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1# CJDNS support in Bitcoin Core
2
3It is possible to run Bitcoin Core over CJDNS, an encrypted IPv6 network that
4uses public-key cryptography for address allocation and a distributed hash table
5for routing.
6
7## What is CJDNS?
8
9CJDNS is like a distributed, shared VPN with multiple entry points where every
10participant can reach any other participant. All participants use addresses from
11the `fc00::/8` network (reserved IPv6 range). Installation and configuration is
12done outside of Bitcoin Core, similarly to a VPN (either in the host/OS or on
13the network router). See https://github.com/cjdelisle/cjdns#readme for more
14information.
15
16Compared to IPv4/IPv6, CJDNS provides end-to-end encryption and protects nodes
17from traffic analysis and filtering.
18
19Used with Tor and I2P, CJDNS is a complementary option that can enhance network
20redundancy and robustness for both the Bitcoin network and individual nodes.
21
22Each network has different characteristics. For instance, Tor is widely used but
23somewhat centralized. I2P connections have a source address and I2P is slow.
24CJDNS is fast but does not hide the sender and the recipient from intermediate
25routers.
26
27## Installing CJDNS
28
29To install and set up CJDNS, follow the instructions at
30https://github.com/cjdelisle/cjdns#how-to-install-cjdns.
31
32## Connecting to the CJDNS network
33
34As of CJDNS v22, nodes automatically discover and connect to peers via DNS
35seeding. After installation, you can verify that your node has peers:
36
37    cjdnstool peers show
38
39If you see peers with status `ESTABLISHED`, your node is connected and no
40further peering setup is needed.
41
42Manual peering may be useful if you want to guarantee a connection to a
43specific node, or if you have disabled DNS seeding for privacy reasons. See
44[doc/peering.md](https://github.com/cjdelisle/cjdns/blob/master/doc/peering.md)
45in the CJDNS repository for details.
46
47## Run Bitcoin Core with CJDNS
48
49Once you are connected to the CJDNS network, the following Bitcoin Core
50configuration option makes CJDNS peers automatically reachable:
51
52```
53-cjdnsreachable
54```
55
56When enabled, this option tells Bitcoin Core that it is running in an
57environment where a connection to an `fc00::/8` address will be to the CJDNS
58network instead of to an [RFC4193](https://datatracker.ietf.org/doc/html/rfc4193)
59IPv6 local network. This helps Bitcoin Core perform better address management:
60  - Your node can consider incoming `fc00::/8` connections to be from the CJDNS
61    network rather than from an IPv6 private one.
62  - If one of your node's local addresses is `fc00::/8`, then it can choose to
63    gossip that address to peers.
64
65## Additional configuration options related to CJDNS
66
67```
68-onlynet=cjdns
69```
70
71Make automatic outbound connections only to CJDNS addresses. Inbound and manual
72connections are not affected by this option. It can be specified multiple times
73to allow multiple networks, e.g. onlynet=cjdns, onlynet=i2p, onlynet=onion.
74
75CJDNS support was added to Bitcoin Core in version 23.0 and there may be fewer
76CJDNS peers than Tor or IP ones. Therefore, using CJDNS alone without other
77networks is discouraged: a node may be unable to fill its outbound connection slots
78but will repeatedly try the few addresses it knows and is more susceptible to
79[Sybil attacks](https://en.bitcoin.it/wiki/Weaknesses#Sybil_attack).
80You can use `bitcoin-cli -addrinfo` to see the
81number of CJDNS addresses known to your node.
82
83In general, a node can be run with both an onion service and CJDNS (or any/all
84of IPv4/IPv6/onion/I2P/CJDNS), which can provide a potential fallback if one of
85the networks has issues. There are a number of ways to configure this; see
86[doc/tor.md](/doc/tor.md) for
87details.
88
89## CJDNS-related information in Bitcoin Core
90
91There are several ways to see your CJDNS address in Bitcoin Core:
92- in the "Local addresses" output of CLI `-netinfo`
93- in the "localaddresses" output of RPC `getnetworkinfo`
94
95To see which CJDNS peers your node is connected to, use `bitcoin-cli -netinfo 4`
96or the `getpeerinfo` RPC (i.e. `bitcoin-cli getpeerinfo`).
97
98You can use the `getnodeaddresses` RPC to fetch a number of CJDNS peers known to your node; run `bitcoin-cli help getnodeaddresses` for details.
99
100`bitcoin rpc` can also be substituted for `bitcoin-cli`.
101

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340 guided files · 2,680 pending. Guides cover key sections, not every line.

cmake/bitcoin-build-config.h.in src/consensus/amount.h src/consensus/consensus.h src/primitives/block.h src/primitives/transaction.h src/crypto/sha256.h src/util/moneystr.h src/clientversion.h src/uint256.h src/script/script.h src/policy/policy.h CMakeLists.txt README.md COPYING src/consensus/tx_check.cpp src/consensus/tx_verify.cpp src/consensus/merkle.cpp src/pow.cpp src/validation.cpp src/script/interpreter.cpp src/script/solver.cpp src/script/sign.cpp src/key_io.cpp src/net.cpp src/net_processing.cpp src/netaddress.cpp src/protocol.h src/wallet/wallet.cpp src/wallet/spend.cpp

Code page 1

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/init.cpp

src/crypto/sha256.cpp

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/util/chaintype.cpp

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/net_permissions.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/rpc/util.h

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/util/rbf.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/any.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

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