Sending a simple TCP message using Netcat

Question

I am trying to use netcat to send a simple message over TCP, e.g. I want to send the digit 1.

So I understood that I write the following in the terminal, after installing netcat

netcat [ip-address] [port]

But how do I specify the message to be sent? i.e. where to I write "1" ?

score 73 · Answer 1 · edited Feb 10 '18 at 17:30

73

Create file something.txt, content of file is 1

netcat [ip-address] [port] <something.txt

At destination you must have something to listen to this.

or

Server:

netcat -l -p [port]

to listen to the connection

Client:

netcat [server-ip-address] [port]

After connection is establish on cilent simple type 1 and hit enter

edited Feb 10 '18 at 17:30

dessert

answered Apr 04 '14 at 08:45

2707974

Submitted an edit changing the useless `cat` command to redirection to `echo`. I use this method to send string data to remote machines that are operating as one for greater bash multi-tasking. – Yokai Nov 14 '17 at 08:27
+1 for the server tip! That's very cool, thanx! – j.c Feb 26 '18 at 14:31
thnks, this is working for me – Buddhika Alwis Jul 11 '18 at 04:52
Just wanted to not that -p is not mandatory, port can be specified directly as non-optional argument `netcat -l [port]` – Do-do-new Jan 11 '23 at 10:31

score 33 · Answer 2 · edited Feb 10 '18 at 17:27

33

I use:

echo text | netcat host port

So you would just need to run this:

echo 1 | netcat localhost 12345

edited Feb 10 '18 at 17:27

dessert

answered Nov 22 '17 at 09:33

AndyGee

2 Answers2