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Tor net-gate

net-gate is an autostarting MicroVM that runs a Tor transparent proxy, isolating anonymity-routed traffic in its own kernel and network namespace.

Topology

  • Host tap vm-netgate → 192.168.100.1/24; guest → 192.168.100.2/24.
  • Resources: cloud-hypervisor, 512 MB RAM, 1 vCPU, vsock CID 10.
  • The guest mounts the host's SSH keys read-only over virtiofs (/persist/etc/ssh → /etc/ssh) so sops can decrypt inside the guest.

Tor service

services.tor = {
  enable = true;
  client.enable = true;
  settings = {
    TransPort = [{ addr = "0.0.0.0"; port = 9040; }];
    SOCKSPort = [{ addr = "0.0.0.0"; port = 9050; }];
    DNSPort   = [{ addr = "0.0.0.0"; port = 5353; }];
    VirtualAddrNetworkIPv4 = "172.16.0.0/12";
    AutomapHostsOnResolve = true;
  };
};

The guest firewall opens TCP 9040 (TransPort) and 9050 (SOCKS5), plus UDP 5353 (DNSPort):

networking.firewall = {
  enable = true;
  allowedTCPPorts = [ 9040 9050 ];
  allowedUDPPorts = [ 5353 ];
};

Per-app wrappers

home/scripts.nix installs wrapper scripts that route individual applications through the guest's SOCKS5 proxy (192.168.100.2:9050), each checking VM reachability first:

Wrapper Behavior
tor-brave Brave with --proxy-server=socks5://… and a dedicated Brave-Browser-Tor profile
tor-curl curl --socks5-hostname …
tor-check Queries check.torproject.org/api/ip through the proxy
anon-run Runs a command as anon-user with http(s)_proxy=socks5h://… set

Anonymous mode (anonymous.target)

For whole-process transparent routing, nixos/configuration.nix defines an on-demand anonymous.target (armed/disarmed with the Fish abbreviations anon-on / anon-off):

  • UID isolation — an anon-user (UID 10000); an iptables mangle OUTPUT rule marks only that UID's packets with fwmark 0x1 (nftables is deliberately not used — it breaks Docker/libvirt networking on this host).
  • anon-routing.service — policy-routes fwmark 0x1 via routing table 100, whose default route is the net-gate guest (192.168.100.2). On-demand only (partOf = anonymous.target), so it never races the VM tap at boot.
  • anon-socks-check.service — readiness gate: blocks until the guest's Tor SOCKS5 (192.168.100.2:9050) actually answers, since the VM unit being active ≠ Tor bootstrapped.

Usage

Ad-hoc: use the per-app wrappers above, or point any SOCKS5-capable client at 192.168.100.2:9050. Transparent: send TCP to 192.168.100.2:9040 and DNS to 192.168.100.2:5353. AutomapHostsOnResolve + VirtualAddrNetworkIPv4 provide .onion name resolution.

WireGuard scaffold

nixos/vms.nix contains a commented networking.wg-quick block and a wg_private_key sops placeholder for chaining an upstream VPN ahead of Tor. It is inactive until a key is added to nixos/vm-secrets.yaml.

Start the runner directly with make run-netgate (nix run .#net-gate).