how to backdooring using nc

the next duty about NC (net cat) not (net cut)...first what is nc....
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.
actually this is use full tool that can listening to the some port etc. 
by default is included in the linux OS but when we practice in the class we found that nc does not exist on the system. so what the solution?? the solutions is copy the binary of nc.traditional from the bt5 and then put the file binary in the /bin/ directory.
after nc properly copied into the ubuntu system we can try to execute nc with a command 

root@ubuntu-VirtualBox:/bin# ./nc.traditional -l -p 9000

the meaning of the command above is to execute nc and listening into port 9000. in our host use nc with a command

nc 192.168.43.129 9000

to identify that our connection is done. we can type anything in the console. and all anything that we have type will show up in the other side. more clear we can see an illustration picture bellow :

from picture above we can see that anything we type will show in other host(guest host). picture above is describe that we conecting using nc. if we were connect the next step is send the cymothoa to the guest. how to do that. but before   we do that may be we confuse about what is cymothoa is???

Cymothoa is a stealth backdooring tool, that inject backdoor’s shellcode into an existing process. The tool uses the ptrace library (available on nearly all * nix), to manipulate processes and infect them.

back again tothe main point or the next step to send cymothoa to the ubuntu system we can use command lke bellow :

nc 192.168.43.129 9000 < cymothoa

 important note before we execute command above we must make sure that we were be in the cymothoa file directory /pentest/backdoors/cymotho/   in the client side(UBUNTU we must type

>cymothoa

if it is done well so in the path that we get well created file named cymothoa. just gift permission to 777 and then to test that the file are work type command bellow

./cymothoa

 if all anything doing fine so will look like picture bellow