Netcat Chat – How to Build a Simple Chat Using Netcat

ccommand linenetcatnetworking

I am currently working on a project and I have implemented a simple chat application using the netcat libraries.

The client is prompted to enter port number and the command

nc -l -p xxxx

where xxxx is the port number entered by the client.

Similarly, the host is prompted for the same port number and a connection is established using

nc <ip_address> -p xxxx

However, this gives a blank chat experience as it does not show the username of the person typing the messages, something like

hey
hello
what's up
Nothing

Instead, I want it to be something like,

Foo : hey
Boo : hello
Foo : what's up
Boo : Nothing

Can I use netcat to achieve this functionality or is there anything else that does this?

Best Answer

You can do something like this.

Assume Alice is the server. She types:

mawk -W interactive '$0="Alice: "$0' | nc -l -p <port_number> <ip_of_alice>

Then Bob connects to that server. He types:

mawk -W interactive '$0="Bob: "$0' | nc <ip_of_alice> <port_number>

The mawk lines just adds the prepending name of the person to the "chat". We need -W interactive to set unbuffered writes to stdout and line buffered reads from stdin.

Now Alice types Hi Bob and sees:

Hi Bob

Bob sees:

Alice: Hi Bob

Bob types Hi Alice and sees:

Alice: Hi Bob
Hi Alice

Alice sees:

Hi Bob
Bob: Hi Alice
Related Question