How to prevent multiple nodes with same PeerId?

[erhant]

Hi, in our network (https://github.com/firstbatchxyz/dkn-compute-node) we currently have the issue of people running multiple nodes using the same private key, and therefore having the same PeerId in different machines. We would like to prevent that, but could not yet see how to do it. Would love some ideas 🙏🏻

I have tried a simple check within identify::Event::Received handler, such as:

if peer_id == *self.swarm.local_peer_id() {
  panic!("Identify: Received self identify event, are you running multiple nodes with same wallet?");
}

but that did not catch the node with same PeerId.

For additional context, here is where we handle the identify event, and add the identified peer to our table.

[guillaumemichel]

I don't understand why nodes would share their private keys with one another.

If you are using kademlia you can always try to lookup the newly generated identity when joining the network. If the peerid already exist, generate a fresh id.

[erhant]

Hmm, thankfully we are in Server mode (https://github.com/firstbatchxyz/dkn-compute-node/blob/master/p2p/src/client.rs#L92 to confirm). I can check the multiaddr indeed, will try! Thank you for the quick reply.

[erhant]

Where should I handle this exactly though?

[guillaumemichel]

I would say generating a new identity for the DHT lookup and using the private key only if the DHT lookup didn't find any peer using the private key is probably the easier and safer approach.

[erhant]

I'm still unsure how to check my own identity within DHT. Even when I make a request to swarm.behaviour_mut().kademlia.get_closest_peers with my own peer id, I cant find myself in the emitted events.

For event, im handing it as:

match self.swarm.select_next_some().await {
                SwarmEvent::Behaviour(DriaBehaviourEvent::Kademlia(
                    kad::Event::OutboundQueryProgressed {
                        result: QueryResult::GetClosestPeers(result),
                        ..
                    },
                )) => self.handle_closest_peers_result(result),
// ...

where handle_closest_peers_result is:

 fn handle_closest_peers_result(
        &mut self,
        result: Result<GetClosestPeersOk, GetClosestPeersError>,
    ) {
        match result {
            Ok(GetClosestPeersOk { peers, .. }) => {
                // log stuff, cant find my own peer id in `peers`
            }
            Err(GetClosestPeersError::Timeout { peers, .. }) => {
                // log stuff here
            }
        }
    }

Am I doing something wrong?

[guillaumemichel]

IIRC kad is filtering out results about self, so this technique won't work indeed.

I suggest to generate a random identity to make the kad lookup about the identity/privkey you are interested in. If you don't find it in the DHT, you can use it safely.