Where can I find a practical example of building a P2P network with several nodes?

Question

Programming

I am looking for any simple examples of building a peer-to-peer network with several nodes.
To understand the essence.

Answer 1

It's worth to google the torrent network, the most described network at the moment, plus a giant field for "playing around". having understood its essence, you can look at other p2p options.
I'll add a little on the issue of searching for data by hash:
1. dedicated server "torrent tracker" for special. the hash search protocol will send a list of IP addresses that have data. well, you will be included in the list
2. search by lan - a broadcast request over the local network to search for other torrent programs.
3. exchange of peers - any member of the network that has a piece of data accumulates a list of other owners, which he gives on request.
4. DHT - distributed hash table, distributed hash table. p2p search system for guardians. each participant takes a random address to participate in the network. There is a "proximity" function of the hash and dht address, by which the seeker bypasses the network in search of those who have it. each participant keeps a set of IP address lists for hashes "close" to his dht address and about 350 (utorrent) other dht network participants.