It is possible to run Bitcoin ABC as an I2P (Invisible Internet Project) service and connect to such services.
This glossary may be useful to get started with I2P terminology.
A running I2P router (proxy) with SAM
enabled is required (there is an official one and
a few alternatives). Notice the IP
address and port the SAM proxy is listening to; usually, it is
127.0.0.1:7656. Once it is up and running with SAM enabled, use the following
Bitcoin ABC options:
-i2psam=<ip:port> I2P SAM proxy to reach I2P peers and accept I2P connections (default: none) -i2pacceptincoming If set and -i2psam is also set then incoming I2P connections are accepted via the SAM proxy. If this is not set but -i2psam is set then only outgoing connections will be made to the I2P network. Ignored if -i2psam is not set. Listening for incoming I2P connections is done through the SAM proxy, not by binding to a local address and port (default: 1)
In a typical situation, this suffices:
The first time Bitcoin ABC connects to the I2P router, its I2P address (and
corresponding private key) will be automatically generated and saved in a file
i2p_private_key in the Bitcoin ABC data directory.
You may set the
debug=i2p config logging option to have additional
information in the debug log about your I2P configuration and connections. Run
bitcoin-cli help logging for more information.
It is possible to restrict outgoing connections in the usual way with
onlynet=i2p. I2P support was added to Bitcoin ABC in version 22.0 (mid 2021)
and there may be fewer I2P peers than Tor or IP ones. Therefore, using
onlynet=i2p alone (without other
onlynet=) may make a node more susceptible
to Sybil attacks. Use
bitcoin-cli -addrinfo to see the number of I2P addresses known to your node.
There are several ways to see your I2P address in Bitcoin ABC:
AddLocal, the I2P address ends in
getnetworkinfoRPC in the “localaddresses” section
bitcoin-cli -netinfopeer connections dashboard
To see which I2P peers your node is connected to, use
bitcoin-cli -netinfo 4
getpeerinfo RPC (e.g.
To see which I2P addresses your node knows, use the
getnodeaddresses 0 i2p
Bitcoin ABC uses the SAM v3.1 protocol to connect to the I2P network. Any I2P router that supports it can be used.
Bitcoin ABC uses the SAM v3.1 protocol. One particularity of SAM v3.1 is that it does not support ports, unlike newer versions of SAM (v3.2 and up) that do support them and default the port numbers to 0. From the point of view of peers that use newer versions of SAM or other protocols that support ports, a SAM v3.1 peer is connecting to them on port 0, from source port 0.
To allow future upgrades to newer versions of SAM, Bitcoin ABC sets its
listening port to 0 when listening for incoming I2P connections and advertises
its own I2P address with port 0. Furthermore, it will not attempt to connect to
I2P addresses with a non-zero port number because with SAM v3.1 the destination
TO_PORT) is always set to 0 and is not in the control of Bitcoin ABC.