Check-Host.cc

資訊 Ping HTTP TCP UDP MTR DNS

檢查 :target TCP 連接埠 gb-lon-abr.check-host.eu:80

永久連結 |
節點位置 結果 時間 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

我們的 TCP 連接埠檢查工具會從全球多個測試節點，嘗試與目標主機的特定連接埠建立底層的傳輸控制協定 (TCP) 握手 (handshake) 連線。這是驗證關鍵連接埠 (如 SSH 的 22、MySQL 的 3306 或 SMTP 的 25) 是否開啟並主動接受連線的最直接方式。

Firewall & Routing Validation

不同於要求伺服器解析標頭並回傳特定 200 OK 內容的 HTTP 檢查，TCP 檢查只針對傳輸層 (transport layer) 進行驗證。如果我們的監控節點成功完成 SYN-SYN/ACK-ACK 握手連線，便代表該連接埠為開放狀態。如果連線逾時或回傳「連線被拒 (Connection Refused)」錯誤，則代表該連接埠可能被嚴格的防火牆保護，或者背後運作的服務已經崩潰 (crashed)。

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.