ℹ️ NOTE: This section has been recently added to the course and is an early draft that may still be awaiting review. Caveat reader.
When you played with Bitcoin you were accessing an existing network, and that made it relatively easy to work with: you just turned on bitcoind and you were immediately interacting with the network. That's now how Lightning works: it's fundamentally a peer-to-peer network, built up from the connections between any two individual nodes. In other words, to interact with the Lightning Network, you'll need to first find a node to connect to.
There are four ways to do so (the first three of which are possible for your first connection):
If someone else already has a Lightning node on the network of your choice, just ask them for their ID.
If they are are running c-lightning, they just need to use the getinfo command:
$ lightning-cli getinfo
lightning-cli: WARNING: default network changing in 2020: please set network=testnet in config!
"id": "03240a4878a9a64aea6c3921a434e573845267b86e89ab19003b0c910a86d17687",
"alias": "VIOLETGLEE",
"color": "03240a",
"num_peers": 0,
"num_pending_channels": 0,
"num_active_channels": 0,
"num_inactive_channels": 0,
"address": [
{
"type": "ipv4",
"address": "74.207.240.32",
"port": 9735
}
],
"binding": [
{
"type": "ipv6",
"address": "::",
"port": 9735
},
{
"type": "ipv4",
"address": "0.0.0.0",
"port": 9735
}
],
"version": "v0.9.1-96-g6f870df",
"blockheight": 1862854,
"network": "testnet",
"msatoshi_fees_collected": 0,
"fees_collected_msat": "0msat",
"lightning-dir": "/home/standup/.lightning/testnet"
}
They can then tell you their id (03240a4878a9a64aea6c3921a434e573845267b86e89ab19003b0c910a86d17687). They will also need to tell you their IP address (74.207.240.32) and port (9735).
However, for testing purposes, you probably want to have a second node under you own control. The easiest way to do so is to create a second c-lightning node on a new machine, using either Bitcoin Standup, per §2.1 or compiling it by hand, per §19.1.
Once you have your node running, you can run getinfo to retrieve your information, as shown above.
However, for our examples in the next chapter, we're instead going to create an LND node. This will allow us to demonstrate a bit of the depth of the Lightning ecosystem by showing how similar commands work on the two different platforms.
One way to create an LND node is to run the Bitcoin Standup Scripts again on a new machine, but this time to choose LND, per §2.1.
Another is to compile LND from source code on a machine where you'rea already running a Bitcoin node, as follows.
First, you need to download and install Go:
$ wget --progress=bar:force https://dl.google.com/go/"go1.14.4"."linux"-"amd64".tar.gz -O ~standup/"go1.14.4"."linux"-"amd64".tar.gz
$ /bin/tar xzf ~standup/"go1.14.4"."linux"-"amd64".tar.gz -C ~standup
$ sudo mv ~standup/go /usr/local
Be sure that the Go version is the most up to date (it's go1.14.4 at the current time), and the platform and architecture are right for your machine. (The above will work for Debian.)
Update your path:
$ export GOPATH=~standup/gocode
$ export PATH="$PATH":/usr/local/go/bin:"$GOPATH"/bin
Then be sure that go works:
$ go version
go version go1.14.4 linux/amd64
You'll also need git and make:
$ sudo apt-get install git
$ sudo apt-get install build-essential
You're now ready to retrieve LND. Be sure to get the current verison (currently v0.11.0-beta.rc4).
$ go get -d github.com/lightningnetwork/lnd
And now you can compile:
$ cd "$GOPATH"/src/github.com/lightningnetwork/lnd
$ git checkout v0.11.0-beta.rc4
$ make
$ make install
This will install to ~/gocode/bin, which is $GOPATH/bin.
You should move it to global directories:
$ sudo cp $GOPATH/bin/lnd $GOPATH/bin/lncli /usr/bin
Unlike with c-lightning, you will need to create a default config file for LND.
However first, you need to enable ZMQ on your Bitcoind, if you didn't already in §16.3.
This requires adding the following to your ~/.bitcoin/bitcoin.conf file if it's not already there:
zmqpubrawblock=tcp://127.0.0.1:28332
zmqpubrawtx=tcp://127.0.0.1:28333
If you're using a Bitcoin config file from Standup or some other specialized conf, be sure you're putting your new commands in the correct section. Ideally, they should go near the top of the file, otherwise in the [test] section (assuming, as usual, that you're testing on testnet).
You must then restart bitcoin (or just reboot your machine). You can test that it's working as follows:
$ bitcoin-cli getzmqnotifications
[
{
"type": "pubrawblock",
"address": "tcp://127.0.0.1:28332",
"hwm": 1000
},
{
"type": "pubrawtx",
"address": "tcp://127.0.0.1:28333",
"hwm": 1000
}
]
Now you're ready to create a config file.
First, you need to retrieve your rpcuser and rpcpassword. Here's an automated way to do so:
$ BITCOINRPC_USER=$(cat ~standup/.bitcoin/bitcoin.conf | grep rpcuser | awk -F = '{print $2}')
$ BITCOINRPC_PASS=$(cat ~standup/.bitcoin/bitcoin.conf | grep rpcpassword | awk -F = '{print $2}')
⚠️ WARNING: Obviously, never store your RPC password in a shell variable in a production environment.
Then, you can write the file:
$ mkdir ~/.lnd
$ cat > ~/.lnd/lnd.conf << EOF
[Application Options]
maxlogfiles=3
maxlogfilesize=10
#externalip=1.1.1.1 # change to your public IP address if required.
alias=StandUp
listen=0.0.0.0:9735
debuglevel=debug
[Bitcoin]
bitcoin.active=1
bitcoin.node=bitcoind
bitcoin.testnet=true
[Bitcoind]
bitcoind.rpchost=localhost
bitcoind.rpcuser=$BITCOINRPC_USER
bitcoind.rpcpass=$BITCOINRPC_PASS
bitcoind.zmqpubrawblock=tcp://127.0.0.1:28332
bitcoind.zmqpubrawtx=tcp://127.0.0.1:28333
EOF
Finally, you can create an LND service to automatically run lnd:
$ cat > ~/lnd.service << EOF
# It is not recommended to modify this file in-place, because it will
# be overwritten during package upgrades. If you want to add further
# options or overwrite existing ones then use
# $ systemctl edit lnd.service
# See "man systemd.service" for details.
# Note that almost all daemon options could be specified in
# /etc/lnd/lnd.conf, except for those explicitly specified as arguments
# in ExecStart=
[Unit]
Description=LND Lightning Network Daemon
Requires=bitcoind.service
After=bitcoind.service
[Service]
ExecStart=/usr/bin/lnd
ExecStop=/usr/bin/lncli --lnddir /var/lib/lnd stop
PIDFile=/run/lnd/lnd.pid
User=standup
Type=simple
KillMode=process
TimeoutStartSec=60
TimeoutStopSec=60
Restart=always
RestartSec=60
[Install]
WantedBy=multi-user.target
EOF
You'll then need to install that and start things up:
$ sudo cp ~/lnd.service /etc/systemd/system
$ sudo systemctl enable lnd
$ sudo systemctl start lnd
(Expect this to take a minute the first time.)
Just as with c-lightning, you're going to need to make LND accessible to other nodes. Here's how to do so if you use ufw, as per the Bitcoin Standup setups:
$ sudo ufw allow 9735
The first time you run LND, you must create a wallet:
$ lncli --network=testnet create
LND will ask you for a password and then ask if you want to enter an existing mnemonic (just hit n for the latter one).
You should now have a functioning lnd, which you can verify with getinfo:
$ lncli --network=testnet getinfo
{
"version": "0.11.0-beta.rc4 commit=v0.11.0-beta.rc4",
"commit_hash": "fc12656a1a62e5d69430bba6e4feb8cfbaf21542",
"identity_pubkey": "032a7572dc013b6382cde391d79f292ced27305aa4162ec3906279fc4334602543",
"alias": "StandUp",
"color": "#3399ff",
"num_pending_channels": 0,
"num_active_channels": 0,
"num_inactive_channels": 0,
"num_peers": 2,
"block_height": 1862848,
"block_hash": "000000000000000ecb6fd95e1f486283d48683aa3111b6c23144a2056f5a1532",
"best_header_timestamp": "1602632294",
"synced_to_chain": true,
"synced_to_graph": false,
"testnet": true,
"chains": [
{
"chain": "bitcoin",
"network": "testnet"
}
],
"uris": [
],
"features": {
"0": {
"name": "data-loss-protect",
"is_required": true,
"is_known": true
},
"5": {
"name": "upfront-shutdown-script",
"is_required": false,
"is_known": true
},
"7": {
"name": "gossip-queries",
"is_required": false,
"is_known": true
},
"9": {
"name": "tlv-onion",
"is_required": false,
"is_known": true
},
"13": {
"name": "static-remote-key",
"is_required": false,
"is_known": true
},
"15": {
"name": "payment-addr",
"is_required": false,
"is_known": true
},
"17": {
"name": "multi-path-payments",
"is_required": false,
"is_known": true
}
}
}
This node's ID is 032a7572dc013b6382cde391d79f292ced27305aa4162ec3906279fc4334602543. Although this command doesn't show you the IP address and port, they should be the IP address for your machine and port 9735.
If you were already connected to the Lightning Network, and were "gossipping" with peers, you might also be able to find information on peers automatically, through the listpeers command:
c$ lightning-cli --network=testnet listpeers
{
"peers": [
{
"id": "0302d48972ba7eef8b40696102ad114090fd4c146e381f18c7932a2a1d73566f84",
"connected": true,
"netaddr": [
"127.0.0.1:9736"
],
"features": "02a2a1",
"channels": []
}
]
}
However, that definitely won't be the case for your first interaction with the Lightning Network.
You always need two Lightning nodes to form a channel. If you don't have someone else who is testing things out with you, you're going to need to create a second one, either using c-lightning or (as we will in our examples) LND.
Though you've possibly created an LND, c-lightning will remain the heart of our examples until we need to start using both of them, in Chapter 19.
Continue "Understanding Your Lightning Setup" with §19.3: Setting Up_a_Channel.