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BONUS: Fulcrum

  • In this section we will install and use Fulcrum.
  • Fulcrum is a high-performance full-index personal electrum server.
  • You can use it as the backend for many wallet, including Sparrow and Electrum.
  • We'll try it with Sparrow in this section.

Exercise: Install and run Fulcrum

Add Fulcrum to your config​

  services.fulcrum = {
    enable = true;
  };

Switch to the new config​

sudo nixos-rebuild switch --flake /etc/nixos/#btcpp-berlin-mutinynet

Start an SSH tunnel​

Then, open a terminal window and start a new SSH session like this:

ssh -L 50001:127.0.0.1:50001 bitcoiner@<VPS IP address>

If you want to use the same SSH session for both RTL and Fulcrum, you can instead do:

ssh -L 3000:127.0.0.1:3000 -L 50001:127.0.0.1:50001 bitcoiner@<VPS IP address>
  • This will open an SSH tunnel from localhost on your VPS (where Fulcrum is exposed on port 50001) to localhost on your local machine.
  • If you're having trouble connecting, try deactivating any VPNs and restarting the tunnel.
  • Make sure you don't have two tunnels open to the same port.

You can now use your Fulcrum server as a backend for any desktop wallet, such as Sparrow.

Install Sparrow​

Go to https://sparrowwallet.com/download/ and install Sparrow for your machine.

Run Sparrow​

The exact method will vary depending on your OS.

Connect Sparrow to your Fulcrum instance​

  • Go to File->Preferences->Server->Edit Existing Connection
  • In "URL" put 127.0.0.1 and 50001 for the port
  • Make sure SSL is off
  • Make sure Use Proxy is off
  • Click Test Connection. This should say "Connected to Fulcrum"

Restart in Testnet Mode​

  • Go to Tools->Restart in Testnet to be able to interact with Mutinynet wallets.

Create a wallet and send some transactions​

  • Your CLN node can be used as a second on-chain mutinynet wallet
  • You can also send to your fellow mutinynet users

  • Install Fulcrum
  • Create an SSH tunnel to your Fulcrum instance
  • Connect Sparrow Desktop to your Fulcrum instance