Netcat - Network Swiss Army Knife

Network Connection Utility

Protocol

TCP

Reliable connection-oriented protocol

UDP

Fast connectionless protocol

Target Host Hostname or IP address

Port Port number (1-65535)

Data to Send (Optional) Data to send after connection. Leave empty for connection test only.

Advanced Options

Connection Timeout (seconds)

Wait Time for Response (seconds)

Verbose Output (show connection details)

Zero I/O Mode (scan only, no data transfer)

Source Port (Optional) Specify source port for connection

Quick Actions

Common Use Cases

Port Scanning

Check if a port is open on a remote host:

Host: example.com
Port: 80
Protocol: TCP
Zero I/O Mode: ✓

Banner Grabbing

Connect to a service and grab its banner:

Host: example.com
Port: 22 (SSH) or 25 (SMTP)
Send Data: (leave empty)

HTTP Request

Send a custom HTTP request:

Host: example.com
Port: 80
Data to Send:
GET / HTTP/1.1
Host: example.com

(blank line at end is important)

UDP Testing

Test UDP services like DNS:

Host: 8.8.8.8
Port: 53
Protocol: UDP
Data: (DNS query packet)

About Netcat

Netcat is often referred to as the "Swiss Army knife" of networking tools. It's a versatile utility that can read and write data across network connections using TCP or UDP protocols.

Features

TCP and UDP connection testing
Port scanning and availability checks
Banner grabbing for service identification
Custom data transmission
Connection timeout configuration
Verbose debugging output

Security Note

⚠️ Important: Only test connections to hosts and services you own or have explicit permission to test. Unauthorized port scanning or connection attempts may be illegal in your jurisdiction.

🔌 Netcat