nix-bitcoin/modules/presets/wireguard.nix

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{ config, pkgs, lib, ... }:
# Create a WireGuard server with a single peer.
# Private/public keys are created via the secrets system.
# Add helper binaries `nix-bitcoin-wg-connect` and optionally `lndconnect-wg`, `lndconnect-clightning-wg`.
# See ../../docs/services.md ("Use Zeus (mobile lightning wallet) via WireGuard")
# for usage instructions.
# This is a rather opinionated implementation that lacks the flexibility offered by
# other nix-bitcoin modules, so ship this as a `preset`.
# Some users will prefer to use `lndconnect` with their existing WireGuard or Tailscale setup.
with lib;
let
options.nix-bitcoin.wireguard = {
subnet = mkOption {
type = types.str;
default = "10.10.0";
description = mdDoc "The /24 subnet of the wireguard network.";
};
restrictPeer = mkOption {
type = types.bool;
default = true;
description = mdDoc ''
Prevent the peer from connecting to any addresses except for the WireGuard server address.
'';
};
};
cfg = config.nix-bitcoin.wireguard;
wgSubnet = cfg.subnet;
inherit (config.networking.wireguard.interfaces) wg-nb;
inherit (config.services)
lnd
clightning-rest;
lndconnect = lnd.enable && lnd.lndconnect.enable;
lndconnect-clightning = clightning-rest.enable && clightning-rest.lndconnect.enable;
serverAddress = "${wgSubnet}.1";
peerAddress = "${wgSubnet}.2";
secretsDir = config.nix-bitcoin.secretsDir;
wgConnectUser = if config.nix-bitcoin.operator.enable
then config.nix-bitcoin.operator.name
else "root";
# A script that prints a QR code to connect a peer to the server.
# The QR code encodes a wg-quick config that can be imported by the wireguard
# mobile app.
wgConnect = pkgs.writers.writeBashBin "nix-bitcoin-wg-connect" ''
set -euo pipefail
text=
host=
for arg in "$@"; do
case $arg in
--text)
text=1
;;
*)
host=$arg
;;
esac
done
if [[ ! $host ]]; then
# Use lndconnect to fetch the external ip.
# This internally uses https://github.com/GlenDC/go-external-ip, which
# queries a set of external ip providers.
host=$(
${getExe config.nix-bitcoin.pkgs.lndconnect} --url --nocert \
--configfile=/dev/null --adminmacaroonpath=/dev/null \
| sed -nE 's|.*?/(.*?):.*|\1|p'
)
fi
config="[Interface]
PrivateKey = $(cat ${secretsDir}/wg-peer-private-key)
Address = ${peerAddress}/24
[Peer]
PublicKey = $(cat ${secretsDir}/wg-server-public-key)
AllowedIPs = ${wgSubnet}.0/24
Endpoint = $host:${toString wg-nb.listenPort}
PersistentKeepalive = 25
"
if [[ $text ]]; then
echo "$config"
else
echo "$config" | ${getExe pkgs.qrencode} -t UTF8 -o -
fi
'';
in {
inherit options;
config = {
assertions = [
{
# Don't support `netns-isolation` for now to keep things simple
assertion = !(config.nix-bitcoin.netns-isolation.enable or false);
message = "`nix-bitcoin.wireguard` is not compatible with `netns-isolation`.";
}
];
networking.wireguard.interfaces.wg-nb = {
ips = [ "${serverAddress}/24" ];
listenPort = mkDefault 51820;
privateKeyFile = "${secretsDir}/wg-server-private-key";
allowedIPsAsRoutes = false;
peers = [
{
# To use the actual public key from the secrets file, use dummy pubkey
# `peer0` and replace it via `getPubkeyFromFile` (see further below)
# at peer service runtime.
publicKey = "peer0";
allowedIPs = [ "${peerAddress}/32" ];
}
];
};
systemd.services = {
wireguard-wg-nb = rec {
wants = [ "nix-bitcoin-secrets.target" ];
after = wants;
};
# HACK: Modify start/stop scripts of the peer setup service to read
# the pubkey from a secrets file.
wireguard-wg-nb-peer-peer0 = let
getPubkeyFromFile = mkBefore ''
if [[ ! -v inPatchedSrc ]]; then
export inPatchedSrc=1
publicKey=$(cat "${secretsDir}/wg-peer-public-key")
<"''${BASH_SOURCE[0]}" sed "s|\bpeer0\b|$publicKey|g" | ${pkgs.bash}/bin/bash -s
exit
fi
'';
in {
script = getPubkeyFromFile;
postStop = getPubkeyFromFile;
};
};
environment.systemPackages = [
wgConnect
] ++ (optional lndconnect
(pkgs.writers.writeBashBin "lndconnect-wg" ''
exec lndconnect --host "${serverAddress}" --nocert "$@"
'')
) ++ (optional lndconnect-clightning
(pkgs.writers.writeBashBin "lndconnect-clightning-wg" ''
exec lndconnect-clightning --host "${serverAddress}" --nocert "$@"
'')
);
networking.firewall = let
restrictPeerRule = "-s ${peerAddress} ! -d ${serverAddress} -j REJECT";
in {
allowedUDPPorts = [ wg-nb.listenPort ];
extraCommands =
optionalString lndconnect ''
iptables -w -A nixos-fw -p tcp -s ${wgSubnet}.0/24 --dport ${toString lnd.restPort} -j nixos-fw-accept
''
+ optionalString lndconnect-clightning ''
iptables -w -A nixos-fw -p tcp -s ${wgSubnet}.0/24 --dport ${toString clightning-rest.port} -j nixos-fw-accept
''
+ optionalString cfg.restrictPeer ''
iptables -w -A nixos-fw ${restrictPeerRule}
iptables -w -A FORWARD ${restrictPeerRule}
'';
extraStopCommands =
# Rules added to chain `nixos-fw` are automatically removed when restarting
# the NixOS firewall service.
mkIf cfg.restrictPeer ''
iptables -w -D FORWARD ${restrictPeerRule} || :
'';
};
# Listen on all addresses, including `serverAddress`.
# This is safe because the listen ports are secured by the firewall.
services.lnd.restAddress = mkIf lndconnect "0.0.0.0";
# clightning-rest always listens on "0.0.0.0"
nix-bitcoin.secrets = {
wg-server-private-key = {};
wg-server-public-key = { user = wgConnectUser; group = "root"; };
wg-peer-private-key = { user = wgConnectUser; group = "root"; };
wg-peer-public-key = {};
};
nix-bitcoin.generateSecretsCmds.wireguard = let
wg = "${pkgs.wireguard-tools}/bin/wg";
in ''
makeWireguardKey() {
local name=$1
local priv=wg-$name-private-key
local pub=wg-$name-public-key
if [[ ! -e $priv ]]; then
${wg} genkey > $priv
fi
if [[ $priv -nt $pub ]]; then
${wg} pubkey < $priv > $pub
fi
}
makeWireguardKey server
makeWireguardKey peer
'';
};
}