Peers and seeds

A node on its own is useless: it can’t hear about new blocks or share its own. It needs peers, other nodes it keeps a connection open with. But a brand-new node, just installed, doesn’t know the address of a single one.

The fix is the same as Bitcoin’s. A few well-known names, the DNS seeds, answer with a list of working nodes. After the first connections, the node learns more addresses from its peers and never needs the seeds again.

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The live state of the network those peers keep in sync: tip height, difficulty and pace.

Which DNS seeds does Pearl use?

Three, built into pearld for mainnet:

DNS seed

reef

reef.seeder.pearlnetwork.net

DNS seed

tide

tide.seeder.pearlnetwork.net

DNS seed

stream

stream.seeder.pearlnetwork.net

A node looks these names up like any website. Instead of one server’s address, the answer is a handful of IP addresses of Pearl nodes. The node then connects to some of them on port 44108.

Testnet and testnet2 have their own seeds, under seeder.testnet.pearlnetwork.net and seeder.testnet2.pearlnetwork.net.

Which nodes does a seed list?

Pearl’s seeder is a plugin for CoreDNS, a common DNS server, and it’s in Pearl’s repository. It crawls the network in the background and only lists a node that passes every check below. The rules are fixed in code, not configurable:

1. It completes a handshake

   The seeder connects and swaps version messages, as a real peer would.

2. It speaks a recent enough protocol

   At least the minimum protocol version, 2.

3. It's a full node

   It advertises the full-node service bits.

4. It's on the current chain

   It reports a height at or above the latest checkpoint, which, in the README’s words, “weeds out nodes stranded on a pre-fork chain”.

5. It listens on the default port

   44108 on mainnet.

Each crawl re-checks the nodes it serves, asks live peers for more addresses with getaddr, and checks those too. A served node that fails two crawls in a row stops being listed and enters a three-hour cooldown.

A DNS answer holds a random sample of up to 25 addresses, and resolvers may cache it for 3,600 seconds, an hour.

What happens after the seeds?

Address gossip, inherited from Bitcoin via btcd:

• A node asks its peers for addresses with getaddr.
• Peers answer with addr messages, or addrv2 (BIP-155) once both sides have said sendaddrv2; addrv2 can carry newer address types.
• The node keeps everything in an address book on disk and picks future peers from it.

So the seeds matter once, at first start. A node that has run for a while can rejoin the network from its address book alone.

What does a node say about itself?

When two nodes connect, after encrypting the connection, each sends a version message. Three fields matter here:

The user agent is the same one Pearl’s public Blockbook reports for its own backend node, so you can see which software the explorer runs. The protocol version and services are what a peer actually relies on.

DefaultPort: "44108",
DNSSeeds: []DNSSeed{
	{"reef.seeder.pearlnetwork.net", false},
	{"tide.seeder.pearlnetwork.net", false},
	{"stream.seeder.pearlnetwork.net", false},
},