Document connecting to ssh Tor Hidden Service

2019-04-06 16:18:37 +02:00

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nix-bitcoin

Nix packages and nixos modules with profiles for easily installing Bitcoin nodes and higher layer protocols. This is a work in progress - don't expect it to be bug free or secure.

The 'full' profile right now sets up a Bitcoin Core node and c-lightning, accessable with a smartphone using spark-wallet. A simple webpage shows the lightning nodeid and links to nanopos allowing to receive donations. It also includes liquid-daemon. Outbound peer-to-peer traffic is forced through Tor and listening services are bound to onion addresses.

A demo installation is running at http://6tr4dg3f2oa7slotdjp4syvnzzcry2lqqlcvqkfxdavxo6jsuxwqpxad.onion. The following screen cast shows how a fresh deployment of the full profile.

The goal is too make it easy to deploy a reasonably secure Bitcoin node with a usable wallet. It should allow managing bitcoin (the currency) effectively and providing public infrastructure. It should be a reproducible and extensible platform applications building on Bitcoin.

Profiles

The nix-bitcoin.nix module provides the two profiles "minimal" and "all":

minimal
- bitcoind (pruned) with outbound connections through Tor and inbound connections through a hidden service. By default loaded with banlist of spy nodes.
- clightning with outbound connections through Tor, not listening
- includes "nodeinfo" script which prints basic info about the node
- adds non-root user "operator" which has access to bitcoin-cli and lightning-cli
all
- adds clightning hidden service
- liquid-daemon
- lightning charge
- nanopos
- adds an index page using nginx to display node information and link to nanopos
- spark-wallet
  - Notes: run journalctl -eu spark-wallet to get the onion address, access key and QR access code for the spark wallet android app.
other
- electrs can be enabled by setting services.electrs.enable in modules nix-bitcoin.nix to true

The data directories of the services can be found in /var/lib on the deployed machines.

Installing profiles

The easiest way is to run nix-shell (on a Linux machine) in the nix-bitcoin directory and then create a NixOps deployment with the provided network.nix. Fix the FIXMEs in configuration.nix and deploy with nixops in nix-shell. See below for a detailed tutorial.

The profiles require 300 GB (235GB for Bitcoin blockchain + some room) of disk space and 2GB of memory. Bitcoin Core pruning is not supported at the moment because it's not supported by c-lightning. It's possible to use pruning but you need to know what you're doing.

Tutorial: install a nix-bitcoin node

Get a machine to deploy nix-bitcoin on. This could be a VirtualBox, a machine that is already running NixOs or a cloud provider. Have a look at the options in the NixOps manual. There's a tutorial for installing and configuring VirtualBox in the appendix.

The following steps are meant to be run on the machine you deploy from, not the machine you deploy to.

Install Dependencies (Debian 9 stretch)

sudo apt-get install curl git gnupg2 dirmngr

Install Latest Nix with GPG Verification

curl -o install-nix-2.2.1 https://nixos.org/nix/install
curl -o install-nix-2.2.1.sig https://nixos.org/nix/install.sig
gpg2 --recv-keys B541D55301270E0BCF15CA5D8170B4726D7198DE
gpg2 --verify ./install-nix-2.2.1.sig
sh ./install-nix-2.2.1
. /home/user/.nix-profile/etc/profile.d/nix.sh

Sandboxing is enabled by default on Nix <2.2. This may cause problems on your system. If you get an error similar to

error: cloning builder process: Operation not permitted
error: unable to start build process
/tmp/nix-binary-tarball-unpack.hqawN4uSPr/unpack/nix-2.2.1-x86_64-linux/install: unable to install Nix into your default profile

try installing as root or building as user (see https://nixos.org/nix/manual/#conf-sandbox for more information).

Clone this project

cd
git clone https://github.com/jonasnick/nix-bitcoin
cd ~/nix-bitcoin

Setup environment

nix-shell

Create nixops deployment in nix-shell. When deploying in a VirtualBox you can use the provided network-vbox.nix file (ensure that you've created a host adaptor as explained in the appendix).

nixops create network.nix network-vbox.nix -d bitcoin-node

Otherwise replace it with a network file as explained in the NixOps manual.

Adjust configuration by opening configuration.nix and removing FIXMEs.

Deploy Nixops in nix-shell

nixops deploy -d bitcoin-node

This will now create a nix-bitcoin node on the target machine.

Nixops automatically creates an ssh key for use with nixops ssh. Access bitcoin-node through ssh in nix-shell with

nixops ssh operator@bitcoin-node

Run nodeinfo to see your onion addresses for the webindex, spark, etc. if they are included in the profile.

If you change anything in the configuration you can run

nixops deploy -d bitcoin-node

in the nix-shell again to redeploy the configuration to the node.

Updating

Run git pull in the nix-bitcoin directory, enter the nix shell with nix-shell and redeploy with nixops deploy -d bitcoin-node.

FAQ

Q: When deploying or trying to SSH into the machine I see
```
bitcoin-node> waiting for SSH...
Received disconnect from 10.1.1.200 port 22:2: Too many authentication failures
```
- A: Somehow ssh-agent and nixops don't play well together. Try killing the ssh-agent.

Q: When deploying or trying to SSH into the machine I see

root@xxx.xxx.xxx.xxx: Permission denied (publickey,password,keyboard-interactive).

Make sure you don't have something like

Host *
    PubkeyAuthentication no

in your ssh config.

Q: When deploying to virtualbox for the first time I see

bitcoin-node> Mar 19 09:22:27 bitcoin-node systemd[1]: Started Get NixOps SSH Key.
bitcoin-node> Mar 19 09:22:27 bitcoin-node get-vbox-nixops-client-key-start[2226]: VBoxControl: error: Failed to connect to the guest property service, error VERR_INTERNAL_ERROR
bitcoin-node> Mar 19 09:22:27 bitcoin-node systemd[1]: get-vbox-nixops-client-key.service: Main process exited, code=exited, status=1/FAILURE
bitcoin-node> Mar 19 09:22:27 bitcoin-node systemd[1]: get-vbox-nixops-client-key.service: Failed with result 'exit-code'.
bitcoin-node> error: Traceback (most recent call last):
  File "/nix/store/6zyvpi0q6mvprycadz2dpdqag4742y18-python2.7-nixops-1.6pre0_abcdef/lib/python2.7/site-packages/nixops/deployment.py", line 731, in worker
    raise Exception("unable to activate new configuration")
Exception: unable to activate new configuration

A: This is issue https://github.com/NixOS/nixops/issues/908. The machine needs to be rebooted. You can do that by running nixops deploy with the --force-reboot flag once.

Q: I'm deploying to virtualbox it's not able to connect anymore.
- A: Maybe the IP address of the box changed. Run nixops deploy --check to update nixops with the new IP address. Sometimes you also need to remove the old IP address from ~/.ssh/known_hosts.
Q: The clightning service is running but when I try to use it (f.e. by running lightning-cli getinfo as user operator) all I get is lightning-cli: Connecting to 'lightning-rpc': Connection refused.
- A: Check your clightning logs with journalctl -eu clightning. Do you see something like bitcoin-cli getblock ... false failed? Are you using pruned mode? That means that clightning hasn't seen all the blocks it needs to and it can't get that block because your node is pruned. If you're just setting up a new node you can systemctl stop clightning and wipe your /var/lib/clightning directory. Otherwise you need to reindex the Bitcoin node.
Q: My disk space is getting low due to nix.
- A: run nix-collect-garbage -d
Q: How do I connect to my nix-bitcoin node through the ssh Tor Hidden Service?
- A:
1. Run nodeinfo on your nix-bitcoin node and note the SSHD_ONION
```
nixops ssh operator@bitcoin-node
nodeinfo | grep 'SSHD_ONION'
```
1. Create a SSH key
```
ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519
```
1. Place the ed25519 key's fingerprint in the configuration.nix openssh.authorizedKeys.keys field like so
```
# FIXME: Add your SSH pubkey
services.openssh.enable = true;
users.users.root = {
  openssh.authorizedKeys.keys = [ "[contents of ~/.ssh/id_ed25519.pub]" ];
};
```
1. Connect to your nix-bitcoin node's ssh Tor Hidden Service, forwarding a local port to the nix-bitcoin node's ssh server
```
ssh -i ~/.ssh/id_ed25519 -L [random port of your choosing]:localhost:22 root@[your SSHD_ONION]
```
1. Edit your network-nixos.nix to look like this
```
{
  bitcoin-node =
    { config, pkgs, ... }:
    { deployment.targetHost = "127.0.0.1";
    deployment.targetPort = [random port of your choosing];
    };
}
```
1. Now you can run nixops deploy -d bitcoin-node and it will connect through the ssh tunnel you established in step iv. This also allows you to do more complex ssh setups that nixops ssh doesn't support. An example would be authenticating with Trezor's ssh agent, which provides extra security.

Appendix

Tutorial: install and configure VirtualBox for nix-bitcoin on Debian 9 Stretch

Add virtualbox.list to /etc/apt/sources.list.d

deb http://download.virtualbox.org/virtualbox/debian stretch contrib

Add Oracle VirtualBox public key

wget https://www.virtualbox.org/download/oracle_vbox_2016.asc
gpg2 oracle_vbox_2016.asc

Proceed only if fingerprint reads B9F8 D658 297A F3EF C18D 5CDF A2F6 83C5 2980 AECF

sudo apt-key add oracle_vbox_2016.asc

Install virtualbox-5.2

sudo apt-get update
sudo apt-get install virtualbox-5.2

IMPORTANT: Create Host Adapter in VirtualBox

Open VirtualBox
File -> Host Network Manager -> Create
This should create a hostadapter named vboxnet0

Tutorial: install and configure NixOS for nix-bitcoin on your own hardware

1. NixOS installation

This is borrowed from the NixOS manual. Look there for more information.

Obtain latest NixOS. For example:

wget https://releases.nixos.org/nixos/18.09/nixos-18.09.2257.235487585ed/nixos-graphical-18.09.2257.235487585ed-x86_64-linux.iso

Write NixOS iso to install media (USB/CD). For example:
```
dd if=nixos-graphical-18.09.2257.235487585ed-x86_64-linux.iso of=/dev/sdX
```
Replace /dev/sdX with the correct device name. You can find this using sudo fdisk -l
Boot the system

You will have to find out if your hardware uses UEFI or Legacy Boot for the next step.

Option 1: Partition and format for UEFI

parted /dev/sda -- mklabel gpt
parted /dev/sda -- mkpart primary 512MiB -8GiB
parted /dev/sda -- mkpart primary linux-swap -8GiB 100%
parted /dev/sda -- mkpart ESP fat32 1MiB 512MiB
parted /dev/sda -- set 3 boot on
mkfs.ext4 -L nixos /dev/sda1
mkswap -L swap /dev/sda2
mkfs.fat -F 32 -n boot /dev/sda3
mount /dev/disk/by-label/nixos /mnt
mkdir -p /mnt/boot
mount /dev/disk/by-label/boot /mnt/boot
swapon /dev/sda2

Option 2: Partition and format for Legacy Boot (MBR)

parted /dev/sda -- mklabel msdos
parted /dev/sda -- mkpart primary 1MiB -8GiB
parted /dev/sda -- mkpart primary linux-swap -8GiB 100%
mkfs.ext4 -L nixos /dev/sda1
mkswap -L swap /dev/sda2
mount /dev/disk/by-label/nixos /mnt
swapon /dev/sda2

Generate NixOS config

nixos-generate-config --root /mnt
nano /mnt/etc/nixos/configuration.nix

Option 1: Edit NixOS configuration for UEFI

{ config, pkgs, ... }: {
  imports = [
    # Include the results of the hardware scan.
    ./hardware-configuration.nix
  ];

  boot.loader.systemd-boot.enable = true;

  # Note: setting fileSystems is generally not
  # necessary, since nixos-generate-config figures them out
  # automatically in hardware-configuration.nix.
  #fileSystems."/".device = "/dev/disk/by-label/nixos";

  # Enable the OpenSSH server.
  services.openssh = {
    enable = true;
    permitRootLogin = "yes";
  };
}

Option 2: Edit NixOS configuration for Legacy Boot (MBR)

{ config, pkgs, ... }: {
  imports = [
    # Include the results of the hardware scan.
    ./hardware-configuration.nix
  ];

  boot.loader.grub.device = "/dev/sda"; 

  # Note: setting fileSystems is generally not
  # necessary, since nixos-generate-config figures them out
  # automatically in hardware-configuration.nix.
  #fileSystems."/".device = "/dev/disk/by-label/nixos";

  # Enable the OpenSSH server.
  services.openssh = {
    enable = true;
    permitRootLogin = "yes";
  };
}

Do the installation

nixos-install

Set root password

setting root password...
Enter new UNIX password: 
Retype new UNIX password:

If everything went well
```
reboot
```

2. nix-bitcoin installation

On the machine you are deploying from: