XE Testnet

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 routing + rendezvous discovery	`/xe` prefix; namespace `xe/discovery/1/<network_id>`

Bootstrap peers — explicit via --dial; a watchdog re-dials disconnected bootstraps every 30s (10s timeout per dial). This is the only way a fresh node learns of the network, so configure more than one.
Ambient DHT discovery — once connected, the node advertises itself under xe/discovery/1/<network_id> and, every 60s while below the target peer count (default 24, --discovery-peers), looks up and dials up to 8 peers found there (15s dial timeout, 5 min backoff). --no-discovery disables it, leaving the node peered only with its --dial list.
mDNS — LAN discovery; --disable-mdns turns it off on shared networks.

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, protocol version and advertised features over /xe/netcheck/1 (1 KB handshake, 5s timeout); a network-ID mismatch disconnects the peer with a 10-minute ban, a protocol-version mismatch (beyond two minor versions, or below sys.min_protocol_version) with a 1-hour ban. After a testnet wipe, this is why a node started with the old genesis logs CANNOT JOIN NETWORK rather than syncing.
Inbound connections are capped per source IP (default 8, --max-conns-per-ip) and in total (default 256, --max-inbound-conns), reserving the rest of the connection budget for peers this node dials
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