f0da26cfc8
b0735336eep2p: Don't participate in addr relay with feeler connections (Daniela Brozzoni) Pull request description: Feeler connections are short-lived connection made to check that a node is alive, useful for test-before-evict, and for moving addresses from the new to the tried table. We currently send a GETADDR message to feelers, but then disconnect before being able to receive a response. This GETADDR is not useful and can be removed. I couldn't find any previous discussion about this, but I found PR #22777, that similarly made sure that we don't ask for tx relay to feelers. --- I noticed this behavior on my peer-observer instance: I would see the number of sent GETADDR messages increase over time, but the number of ADDR messages with >100 addresses received (which are likely GETADDR responses and not self announcements relays) wouldn't increase as much. I later realized that it was my node opening feeler connections, sending a GETADDR, and closing the connection. You can see the same behavior using this command - the node is making feeler connections, sending getaddr to them, closing before receiving the addr response: ``` ~ ₿ tail -f ~/.bitcoin/debug.log | grep -E "(Making feeler connection|Added connection to|sending getaddr|feeler connection completed|Received addr: [0-9]{2,} addresses)" 2026-04-02T13:25:50Z [net] Making feeler connection to xyz.onion:8333 2026-04-02T13:26:06Z [net] Added connection to xyz.onion:8333 peer=27 2026-04-02T13:26:08Z [net] sending getaddr (0 bytes) peer=27 2026-04-02T13:26:08Z [net] feeler connection completed, disconnecting peer=27, peeraddr=xyz.onion:8333 ``` On a node that accepts inbounds connections, this command can be used to see in the logs all the nodes that connected, sent a getaddr, and disconnected before receiving a reply. It is possible that these nodes connected to us as a feeler: ``` ~ ₿ cat .bitcoin/debug.log | awk ' /received: getaddr/ { split($0, a, "peer=") got_getaddr[a[2]] = $0 } /sending addr/ { split($0, a, "peer=") sent_addr[a[2]] = 1 } /socket closed/ { split($0, a, "peer=") id = a[2] if (id in got_getaddr && !(id in sent_addr)) { print "possible feeler: " got_getaddr[id] print " " $0 } delete got_getaddr[id] delete sent_addr[id] } ' possible feeler: 2026-04-01T21:45:13Z [net] received: getaddr (0 bytes) peer=2311974 2026-04-01T21:45:13Z [net] socket closed, disconnecting peer=2311974 possible feeler: 2026-04-02T00:18:58Z [net] received: getaddr (0 bytes) peer=2426389 2026-04-02T00:18:58Z [net] socket closed, disconnecting peer=2426389 ... ``` Then, you can manually inspect one of them: ``` ~ ₿ cat .bitcoin/debug.log | grep -E "peer=2311974" 2026-04-01T21:45:13Z [net] Added connection peer=2311974 2026-04-01T21:45:13Z [net] received: version (102 bytes) peer=2311974 2026-04-01T21:45:13Z [net] sending version (102 bytes) peer=2311974 2026-04-01T21:45:13Z [net] send version message: version 70016, blocks=943279, txrelay=0, peer=2311974 2026-04-01T21:45:13Z [net] sending wtxidrelay (0 bytes) peer=2311974 2026-04-01T21:45:13Z [net] sending sendaddrv2 (0 bytes) peer=2311974 2026-04-01T21:45:13Z [net] sending verack (0 bytes) peer=2311974 2026-04-01T21:45:13Z [net] receive version message: /Satoshi:27.0.0/: version 70016, blocks=943279, us=x.x.x.x:8333, txrelay=0, peer=2311974 2026-04-01T21:45:13Z [net] received: wtxidrelay (0 bytes) peer=2311974 2026-04-01T21:45:13Z [net] received: sendaddrv2 (0 bytes) peer=2311974 2026-04-01T21:45:13Z [net] received: verack (0 bytes) peer=2311974 2026-04-01T21:45:13Z New inbound v1 peer connected: version: 70016, blocks=943279, peer=2311974 2026-04-01T21:45:13Z [net] sending sendcmpct (9 bytes) peer=2311974 2026-04-01T21:45:13Z [net] sending ping (8 bytes) peer=2311974 2026-04-01T21:45:13Z [net] sending getheaders (1029 bytes) peer=2311974 2026-04-01T21:45:13Z [net] initial getheaders (943278) to peer=2311974 (startheight:943279) 2026-04-01T21:45:13Z [net] received: getaddr (0 bytes) peer=2311974 2026-04-01T21:45:13Z [net] Advertising address x.x.x.x:8333 to peer=2311974 2026-04-01T21:45:13Z [net] socket closed, disconnecting peer=2311974 2026-04-01T21:45:13Z [net] Resetting socket for peer=2311974 2026-04-01T21:45:13Z [net] sending addrv2 (24665 bytes) peer=2311974 2026-04-01T21:45:13Z [net] Cleared nodestate for peer=2311974 ``` ACKs for top commit: 0xB10C: ACKb0735336eeachow101: ACKb0735336eeandrewtoth: ACKb0735336eestratospher: ACKb073533. didn't see any addr message from feelers in my node's last 24 hours/it would disconnect before addr message is received. so consistent with today's behaviour. Tree-SHA512: 1ac220dfd8361c4687399546a0d968d268e447446053fb8b90ba6b987482cc038e2ad94e670f33181d08d6d0c576882328bb5d0a8b8b1175a5e2ec31ff051833
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
What is Bitcoin Core?
Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.
Further information about Bitcoin Core is available in the doc folder.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/license/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled during the generation of the build system) with: ctest. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: build/test/functional/test_runner.py
(assuming build is your build directory).
The CI (Continuous Integration) systems make sure that every pull request is tested on Windows, Linux, and macOS. The CI must pass on all commits before merge to avoid unrelated CI failures on new pull requests.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.