This post is a collaboration with the Bitcoin community to create a one-stop source for Lightning Network information.
There are still questions in the FAQ that are unanswered, if you know the answer and can provide a source please do so!
Specifications / White Papers
Lightning Network Experts on Reddit
Lightning Network Experts on Twitter
- @starkness – (Elizabeth Stark – Lightning Labs)
- @roasbeef – (Olaoluwa Osuntokun – Lightning Labs)
- @stile65 – (Alex Akselrod – Lightning Labs)
- @bitconner – (Conner Fromknecht – Lightning Labs)
- @johanth – (Johan Halseth – Lightning Labs)
- @bvu – (Bryan Vu – Lightning Labs)
- @rusty_twit – (Rusty Russell – Blockstream)
- @snyke – (Christian Decker – Blockstream)
- @JackMallers – (Jack Mallers – Zap)
- @tdryja – (Tadge Dryja – Digital Currency Initiative)
- @jcp – (Joseph Poon)
- @alexbosworth – (Alex Bosworth – yalls.org)
Tutorials and resources
Lightning on Testnet
Place a testnet transaction
Altcoin Trading using Lightning
- ZigZag – Disclaimer You must trust ZigZag to send to Target Address
Lightning on Mainnet
Developer Documentation and Resources
- LND – Lightning Network Daemon (Golang)
- eclair – A Scala implementation of the Lightning Network (Scala)
- c-lightning – A Lightning Network implementation in C
- lit – Lightning Network node software (Golang)
- lightning-onion – Onion Routed Micropayments for the Lightning Network (Golang)
- lightning-integration – Lightning Integration Testing Framework
- ptarmigan – C++ BOLT-Compliant Lightning Network Implementation [Incomplete]
Lightning Network Visualizer (Testnet)
- #lightning-dev (on Freenode) – Lightning protocol development
- #lnd – Channel for lnd development that also has a bot for github commits.
⚡ Lightning FAQs ⚡
If you can answer please PM me and include source if possible. Feel free to help keep these answers up to date and as brief but correct as possible
Is Lightning Bitcoin?
Yes. You pick a peer and after some setup, create a bitcoin transaction to fund the lightning channel; it’ll then take another transaction to close it and release your funds. You and your peer always hold a bitcoin transaction to get your funds whenever you want: just broadcast to the blockchain like normal. In other words, you and your peer create a shared account, and then use Lightning to securely negotiate who gets how much from that shared account, without waiting for the bitcoin blockchain.
Is the Lightning Network open source?
Yes, Lightning is open source. Anyone can review the code (in the same way as the bitcoin code)
Who owns and controls the Lightning Network?
Similar to the bitcoin network, no one will ever own or control the Lightning Network. The code is open source and free for anyone to download and review. Anyone can run a node and be part of the network.
I’ve heard that Lightning transactions are happening “off-chain”…Does that mean that my bitcoin will be removed from the blockchain?
No, your bitcoin will never leave the blockchain. Instead your bitcoin will be held in a multi-signature address as long as your channel stays open. When the channel is closed; the final transaction will be added to the blockchain. “Off-chain” is not a perfect term, but it is used due to the fact that the transfer of ownership is no longer reflected on the blockchain.
Do I need a constant connection to run a lightning node?
Example: A and B have a channel. 1 BTC each. A sends B 0.5 BTC. B sends back 0.25 BTC. Balance should be A = 0.75, B = 1.25. If A gets disconnected, B can publish the first Tx where the balance was A = 0.5 and B = 1.5. If the node B does in fact attempt to cheat by publishing an old state (such as the A=0.5 and B=1.5 state), this cheat can then be detected on-chain and used to steal the cheaters funds, i.e., A can see the closing transaction, notice it’s an old one and grab all funds in the channel (A=2, B=0). The time that A has in order to react to the cheating counterparty is given by the CheckLockTimeVerify (CLTV) in the cheating transaction, which is adjustable. So if A foresees that it’ll be able to check in about once every 24 hours it’ll require that the CLTV is at least that large, if it’s once a week then that’s fine too. You definitely do not need to be online and watching the chain 24/7, just make sure to check in once in a while before the CLTV expires. Alternatively you can outsource the watch duties, in order to keep the CLTV timeouts low. This can be achieved both with trusted third parties or untrusted ones (watchtowers). In the case of a unilateral close, e.g., you just go offline and never come back, the other endpoint will have to wait for that timeout to expire to get its funds back. So peers might not accept channels with extremely high CLTV timeouts. — Source
What Are Lightning’s Advantages?
Tiny payments are possible: since fees are proportional to the payment amount, you can pay a fraction of a cent; accounting is even done in thousandths of a satoshi. Payments are settled instantly: the money is sent in the time it takes to cross the network to your destination and back, typically a fraction of a second.
Does Lightning require Segregated Witness?
Yes, but not in theory. You could make a poorer lightning network without it, which has higher risks when establishing channels (you might have to wait a month if things go wrong!), has limited channel lifetime, longer minimum payment expiry times on each hop, is less efficient and has less robust outsourcing. The entire spec as written today assumes segregated witness, as it solves all these problems.
Can I Send Funds From Lightning to a Normal Bitcoin Address?
No, for now. For the first version of the protocol, if you wanted to send a normal bitcoin transaction using your channel, you have to close it, send the funds, then reopen the channel (3 transactions). In future versions, you and your peer would agree to spend out of your lightning channel funds just like a normal bitcoin payment, allowing you to use your lightning wallet like a normal bitcoin wallet.
Can I Make Money Running a Lightning Node?
Not really. Anyone can set up a node, and so it’s a race to the bottom on fees. In practice, we may see the network use a nominal fee and not change very much, which only provides an incremental incentive to route on a node you’re going to use yourself, and not enough to run one merely for fees. Having clients use criteria other than fees (e.g. randomness, diversity) in route selection will also help this.
What is the release date for Lightning on Mainnet?
Would there be any KYC/AML issues with certain nodes?
Nope, because there is no custody ever involved. It’s just like forwarding packets. — Source
What is the delay time for the recipient of a transaction receiving confirmation?
Furthermore, the Lightning Network scales not with the transaction throughput of the underlying blockchain, but with modern data processing and latency limits – payments can be made nearly as quickly as packets can be sent. — Source
How does the lightning network prevent centralization?
What are Channel Factories and how do they work?
How does the Lightning network work in simple terms?
How are paths found in Lightning Network?
How would the lightning network work between exchanges?
Each exchange will get to decide and need to implement the software into their system, but some ideas have been outlined here: Google Doc – Lightning Exchanges
Note that by virtue of the usual benefits of cost-less, instantaneous transactions, lightning will make arbitrage between exchanges much more efficient and thus lead to consistent pricing across exchange that adopt it. — Source
How do lightning nodes find other lightning nodes?
Does every user need to store the state of the complete Lightning Network?
According to Rusty’s calculations we should be able to store 1 million nodes in about 100 MB, so that should work even for mobile phones. Beyond that we have some proposals ready to lighten the load on endpoints, but we’ll cross that bridge when we get there. — Source
Would I need to download the complete state every time I open the App and make a payment?
No you’d remember the information from the last time you started the app and only sync the differences. This is not yet implemented, but it shouldn’t be too hard to get a preliminary protocol working if that turns out to be a problem. — Source
What needs to happen for the Lightning Network to be deployed and what can I do as a user to help?
Lightning is based on participants in the network running lightning node software that enables them to interact with other nodes. This does not require being a full bitcoin node, but you will have to run “lnd”, “eclair”, or one of the other node softwares listed above.
All lightning wallets have node software integrated into them, because that is necessary to create payment channels and conduct payments on the network, but you can also intentionally run lnd or similar for public benefit – e.g. you can hold open payment channels or channels with higher volume, than you need for your own transactions. You would be compensated in modest fees by those who transact across your node with multi-hop payments. — Source
Is there anyway for someone who isn’t a developer to meaningfully contribute?
Sure, you can help write up educational material. You can learn and read more about the tech at http://dev.lightning.community/resources. You can test the various desktop and mobile apps out there (Lightning Desktop, Zap, Eclair apps). — Source
Do I need to be a miner to be a Lightning Network node?
No — Source
Do I need to run a full Bitcoin node to run a lightning node?
LND uses a light client mode, so it doesn’t require a full node. The name of the light client it uses is called neutrino
How does the lightning network stop “Cheating” (Someone broadcasting an old transaction)?
Upon opening a channel, the two endpoints first agree on a reserve value, below which the channel balance may not drop. This is to make sure that both endpoints always have some skin in the game as /u/rustyreddit puts it 🙂
For a cheat to become worth it, the opponent has to be absolutely sure that you cannot retaliate against him during the timeout. So he has to make sure you never ever get network connectivity during that time. Having someone else also watching for channel closures and notifying you, or releasing a canned retaliation, makes this even harder for the attacker. This is because if he misjudged you being truly offline you can retaliate by grabbing all of its funds.
Spotty connections, DDoS, and similar will not provide the attacker the necessary guarantees to make cheating worthwhile. Any form of uncertainty about your online status acts as a deterrent to the other endpoint. — Source
How many times would someone need to open and close their lightning channels?
You typically want to have more than one channel open at any given time for redundancy’s sake. And we imagine open and close will probably be automated for the most part. In fact we already have a feature in LND called autopilot that can automatically open channels for a user.
Frequency will depend whether the funds are needed on-chain or more useful on LN. — Source
Will the lightning network reduce BTC Liquidity due to “locking-up” funds in channels?
Can the Lightning Network work on any other cryptocurrency? How?
When setting up a Lightning Network Node are fees set for the entire node, or each channel when opened?
You don’t really set up a “node” in the sense that anyone with more than one channel can automatically be a node and route payments. Fees on LN can be set by the node, and can change dynamically on the network. — Source
Can Lightning routing fees be changed dynamically, without closing channels?
Yes but it has to be implemented in the Lightning software being used. — Source
How can you make sure that there will be routes with large enough balances to handle transactions?
How does the Lightning Network stop flooding nodes (DDoS) with micro transactions? Is this even an issue?
How do on-chain fees work when opening and closing channels? Who pays the fee?
How does the Lightning Network work for mobile users?
What are the best practices for securing a lightning node?
What is a lightning “hub”?
How does lightning handle cross chain (Atomic) swaps?
Based Blockchain Network