lnpeer: add some rate-limiting against ping flood#10665
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SomberNight merged 2 commits intoMay 26, 2026
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f321x
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May 26, 2026
| await asyncio.sleep(min_delay - elapsed_since_last) | ||
| self._last_ping_recv_time = time.monotonic() | ||
| l = payload['num_pong_bytes'] | ||
| self.send_message('pong', byteslen=l) |
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Maybe it would be good to drain the transport like this as well?
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| self.send_message('pong', byteslen=l) | |
| msg = encode_msg('pong', byteslen=l) | |
| await self.transport.send_bytes_and_drain(msg) |
Otherwise, maybe a peer could just fill up our sockets outgoing buffer by ~234mb/h if they stop reading from their socket and keep sending pings every second.
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uuuuuu nice observation.
I don't know if such an attack would actually work though -- I would expect some kind of TCP timeout to get triggered from the OS. But maybe I am wrong?
In any case, let's do this, defense in depth.
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if they stop reading
I guess if they keep reading reeeeeeaaaalllyy slow, but send stuff at a steady pace, that might work, maybe.
A remote peer could send us lots of small ping messages, requesting large pong responses. This is cheap for them but potentially expensive for us. Does not seem too serious, but I think we could add some rate-limiting. note: There are many ways for a remote peer to inflate our incoming traffic usage, but the cost of that is usually shared between them and us (they need to send the data, we receive it).
might help against some memory exhaustion attacks f321x said: > maybe a peer could just fill up our sockets outgoing buffer by ~234mb/h > if they stop reading from their socket and keep sending pings every second. Co-authored-by: f321x <f@f321x.com>
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A remote peer could send us lots of small ping messages, requesting large pong responses. This is cheap for them but potentially expensive for us. Does not seem too serious, but I think we could add some rate-limiting.
note: There are many ways for a remote peer to inflate our incoming traffic usage, but the cost of that is usually shared between them and us (they need to send the data, we receive it).