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PORT (CHECKING)

Berikut cara cepat mengecek status port (open/closed) di jaringan LAN/private melalui Windows 11 menggunakan CMD:

1. Menggunakan telnet (Cara Paling Cepat)

Langkah:

  1. Aktifkan Telnet Client (jika belum):

    • Buka Control Panel > Programs > Turn Windows features on or off.
    • Centang Telnet Client → OK.

  2. Buka CMD sebagai admin, ketik:

    telnet [IP_TARGET] [PORT]

    Contoh:

    telnet 192.168.1.100 80
    • Jika muncul blank screen/kursor berkedip: port open.
    • Jika muncul "Could not open connection": port closed/filtered.

2. Menggunakan Test-NetConnection (PowerShell)

Langkah:

  1. Buka PowerShell (Admin), ketik:
    powershell Test-NetConnection -ComputerName [IP_TARGET] -Port [PORT] Contoh:
    powershell Test-NetConnection -ComputerName 192.168.1.100 -Port 3389
    • "TcpTestSucceeded: True" → Port open.
    • "TcpTestSucceeded: False" → Port closed.

3. Menggunakan netstat (Cek Port Lokal)

Langkah:

  1. Di CMD, ketik:
    bash netstat -ano | findstr "[PORT]" Contoh:
    bash netstat -ano | findstr "80"
    • Jika muncul hasil → Port sedang digunakan (open).
    • Jika kosong → Port tidak aktif.

4. Menggunakan nc (Netcat - Jika Terinstall)

  1. Download Netcat for Windows (Nmap.org).
  2. Di CMD, ketik:
    bash nc -zv [IP_TARGET] [PORT] Contoh:
    bash nc -zv 192.168.1.100 22
    • "succeeded" → Port open.
    • "failed" → Port closed.

5. Menggunakan ping + Port (Teknik Simpel)

Langkah:

  1. Di CMD, ketik:
    bash ping [IP_TARGET] -t
  2. Di jendela CMD terpisah, gunakan telnet atau Test-NetConnection seperti di atas.

Perbedaan Hasil Open vs Closed

Tool Port Open Port Closed
telnet Blank screen Error connection
Test-NetConnection "TcpTestSucceeded: True" "TcpTestSucceeded: False"
netstat Menampilkan PID proses Tidak ada output

Catatan Penting:

  • Firewall/ACL: Port mungkin terbuka di server tapi diblokir firewall.
  • Port Scanning: Untuk scan banyak port, gunakan Nmap (nmap -p 80,443 192.168.1.100).
  • Port Umum:
    • 80 (HTTP), 443 (HTTPS), 3389 (RDP), 22 (SSH).

Contoh Praktis:

# Cek port 80 di router LAN
telnet 192.168.1.1 80

# Cek port RDP di PC lain
Test-NetConnection -ComputerName 192.168.1.50 -Port 3389

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