For our fun session on 10.02.23!
This is a very simple p2p chat program running in your terminal and only on your local network. It makes use of mDNS to find other peers who are available for chatting. After discovery these peers are added to your chat. You can write messages by typing directly in the terminal.
To play with it in your local network you can start the process in multiple shell sessions, better even on different computers on the same network if you have more than one.
- NodeJS environment (works only from
v17!) - Running mDNS service (Bonjour, Avahi, etc. - you probably have that already)
- Wireshark (to have fun)
# Install dependencies
npm install
# Run it!
npm start- Make sure to run wireshark with
sudorights to be able to inspect packages on your network interfaces. - Select the interface you want to inspect traffic on, it is usually your wlan interface
wlan0,wlp3s0, etc. - You can filter incoming packages by type, just write
mdnsorudpin the filter input on the top
For this we can't use mDNS anymore as this only works on local networks. To find others in p2p manner on the internet there are different techniques, but all of them usually need something like a "rendevouz" or "bootstrapping" server which helps to establish a connection between two peers. Another problem is that usually computers are behind NATs, so other peers can't know your local IP address from the outside. For this we need a technique called UDP hole-punching.
UNLICENSE