK).

Firewall & Routing Validation

When deploying new infrastructure, verifying port reachability is the first step. If a local test succeeds but the global TCP check fails or times out, it indicates strict regional geoblocking, upstream ISP filtering, or an improperly configured edge firewall (like AWS Security Groups or iptables) dropping inbound packets.

Application vs. Transport Layer

Unlike an HTTP check which requires a fully formed layer-7 response, the TCP check operates purely at layer 4. This means you can test the availability of databases (MySQL port 3306), mail servers (SMTP port 25), or remote access gateways (SSH port 22 or RDP port 3389) without needing application-level authentication credentials.

Handshake Latency Analysis

The time measured in a TCP check is specifically the round-trip time required to complete the TCP handshake. Tracking this latency globally helps identify suboptimal BGP routing or unoptimized Anycast networks. Our Live TCP mode allows for real-time monitoring of this latency to catch intermittent connection drops.