|
|
|
|
# I2P support in Bitcoin Core
|
|
|
|
|
|
|
|
|
|
It is possible to run Bitcoin Core as an
|
|
|
|
|
[I2P (Invisible Internet Project)](https://en.wikipedia.org/wiki/I2P)
|
|
|
|
|
service and connect to such services.
|
|
|
|
|
|
|
|
|
|
This [glossary](https://geti2p.net/en/about/glossary) may be useful to get
|
|
|
|
|
started with I2P terminology.
|
|
|
|
|
|
|
|
|
|
## Run Bitcoin Core with an I2P router (proxy)
|
|
|
|
|
|
|
|
|
|
A running I2P router (proxy) with [SAM](https://geti2p.net/en/docs/api/samv3)
|
|
|
|
|
enabled is required (there is an [official one](https://geti2p.net) and
|
|
|
|
|
[a few alternatives](https://en.wikipedia.org/wiki/I2P#Routers)). 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 Core 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:
|
|
|
|
|
|
|
|
|
|
```
|
|
|
|
|
bitcoind -i2psam=127.0.0.1:7656
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
The first time Bitcoin Core connects to the I2P router, its I2P address (and
|
|
|
|
|
corresponding private key) will be automatically generated and saved in a file
|
|
|
|
|
named `i2p_private_key` in the Bitcoin Core data directory.
|
|
|
|
|
|
|
|
|
|
## Additional configuration options related to I2P
|
|
|
|
|
|
|
|
|
|
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 Core 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](https://en.bitcoin.it/wiki/Weaknesses#Sybil_attack). Use
|
|
|
|
|
`bitcoin-cli -addrinfo` to see the number of I2P addresses known to your node.
|
|
|
|
|
|
|
|
|
|
Another consideration with `onlynet=i2p` is that the initial blocks download
|
|
|
|
|
phase when syncing up a new node can be very slow. This phase can be sped up by
|
|
|
|
|
using other networks, for instance `onlynet=onion`, at the same time.
|
|
|
|
|
|
|
|
|
|
In general, a node can be run with both onion and I2P hidden services (or
|
|
|
|
|
any/all of IPv4/IPv6/onion/I2P), which can provide a potential fallback if one
|
|
|
|
|
of the networks has issues.
|
|
|
|
|
|
|
|
|
|
## I2P-related information in Bitcoin Core
|
|
|
|
|
|
|
|
|
|
There are several ways to see your I2P address in Bitcoin Core:
|
|
|
|
|
- in the debug log (grep for `AddLocal`, the I2P address ends in `.b32.i2p`)
|
|
|
|
|
- in the output of the `getnetworkinfo` RPC in the "localaddresses" section
|
|
|
|
|
- in the output of `bitcoin-cli -netinfo` peer connections dashboard
|
|
|
|
|
|
|
|
|
|
To see which I2P peers your node is connected to, use `bitcoin-cli -netinfo 4`
|
|
|
|
|
or the `getpeerinfo` RPC (e.g. `bitcoin-cli getpeerinfo`).
|
|
|
|
|
|
|
|
|
|
To see which I2P addresses your node knows, use the `getnodeaddresses 0 i2p`
|
|
|
|
|
RPC.
|
|
|
|
|
|
|
|
|
|
## Compatibility
|
|
|
|
|
|
|
|
|
|
Bitcoin Core uses the [SAM v3.1](https://geti2p.net/en/docs/api/samv3) protocol
|
|
|
|
|
to connect to the I2P network. Any I2P router that supports it can be used.
|
|
|
|
|
|
|
|
|
|
## Ports in I2P and Bitcoin Core
|
|
|
|
|
|
|
|
|
|
Bitcoin Core uses the [SAM v3.1](https://geti2p.net/en/docs/api/samv3)
|
|
|
|
|
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 Core 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
|
|
|
|
|
port (`TO_PORT`) is always set to 0 and is not in the control of Bitcoin Core.
|
