Qtum has now its own implementation of the lightning network, it uses the eclair client. Currently, this is only supported on testnet, let's check how to set it up and run our very own lightning network client!.
it is recommended to run Debian 10 (buster) as it has all the library versions we need
Let's go ahead and install Qtum on our Debian 10, the easy way is to use the Qtum Debian repository:
These two packages are needed to enable the Qtum repository on Debian, let's install them:
apt install -y apt-transport-https dirmngr
sudo su - Sudo to root first
echo "deb https://repo.qtum.info/apt/debian/ buster main" >> /etc/apt/sources.list.d/qtum.list
Before installing, we need to add the Qtum apt key
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys BF5B197D
sudo apt update && sudo apt install qtum
Qtum should be installed now, let's continue
We need to create the .qtum folder manually, also, we will create the configuration file inside of that folder, here's how:
This will create a text file using the nano editor, copy/paste the following inside that file:
Let's install some dependencies to prepare for the lightning client:
Qtum Eclair is developed using the Scala language. To run Qtum Eclair, you must first install the JDK, and OpenJDK 11 or above is recommended.
apt-get install default-jdk
apt install maven
Now that we have every dependency installed, it's time to build the Eclair lightning client for Qtum. Again, inside our terminal we type:
git clone https://github.com/qtumproject/lightning-demo.git
mvn install -DskipTests
You should see something like this, if there's no errors, we can proceed with creating the configuration file and launch Qtum Eclair now.
Create and edit the configuration file ~/.qtum-eclair/eclair.conf as follows:
chain = "testnet" // "mainnet" for mainnet, "testnet" for testnet, "regtest" for regtest
public-ips = 
binding-ip = "0.0.0.0"
port = 9735
enabled = false
binding-ip = "127.0.0.1"
port = 8080
password = "qtum-eclair"
use-old-api = false
watcher-type = "bitcoind"
host = "localhost"
rpcport = 13889
bitdir = ""
rpcuser = "foo"
rpcpassword = "bar"
zmqblock = "tcp://127.0.0.1:29000"
zmqtx = "tcp://127.0.0.1:29000"
1 = 1200000
2 = 1000000
6 = 800000
12 = 600000
36 = 500000
72 = 410000
min-feerate = 400
smooth-feerate-window = 6 // 1 = no smoothing
node-alias = "qtum-eclair"
node-color = "49daaa"
global-features = ""
local-features = "8a"
override-features = 
channel-flags = 1
dust-limit-satoshis = 72800
max-htlc-value-in-flight-msat = 500000000000 // 5 QTUM
htlc-minimum-msat = 1
max-accepted-htlcs = 30
reserve-to-funding-ratio = 0.01
max-reserve-to-funding-ratio = 0.05
to-remote-delay-blocks = 3600
max-to-local-delay-blocks = 10080
mindepth-blocks = 3
expiry-delta-blocks = 720
fee-base-msat = 400000
fee-proportional-millionths = 100
max-feerate-mismatch = 1.56
update-fee_min-diff-ratio = 0.1
revocation-timeout = 20 seconds
ping-interval = 30 seconds
ping-timeout = 10 seconds
ping-disconnect = true
auto-reconnect = true
payment-handler = "local"
payment-request-expiry = 1 hour
min-funding-satoshis = 1000000 // 0.01 Qtum
max-payment-attempts = 5
autoprobe-count = 0
randomize-route-selection = true
channel-exclude-duration = 60 seconds
broadcast-interval = 60 seconds
init-timeout = 5 minutes
max-route-length = 6 max-cltv = 5040 fee-threshold-sat = 8400 max-fee-pct = 0.03 heuristics-enable = true ratio-cltv = 0.15 ratio-channel-age = 0.35 ratio-channel-capacity = 0.5 }
// do not edit or move this section
mailbox-type = "akka.dispatch.BoundedMailbox"
mailbox-capacity = 1
mailbox-push-timeout-time = 0
executor = "thread-pool-executor"
type = PinnedDispatcher
PLEASE NOTE if you modified the rpcuser and rpcpassword on qtum.conf, please modify this config file accordingly .
Start the client with the command java -jar ./eclair-node-gui/target/lightning-capsule.jar
You should see the eclair desktop client as on the screenshot below:
Right-click the lower left corner of the local Qtum Eclair client and select “Copy URI” to get its node address (public key).
Click the “Channel” button in the upper left corner and select “Open Channel”.
In the pop-up page, fill in the URI of the channel partner, and the capacity of the channel, which is set to 10 QTUM as an example, this will be the maximum capacity for this channel, this means, you can only transact up to 10 QTUM.
Click “Connect” to create the channel. At this point, you need to wait for 6 blocks to confirm the transaction and the channel will be created successfully.
Once the channel is set up, you can use the Lightning Network for micropayments.
Click the “Channel” button in the upper left corner, select “Receive Payment”, fill in the receipt amount in the pop-up page, click the “Generate” button to get your own receipt address. Here we choose a very small amount of 1 Satoshi, which is equivalent to 0.00000001 QTUM. Such a small transferred amount is unimaginable without using a lightning network.
Click the “Channel” button in the upper left corner, select “Send Payment”, fill in the other party’s lightning network receipt address and amount in the pop-up page, and click the “Send” button, then you can transfer tokens to the other party.
After the transfer is completed, the amount of the two parties’ changes instantaneously. Because this is a pure transaction off the chain, there is no need to wait for the block confirmation, and it is free of fees.
The channel can be closed when the channel is no longer needed.
Click the “Close” button to close the channel.
Once closed, the remaining QTUM in the channel will be refunded to the origin Qtum Core wallet.