libp2p / js-libp2p-example-circuit-relay

How to use Circuit Relay to connect two nodes

@libp2p/example-circuit-relay

Shows how to configure relayed connections

Table of contents

• 0. Setup the example
• 1. Set up a relay node
• 2. Set up a listener node with discoverRelays Enabled
• 3. Set up a dialer node for testing connectivity
• 4. What is next?
• License
• Contribution

0. Setup the example

First of all run npm install in the example folder. This will install all required dependencies and you'll be ready to go.

This example comes with 3 main files. A relay.js file to be used in the first step, a listener.js file to be used in the second step and a dialer.js file to be used on the third step. All of these scripts will run their own libp2p node, which will interact with the previous ones. All nodes must be running in order for you to proceed.

1. Set up a relay node

In the first step of this example, we need to configure and run a relay node in order for our target node to bind to for accepting inbound connections.

The relay node will need to have a relay service added which will allow a limited number of remote peers to make relay reservations with it.

It can be configured as follows:

import { noise } from '@chainsafe/libp2p-noise'
import { yamux } from '@chainsafe/libp2p-yamux'
import { circuitRelayServer } from '@libp2p/circuit-relay-v2'
import { identify } from '@libp2p/identify'
import { webSockets } from '@libp2p/websockets'
import { createLibp2p } from 'libp2p'

const node = await createLibp2p({
  addresses: {
    listen: ['/ip4/0.0.0.0/tcp/0/ws']
    // TODO check "What is next?" section
    // announce: ['/dns4/auto-relay.libp2p.io/tcp/443/wss/p2p/QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3']
  },
  transports: [
    webSockets()
  ],
  connectionEncryption: [
    noise()
  ],
  streamMuxers: [
    yamux()
  ],
  services: {
    identify: identify(),
    relay: circuitRelayServer()
  }
})

console.log(`Node started with id ${node.peerId.toString()}`)
console.log('Listening on:')
node.getMultiaddrs().forEach((ma) => console.log(ma.toString()))

You should now run the following to start the relay node:

node relay.js

This should print out something similar to the following:

Node started with id QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3
Listening on:
/ip4/127.0.0.1/tcp/61592/ws/p2p/QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3
/ip4/192.168.1.120/tcp/61592/ws/p2p/QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3

2. Set up a listener node with discoverRelays Enabled

One of the typical use cases for Circuit Relay is nodes behind a NAT or browser nodes due to their inability to expose a public address.

For running a libp2p node that automatically discovers available relays, you can see the following:

import { noise } from '@chainsafe/libp2p-noise'
import { yamux } from '@chainsafe/libp2p-yamux'
import { circuitRelayTransport } from '@libp2p/circuit-relay-v2'
import { identify } from '@libp2p/identify'
import { webSockets } from '@libp2p/websockets'
import { multiaddr } from '@multiformats/multiaddr'
import { createLibp2p } from 'libp2p'

const relayAddr = process.argv[2]
if (!relayAddr) {
  throw new Error('the relay address needs to be specified as a parameter')
}

const node = await createLibp2p({
  transports: [
    webSockets(),
    circuitRelayTransport({
      discoverRelays: 2
    })
  ],
  connectionEncryption: [
    noise()
  ],
  streamMuxers: [
    yamux()
  ],
  services: {
    identify: identify()
  }
})

console.log(`Node started with id ${node.peerId.toString()}`)

const conn = await node.dial(relayAddr)

console.log(`Connected to the relay ${conn.remotePeer.toString()}`)

// Wait for connection and relay to be bind for the example purpose
node.addEventListener('self:peer:update', (evt) => {
  // Updated self multiaddrs?
  console.log(`Advertising with a relay address of ${node.getMultiaddrs()[0].toString()}`)
})

As you can see in the code, we need to provide the relay address, relayAddr, as a process argument. This node will dial the provided relay address and automatically bind to it.

You should now run the following to start the node running Auto Relay:

node listener.js /ip4/192.168.1.120/tcp/61592/ws/p2p/QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3

This should print out something similar to the following:

Node started with id QmerrWofKF358JE6gv3z74cEAyL7z1KqhuUoVfGEynqjRm
Connected to the HOP relay QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3
Advertising with a relay address of /ip4/192.168.1.120/tcp/61592/ws/p2p/QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3/p2p-circuit/p2p/QmerrWofKF358JE6gv3z74cEAyL7z1KqhuUoVfGEynqjRm

Per the address, it is possible to verify that the auto relay node is listening on the circuit relay node address.

Instead of dialing this relay manually, you could set up this node with the Bootstrap module and provide it in the bootstrap list. Moreover, you can use other peer-discovery modules to discover peers in the network and the node will automatically bind to the relays that support HOP until reaching the maximum number of listeners.

3. Set up a dialer node for testing connectivity

Now that you have a relay node and a node bound to that relay, you can test connecting to the auto relay node via the relay.

import { createLibp2p } from 'libp2p'
import { webSockets } from '@libp2p/websockets'
import { noise } from '@chainsafe/libp2p-noise'
import { mplex } from '@libp2p/mplex'
import { yamux } from '@chainsafe/libp2p-yamux',

const autoRelayNodeAddr = process.argv[2]
if (!autoRelayNodeAddr) {
  throw new Error('the auto relay node address needs to be specified')
}

const node = await createLibp2p({
  transports: [webSockets()],
  connectionEncryption: [noise()],
  streamMuxers: [yamux(), mplex()]
})

console.log(`Node started with id ${node.peerId.toString()}`)

const conn = await node.dial(autoRelayNodeAddr)
console.log(`Connected to the auto relay node via ${conn.remoteAddr.toString()}`)

You should now run the following to start the relay node using the listen address from step 2:

node dialer.js /ip4/192.168.1.120/tcp/61592/ws/p2p/QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3

Once you start your test node, it should print out something similar to the following:

Node started: Qme7iEzDxFoFhhkrsrkHkMnM11aPYjysaehP4NZeUfVMKG
Connected to the auto relay node via /ip4/192.168.1.120/tcp/61592/ws/p2p/QmWDn2LY8nannvSWJzruUYoLZ4vV83vfCBwd8DipvdgQc3/p2p-circuit/p2p/QmerrWofKF358JE6gv3z74cEAyL7z1KqhuUoVfGEynqjRm

As you can see from the output, the remote address of the established connection uses the relayed connection.

4. What is next?

Before moving into production, there are a few things that you should take into account.

A relay node should not advertise its private address in a real world scenario, as the node would not be reachable by others. You should provide an array of public addresses in the libp2p addresses.announce option. If you are using websockets, bear in mind that due to browser’s security policies you cannot establish unencrypted connection from secure context. The simplest solution is to setup SSL with nginx and proxy to the node and setup a domain name for the certificate.

License

Licensed under either of

• Apache 2.0, (LICENSE-APACHE / http://www.apache.org/licenses/LICENSE-2.0)
• MIT (LICENSE-MIT / http://opensource.org/licenses/MIT)

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.