A1/A1 Mini printers fail to connect through VP proxy mode while
X1C/P2S/H2C work fine with identical transparent TCP proxy code.
Root cause unknown — the proxy is model-agnostic, so the failure
suggests BambuStudio uses a different connection flow for A1 models
that hits ports we don't proxy.
Add diagnostic probe listeners on ports 21, 80, and 443 on each
proxy VP's dedicated bind IP. If the slicer connects to any of
these un-proxied ports, a WARNING is logged so debug logs and
tcpdump can reveal what's missing.
The closed-source bambu_networking DLL validates TLS connection parameters
and rejects connections where the certificate doesn't match the printer's
real BBL CA certificate. The TLS-terminating proxy presented Bambuddy's
own certificate, causing X1C/X1 prints to silently fail after verify_job.
Switch to transparent TCP proxying for FTP, FileTransfer, Camera, and FTP
data — only MQTT remains TLS-terminated (required for IP rewriting). The
slicer now gets end-to-end TLS directly with the printer's real certificate.
Changes:
- SlicerProxyManager uses TCPProxy for FTP (990), FileTransfer (6000),
Camera (322), and pre-listens on FTP data ports (50000-50100)
- Only MQTT (8883) uses TLSProxy for IP rewriting
- Remove debug logging from MQTT and FTP proxy code
- Fix install.sh missing AmbientCapabilities=CAP_NET_BIND_SERVICE
- Update module docstring, migration docs, README proxy description
- Add tests verifying transparent proxy architecture
When the slicer and printer are on different VLANs, Bambu Studio could
not send prints through the proxy because the printer's real IP leaked
through MQTT payloads, the bind protocol forwarded the real printer's
identity, file transfer and camera ports were not proxied, and FTP
data connections raced the TLS handshake on zero-byte uploads.
- Rewrite IP addresses in MQTT PUBLISH payloads (string + integer)
with proper packet framing and cross-chunk buffering
- Respond to bind/detect with VP identity via BindServer
- Add TLS proxies for port 6000 (file transfer) and 322 (RTSP camera)
- Buffer slicer FTP data during printer connection setup
- Advertise configured VP name in SSDP proxy
- Add cross-subnet SSDP wildcard listener for VPN setups
- Register UserEmailPreference model in models/__init__.py
- Add 11 unit tests for MQTT rewrite, IP conversion, SSDP name
When the slicer and printer are on different VLANs, Bambu Studio could
not send prints through the proxy because the printer's real IP leaked
through MQTT payloads, the bind protocol forwarded the real printer's
identity, the port 6000 file transfer tunnel was not proxied, and FTP
data connections raced the TLS handshake on zero-byte uploads.
- Rewrite IP addresses in MQTT PUBLISH payloads (string + integer)
with proper packet framing and cross-chunk buffering
- Respond to bind/detect with VP identity via BindServer
- Add TLS proxy for port 6000 (file transfer tunnel)
- Buffer slicer FTP data during printer connection setup
- Advertise configured VP name in SSDP proxy
- Add cross-subnet SSDP wildcard listener for VPN setups
- Register UserEmailPreference model in models/__init__.py
- Add 11 unit tests for MQTT rewrite, IP conversion, SSDP name
When running multiple virtual printers with different access codes on
separate bind IPs, FTP connections were always routed to the wrong VP.
Root cause: the iptables REDIRECT rule (990→9990) rewrites the
destination IP to the incoming interface's primary address. With Linux's
weak host model (arp_filter=0), packets for secondary IPs arrive on the
primary interface, and REDIRECT sends them all to the first VP's FTP
server. MQTT was unaffected because port 8883 had no redirect.
Fix: FTP server now binds directly to port 990 (standard implicit FTPS),
eliminating the iptables redirect entirely. Requires CAP_NET_BIND_SERVICE
(already set in the systemd service file and Docker image).
Also removed a global asyncio set_exception_handler() in the MQTT server
that was overwritten by each VP instance, causing spurious "Unhandled
exception in client_connected_cb" errors on startup.
Changes:
- FTP_PORT: 9990 → 990 (ftp_server.py)
- Removed set_exception_handler() from MQTT server
- Updated Dockerfile, docker-compose.yml port mappings
- Deprecated --redirect-990 in install script
- Updated wiki: removed iptables instructions for all platforms
- Added migration guide (docs/migration-vp-ftp-port.md)
- Added unit tests for port constant and no-global-state invariant
Bambu printers only support plain RSA key exchange ciphers
(AES256-GCM-SHA384, AES128-GCM-SHA256), but Python's OpenSSL 3.x
defaults exclude them in favor of forward-secrecy (ECDHE/DHE) only.
Add the RSA ciphers to the client SSL context so the TLS proxy can
connect to the printer's bind port (3002).
BambuStudio uses TLS on port 3002 for certain printer models (e.g. A1
Mini / N1). The bind server only spoke plain TCP on both ports, so the
TLS ClientHello was rejected as "invalid frame" and the slicer could
never discover or connect to the virtual printer.
Port 3002 now uses TLS (reusing the VP's existing certificate), port
3000 remains plain TCP. Also updated proxy-mode to use TLSProxy for
the port 3002 bind proxy instead of raw TCPProxy.
Multiple Virtual Printers:
- Each VP gets a dedicated bind IP with independent FTP, MQTT, SSDP, and Bind services
- New VirtualPrinter DB model, CRUD API (/api/virtual-printers), React UI
- VirtualPrinterList, VirtualPrinterCard, VirtualPrinterAddDialog components
- Per-instance TLS certificates (shared CA), 11 printer models, all 4 modes
- Auto-incremented serial suffixes, network interface override per VP
Dual Bind/Detect Ports (#445):
- Listen on both ports 3000 and 3002 for slicer bind/detect handshake
- Different BambuStudio/OrcaSlicer versions use different ports
- Applies to BindServer (server mode) and SlicerProxyManager (proxy mode)
- Updated Dockerfile, docker-compose.yml, firewall rules in wiki
Also:
- Rewrote VP test suite for new multi-instance architecture (75 tests)
- Rewritten "How it works" section with 3-step workflow explanation
- Updated all 5 locales (en, de, ja, fr, it)
- Updated wiki and website for multi-VP + dual ports
- New multi-VP screenshot
Recent BambuStudio/OrcaSlicer updates require a bind/detect handshake on
port 3000 before connecting via MQTT/FTP. Without this, slicers cannot
discover or connect to the virtual printer in any mode.
- Add BindServer for server modes (immediate/review/print_queue)
- Add TCPProxy for raw TCP forwarding (proxy mode)
- Update Dockerfile (EXPOSE 3000) and docker-compose.yml (bridge port)
- Add 10 new tests for BindServer protocol and integration
Enable Bambu Studio on a remote network to print through BamBuddy
acting as a TLS-terminating proxy for both MQTT and FTP connections.
- Add TLSProxy base class and FTPTLSProxy with PASV response rewriting,
EPSV→PASV translation, PROT P/C tracking, and one-shot data proxies
- Add SlicerProxyManager to coordinate per-slicer MQTT + FTP proxy pairs
- Support additional SAN IPs in certificate generation for proxy mode
- Broadcast SSDP on LAN B so slicers discover the proxy as a printer
- Narrow FTP passive port range to 50000-50100 with retry logic
- Expose proxy ports (8883, 9990, 50000-50100) in Dockerfile
- Document passive port range in docker-compose.yml
Enable Bambu Studio on a remote network to print through BamBuddy
acting as a TLS-terminating proxy for both MQTT and FTP connections.
- Add TLSProxy base class and FTPTLSProxy with PASV response rewriting,
EPSV→PASV translation, PROT P/C tracking, and one-shot data proxies
- Add SlicerProxyManager to coordinate per-slicer MQTT + FTP proxy pairs
- Support additional SAN IPs in certificate generation for proxy mode
- Broadcast SSDP on LAN B so slicers discover the proxy as a printer
- Narrow FTP passive port range to 50000-50100 with retry logic
- Expose proxy ports (8883, 9990, 50000-50100) in Dockerfile
- Document passive port range in docker-compose.yml
- SSDP proxy for cross-network setups: select slicer network interface for automatic printer discovery via SSDP relay
- FTP proxy now listens on privileged port 990 (matching Bambu Studio expectations) instead of 9990
- For systemd: requires `AmbientCapabilities=CAP_NET_BIND_SERVICE` capability
- Automatic directory permission checking at startup with clear error messages for Docker/bare metal
Introduces a new "Proxy Mode" for the Virtual Printer that enables
remote printing from anywhere in the world without VPN, port forwarding,
or Bambu Cloud dependency.
Bambuddy acts as a TLS relay between a remote slicer (Bambu Studio/
OrcaSlicer) and the local Bambu Lab printer:
Remote Slicer → Internet → Bambuddy Server → Local Network → Printer
The slicer connects to Bambuddy using the real printer's serial number
and access code. Bambuddy authenticates and relays all FTP (file transfer)
and MQTT (commands/status) traffic with end-to-end TLS encryption.
- No port forwarding required - printer stays safely on local network
- No VPN needed - connect from coffee shops, hotels, work, anywhere
- No Bambu Cloud dependency - fully self-hosted solution
- End-to-end TLS encryption on FTP (port 9990) and MQTT (port 8883)
- Works with Bambu Studio and OrcaSlicer
- Uses real printer credentials for authentication
- Automatic printer selection from connected printers
- Add SlicerProxyManager class for TLS relay (tcp_proxy.py)
- TLS termination with auto-generated certificates
- Concurrent FTP and MQTT proxy servers
- Connection lifecycle management with proper cleanup
- Extend VirtualPrinterManager with proxy mode support
- New 'proxy' mode alongside archive/review/queue modes
- Target printer selection and credential management
- Add proxy configuration endpoints to settings API
- Add permission checks for proxy endpoints
- Add Proxy Mode card to Virtual Printer settings
- Target printer dropdown for proxy destination
- Real-time proxy status display (ports, target, running state)
- Full i18n support (English, German)
- Add network architecture diagram
- Add proxy mode section to README
- Add comprehensive guide to wiki
- Add prominent feature section to website
- Backend unit tests for SlicerProxyManager
- Backend unit tests for proxy mode configuration
- Frontend tests for proxy mode UI components
Closes#207#170
Proxy mode changes:
- Replace transparent TCP proxy with TLS-terminating proxy
- Slicer connects to Bambuddy cert, Bambuddy connects to printer
- Use real printer's serial number for SSDP and certificate
- This ensures MQTT topic subscriptions match the real printer
The proxy now:
1. Accepts TLS from slicer using Bambuddy's certificate
2. Opens TLS connection to real printer
3. Forwards decrypted data bidirectionally
Also: Complete i18n localization for VirtualPrinterSettings component
MartinNYHC