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.

Pemeriksaan Port TCP untuk 8.8.8.8:53

Pengaturan Lanjutan

Tampilkan peta dunia

Info Ping HTTP TCP UDP MTR DNS

Uji Tembus Port Konektivitas (TCP Probe) 8.8.8.8:53

Tautan permanen |

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United States Kansas City
United States Dallas
South Africa Johannesburg

Interogasi Penembus Port Distribusi Skala Lebar (TCP Global Port Audit)

Lebih mendalam dari sekadar ICMP Ping yang mengaburkan realita, pemeriksaan TCP (Transmission Control Protocol) memaksa terminal host memverifikasi apakah pelayanan aplikasi spesifik benar-benar hidup. Metode ini mengunci keakuratan dengan prosedur legal jabat tangan 3 arah (SYN-SYN ACK-ACK), ideal untuk menghindari blokir ICMP (Ping) oleh tembok pertahanan firewall keamanan umum.

Penyingkapan Jejak Penguburan Perjalanan Paket dari Tembok Pagar (Firewall Inspections)

Waktu komputasi yang terlampau parah pada pengujian TCP sering kali membongkar gejala awal pendarahan DDoS, pemblokadean sengaja regional (Geo-Blocking limitasi trafik negara spesifik), atau kelebihan muatan parah pada komponen peladen pembuang.

Diagnostik Gangguan Connection Refused Melawan Timeout Bisu

Pemeriksa menterjemahkan keluhan secara eksplisit. Kasus "Connection Refused" membeberkan telak bahwa port tertutup oleh aplikasi sasaran, sedangkan kelumpuhan jenis "Timeout" tanpa keluhan menandakan adanya tameng keamanan filter perute secara rahasia membunuh dan menjerat transmisi (biasanya penyaringan proxy jaringan VPN, pelindung IPS awan mitigatif).

Peninjauan Ulang Resolusi Akses Rute Jaringan Anycast Load Balancing

Validasi tumpuan ini sangat bermanfaat saat pengelola menggunakan konfigurasi distribusi perute BGP kasta Anycast CDN (semacam integrasi Cloudflare). Pengelola sistem bakal diyakinkan mutlak bahwa pelacakan titik koneksi dari setiap benua tiba secara efisien melalui simpul peladen proksi penyeimbang muatan geografi awan terdekat dengan lancar.