Set up a Boot Node

note

When you first start a node, it has to find a way to find other nodes in the network. For that purpose, you need "bootnodes". After the first bootnode is found, it can use that node’s connections to continue expanding and play its role in the network, like participating as a validator.

Accessing the Bootnode

The consensus is that bootnodes have to be accessible in three ways:

• p2p: the p2p port, which can be set by --listen-addr /ip4/0.0.0.0/tcp/<port>. This port is not automatically set on a non-validator node (for example, an archive RPC node).
• p2p/ws: the WebSocket version, which can be set by --listen-addr /ip4/0.0.0.0/tcp/<port>/ws.
• p2p/wss: the secure websocket version. An SSL-secured connection to the p2p/ws port must be achieved by a proxy since the node cannot include certificates. It is needed for light clients. See here for info about setting this up.

Network Key

Starting a node creates its node key in the chains/<chain>/network/secret_ed25519 file. You can also create a node-key by polkadot key generate-node-key and use that node-key in the startup command line.

It is essential you backup the node key, especially if it gets included in the polkadot binary because it gets hardcoded in the binary and needs to be recompiled to change.

Running the Bootnode

Say we are running a polkadot node with polkadot --chain polkadot --name dot-bootnode --listen-addr /ip4/0.0.0.0/tcp/30310 --listen-addr /ip4/0.0.0.0/tcp/30311/ws then we would have the p2p on port 30310 and p2p/ws on port 30311. For the p2p/wss port, we need to set up a proxy, a DNS name, and a corresponding certificate. These concepts and example setups are described here. The following example is for the popular nginx server and enables p2p/wss on port 30312 by proxying the p2p/ws port 30311:

/etc/nginx/sites-enabled/dot-bootnode

server {
       listen       30312 ssl http2 default_server;
       server_name  dot-bootnode.stakeworld.io;
       root         /var/www/html;

       ssl_certificate "<your_cert";
       ssl_certificate_key "<your_key>";

       location / {
         proxy_buffers 16 4k;
         proxy_buffer_size 2k;
         proxy_pass http://localhost:30311;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection "Upgrade";
         proxy_set_header Host $host;
   }

}

Testing Bootnode Connection

If we have the above node running with DNS name dot-bootnode.stakeworld.io, proxied with a valid certificate and node-id 12D3KooWAb5MyC1UJiEQJk4Hg4B2Vi3AJdqSUhTGYUqSnEqCFMFg then the following commands should give you a: "syncing 1 peers".

tip

You can add -lsub-libp2p=trace on the end to get libp2p trace logging for debugging purposes.

p2p:

polkadot --chain polkadot --base-path /tmp/node --name "Bootnode testnode" --reserved-only --reserved-nodes "/dns/dot-bootnode.stakeworld.io/tcp/30310/p2p/12D3KooWAb5MyC1UJiEQJk4Hg4B2Vi3AJdqSUhTGYUqSnEqCFMFg" --no-hardware-benchmarks

p2p/ws:

polkadot --chain polkadot --base-path /tmp/node --name "Bootnode testnode" --reserved-only --reserved-nodes "/dns/dot-bootnode.stakeworld.io/tcp/30311/ws/p2p/12D3KooWAb5MyC1UJiEQJk4Hg4B2Vi3AJdqSUhTGYUqSnEqCFMFg" --no-hardware-benchmarks

p2p/wss:

polkadot --chain polkadot --base-path /tmp/node --name "Bootnode testnode" --reserved-only --reserved-nodes "/dns/dot-bootnode.stakeworld.io/tcp/30312/wss/p2p/12D3KooWAb5MyC1UJiEQJk4Hg4B2Vi3AJdqSUhTGYUqSnEqCFMFg" --no-hardware-benchmarks