3.4 Mobile app: Zeus

We install Zeus, a cross-platform mobile app that connects to your Lightning network node. Make payments with lightning or on-chain and manage your channels while you're on the go.

Requirements

• Bitcoin Core

• LND

Preparations

Configure LND

• Login as admin user, and configure LND to allow LND REST from anywhere. Edit lnd.conf

sudo nano /data/lnd/lnd.conf

• Add the next line under the [Application Options] section. Save and exit

# Specify all ipv4 interfaces to listen on for REST connections
restlisten=0.0.0.0:8080

• Restart LND to apply changes

sudo systemctl restart lnd

• Ensure the gRPC proxy port is now binding to the 0.0.0.0 host instead of 127.0.0.1

sudo ss -tulpn | grep LISTEN | grep lnd | grep 8080

Expected output:

tcp   LISTEN 0      4096         0.0.0.0:       0.0.0.0:*    users:(("lnd",pid=774047,fd=32))

Configure Firewall

• Configure the Firewall to allow LND REST incoming requests

sudo ufw allow 8080/tcp comment 'allow LND REST from anywhere'

Installation

Install lndconnect

lndconnect, created by Zap, is a utility that generates QR Code or URI to connect applications to LND instances.

• As admin user, navigate to the tmp folder

cd /tmp

• Set the environment variable

VERSION=0.2.0

• Download

wget https://github.com/LN-Zap/lndconnect/releases/download/v$VERSION/lndconnect-linux-amd64-v$VERSION.tar.gz

• Extract

tar -xvf lndconnect-linux-amd64-v$VERSION.tar.gz

• Install it

sudo install -m 0755 -o root -g root -t /usr/local/bin lndconnect-linux-amd64-v$VERSION/lndconnect

• Ensure lndconnect is correctly installed

lndconnect -h

Expected output ⬇️

Usage:
  lndconnect [OPTIONS]

Application Options:
      --lnddir=               The base directory that contains lnd's data, logs, configuration file, etc. (default: /home/admin/.lnd)
      --configfile=           Path to configuration file (default: /home/admin/.lnd/lnd.conf)
  -b, --datadir=              The directory to find lnd's data within (default: /home/admin/.lnd/data)
      --tlscertpath=          Path to read the TLS certificate from (default: /home/admin/.lnd/tls.cert)
      --adminmacaroonpath=    Path to read the admin macaroon from
      --readonlymacaroonpath= Path to read the read-only macaroon from
      --invoicemacaroonpath=  Path to read the invoice-only macaroon from
[...]

Remote access over Tor (optional)

• Ensure that you are logged in with the user admin and add the following lines in the "location hidden services" section, below "## This section is just for location-hidden services ##" in the torrc file. Save and exit

sudo nano /etc/tor/torrc

# Hidden Service LND REST
HiddenServiceDir /var/lib/tor/hidden_service_lnd_rest/
HiddenServiceVersion 3
HiddenServicePoWDefensesEnabled 1
HiddenServicePort 8080 127.0.0.1:8080

• Reload the Tor configuration and get your connection address

sudo systemctl reload tor

sudo cat /var/lib/tor/hidden_service_lnd_rest/hostname

Example expected output:

abcdefg..............xyz.onion

• Save the onion address in a safe place (e.g., password manager)

Create a lndconnect QR code

lndconnect generates a URI and displays it as a QR code that Zeus can read.

• Still with the admin user, and use the following command depending on if you want If you want to use the:

Tor connection

Set the --host parameter with the .onion address with the one you generated above. e.g. abcdefg......xyz.onion

lndconnect --host=abcdefg......xyz.onion --port=8080 --nocert

Wireguard VPN connection (recommended)

After following the Wireguard VPN bonus guide set the --host parameter address with the private Wireguard VPN IP address. e.g. 10.0.0.1

lndconnect --host=10.0.0.1 --port=8080 --nocert

Local network connection

Set the --host parameter with the IP address of MiniBolt. e.g 192.168.1.10

lndconnect --host=192.168.X.XXX --port=8080

• It will be a big QR code, so maximize your terminal window and use CTRL+- / "Terminal unzoom" / "Zoom out" options of your terminal, to shrink the code further to fit the screen or if you prefer you can use -j parameter to get a code you can copy and paste into the app

Keep the SSH session with the QR code open, it will be necessary later to scan the obtained QR code

Install the Zeus app

On Android, you can get Zeus from Google Play or the GitHub repository if you can’t or do not want to use Google Play. Tap it, download it, and install it. If it's the first time you install an APK on your phone you will be asked to authorize the app to install unknown apps, follow the on-screen instructions to do so.

Connect Zeus to LND

• Open Zeus and tap on "SCAN LNDCONNECT CONFIG" and, if prompted, allow Zeus to use the camera

• Scan the QR code generated earlier

• Enter a Nickname for your node (e.g. "MiniBolt LN")

If you will use the Tor connection hit on the switch "Use Tor"

• Click on "SAVE NODE CONFIG"

• A "Warning" banner will appear, push on "I understand, save node config"

Zeus is now connecting to your node, and it might take a while the first time depending on the selected connection ⏰

Once you verify that the connection has been made correctly with your Lightning Node, you can close the SSH session by pressing Ctrl + D

Security

Anyone using Zeus on your phone controls your node and all its funds. Setting up a password or biometrics identification for the app is strongly recommended.

• In the app, tap on the Zeus icon in the top-left corner

• Click on Security and Set/Change Password to enter a Password/PIN or enable the Biometrics feature

• Save your password or PIN somewhere safe, e.g., in your password manager

Privacy

To preserve your privacy, you can choose your private blockchain explorer when making inquiries about on-chain transactions.

• In the app, tap on the Zeus icon in the top-left corner

• Click on Privacy and change Default Block explorer, by selecting Custom, on the Custom block explorer box, enter your preferred Block Explorer URL, .onion, the local IP address of BTC RPC explorer: https://192.168.X.XXX:4000, or Wireguard VPN IP address: https://10.0.0.1:4000, depending on the situation

Upgrade

To update Zeus, update the app using the same app store or the app source you chose to install it.

Uninstall

Uninstall Firewall

• Ensure you are logged in with the user admin, display the UFW firewall rules, and note the numbers of the rules for LND REST (e.g. "Y" below)

sudo ufw status numbered

Expected output:

[Y] 8080           ALLOW IN    Anywhere          # allow LND REST from anywhere

• Delete the rule with the correct number and confirm with "yes"

sudo ufw delete X

Uninstall Tor

You must uninstall the app on your phone and delete the LND REST API on Tor hidden service.

• Uninstall the app on your phone

• To deactivate the LND REST API Tor hidden service, comment out the hidden service lines in torrc and reload Tor

sudo nano /etc/tor/torrc

# Hidden Service LND REST
#HiddenServiceDir /var/lib/tor/hidden_service_lnd_rest/
#HiddenServiceVersion 3
HiddenServicePoWDefensesEnabled 1
#HiddenServicePort 8080 127.0.0.1:8080

• Reload Tor to apply changes

sudo systemctl reload tor

Port reference

Port	Protocol	Use
8080	TCP	LND REST port