Security: avoid a single peer providing a majority of Zebra's peer addresses #2004
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Zebra avoids having a majority of addresses from a single peer by asking 3 peers for new addresses. Also update a bunch of security comments and related documentation.
teor2345
added
A-rust
2 tasks
dconnolly
reviewed
Apr 15, 2021
Comment on lines
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| /// The fanout should be greater than 2, so that Zebra avoids getting a majority | ||
| /// of its initial address book entries from a single peer. | ||
| /// | ||
| /// Zebra regularly crawls for new peers, initiating a new crawl every | ||
| /// [`crawl_new_peer_interval`](crate::config::Config.crawl_new_peer_interval). | ||
| /// | ||
| /// TODO: limit the number of addresses that Zebra uses from a single peer | ||
| /// response (#1869) | ||
| pub const GET_ADDR_FANOUT: usize = 3; |
dconnolly
approved these changes
Apr 15, 2021
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Motivation
We don't want a single peer to supply a majority of Zebra's addresses, because that makes takeover attacks easier.
Solution
Zebra avoids having a majority of addresses from a single peer by asking 3 peers for new addresses.
(This is a best-effort preventative measure - for a stronger guarantee, see #1869.)
Also update a bunch of security comments and related documentation.
The code in this pull request has:
Review
@dconnolly and I discussed this change as part of #1850. It's not an urgent fix, but it's worth doing soon.
Follow Up Work
Limit the number of addresses we use from each peer (#1869)