Design issues with BEP42 about bittorrent.org HOT 1 CLOSED

Thank you for your comments. I have forwarded them to the BEP author, and
invited him to join in the discussion.

Adam Kelly
BitTorrent, Inc.

On Wed, Jun 24, 2015 at 12:11 PM, the8472 [email protected] wrote:

I have found some issues in BEP42
http://www.bittorrent.org/beps/bep_0042.html.

Once enforced, write tokens from peers whose node ID does not match its
external IP should be considered dropped.

This is somewhat ambiguous. Context clarifies it but it would be better to
phrase it as follows:

Once enforced, responses to get_peers requests whose node ID does not
match its external IP should be considered to not contain a token and thus
not be eligible as storage target. I.e. implementations should take care
that they find the closest set of nodes which return a token and whose
IDs matches their IPs and announce to those.

Additionally the prescribed behavior does not prevent an attacker who has
colluding nodes along the lookup path to effectively short-circuit the
lookup so that the terminal set consists of non-compliant nodes. This might
cause implementations that have lax "is lookup done" conditions to store
their announces on far-away nodes and thus rendering this BEP ineffective.

So it's probably necessary to also mandate stricter termination conditions
for a lookup.

Additionally the transition mechanism should be improved by stating:

Enforcing nodes MAY also announce to non-compliant nodes as long as
they also announce to the closest set of compliant nodes.

—
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#9.

Adam Kelly
BitTorrent, Inc.
-- Ship it!

from bittorrent.org.