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0 sats \ 8 replies \ @k00b OP 19h \ parent \ on: Lightning payment probing behavior is implementation dependent lightning
I suspect probing isn't specified because we all agree that probing is undesirable and hope that MPP and better payment predictions via statistical analysis will decrease the motivation to probe. Yet everyone probes in the meantime because deterministic UX is good UX.
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Is this mainly a privacy concern, or just spammy?
Both! (At least I think so.)
It's spammy cause you're briefly using routes and resources without paying for them.
It's a privacy problem too. If you probe enough you can determine channel balances which are otherwise not public info.
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Meant to say sub-optimal
I see! But if a node processes a payment through a channel, ergo, you know that its capacity is greater than the payment. Isn't this comparible to paying for a chocolate bar in cash with a $20 note and the other witnesses knowing you have $20? I.e. participation requires some kind of reveal?
Does the privacy problem lie with network stats analysis tools?
The spam part is clearer as a problem to me. However, if all channels have a minimum fee, does this not help?
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Sounds curiously like the L1 spam problem, in that if you have some filters it stops some spam, but if your channels are all zero-fee, it's kind of like leaving your letter box open to mail or anything that will fit in that hole.
Default channel base-fee to 10 sats, what would that do for probing?
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Default channel base-fee to 10 sats, what would that do for probing?
Not much because probing is free except for the time value of the bitcoin locked up to be used during the probe. You may get fewer probes with a high base fee, assuming the probe is designed to find cheap routes. But spammy/privacy revealing kind of probes, the ones that are bad, won't care about your base fee.
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However, if all channels have a minimum fee, does this not help?
Probing is free currently, but there are a few proposals for rate-limiting and charging for abuses like this.
Isn't this comparible to paying for a chocolate bar in cash with a $20 note and the other witnesses knowing you have $20?
It's more like asking everyone in the restaurant to pay $20 for your chocolate bar, recording who could, then telling them never mind. Then asking them to pay $100 for your bottle of wine then never mind. Then asking them to pay for your $500 dinner and so on.
participation requires some kind of reveal?
It does. The problem is that nodes trust that participation is genuine. Probing works by pretending that you're making a payment when you know it will fail once it reaches its destination. There's no way for a node to turn off probing if they want to participate in routing payments.
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I was thinking many of these tiny ad-like transaction were all of the probes. So, they just use HTLC, then release it. Thanks for the explainer. That's much clearer now.
I wonder whether they'd be some kind of WOT system for nodes that are well-established and known to you. A rule set, like, has this node opened a channel to you in the past, did you initiate a channel with this node in the past, has one of your trusted nodes opened a channel to this node in the past, and so on.. that might develop.
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Trust is tricky in distributed systems. It introduces subjectivity which can be manipulated and tends to discriminate in uneven and unintended ways. But it could allow trusted peers to pay lower sybil fees which should make the network healthier as a whole.
Brink researchers released a paper using a trust+sybil fee approach. Other proposals have escalating fees when abuse is detected.
Sharing because it’s interesting, but SN uses a trust+sybil fee approach to deal with a similar class of problems. I was surprised to learn people were independently exploring trust+sybil fee for the lightning network itself.
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