```
|\        /|
| \______/ |
| ,,,,,,,, |
| |||||||| |
| |||||||| |
| ¯¯¯¯¯¯¯¯ |
|__________|
  \-    -/
```

# EtherCat

A simple tool written in C that connects a Linux tap interface to stdin and stdout

## How to build

- Prerequisites: Linux, C compiler
  - Might be easily portable to other systems that support tap interfaces, Idk.
- Run `./build.sh`
- Install by copying to `/usr/local/bin` or just leave it where it is

## How to use

Run as root:
```
ip tuntap add mode tap user USERNAME group GROUPNAME name tapN
ip link set tapN up
```
Run as user:
`ethercat tapN`

## Simple network tunnel:

Be warned: This will behave as if you had both sides connected with a (slow and less reliable) cable. This is more of a bridge than a regular VPN.
If you bridge both sides to a real NIC and you have DHCP servers on both networks, you will end up with two DHCP servers on the same network.

- Set up a bridge between a physical NIC and the tap interface on one or both sides
- Connect a port between the hosts, for example using SSH port forwarding
- Make two FIFOs on both hosts (mkfifo)
- Use netcat to connect the FIFOs between the hosts through the forwarded port
  - `nc -l 10000 < fifo1 > fifo2`
  - `nc localhost 10000 < fifo1 > fifo2`
- Start an instance of EtherCat with the other ends of the FIFOs on both hosts
  - `./ethercat tapN < fifo2 > fifo1`