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Wladimir J. van der Laan a36834f10b
Merge #9037: net: Add test-before-evict discipline to addrman 
e68172ed9 Add test-before-evict discipline to addrman (Ethan Heilman)

Pull request description:

  This change implement countermeasures 3 (test-before-evict) suggested in our paper: ["Eclipse Attacks on Bitcoin’s Peer-to-Peer Network"](http://cs-people.bu.edu/heilman/eclipse/).
  # Design:

  A collision occurs when an address, addr1, is being moved to the tried table from the new table, but maps to a position in the tried table which already contains an address (addr2). The current behavior is that addr1 would evict addr2 from the tried table.

  This change ensures that during a collision, addr1 is not inserted into tried but instead inserted into a buffer (setTriedCollisions). The to-be-evicted address, addr2, is then tested by [a feeler connection](https://github.com/bitcoin/bitcoin/pull/8282). If addr2 is found to be online, we remove addr1 from the buffer and addr2 is not evicted, on the other hand if addr2 is found be offline it is replaced by addr1.

  An additional small advantage of this change is that, as no more than ten addresses can be in the test buffer at once, and addresses are only cleared one at a time from the test buffer (at 2 minute intervals), thus an attacker is forced to wait at least two minutes to insert a new address into tried after filling up the test buffer. This rate limits an attacker attempting to launch an eclipse attack.
  # Risk mitigation:
  - To prevent this functionality from being used as a DoS vector, we limit the number of addresses which are to be tested to ten. If we have more than ten addresses to test, we drop new addresses being added to tried if they would evict an address. Since the feeler thread only creates one new connection every 2 minutes the additional network overhead is limited.
  - An address in tried gains immunity from tests for 4 hours after it has been tested or successfully connected to.
  # Tests:

  This change includes additional addrman unittests which test this behavior.

  I ran an instance of this change with a much smaller tried table (2 buckets of 64 addresses) so that collisions were much more likely and observed evictions.

  ```
  2016-10-27 07:20:26 Swapping 208.12.64.252:8333 for 68.62.95.247:8333 in tried table
  2016-10-27 07:20:26 Moving 208.12.64.252:8333 to tried
  ```

  I documented tests we ran against similar earlier versions of this change in #6355.
  # Security Benefit

  This is was originally posted in PR #8282 see [this comment for full details](https://github.com/bitcoin/bitcoin/pull/8282#issuecomment-237255215).

  To determine the security benefit of these larger numbers of IPs in the tried table I modeled the attack presented in [Eclipse Attacks on Bitcoin’s Peer-to-Peer Network](https://eprint.iacr.org/2015/263).

  ![attackergraph40000-10-1000short-line](https://cloud.githubusercontent.com/assets/274814/17366828/372af458-595b-11e6-81e5-2c9f97282305.png)

  **Default node:** 595 attacker IPs for ~50% attack success.
  **Default node + test-before-evict:** 620 attacker IPs for ~50% attack success.
  **Feeler node:** 5540 attacker IPs for ~50% attack success.
  **Feeler node + test-before-evict:** 8600 attacker IPs for ~50% attack success.

  The node running feeler connections has 10 times as many online IP addresses in its tried table making an attack 10 times harder (i.e. requiring the an attacker require 10 times as many IP addresses in different /16s). Adding test-before-evict increases resistance of the node by an additional 3000 attacker IP addresses.

  Below I graph the attack over even greater attacker resources (i.e. more attacker controled IP addresses). Note that test-before-evict maintains some security far longer even against an attacker with 50,000 IPs. If this node had a larger tried table test-before-evict could greatly boost a nodes resistance to eclipse attacks.

  ![attacker graph long view](https://cloud.githubusercontent.com/assets/274814/17367108/96f46d64-595c-11e6-91cd-edba160598e7.png)

Tree-SHA512: fdad4d26aadeaad9bcdc71929b3eb4e1f855b3ee3541fbfbe25dca8d7d0a1667815402db0cb4319db6bd3fcd32d67b5bbc0e12045c4252d62d6239b7d77c4395
2018-03-06 21:36:56 +01:00
.github Make default issue text all comments to make issues more readable 2017-11-16 11:50:56 -05:00
.tx tx: Update transifex slug for 0.16 2018-01-24 16:35:40 +01:00
build-aux/m4 Merge #12294: [Docs] Create NetBSD build instructions and fix compilation 2018-01-30 09:57:45 +01:00
contrib Merge #12588: [Utils] Remove deprecated PyZMQ call from Python ZMQ example 2018-03-06 19:03:13 +01:00
depends depends: patch pthread_set_name_np out of zeromq 2018-03-05 15:08:31 -05:00
doc Merge #12373: Build: Add build support for profiling. 2018-03-06 20:21:44 +01:00
share Increment MIT Licence copyright header year on files modified in 2017 2018-01-03 02:26:56 +09:00
src Merge #9037: net: Add test-before-evict discipline to addrman 2018-03-06 21:36:56 +01:00
test Merge #12512: Don't test against the mempool min fee information in mempool_limit.py 2018-03-05 22:08:19 +01:00
.gitattributes Separate protocol versioning from clientversion 2014-10-29 00:24:40 -04:00
.gitignore [build] .gitignore: add QT Creator artifacts 2017-12-22 12:37:00 +01:00
.travis.yml [tests] Fix names of excluded extended tests for travis 2018-01-29 20:09:15 +10:00
autogen.sh Add MIT license to autogen.sh and share/genbuild.sh 2016-09-21 23:01:36 +00:00
configure.ac Merge #12373: Build: Add build support for profiling. 2018-03-06 20:21:44 +01:00
CONTRIBUTING.md [docs] links to code style guides 2017-11-20 13:47:01 +01:00
COPYING [Trivial] Update license year range to 2018 2018-01-01 04:33:09 +09:00
INSTALL.md Update INSTALL landing redirection notice for build instructions. 2016-10-06 12:27:23 +13:00
libbitcoinconsensus.pc.in Unify package name to as few places as possible without major changes 2015-12-14 02:11:10 +00:00
Makefile.am Build: Add a makefile target for Doxygen documentation 2018-01-25 19:43:19 +01:00
README.md Rename test/pull-tester/rpc-tests.py to test/functional/test_runner.py 2017-03-20 10:40:31 -04:00

README.md

Bitcoin Core integration/staging tree

Build Status

https://bitcoincore.org

What is Bitcoin?

Bitcoin is an experimental digital currency that enables instant payments to anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate with no central authority: managing transactions and issuing money are carried out collectively by the network. Bitcoin Core is the name of open source software which enables the use of this currency.

For more information, as well as an immediately useable, binary version of the Bitcoin Core software, see https://bitcoin.org/en/download, or read the original whitepaper.

License

Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/licenses/MIT.

Development Process

The master branch is regularly built and tested, but is not guaranteed to be completely stable. Tags are created regularly to indicate new official, stable release versions of Bitcoin Core.

The contribution workflow is described in CONTRIBUTING.md.

The developer mailing list should be used to discuss complicated or controversial changes before working on a patch set.

Developer IRC can be found on Freenode at #bitcoin-core-dev.

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 in configure) with: make check. 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, that are run automatically on the build server. These tests can be run (if the test dependencies are installed) with: test/functional/test_runner.py

The Travis CI system makes sure that every pull request is built for Windows, Linux, and OS X, and that unit/sanity tests are run automatically.

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.

Translators should also subscribe to the mailing list.