# c-lightning: A specification compliant Lightning Network implementation in C c-lightning is a [standard compliant](https://github.com/lightningnetwork/lightning-rfc) implementation of the Lightning Network protocol. The Lightning Network is a scalability solution for Bitcoin, enabling secure and instant transfer of funds between any two parties for any amount. For more information about the Lightning Network please refer to http://lightning.network. ## Project Status [![Build Status](https://travis-ci.org/ElementsProject/lightning.svg?branch=master)](https://travis-ci.org/ElementsProject/lightning) [![Pull Requests Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat)](http://makeapullrequest.com) [![Irc](https://img.shields.io/badge/chat-on%20freenode-brightgreen.svg)](https://webchat.freenode.net/?channels=c-lightning) This implementation is still very much a work in progress. It can be used for testing, but __it should not be used for real funds__. We do our best to identify and fix problems, and implement missing features. Any help testing the implementation, reporting bugs, or helping with outstanding issues is very welcome. Don't hesitate to reach out to us on IRC at [#lightning-dev @ freenode.net](http://webchat.freenode.net/?channels=%23lightning-dev), [#c-lightning @ freenode.net](http://webchat.freenode.net/?channels=%23c-lightning), or on the mailing list [lightning-dev@lists.linuxfoundation.org](https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev). ## Getting Started c-lightning currently only works on Linux (and possibly Mac OS with some tweaking), and requires a locally running `bitcoind` (version 0.15 or above) that is fully caught up with the network you're testing on. ### Installation Please refer to the [installation documentation](doc/INSTALL.md) for detailed instructions. For the impatient here's the gist of it for Ubuntu and Debian: ``` sudo apt-get install -y autoconf automake build-essential git libtool libgmp-dev libsqlite3-dev python python3 net-tools libsodium-dev git clone https://github.com/ElementsProject/lightning.git cd lightning make ``` Or if you like to throw `docker` into the mix: ``` sudo docker run \ -v $HOME/.lightning:/root/.lightning \ -v $HOME/.bitcoin:/root/.bitcoin \ -p 9735:9735 \ cdecker/lightningd:latest ``` ### Starting `lightningd` In order to start `lightningd` you will need to have a local `bitcoind` node running in either testnet or regtest mode: ``` bitcoind -daemon -testnet ``` Wait until `bitcoind` has synchronized with the testnet network. In case you use regtest, make sure you generate at least 432 blocks to activate SegWit. Make sure that you do not have `walletbroadcast=0` in your `~/.bitcoin/bitcoin.conf`, or you may run into trouble. Notice that currently pruned nodes are not supported and may result in `lightningd` being unable to synchronize with the blockchain. You can start `lightningd` with the following command: ``` lightningd/lightningd --network=testnet --log-level=debug ``` ### Listing all commands: `cli/lightning-cli help` will print a table of the API and lists the following commands ### Opening a channel on the Bitcoin testnet First you need to transfer some funds to `lightningd` so that it can open a channel: ``` # Returns an address
cli/lightning-cli newaddr # Returns a transaction id bitcoin-cli -testnet sendtoaddress
``` `lightningd` will register the funds once the transaction is confirmed. If you don't have any testcoins you can get a few from a faucet such as [TPs' testnet faucet](http://tpfaucet.appspot.com/) or [Kiwi's testnet faucet](https://testnet.manu.backend.hamburg/faucet). You can send it directly to the `lightningd` address. Confirm `lightningd` got funds by: ``` # Returns an array of on-chain funds. cli/lightning-cli listfunds ``` Once `lightningd` has funds, we can connect to a node and open a channel. Let's assume the **remote** node is accepting connections at `` (and optional ``, if not 9735) and has the node ID ``: ``` cli/lightning-cli connect [] cli/lightning-cli fundchannel ``` This opens a connection and, on top of that connection, then opens a channel. The funding transaction needs 1 confirmations in order for the channel to be usable, and 6 to be broadcast for others to use. You can check the status of the channel using `cli/lightning-cli listpeers`, which after 1 confirmation should say that `state` is `CHANNELD_NORMAL`; after 6 confirmations you can use `cli/lightning-cli listchannels` to verify that the `public` field is now `true`. ### Different states States starting with `ONCHAIND` mean that the channel has been closed and an onchain transaction exists reflecting the resulting balances * `ONCHAIND_OUR_UNILATERAL` > Closed by you without cooperation of the counterparty * `ONCHAIND_THEIR_UNILATERAL` > Closed by the counterparty without your cooperation * `ONCHAIND_MUTUAL` > Negotiated closing by both sides States starting with `CHANNELD` mean that funds are not available onchain, and from that moment they can only be moved offchain, this is, through the Lightning Network * `CHANNELD_AWAITING_LOCKIN` > Waiting for confirmation of the channel funding transaction * `CHANNELD_NORMAL` > Channel is active The `GOSSIPING` state means that you are connected to a peer but there is no payment channel yet. ### Sending and receiving payments Payments in Lightning are invoice based. The recipient creates an invoice with the expected `` in millisatoshi (or `"any"` for a donation), a unique `