Networking

libp2p host, peer admission, GossipSub topics, frontier sync, DHT, and request-response messaging.

Fully peer-to-peer using libp2p. No central servers.

Components

Component	Purpose	Protocol
Host	TCP transport, connection management	libp2p core
Netcheck	Peer admission — network-ID + version handshake	`/xe/netcheck/1`
GossipSub	Broadcast blocks, votes, marketplace, statechain, directory	libp2p GossipSub
Sync	Frontier-based block synchronization	`/xe/sync/1.0.0`
Statechain sync	State-chain block synchronization	`/xe/statechain-sync/1.0.0`
Messaging	Request-response over streams	`/xe/msg/1.0.0`
Tunnel	SSH-over-network tunnels to leased VMs	`/xe/tunnel/2.0.0`
DHT	Kademlia peer discovery	`/xe` prefix

mDNS — automatic local network discovery
Bootstrap peers — explicit via -dial flag; a watchdog re-dials disconnected bootstraps every 30s (10s timeout per dial)
Kademlia DHT — distributed hash table with /xe prefix

Max gossip message size: 256 KB.

Frontier-based: exchange account → latest block hash
Paginated responses (default 64 blocks/page, max 256)
Max 10,000 blocks per sync session
5-second per-peer cooldown
Periodic re-sync every 10 seconds (with dirty flag optimization)
Cross-account dependency retry passes, with early exit when a pass makes no progress
Block quarantine for permanently invalid blocks

Request-response semantics
30-second stream deadline
64 KB max request/response
Message types: vm_credentials, vm_status, account_chat, attest_timestamp, block_request, vote_request, cert_request
block_request, vote_request, and cert_request are targeted sync-repair RPCs — a node missing a block body, an election's votes, or a lease certificate asks a peer for it directly
DHT-based peer discovery fallback

Peer admission: on connect, peers exchange network ID and protocol version over /xe/netcheck/1; a mismatch disconnects the peer and applies a bounded ban. After a testnet wipe, this is why a node built against the wrong network ID silently fails to join.
Inbound connections are capped per source IP (default 8, --max-conns-per-ip)
Transport encryption (Noise or TLS 1.3)
Persistent Ed25519 identity
GossipSub pre-validates field lengths
Sync rate limiting (5s per peer)
Max message sizes enforced