Sovran Systems
2867954808
Clarified access and security details for the Hub, including SSH Remote Access and support access.
5.6 KiB
Security Policy
Supported versions
| Release | Supported |
|---|---|
| Latest stable release | Yes |
main / staging-dev |
Development only |
Older than 1.0.0 |
No |
Install the newest stable point release to receive security fixes.
Report a vulnerability
Do not open a public issue or pull request. Report privately through:
Include the affected version, impact, reproduction steps, and a minimal proof of concept. Never send wallet recovery words, private keys, or live credentials.
We aim to acknowledge reports within two business days. Please allow reasonable time for a fix and coordinated disclosure.
Security model
Local-first operation
The Hub and core data run on operator-owned hardware. The Hub is for a trusted local network and must not be port-forwarded to the internet. It uses HTTP, so authentication does not encrypt local network traffic.
The Hub is served on port 8937 and is not fronted by Caddy. Server + Desktop and
Bitcoin Node Only open that port in the firewall, so local devices reach the Hub
at http://sovransystemsos.local:8937. On Desktop Only the Hub is not published
at all: reachable only from the machine itself, on localhost, with no TCP port
open in the firewall (UDP 5353 for mDNS only).
sovran_systemsOS.hub.directPort = true in custom.nix opens port 8937 if you
want to reach a Desktop Only Hub from another device.
The Hub checks every client before showing a login page. It runs as root, so it
answers only loopback, private, VPN and link-local addresses and turns everyone
else away. The check goes by the address a connection comes from, so it is a
second lock and not a reason to forward port 8937: don't. Addresses outside the
local ranges go in sovran_systemsOS.hub.extraLanNetworks in custom.nix;
sovran_systemsOS.hub.lanOnly = false turns the check off.
Public services and your home IP address
Publishing public services on Server + Desktop points a DDNS record at your home's public IP address, which anyone can look up, and lists your service hostnames in Certificate Transparency logs. Desktop publishes nothing. Node publishes nothing unless Put BTCPay Server Online or Lightning Wallet Connections is on. See Server + Desktop and your home IP address for what this means and the alternatives.
Bitcoin stack
Bitcoin and Lightning modules live in the standalone
Sovran_Bitcoin repository,
consumed as a flake input and bridged by
modules/sovran-bitcoin-integration.nix. The nix-bitcoin.* namespace and
/etc/nix-bitcoin-secrets path remain only for upgrade compatibility.
Supply chain and integrity
flake.lock pins flake inputs, and fetched source archives use fixed hashes.
Builds still depend on pinned Nixpkgs and other inputs, upstream source
archives, and any configured binary cache.
The Hub integrity check verifies Nix store contents against a build from local
/etc/nixos. It does not authenticate the release publisher or protect against
an attacker who already controls root.
Access and service isolation
- Firewall enabled by default
- SSH Remote Access and remote desktop disabled by default
- Separate service users and systemd sandboxing where supported
- Administrative service ports bound to loopback where practical
- Tor enforced for supported Bitcoin traffic and onion services
- Public web services exposed only when enabled by the operator (this makes your home IP address public)
SSH Remote Access is the only supported administrative port that faces the network, and it is off by default. Enabling it listens on all interfaces and opens TCP port 22; the Hub then asks you to forward port 22, which puts SSH on the public internet. Key authentication only. Turn it off when you are done.
Tor reduces network exposure for configured Bitcoin services. It is not a guarantee against every IP leak, application bug, or traffic-analysis attack.
Restricted support access
Tech Support runs over SSH, and the Hub refuses to start a session until SSH
Remote Access is enabled (see above). Support uses a per-session SSH key on the
non-root sovran-support account.
Sessions expire after 24 hours and have a small allowlist of sudo commands.
Wallet paths receive deny ACLs unless the operator explicitly removes them.
Disabling support removes the key and reapplies the ACLs but leaves SSH
enabled.
Support events are written to /var/log/sovran-support-audit.log. This is a
local audit log, not a cryptographically tamper-evident record.
Out of scope
Sovran_SystemsOS cannot protect against:
- Compromised root or administrator credentials
- Stolen recovery words, private keys, or backups
- Malicious or compromised hardware, firmware, or build infrastructure
- Services the operator deliberately exposes or weakens
- Physical access without appropriate disk and firmware protections
Operator basics
- Verify downloads and stop if the checksum does not match.
- Apply stable security updates promptly.
- Use unique passwords and keep SSH/RDP off when not needed.
- Prefer a well-reviewed hardware signer for meaningful Bitcoin balances.
- Keep tested, offline backups in separate secure locations.
- Never share recovery words or private keys with support.
- Disable support access when the session ends and review the audit log.
No software can provide absolute security. Review your configuration and threat model before storing important funds or data.