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On bitcoin-qt, some peers are called "Out" and some are "In". Is there any difference besides who initiated the connection?
Is there a difference between "In" and "Out" peer connections?
Answers
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No, connection directionality doesn't affect peer behavior in Bitcoin P2P at all. The same rules for relaying inventory, and punishments for misbehavior apply to both. The software will avoid making outgoing connections to peers in close proximity in the IP address space to one another, but this does not apply to incoming connections where many connections from even the same IP address are allowed.
3There is a small difference: Bitcoin Core tries to avoid synchronizing from incoming peers, in order to retain the "if you don't listen, you won't have huge transfer volumes" invariant. – Pieter Wuille – 2015-07-13T02:41:32.097