What is lancat?

lancat is a tool that extends the behaviour of cat linux utility to the LAN. It sends a multicast message for searching lancat listeners in the LAN, then creates one-to-one tcp connection for each listener found in order to transfer the information in a reliable way and without saturating the network.

Installation

lancat is a rust application. You can use the cargo package manager in order to install it.

$ cargo install lancat

If you have ~/.cargo/bin in your PATH, you will be able to use lancat everywhere in your computer!

Windows users can also use the redistributable that comes with each release instead of install it.

Supports linux and windows, but could work in others platforms.

How it works?

It has two main modes: write to the LAN, and read from the LAN.

To the LAN

To write data to the LAN, run lancat into write mode with w:

$ lancat -w
hello lan

Furthermore, you can redirect the standard input from a file to write it into the LAN:

$ lancat -w < to_share.txt

From the LAN

To read data from the LAN, run lancat into read mode with -r:

$ lancat -r
=========== username - 192.168.1.35:43230 ===========
hello lan

In the case you want to send the incoming data to a certain file, you can redirect the standard output:

$ lancat -r -q > shared.txt

the -q flag (also --quiet) will avoid to write the user name line into the file.

Filtering users

By default lancat notifies to the LAN with your OS user name. It is possbile to change this name with the -n flag.

You can filter for writing or reading only for certain users:

$ lancat -w -u user1 user2

$ lancat -r -u user1 user2

In order to see which users are listening the lan, you can run lancat in search mode with -s:

$ lancat -s
Found 'user1' at: 192.168.1.72:44435
Found 'user2' at: 192.168.1.72:44439
Found 'user3' at: 192.168.1.54:44432

To see all available options see the help: lancat --help.

Usage Examples

Pair to pair LAN communication

Default user names

Sending a message filtering by user1:

$ echo "Hello user1" | lancat -w -u user1

Receiving messages filtering by user2:

$ lancat -r -q -u user2
Hello user1

Only users with names user1 and user2 will be able participate in the communication.

Aliasing names

Sending a message to Juanito identifying us as Pepito:

$ echo "Hello Juanito, I'm Pepito" | lancat -w -n Pepito -u Juanito

Receiving messages intended for Juanito that only Pepito sends:

$ lancat -r -q -n Juanito -u Pepito
Hello Juanito, I'm Pepito

File listener server: log the LAN

The following is a script that saves the received data of each connection to a log file continually.

#!/bin/bash
while true
do
    lancat -r -o -q > latest.log
    DATE=`date "+%m-%d-%Y_%H-%M-%S"`
    mv latest.log $DATE.log
    echo "Received file at: $DATE"
done