simple_p2p

Hole-punching implementation using DCUtR, AutoNAT, and relay via the libp2p networking stack.

Setup

Three components must be started in order:

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1. Relay Server over a publicly accesible IP

cd relay
cargo run

Note the PeerID and port printed on startup — needed for the next two steps.

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2. Listener (hole-punching)

cd hole-punching
cargo run -- --mode listen \
  --relay-addr /ip4/<relay-ip>/tcp/<relay-port>/p2p/<relay-peer-id>

Note the Local PeerID printed on startup — needed for the dialer.

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3. Dialer (hole-punching)

cd hole-punching
cargo run -- --mode dial \
  --relay-addr /ip4/<relay-ip>/tcp/<relay-port>/p2p/<relay-peer-id> \
  --remote-peer-id <listener-peer-id>

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Simple Relay Setup

Three components must be started in order. No hole-punching — traffic is always forwarded through the relay.

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1. Relay Server over a publicly accessible IP

cd relay
cargo run

Note the PeerID and port printed on startup.

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2. Destination Client (behind NAT)

Registers a reservation with the relay so it becomes reachable via a circuit address.

cd relay_test_client_destination
cargo run -- <relay-peer-id> /ip4/<relay-ip>/tcp/<relay-port>

Note the Local PeerID printed on startup — needed for the source client.

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3. Source Client (behind NAT)

Dials the destination through the relay circuit.

cd relay_test_client_source
cargo run -- --relay-addr /ip4/<relay-ip>/tcp/<relay-port>/p2p/<relay-peer-id>/p2p-circuit/p2p/<destination-peer-id>

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iroh Example

An echo example built on the iroh networking stack (QUIC, with relay + hole-punching and dialing by public key). Connectivity uses the default n0 discovery service, so the listener's Endpoint ID is the only thing the dialer needs.

Two components, started in order:

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1. Listener

cd iroh-connect
cargo run --bin listen

Note the Endpoint ID printed on startup — needed for the dialer.

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2. Dialer

Dials the listener by its Endpoint ID, sends a message, and prints the echoed reply.

cd iroh-connect
cargo run --bin connect -- <endpoint-id> "hello iroh"

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iroh over Tor

The same echo example, but routed over Tor hidden services using the experimental iroh-tor-transport custom transport. The peer's .onion address is derived from its Endpoint ID, so you reach other nodes knowing only their Endpoint ID — no IP address, no NAT hole-punching, and no public relay. This works even behind NATs that plain hole-punching can't traverse (symmetric NATs), at the cost of Tor's latency.

Prerequisite: a running Tor daemon with the control port enabled

tor --ControlPort 9051 --CookieAuthentication 0

Each side automatically publishes its own ephemeral hidden service on startup.

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1. Listener

cd iroh-tor
cargo run --bin listen

Note the Endpoint ID printed on startup — needed for the dialer. To keep the same identity (and onion address) across restarts, export the printed IROH_SECRET before running.

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2. Dialer

cd iroh-tor
cargo run --bin connect -- <endpoint-id> "hello over tor"

Establishing the Tor circuit and resolving the hidden service can take tens of seconds on the first connect.