Bitcoin/Ethereum及其他加密货币节点启动时如何获取对等节点（peer）IP？自建区块链（blockchain）加密货币网络新节点自动发现对等节点的实现咨询

Hey there! Let's dive into peer discovery for crypto networks—covering both established projects like Bitcoin/Ethereum and how to build this automation for your custom blockchain.

When nodes of major blockchains boot up, they use a layered, automated approach to locate peers without manual configuration:

• Hardcoded Seed Nodes: The core client code includes a small set of long-running, reliable seed nodes maintained by the project's dev team. On first launch, the node connects to these seeds to fetch its initial list of active peers.
• DNS Seeds: To avoid relying solely on static hardcoded IPs, projects like Bitcoin use DNS seeds—domain names that resolve to a rotating list of active nodes. The node queries these DNS records on startup to get fresh peer addresses, which is far more flexible than updating client code for new seeds.
• Local Peer Storage: Nodes save previously connected peers to a local file (Bitcoin uses peers.dat, Ethereum uses the nodes directory). On subsequent launches, they first try reconnecting to these known, trusted peers before reaching out to seeds.
• DHT (Distributed Hash Table): Ethereum uses a Kademlia-based DHT to maintain a decentralized peer directory. Once connected to a few nodes, the node joins the DHT, allowing it to query and discover thousands of other peers without relying on central seeds. Bitcoin also uses a DHT variant for larger network discovery.
• Addr Message Sync: Once connected to any peer, nodes exchange addr messages containing lists of other active nodes. This creates a snowball effect—each new connection unlocks access to more peers.

Ditching manual config file IPs is totally feasible by adapting the proven patterns used by major chains. Here's a step-by-step approach tailored to your project:

• Start with Hardcoded Seed Nodes: Deploy 2-3 stable, always-online nodes (run on your own servers or trusted partners) and hardcode their IPs into your blockchain's core client. These act as the "on-ramp" for new nodes to join the network.
• Implement Peer Address Sync: Build a simple protocol where new nodes send a getaddr request to seed nodes, which respond with a list of active peers. Once the new node connects to these peers, it should broadcast its own IP via an addr message, so other nodes can add it to their peer lists.
• Add DNS Seeds (Optional but Recommended): Set up a DNS record (e.g., seeds.yourchain.com) that points to your seed nodes. Update your client to query this DNS on startup instead of relying only on hardcoded IPs—this lets you update seed nodes without pushing client updates to users.
• Integrate DHT for Decentralized Discovery: As your network grows, implement a Kademlia DHT (well-documented with open-source implementations in most languages). Each node will store a small portion of the peer directory, so new nodes can find peers even if some seeds go offline.
• Persist Peer Lists Locally: Have your client save successful peer connections to a local file (like known_peers.json). On startup, prioritize connecting to these peers first—this speeds up discovery and reduces load on your seed nodes.
• Add Peer Health Checks: Implement logic to ping peers periodically and remove offline/unresponsive nodes from your list. You can also add a scoring system to prioritize stable, high-bandwidth peers.

For smaller private chains, you might only need the first three steps. As your network scales up, adding DHT will make the discovery process more resilient and decentralized.

内容的提问来源于stack exchange，提问作者lucky_rydar